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Val C Sheffield - One of the best experts on this subject based on the ideXlab platform.

  • BBS4 is required for intraflagellar transport coordination and basal body number in mammalian olfactory cilia.
    Journal of cell science, 2019
    Co-Authors: Cedric R. Uytingco, Val C Sheffield, Darryl Y Nishimura, Corey L. Williams, Chao Xie, Dana T. Shively, Warren W. Green, Kirill Ukhanov, Lian Zhang, Jeffrey R. Martens
    Abstract:

    ABSTRACT Bardet–Beidl syndrome (BBS) manifests from genetic mutations encoding for one or more BBS proteins. BBS4 loss impacts olfactory ciliation and odor detection, yet the cellular mechanisms remain unclear. Here, we report that BBS4 -/− mice exhibit shorter and fewer olfactory sensory neuron (OSN) cilia despite retaining odorant receptor localization. Within BBS4 −/− OSN cilia, we observed asynchronous rates of IFT-A/B particle movements, indicating miscoordination in IFT complex trafficking. Within the OSN dendritic knob, the basal bodies are dynamic, with incorporation of ectopically expressed centrin-2 and γ-tubulin occurring after nascent ciliogenesis. Importantly, BBS4 loss results in the reduction of basal body numbers separate from cilia loss. Adenoviral expression of BBS4 restored OSN cilia lengths and was sufficient to re-establish odor detection, but failed to rescue ciliary and basal body numbers. Our results yield a model for the plurality of BBS4 functions in OSNs that includes intraciliary and periciliary roles that can explain the loss of cilia and penetrance of ciliopathy phenotypes in olfactory neurons.

  • Ciliopathy is differentially distributed in the brain of a Bardet-Biedl syndrome mouse model.
    PloS one, 2014
    Co-Authors: Khristofor Agassandian, Val C Sheffield, Kamal Rahmouni, M. Agassandian, M. Patel, Karina E. Steren, J. Patrick Card
    Abstract:

    Bardet-Biedl syndrome (BBS) is a genetically heterogeneous inherited human disorder displaying a pleotropic phenotype. Many of the symptoms characterized in the human disease have been reproduced in animal models carrying deletions or knock-in mutations of genes causal for the disorder. Thinning of the cerebral cortex, enlargement of the lateral and third ventricles, and structural changes in cilia are among the pathologies documented in these animal models. Ciliopathy is of particular interest in light of recent studies that have implicated primary neuronal cilia (PNC) in neuronal signal transduction. In the present investigation, we tested the hypothesis that areas of the brain responsible for learning and memory formation would differentially exhibit PNC abnormalities in animals carrying a deletion of the BBS4 gene (BBS4-/-). Immunohistochemical localization of adenylyl cyclase-III (ACIII), a marker restricted to PNC, revealed dramatic alterations in PNC morphology and a statistically significant reduction in number of immunopositive cilia in the hippocampus and amygdala of BBS4-/- mice compared to wild type (WT) littermates. Western blot analysis confirmed the decrease of ACIII levels in the hippocampus and amygdala of BBS4-/- mice, and electron microscopy demonstrated pathological alterations of PNC in the hippocampus and amygdala. Importantly, no neuronal loss was found within the subregions of amygdala and hippocampus sampled in BBS4-/- mice and there were no statistically significant alterations of ACIII immunopositive cilia in other areas of the brain not known to contribute to the BBS phenotype. Considered with data documenting a role of cilia in signal transduction these findings support the conclusion that alterations in cilia structure or neurochemical phenotypes may contribute to the cognitive deficits observed in the BBS4-/- mouse mode.

  • The centriolar satellite protein AZI1 interacts with BBS4 and regulates ciliary trafficking of the BBSome.
    PLoS genetics, 2014
    Co-Authors: Xitiz Chamling, Charles Searby, Seongjin Seo, Diane C Slusarski, Gunhee Kim, Val C Sheffield
    Abstract:

    Bardet-Biedl syndrome (BBS) is a well-known ciliopathy with mutations reported in 18 different genes. Most of the protein products of the BBS genes localize at or near the primary cilium and the centrosome. Near the centrosome, BBS proteins interact with centriolar satellite proteins, and the BBSome (a complex of seven BBS proteins) is believed to play a role in transporting ciliary membrane proteins. However, the precise mechanism by which BBSome ciliary trafficking activity is regulated is not fully understood. Here, we show that a centriolar satellite protein, AZI1 (also known as CEP131), interacts with the BBSome and regulates BBSome ciliary trafficking activity. Furthermore, we show that AZI1 interacts with the BBSome through BBS4. AZI1 is not involved in BBSome assembly, but accumulation of the BBSome in cilia is enhanced upon AZI1 depletion. Under conditions in which the BBSome does not normally enter cilia, such as in BBS3 or BBS5 depleted cells, knock down of AZI1 with siRNA restores BBSome trafficking to cilia. Finally, we show that azi1 knockdown in zebrafish embryos results in typical BBS phenotypes including Kupffer's vesicle abnormalities and melanosome transport delay. These findings associate AZI1 with the BBS pathway. Our findings provide further insight into the regulation of BBSome ciliary trafficking and identify AZI1 as a novel BBS candidate gene.

  • Abstract 440: Activation of the Brain Renin-angiotensin System is Critically Involved in the Hypertension Associated With Bbs
    Hypertension, 2013
    Co-Authors: Deng Fu Guo, Val C Sheffield, Donald A Morgan, Kamal Rahmouni
    Abstract:

    Bardet-Biedl syndrome (BBS) is a human autosomal recessive disorder characterized by a pleiotropic of phenotypes including obesity, renal abnormalities, mental retardation, retinal pigmentary dystrophy, polydactyly and hypogenitalism. Hypertension is also common in BBS patients, except BBS2. Consistent with this, we previously demonstrated that obese Bbs2 knockout mice are normotensive while obese BBS4 null mice are hypertensive. However, the underlying molecular mechanisms of hypertension in BBS remain poorly defined. Using BBS mice, we tested whether abnormalities in the brain renin-angiotensin system (RAS) may contribute to the increased arterial pressure in BBS. Using real time PCR, we found that mRNA expression of RAS components were differentially altered in Bbs2 -/- and BBS4 -/- mice. Compared to wild type controls, the hypertensive BBS4 -/- mice exhibited significantly (P -/- mice, the expression of renin, AT1aR and AT1bR were significantly (P -/- mice. Consistent with our previous findings, radiotelemetric mean arterial pressure was significantly (P -/- mice (114±3 mmHg) relative to wild type controls (101±1 mmHg). Moreover, BBS4 -/- mice exhibited an exaggerated decrease in arterial pressure in response to intracerebroventricular (ICV) administration of losartan (AT1 receptor antagonist). Indeed, ICV losartan (10 g) decreased mean arterial pressure by 24±7 mmHg in BBS4 -/- mice vs. 5±10 mmHg in wild type controls (P

  • BBS mutations modify phenotypic expression of CEP290-related ciliopathies
    Human molecular genetics, 2013
    Co-Authors: Yan Zhang, Kevin Bugge, Qihong Zhang, Charles Searby, Edwin M. Stone, Seongjin Seo, Arlene V. Drack, Sajag Bhattarai, Val C Sheffield
    Abstract:

    Ciliopathies are a group of heterogeneous disorders associated with ciliary dysfunction. Diseases in this group display considerable phenotypic variation within individual syndromes and overlapping phenotypes among clinically distinct disorders. Particularly, mutations in CEP290 cause phenotypically diverse ciliopathies ranging from isolated retinal degeneration, nephronophthisis and Joubert syndrome, to the neonatal lethal Meckel–Gruber syndrome. However, the underlying mechanisms of the variable expressivity in ciliopathies are not well understood. Here, we show that components of the BBSome, a protein complex composed of seven Bardet–Biedl syndrome (BBS) proteins, physically and genetically interact with CEP290 and modulate the expression of disease phenotypes caused by CEP290 mutations. The BBSome binds to the N-terminal region of CEP290 through BBS4 and co-localizes with CEP290 to the transition zone (TZ) of primary cilia and centriolar satellites in ciliated cells, as well as to the connecting cilium in photoreceptor cells. Although CEP290 still localizes to the TZ and connecting cilium in BBSome-depleted cells, its localization to centriolar satellites is disrupted and CEP290 appears to disperse throughout the cytoplasm in BBSome-depleted cells. Genetic interactions were tested using Cep290rd16- and BBS4-null mutant mouse lines. Additional loss of BBS4 alleles in Cep290rd16/rd16 mice results in increased body weight and accelerated photoreceptor degeneration compared with mice without BBS4 mutations. Furthermore, double-heterozygous mice (Cep290+/rd16;BBS4+/−) have increased body weight compared with single-heterozygous animals. Our data indicate that genetic interactions between BBSome components and CEP290 could underlie the variable expression and overlapping phenotypes of ciliopathies caused by CEP290 mutations.

Philip L. Beales - One of the best experts on this subject based on the ideXlab platform.

  • Altered hematopoietic system and self-tolerance in Bardet-Biedl Syndrome
    2020
    Co-Authors: Oksana Tsyklauri, Philip L. Beales, Veronika Niederlova, Martina Huranova, Avishek Prasai, Elizabeth Forsythe, Ales Drobek, Kathryn Sparks, Zdenek Trachtulec, Ondrej Stepanek
    Abstract:

    Abstract Bardet-Biedl Syndrome (BBS) is a pleiotropic genetic disease caused by dysfunction of primary cilia. The immune system of patients with BBS or another ciliopathy has not been investigated, most likely because hematopoietic cells do not form cilia. However, there are multiple indications that the impairment of the processes typically associated with cilia might influence the hematopoietic compartment and immunity. In this study, we analyzed clinical data of BBS patients as well as a corresponding mouse model of BBS4 deficiency. We uncovered that BBS patients have higher incidence of certain autoimmune diseases. BBS patients and animal models have elevated white blood cell levels and altered red blood cell and platelet compartments. Moreover, we observed that BBS4 deficiency alters the development and homeostasis of B cells in mice. Some of the hematopoietic system alterations were caused by the BBS-induced obesity. Overall, our study reveals a connection between a ciliopathy and the alterations of the immune system and the hematopoietic compartment.

  • Bardet Biedl syndrome proteins 1 and 3 regulate the ciliary trafficking of polycystic kidney disease 1 protein
    Human molecular genetics, 2014
    Co-Authors: Kaitlin Driscoll, Philip L. Beales, Gang Yao, Anas Raed, Jing Zhou
    Abstract:

    Bardet-Biedl syndrome (BBS) and autosomal dominant polycystic kidney disease (ADPKD) are two genetically distinct ciliopathies but share common phenotypes such as renal cysts. Seven BBS proteins form a complex called the BBSome which is localized at the basal body or ciliary axoneme and regulates the ciliary entry or flagellar exit of several signaling molecules. Here, we demonstrate that, unlike the seven-span somatostatin receptor 3 or the leptin receptor that interacts with all subunits of the BBSome, the ADPKD protein polycystin-1 (PC1) interacts with BBS1, BBS4, BBS5 and BBS8, four of the seven components of the BBSome. Only depletion or mutation of BBS1, but not depletion of BBS5 and BBS8, or knockout of BBS4, impairs ciliary trafficking of PC1 in kidney epithelial cells. Depletion of these BBS proteins affects neither the ciliary length nor the plasma membrane targeting of PC1. Expression of a pathogenic BBS3/Arl6 mutant (T31R) that locks Arl6 in the GDP form leads to stunted cilia and inhibition of PC1 on primary cilia. We propose that the 11-span membrane protein PC1 is a BBSome cargo and that the components of the BBSome may possess subunit-specific functions. Moreover, physical interactions between the BBS and ADPKD proteins may underline the overlapping renal phenotypes in these two diseases.

  • Bardet–Biedl syndrome proteins control the cilia length through regulation of actin polymerization
    Human molecular genetics, 2013
    Co-Authors: Victor Hernandez-hernandez, Helen May-simera, Priyanka Pravincumar, Anna Diaz-font, Dagan Jenkins, Martin M. Knight, Philip L. Beales
    Abstract:

    Primary cilia are cellular appendages important for signal transduction and sensing the environment. Bardet-Biedl syndrome proteins form a complex that is important for several cytoskeleton-related processes such as ciliogenesis, cell migration and division. However, the mechanisms by which BBS proteins may regulate the cytoskeleton remain unclear. We discovered that BBS4 and Bbs6 deficient renal medullary cells display a characteristic behaviour comprising poor migration, adhesion and division with an inability to form lamellipodial and filopodial extensions. Moreover, fewer mutant cells were ciliated (48% ± 6 for wild-type cells vs 23% ± 7 for BBS4 null cells; P-value 

  • Mutation analysis in Bardet–Biedl syndrome by DNA pooling and massively parallel resequencing in 105 individuals
    Human Genetics, 2011
    Co-Authors: Sabine Janssen, Philip L. Beales, Gokul Ramaswami, Erica E. Davis, Toby Hurd, Rannar Airik, Jennifer M. Kasanuki, Lauren Kraak, Susan J. Allen, Nicholas Katsanis
    Abstract:

    Bardet–Biedl syndrome (BBS) is a rare, primarily autosomal-recessive ciliopathy. The phenotype of this pleiotropic disease includes retinitis pigmentosa, postaxial polydactyly, truncal obesity, learning disabilities, hypogonadism and renal anomalies, among others. To date, mutations in 15 genes ( BBS1 – BBS14 , SDCCAG8 ) have been described to cause BBS. The broad genetic locus heterogeneity renders mutation screening time-consuming and expensive. We applied a strategy of DNA pooling and subsequent massively parallel resequencing (MPR) to screen individuals affected with BBS from 105 families for mutations in 12 known BBS genes. DNA was pooled in 5 pools of 21 individuals each. All 132 coding exons of BBS1 – BBS12 were amplified by conventional PCR. Subsequent MPR was performed on an Illumina Genome Analyzer II™ platform. Following mutation identification, the mutation carrier was assigned by CEL I endonuclease heteroduplex screening and confirmed by Sanger sequencing. In 29 out of 105 individuals (28%), both mutated alleles were identified in 10 different BBS genes. A total of 35 different disease-causing mutations were confirmed, of which 18 mutations were novel. In 12 additional families, a total of 12 different single heterozygous changes of uncertain pathogenicity were found. Thus, DNA pooling combined with MPR offers a valuable strategy for mutation analysis of large patient cohorts, especially in genetically heterogeneous diseases such as BBS.

  • Patterns of expression of Bardet-Biedl syndrome proteins in the mammalian cochlea suggest noncentrosomal functions.
    The Journal of comparative neurology, 2009
    Co-Authors: Helen May-simera, Alison Ross, Philip L. Beales, Suzanne Rix, Andrew Forge, Daniel J. Jagger
    Abstract:

    Bardet-Biedl syndrome is a heterogeneous disorder causing a spectrum of symptoms, including visual impairment, kidney disease, and hearing impairment. Evidence suggests that BBS gene mutations cause defective ciliogenesis and/or cilium dysfunction. Cochlear development is affected by BBS gene deletion, and adult Bbs6(-/-) and BBS4(-/-) mice are hearing impaired. This study addresses BBS protein expression in the rodent cochlea, to gain a better understanding of its function in vivo. As predicted by in vitro studies, Bbs6 immunofluorescence was localized to the basal bodies of supporting cells and sensory hair cells prior to the onset of hearing. In adult tissue, Bbs6 expression persisted in afferent neurons, including within the dendrites that innervate hair cells, implicating Bbs6 in a sensory neuronal function. Bbs2, which interacts with Bbs6, was also localized to hair cell basal bodies and stereociliary bundles. Additionally, Bbs2 was expressed in supporting cells at their intercellular boundaries, in a spatiotemporal pattern mirroring the development of the microtubule network. BBS4 localized to cilia and developing cytoplasmic microtubule arrays. Pcm-1, a microtubular protein that interacts with BBS4 in vitro, showed a comparable expression. Depolymerization of microtubules in slice preparations of the living cochlea resulted in BBS4 and Pcm-1 mislocalization. Pcm-1 was also mislocalized in BBS4(-/-) mice. This suggests that BBS4/Pcm-1 interactions may be important in microtubule-dependent cytoplasmic trafficking in vivo. In summary, our findings indicate that BBS proteins adopt a range of cellular distributions in vivo, not restricted to the centrosome or cilium, and so broaden the possible underlying pathomechanisms of the disease. J. Comp. Neurol. 514:174-188, 2009. (C) 2009 Wiley-Liss, Inc.

Edwin M. Stone - One of the best experts on this subject based on the ideXlab platform.

  • BBS mutations modify phenotypic expression of CEP290-related ciliopathies
    Human molecular genetics, 2013
    Co-Authors: Yan Zhang, Kevin Bugge, Qihong Zhang, Charles Searby, Edwin M. Stone, Seongjin Seo, Arlene V. Drack, Sajag Bhattarai, Val C Sheffield
    Abstract:

    Ciliopathies are a group of heterogeneous disorders associated with ciliary dysfunction. Diseases in this group display considerable phenotypic variation within individual syndromes and overlapping phenotypes among clinically distinct disorders. Particularly, mutations in CEP290 cause phenotypically diverse ciliopathies ranging from isolated retinal degeneration, nephronophthisis and Joubert syndrome, to the neonatal lethal Meckel–Gruber syndrome. However, the underlying mechanisms of the variable expressivity in ciliopathies are not well understood. Here, we show that components of the BBSome, a protein complex composed of seven Bardet–Biedl syndrome (BBS) proteins, physically and genetically interact with CEP290 and modulate the expression of disease phenotypes caused by CEP290 mutations. The BBSome binds to the N-terminal region of CEP290 through BBS4 and co-localizes with CEP290 to the transition zone (TZ) of primary cilia and centriolar satellites in ciliated cells, as well as to the connecting cilium in photoreceptor cells. Although CEP290 still localizes to the TZ and connecting cilium in BBSome-depleted cells, its localization to centriolar satellites is disrupted and CEP290 appears to disperse throughout the cytoplasm in BBSome-depleted cells. Genetic interactions were tested using Cep290rd16- and BBS4-null mutant mouse lines. Additional loss of BBS4 alleles in Cep290rd16/rd16 mice results in increased body weight and accelerated photoreceptor degeneration compared with mice without BBS4 mutations. Furthermore, double-heterozygous mice (Cep290+/rd16;BBS4+/−) have increased body weight compared with single-heterozygous animals. Our data indicate that genetic interactions between BBSome components and CEP290 could underlie the variable expression and overlapping phenotypes of ciliopathies caused by CEP290 mutations.

  • bbs7 is required for bbsome formation and its absence in mice results in bardet biedl syndrome phenotypes and selective abnormalities in membrane protein trafficking
    Journal of Cell Science, 2013
    Co-Authors: Qihong Zhang, Jianqiang Shao, Calvin S Carter, Kevin Bugge, Ruth E. Swiderski, Darryl Nishimura, Charles Searby, Timothy W Vogel, Edwin M. Stone, Val C Sheffield
    Abstract:

    Bardet-Biedl Syndrome (BBS) is a pleiotropic and genetically heterozygous disorder caused independently by numerous genes (BBS1–BBS17). Seven highly conserved BBS proteins (BBS1, 2, 4, 5, 7, 8 and 9) form a complex known as the BBSome, which functions in ciliary membrane biogenesis. BBS7 is both a unique subunit of the BBSome and displays direct physical interaction with a second BBS complex, the BBS chaperonin complex. To examine the in vivo function of BBS7, we generated Bbs7 knockout mice. Bbs7−/− mice show similar phenotypes to other BBS gene mutant mice including retinal degeneration, obesity, ventriculomegaly and male infertility characterized by abnormal spermatozoa flagellar axonemes. Using tissues from Bbs7−/− mice, we show that BBS7 is required for BBSome formation, and that BBS7 and BBS2 depend on each other for protein stability. Although the BBSome serves as a coat complex for ciliary membrane proteins, BBS7 is not required for the localization of ciliary membrane proteins polycystin-1, polycystin-2, or bitter taste receptors, but absence of BBS7 leads to abnormal accumulation of the dopamine D1 receptor to the ciliary membrane, indicating that BBS7 is involved in specific membrane protein localization to cilia.

  • Intrinsic Protein-Protein Interaction-mediated and Chaperonin-assisted Sequential Assembly of Stable Bardet-Biedl Syndrome Protein Complex, the BBSome
    The Journal of biological chemistry, 2012
    Co-Authors: Qihong Zhang, Edwin M. Stone, Seongjing Seo, Val C Sheffield
    Abstract:

    The pleiotropic features of obesity, retinal degeneration, polydactyly, kidney abnormalities, cognitive impairment, hypertension, and diabetes found in Bardet-Biedl syndrome (BBS) make this disorder an important model disorder for identifying molecular mechanisms involved in common human diseases. To date, 16 BBS genes have been reported, seven of which (BBS1, 2, 4, 5, 7, 8, and 9) code for proteins that form a complex known as the BBSome. The function of the BBSome involves ciliary membrane biogenesis. Three additional BBS genes (BBS6, BBS10, and BBS12) have homology to type II chaperonins and interact with CCT/TRiC proteins and BBS7 to form a complex termed the BBS-chaperonin complex. This complex is required for BBSome assembly. Little is known about the process and the regulation of BBSome formation. We utilized point mutations and null alleles of BBS proteins to disrupt assembly of the BBSome leading to the accumulation of BBSome assembly intermediates. By characterizing BBSome assembly intermediates, we show that the BBS-chaperonin complex plays a role in BBS7 stability. BBS7 interacts with BBS2 and becomes part of a BBS7-BBS2-BBS9 assembly intermediate referred to as the BBSome core complex because it forms the core of the BBSome. BBS1, BBS5, BBS8, and finally BBS4 are added to the BBSome core to form the complete BBSome.

  • bardet biedl syndrome 3 bbs3 knockout mouse model reveals common bbs associated phenotypes and bbs3 unique phenotypes
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Qihong Zhang, Kevin Bugge, Charles Searby, Timothy W Vogel, Edwin M. Stone, Donald A Morgan, Darryl Y Nishimura, Seongjin Seo, Kamal Rahmouni, Val C Sheffield
    Abstract:

    Bardet-Biedl syndrome (BBS) is a heterogeneous disorder characterized by obesity, retinopathy, polydactyly, and congenital anomalies. The incidence of hypertension and diabetes are also increased in BBS patients. Mutation of 16 genes independently causes BBS, and seven BBS proteins form the BBSome that promotes ciliary membrane elongation. BBS3 (ARL6), an ADP ribosylation factor-like small GTPase, is not part of the BBSome complex. The in vivo function of BBS3 is largely unknown. Here we developed a Bbs3 knockout model and demonstrate that Bbs3−/− mice develop BBS-associated phenotypes, including retinal degeneration, male infertility, and increased body fat. Interestingly, Bbs3−/− mice develop some unique phenotypes not seen in other BBS knockout models: no overt obesity, severe hydrocephalus, and elevated blood pressure (shared by some but not all BBS gene knockout mice). We found that endogenous BBS3 and the BBSome physically interact and depend on each other for their ciliary localization. This finding explains the phenotypic similarity between Bbs3−/− mice and BBSome subunit knockout mice. Loss of Bbs3 does not affect BBSome formation but disrupts normal localization of melanin concentrating hormone receptor 1 to ciliary membranes and affects retrograde transport of Smoothened inside cilia. We also show that the endogenous BBSome and BBS3 associate with membranes and the membrane association of the BBSome and BBS3 are not interdependent. Differences between BBS mouse models suggest nonoverlapping functions to individual BBS protein.

  • Gene expression analysis of photoreceptor cell loss in BBS4-knockout mice reveals an early stress gene response and photoreceptor cell damage.
    Investigative ophthalmology & visual science, 2007
    Co-Authors: Ruth E. Swiderski, Edwin M. Stone, Darryl Y Nishimura, Robert F Mullins, Marissa A. Olvera, Jean L. Ross, Jian Huang, Val C Sheffield
    Abstract:

    PURPOSE. To identify and characterize gene expression changes associated with photoreceptor cell loss in a BBS4-knockout mouse model of retinal degeneration. METHODS. Differential gene expression in the eyes of 5-monthold BBS4 / mice undergoing retinal degeneration were analyzed using gene microarrays (Affymetrix, Santa Clara, CA). Elevated ocular transcripts were confirmed by Northern blotting of RNA from BBS4 / and three additional mouse models of Bardet-Biedl Syndrome (BBS). TUNEL assays and transmission electron microscopy were used to study cell death and photoreceptor morphology in these mice. RESULTS. Three hundred fifty-four probes were differentially expressed in BBS4 / eyes compared with controls using a twofold cutoff. Numerous vision-related transcripts decreased because of photoreceptor cell loss. Increased expression of the stress response genes Edn2, Lcn2, Serpina3n, and Socs3 was noted at 5 months of age and as early as postnatal week 4 in the eyes of four BBS mouse model strains. A burst of apoptotic activity in the photoreceptor outer nuclear layer at postnatal week 2 and highly disorganized outer segments by postnatal weeks 4 to 6 was observed in all four strains. CONCLUSIONS. The specific loss of photoreceptors in BBS4 / mice allows us to identify a set of genes that are preferentially expressed in photoreceptors compared with other cell types found in the eye and is a valuable resource in the continuing search for genes involved in retinal disease. The molecular and morphologic changes observed in young BBS animal model eyes implies that BBS proteins play a critical, early role in establishing the correct structure and function of photoreceptors. (Invest Ophthalmol Vis Sci. 2007;48: 3329‐3340) DOI:10.1167/iovs.06-1477

Nicholas Katsanis - One of the best experts on this subject based on the ideXlab platform.

  • BBS4 regulates the expression and secretion of FSTL1, a protein that participates in ciliogenesis and the differentiation of 3T3-L1.
    Scientific reports, 2017
    Co-Authors: Victoria Prieto-echagüe, Nicholas Katsanis, Norann A Zaghloul, Sukanya Lodh, Laura Colman, Natalia Bobba, Leonardo Santos, Carlos Escande, Jose L. Badano
    Abstract:

    Bardet-Biedl syndrome is a model ciliopathy. Although the characterization of BBS proteins has evidenced their involvement in cilia, extraciliary functions for some of these proteins are also being recognized. Importantly, understanding both cilia and cilia-independent functions of the BBS proteins is key to fully dissect the cellular basis of the syndrome. Here we characterize a functional interaction between BBS4 and the secreted protein FSTL1, a protein linked to adipogenesis and inflammation among other functions. We show that BBS4 and cilia regulate FSTL1 mRNA levels, but BBS4 also modulates FSTL1 secretion. Moreover, we show that FSTL1 is a novel regulator of ciliogenesis thus underscoring a regulatory loop between FSTL1 and cilia. Finally, our data indicate that BBS4, cilia and FSTL1 are coordinated during the differentiation of 3T3-L1 cells and that FSTL1 plays a role in this process, at least in part, by modulating ciliogenesis. Therefore, our findings are relevant to fully understand the development of BBS-associated phenotypes such as obesity.

  • Mutation analysis in Bardet–Biedl syndrome by DNA pooling and massively parallel resequencing in 105 individuals
    Human Genetics, 2011
    Co-Authors: Sabine Janssen, Philip L. Beales, Gokul Ramaswami, Erica E. Davis, Toby Hurd, Rannar Airik, Jennifer M. Kasanuki, Lauren Kraak, Susan J. Allen, Nicholas Katsanis
    Abstract:

    Bardet–Biedl syndrome (BBS) is a rare, primarily autosomal-recessive ciliopathy. The phenotype of this pleiotropic disease includes retinitis pigmentosa, postaxial polydactyly, truncal obesity, learning disabilities, hypogonadism and renal anomalies, among others. To date, mutations in 15 genes ( BBS1 – BBS14 , SDCCAG8 ) have been described to cause BBS. The broad genetic locus heterogeneity renders mutation screening time-consuming and expensive. We applied a strategy of DNA pooling and subsequent massively parallel resequencing (MPR) to screen individuals affected with BBS from 105 families for mutations in 12 known BBS genes. DNA was pooled in 5 pools of 21 individuals each. All 132 coding exons of BBS1 – BBS12 were amplified by conventional PCR. Subsequent MPR was performed on an Illumina Genome Analyzer II™ platform. Following mutation identification, the mutation carrier was assigned by CEL I endonuclease heteroduplex screening and confirmed by Sanger sequencing. In 29 out of 105 individuals (28%), both mutated alleles were identified in 10 different BBS genes. A total of 35 different disease-causing mutations were confirmed, of which 18 mutations were novel. In 12 additional families, a total of 12 different single heterozygous changes of uncertain pathogenicity were found. Thus, DNA pooling combined with MPR offers a valuable strategy for mutation analysis of large patient cohorts, especially in genetically heterogeneous diseases such as BBS.

  • recruitment of pcm1 to the centrosome by the cooperative action of disc1 and BBS4 a candidate for psychiatric illnesses
    Archives of General Psychiatry, 2008
    Co-Authors: Atsushi Kamiya, Kenichiro Kubo, Caitlin Engelhard, Koko Ishizuka, Ann E Pulver, Sachiko Tsukita, Kazunori Nakajima, Nicola G Cascella, Akiharu Kubo, Nicholas Katsanis
    Abstract:

    Context A role for the centrosome has been suggested in the pathology of major mental illnesses, especially schizophrenia (SZ). Objectives To show that pericentriolar material 1 protein (PCM1) forms a complex at the centrosome with disrupted-in-schizophrenia 1 (DISC1) and Bardet-Biedl syndrome 4 protein (BBS4), which provides a crucial pathway for cortical development associated with the pathology of SZ. To identify mutations in the PCM1 gene in an SZ population. Design Interaction of DISC1, PCM1, and BBS proteins was assessed by immunofluorescent staining and coimmunoprecipitation. Effects of PCM1, DISC1, and BBS on centrosomal functions and corticogenesis in vivo were tested by RNA interference. The PCM1 gene was examined by sequencing 39 exons and flanking splice sites. Setting Probands and controls were from the collection of one of us (A.E.P.). Patients Thirty-two probands with SZ from families that had excess allele sharing among affected individuals at 8p22 and 219 white controls. Main Outcome Measures Protein interaction and recruitment at the centrosome in cells; neuronal migration in the cerebral cortex; and variant discovery in PCM1 in patients with SZ. Results PCM1 forms a complex with DISC1 and BBS4 through discrete binding domains in each protein. DISC1 and BBS4 are required for targeting PCM1 and other cargo proteins, such as ninein, to the centrosome in a synergistic manner. In the developing cerebral cortex, suppression of PCM1 leads to neuronal migration defects, which are phenocopied by the suppression of either DISC1 or BBS4 and are exacerbated by the concomitant suppression of both. Furthermore, a nonsense mutation that segregates with SZ spectrum psychosis was found in 1 family. Conclusions Our data further support for the role of centrosomal proteins in cortical development and suggest that perturbation of centrosomal function contributes to the development of mental diseases, including SZ.

  • impaired photoreceptor protein transport and synaptic transmission in a mouse model of bardet biedl syndrome
    Vision Research, 2007
    Co-Authors: Muhammad M Abdelbarr, Kristen Sykoudis, Sara Andrabi, E R Eichers, John H. Wilson, Nicholas Katsanis, Mark E. Pennesi, James R Lupski, S. M. Wu
    Abstract:

    Abstract Bardet–Biedl syndrome (BBS) is an oligogenic syndrome whose manifestations include retinal degeneration, renal abnormalities, obesity and polydactylia. Evidence suggests that the main etiopathophysiology of this syndrome is impaired intraflagellar transport (IFT). In this study, we study the BBS4-null mouse and investigate photoreceptor structure and function after loss of this gene. We find that BBS4-null mice have defects in the transport of phototransduction proteins from the inner segments to the outer segments, before signs of cell death. Additionally, we show defects in synaptic transmission from the photoreceptors to secondary neurons of the visual system, demonstrating multiple functions for BBS4 in photoreceptors.

  • Loss of BBS proteins causes anosmia in humans and defects in olfactory cilia structure and function in the mouse
    Nature genetics, 2004
    Co-Authors: Heather M. Kulaga, E R Eichers, Bethan E. Hoskins, Jose L. Badano, Carmen C Leitch, James R Lupski, Philip L. Beales, Alysa Lesemann, Randall R. Reed, Nicholas Katsanis
    Abstract:

    Defects in cilia are associated with several human disorders, including Kartagener syndrome, polycystic kidney disease, nephronophthisis and hydrocephalus. We proposed that the pleiotropic phenotype of Bardet-Biedl syndrome (BBS), which encompasses retinal degeneration, truncal obesity, renal and limb malformations and developmental delay, is due to dysfunction of basal bodies and cilia. Here we show that individuals with BBS have partial or complete anosmia. To test whether this phenotype is caused by ciliary defects of olfactory sensory neurons, we examined mice with deletions of Bbs1 or BBS4. Loss of function of either BBS protein affected the olfactory, but not the respiratory, epithelium, causing severe reduction of the ciliated border, disorganization of the dendritic microtubule network and trapping of olfactory ciliary proteins in dendrites and cell bodies. Our data indicate that BBS proteins have a role in the microtubule organization of mammalian ciliated cells and that anosmia might be a useful determinant of other pleiotropic disorders with a suspected ciliary involvement.

Charles Searby - One of the best experts on this subject based on the ideXlab platform.

  • The centriolar satellite protein AZI1 interacts with BBS4 and regulates ciliary trafficking of the BBSome.
    PLoS genetics, 2014
    Co-Authors: Xitiz Chamling, Charles Searby, Seongjin Seo, Diane C Slusarski, Gunhee Kim, Val C Sheffield
    Abstract:

    Bardet-Biedl syndrome (BBS) is a well-known ciliopathy with mutations reported in 18 different genes. Most of the protein products of the BBS genes localize at or near the primary cilium and the centrosome. Near the centrosome, BBS proteins interact with centriolar satellite proteins, and the BBSome (a complex of seven BBS proteins) is believed to play a role in transporting ciliary membrane proteins. However, the precise mechanism by which BBSome ciliary trafficking activity is regulated is not fully understood. Here, we show that a centriolar satellite protein, AZI1 (also known as CEP131), interacts with the BBSome and regulates BBSome ciliary trafficking activity. Furthermore, we show that AZI1 interacts with the BBSome through BBS4. AZI1 is not involved in BBSome assembly, but accumulation of the BBSome in cilia is enhanced upon AZI1 depletion. Under conditions in which the BBSome does not normally enter cilia, such as in BBS3 or BBS5 depleted cells, knock down of AZI1 with siRNA restores BBSome trafficking to cilia. Finally, we show that azi1 knockdown in zebrafish embryos results in typical BBS phenotypes including Kupffer's vesicle abnormalities and melanosome transport delay. These findings associate AZI1 with the BBS pathway. Our findings provide further insight into the regulation of BBSome ciliary trafficking and identify AZI1 as a novel BBS candidate gene.

  • BBS mutations modify phenotypic expression of CEP290-related ciliopathies
    Human molecular genetics, 2013
    Co-Authors: Yan Zhang, Kevin Bugge, Qihong Zhang, Charles Searby, Edwin M. Stone, Seongjin Seo, Arlene V. Drack, Sajag Bhattarai, Val C Sheffield
    Abstract:

    Ciliopathies are a group of heterogeneous disorders associated with ciliary dysfunction. Diseases in this group display considerable phenotypic variation within individual syndromes and overlapping phenotypes among clinically distinct disorders. Particularly, mutations in CEP290 cause phenotypically diverse ciliopathies ranging from isolated retinal degeneration, nephronophthisis and Joubert syndrome, to the neonatal lethal Meckel–Gruber syndrome. However, the underlying mechanisms of the variable expressivity in ciliopathies are not well understood. Here, we show that components of the BBSome, a protein complex composed of seven Bardet–Biedl syndrome (BBS) proteins, physically and genetically interact with CEP290 and modulate the expression of disease phenotypes caused by CEP290 mutations. The BBSome binds to the N-terminal region of CEP290 through BBS4 and co-localizes with CEP290 to the transition zone (TZ) of primary cilia and centriolar satellites in ciliated cells, as well as to the connecting cilium in photoreceptor cells. Although CEP290 still localizes to the TZ and connecting cilium in BBSome-depleted cells, its localization to centriolar satellites is disrupted and CEP290 appears to disperse throughout the cytoplasm in BBSome-depleted cells. Genetic interactions were tested using Cep290rd16- and BBS4-null mutant mouse lines. Additional loss of BBS4 alleles in Cep290rd16/rd16 mice results in increased body weight and accelerated photoreceptor degeneration compared with mice without BBS4 mutations. Furthermore, double-heterozygous mice (Cep290+/rd16;BBS4+/−) have increased body weight compared with single-heterozygous animals. Our data indicate that genetic interactions between BBSome components and CEP290 could underlie the variable expression and overlapping phenotypes of ciliopathies caused by CEP290 mutations.

  • bbs7 is required for bbsome formation and its absence in mice results in bardet biedl syndrome phenotypes and selective abnormalities in membrane protein trafficking
    Journal of Cell Science, 2013
    Co-Authors: Qihong Zhang, Jianqiang Shao, Calvin S Carter, Kevin Bugge, Ruth E. Swiderski, Darryl Nishimura, Charles Searby, Timothy W Vogel, Edwin M. Stone, Val C Sheffield
    Abstract:

    Bardet-Biedl Syndrome (BBS) is a pleiotropic and genetically heterozygous disorder caused independently by numerous genes (BBS1–BBS17). Seven highly conserved BBS proteins (BBS1, 2, 4, 5, 7, 8 and 9) form a complex known as the BBSome, which functions in ciliary membrane biogenesis. BBS7 is both a unique subunit of the BBSome and displays direct physical interaction with a second BBS complex, the BBS chaperonin complex. To examine the in vivo function of BBS7, we generated Bbs7 knockout mice. Bbs7−/− mice show similar phenotypes to other BBS gene mutant mice including retinal degeneration, obesity, ventriculomegaly and male infertility characterized by abnormal spermatozoa flagellar axonemes. Using tissues from Bbs7−/− mice, we show that BBS7 is required for BBSome formation, and that BBS7 and BBS2 depend on each other for protein stability. Although the BBSome serves as a coat complex for ciliary membrane proteins, BBS7 is not required for the localization of ciliary membrane proteins polycystin-1, polycystin-2, or bitter taste receptors, but absence of BBS7 leads to abnormal accumulation of the dopamine D1 receptor to the ciliary membrane, indicating that BBS7 is involved in specific membrane protein localization to cilia.

  • Ectopic Expression of Human BBS4 Can Rescue Bardet-Biedl Syndrome Phenotypes in BBS4 Null Mice
    PloS one, 2013
    Co-Authors: Xitiz Chamling, Kevin Bugge, Charles Searby, Seongjin Seo, Kamal Rahmouni, Deng F. Guo, Arlene V. Drack, Val C Sheffield
    Abstract:

    Bardet-Biedl syndrome (BBS) is a genetically heterogeneous autosomal recessive disorder characterized by obesity, retinal degeneration, polydactyly, hypogenitalism and renal defects. Recent findings have associated the etiology of the disease with cilia, and BBS proteins have been implicated in trafficking various ciliary cargo proteins. To date, 17 different genes have been reported for BBS among which BBS1 is the most common cause of the disease followed by BBS10, and BBS4. A murine model of BBS4 is known to phenocopy most of the human BBS phenotypes, and it is being used as a BBS disease model. To better understand the in vivo localization, cellular function, and interaction of BBS4 with other proteins, we generated a transgenic BBS4 mouse expressing the human BBS4 gene under control of the beta actin promoter. The transgene is expressed in various tissues including brain, eye, testis, heart, kidney, and adipose tissue. These mice were further bred to express the transgene in BBS4 null mice, and their phenotype was characterized. Here we report that despite tissue specific variable expression of the transgene, human BBS4 was able to complement the deficiency of BBS4 and rescue all the BBS phenotypes in the BBS4 null mice. These results provide an encouraging prospective for gene therapy for BBS related phenotypes and potentially for other ciliopathies.

  • bardet biedl syndrome 3 bbs3 knockout mouse model reveals common bbs associated phenotypes and bbs3 unique phenotypes
    Proceedings of the National Academy of Sciences of the United States of America, 2011
    Co-Authors: Qihong Zhang, Kevin Bugge, Charles Searby, Timothy W Vogel, Edwin M. Stone, Donald A Morgan, Darryl Y Nishimura, Seongjin Seo, Kamal Rahmouni, Val C Sheffield
    Abstract:

    Bardet-Biedl syndrome (BBS) is a heterogeneous disorder characterized by obesity, retinopathy, polydactyly, and congenital anomalies. The incidence of hypertension and diabetes are also increased in BBS patients. Mutation of 16 genes independently causes BBS, and seven BBS proteins form the BBSome that promotes ciliary membrane elongation. BBS3 (ARL6), an ADP ribosylation factor-like small GTPase, is not part of the BBSome complex. The in vivo function of BBS3 is largely unknown. Here we developed a Bbs3 knockout model and demonstrate that Bbs3−/− mice develop BBS-associated phenotypes, including retinal degeneration, male infertility, and increased body fat. Interestingly, Bbs3−/− mice develop some unique phenotypes not seen in other BBS knockout models: no overt obesity, severe hydrocephalus, and elevated blood pressure (shared by some but not all BBS gene knockout mice). We found that endogenous BBS3 and the BBSome physically interact and depend on each other for their ciliary localization. This finding explains the phenotypic similarity between Bbs3−/− mice and BBSome subunit knockout mice. Loss of Bbs3 does not affect BBSome formation but disrupts normal localization of melanin concentrating hormone receptor 1 to ciliary membranes and affects retrograde transport of Smoothened inside cilia. We also show that the endogenous BBSome and BBS3 associate with membranes and the membrane association of the BBSome and BBS3 are not interdependent. Differences between BBS mouse models suggest nonoverlapping functions to individual BBS protein.