The Experts below are selected from a list of 198 Experts worldwide ranked by ideXlab platform
William A. Gahl - One of the best experts on this subject based on the ideXlab platform.
-
Diagnosis of Chediak Higashi disease in a 67-year old woman.
American journal of medical genetics. Part A, 2020Co-Authors: David S. Yarnell, Konrad Krzewski, Joseph C. Roney, Cláudia Teixeira, Maria Inês Freitas, Ana Cipriano, Pedro Leuschner, Joshi Stephen, Heidi Dorward, William A. GahlAbstract:Chediak-Higashi disease is a rare disease caused by bi-allelic mutations in the Lysosomal Trafficking Regulator gene, LYST. Individuals typically present in early childhood with partial oculocutaneous albinism, a bleeding diathesis, recurrent infections secondary to immune dysfunction, and risk of developing hemophagocytic lymphohistiocytosis (HLH). Without intervention, mortality is high in the first decade of life. However, some individuals with milder phenotypes have attenuated hematologic and immunologic presentations, and lower risk of HLH. Both classic and milder phenotypes develop progressive neurodegeneration in early adulthood. Here we present a remarkable patient diagnosed with Chediak-Higashi disease at age 67, many decades after the diagnosis is usually established. Diagnosis was suspected by observing the pathognomonic granules within leukocytes, and confirmed by identification of bi-allelic mutations in LYST, reduced LYST mRNA expression, enlarged lysosomes within fibroblasts, and decreased NK cell lytic activity. This case further expands the phenotype of Chediak-Higashi disease and highlights the need for increased awareness. Individuals with milder phenotypes may escape early diagnosis, but identification is important for close monitoring of potential complications, and to further our understanding of the function of LYST.
-
Generation and characterization of four Chediak-Higashi Syndrome (CHS) induced pluripotent stem cell (iPSC) lines.
Stem cell research, 2020Co-Authors: Jenny Serra-vinardell, William A. Gahl, Maxwell B. Sandler, Evgenia Pak, Wei Zheng, Amalia Dutra, Wendy J. Introne, May Christine V. MalicdanAbstract:Abstract Chediak-Higashi Syndrome (CHS) is a lysosome-related organelle (LRO) disorder caused by biallelic mutations in the Lysosomal Trafficking Regulator gene, LYST. The clinical features of CHS include oculocutaneous albinism, primary immunodeficiency, bleeding diathesis, risk for development of hemophagocytic lymphohistiocytosis, and progressive neurological problems. The pathophysiological mechanisms underlying this disease are unknown, so developing therapeutic options remains challenging. In this study, four induced pluripotent stem (iPSC) lines from unrelated CHS patients have been generated and successfully characterized for exploring the role of LYST in health and disease in diverse cell types.
-
An actin cytoskeletal barrier inhibits lytic granule release from natural killer cells in patients with Chediak-Higashi syndrome.
The Journal of allergy and clinical immunology, 2017Co-Authors: Aleksandra Gil-krzewska, William A. Gahl, John E. Coligan, Wendy J. Introne, Mezida B. Saeed, Anna Oszmiana, Elizabeth R. Fischer, Kathryn Lagrue, Daniel M. Davis, Konrad KrzewskiAbstract:Background Chediak-Higashi syndrome (CHS) is a rare disorder caused by biallelic mutations in the Lysosomal Trafficking Regulator gene (LYST), resulting in formation of giant lysosomes or lysosome-related organelles in several cell types. The disease is characterized by immunodeficiency and a fatal hemophagocytic lymphohistiocytosis caused by impaired function of cytotoxic lymphocytes, including natural killer (NK) cells. Objective We sought to determine the underlying biochemical cause of the impaired cytotoxicity of NK cells in patients with CHS. Methods We generated a human cell model of CHS using Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) technology. We used a combination of classical techniques to evaluate Lysosomal function and cell activity in the model system and super-resolution microscopy to visualize F-actin and lytic granules in normal and LYST-deficient NK cells. Results Loss of LYST function in a human NK cell line, NK92mi, resulted in inhibition of NK cell cytotoxicity and reproduced other aspects of the CHS cellular phenotype, including the presence of significantly enlarged lytic granules with defective exocytosis and impaired integrity of endoLysosomal compartments. The large granules had an acidic pH and normal activity of Lysosomal enzymes and were positive for the proteins essential for lytic granule exocytosis. Visualization of the actin meshwork openings at the immunologic synapse revealed that the cortical actin acts as a barrier for secretion of such large granules at the cell-cell contact site. Decreasing the cortical actin density at the immunologic synapse or decreasing the lytic granule size restored the ability of LYST-deficient NK cells to degranulate and kill target cells. Conclusion The cortical actin and granule size play significant roles in NK cell cytotoxic function. We present evidence that the periodicity of subsynaptic actin is an important factor limiting the release of large lytic granules from NK cells from patients with CHS and could be a novel target for pharmaceutical intervention.
-
Chediak-Higashi syndrome: Lysosomal Trafficking Regulator domains regulate exocytosis of lytic granules but not cytokine secretion by natural killer cells
The Journal of allergy and clinical immunology, 2015Co-Authors: Aleksandra Gil-krzewska, Stephanie M. Wood, Yousuke Murakami, Victoria Nguyen, Samuel C. C. Chiang, Andrew R. Cullinane, Giovanna Peruzzi, William A. Gahl, John E. Coligan, Wendy J.ewell IntroneAbstract:Background Mutations in Lysosomal Trafficking Regulator (LYST) cause Chediak-Higashi syndrome (CHS), a rare immunodeficiency with impaired cytotoxic lymphocyte function, mainly that of natural killer (NK) cells. Our understanding of NK cell function deficiency in patients with CHS and how LYST regulates lytic granule exocytosis is very limited. Objective We sought to delineate cellular defects associated with LYST mutations responsible for the impaired NK cell function seen in patients with CHS. Methods We analyzed NK cells from patients with CHS with missense mutations in the LYST ARM/HEAT (armadillo/huntingtin, elongation factor 3, protein phosphatase 2A, and the yeast kinase TOR1) or BEACH (beige and Chediak-Higashi) domains. Results NK cells from patients with CHS displayed severely reduced cytotoxicity. Mutations in the ARM/HEAT domain led to a reduced number of perforin-containing granules, which were significantly increased in size but able to polarize to the immunologic synapse; however, they were unable to properly fuse with the plasma membrane. Mutations in the BEACH domain resulted in formation of normal or slightly enlarged granules that had markedly impaired polarization to the IS but could be exocytosed on reaching the immunologic synapse. Perforin-containing granules in NK cells from patients with CHS did not acquire certain Lysosomal markers (lysosome-associated membrane protein 1/2) but were positive for markers of transport vesicles (cation-independent mannose 6-phosphate receptor), late endosomes (Ras-associated binding protein 27a), and, to some extent, early endosomes (early endosome antigen 1), indicating a lack of integrity in the endoLysosomal compartments. NK cells from patients with CHS had normal cytokine compartments and cytokine secretion. Conclusion LYST is involved in regulation of multiple aspects of NK cell lytic activity, ranging from governance of lytic granule size to control of their polarization and exocytosis, as well as regulation of endoLysosomal compartment identity. LYST functions in the regulated exocytosis but not in the constitutive secretion pathway.
Hiroyuki Ishiura - One of the best experts on this subject based on the ideXlab platform.
-
autosomal recessive complicated spastic paraplegia with a novel Lysosomal Trafficking Regulator gene mutation
Journal of Neurology Neurosurgery and Psychiatry, 2014Co-Authors: Haruo Shimazaki, Junko Honda, Tametou Naoi, Michito Namekawa, Imaharu Nakano, Masahide Yazaki, Katsuya Nakamura, Kunihiro Yoshida, Shuichi Ikeda, Hiroyuki IshiuraAbstract:Background Autosomal-recessive hereditary spastic paraplegias (AR-HSP) consist of a genetically diverse group of neurodegenerative diseases characterised by pyramidal tracts dysfunction. The causative genes for many types of AR-HSP remain elusive. We tried to identify the gene mutation for AR-HSP with cerebellar ataxia and neuropathy. Methods This study included two patients in a Japanese family with their parents who are first cousins. Neurological examination and gene analysis were conducted in the two patients and two normal family members. We undertook genome-wide linkage analysis employing single nucleotide polymorphism arrays using the two patients’ DNAs and exome sequencing using one patient9s sample. Results We detected a homozygous missense mutation (c.4189T>G, p.F1397V) in the Lysosomal Trafficking Regulator ( LYST ) gene, which is described as the causative gene for Chediak–Higashi syndrome (CHS). CHS is a rare autosomal-recessive syndrome characterised by hypopigmentation, severe immune deficiency, a bleeding tendency and progressive neurological dysfunction. This mutation was co-segregated with the disease in the family and was located at well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Microscopic observation of peripheral blood in the two patients disclosed large peroxidase-positive granules in both patients’ granulocytes, although they had no symptoms of immune deficiency or bleeding tendency. Conclusions We diagnosed these patients as having adult CHS presenting spastic paraplegia with cerebellar ataxia and neuropathy. The clinical spectrum of CHS is broader than previously recognised. Adult CHS must be considered in the differential diagnosis of AR-HSP.
-
Adult Chediak-Higashi Syndrome Presenting as Spastic Paraplegia, Cerebellar Ataxia and Neuropathy (P06.221)
Neurology, 2013Co-Authors: Haruo Shimazaki, Masahide Yazaki, Hiroyuki Ishiura, Yoshihisa Takiyama, Shoji Tsuji, Imaharu NakanoAbstract:OBJECTIVE: To identify the gene mutation responsible for a family presenting spastic paraplegia, cerebellar ataxia and neuropathy with autosomal recessive transmission. BACKGROUND: Autosomal recessive hereditary spastic paraplegias (AR-HSP) constitute a heterogeneous group of neurodegenerative diseases involving pyramidal tracts dysfunction. The genes responsible for many types of AR-HSPs remain unknown. We attempted to identify the gene responsible for autosomal recessive hereditary spastic paraplegia with cerebellar ataxia and neuropathy. DESIGN/METHODS: The present study included two patients in a Japanese consanguineous family. Their onset of symptoms was 48 and 58 years of age. Neurologic examination and DNA analysis were underwent in two patients and two normal family members. We performed a genomewide linkage analysis employing SNP arrays with two patients9 DNAs and exome sequencing using one patient9s sample. RESULTS: We identified a homozygous missense mutation in the Lysosomal Trafficking Regulator (LYST) gene in the two patients. This mutation co-segregated with the disease in the family, and located at the well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Subsequent hematological analysis in one patient could disclose peroxidase-positive large granules in the patient9s granulocytes, although he had no symptoms according to immunodeficiency or bleeding tendency. CONCLUSIONS: We considered these patients as adult Chediak-Higashi syndrome (CHS) presenting spastic paraplegia with cerebellar ataxia and neuropathy. As far as we know, this family is one of the oldest adult CHS cases in the literatures. Clinical spectrum of CHS is broader than previously recognized. Adult CHS must be considered in the differential diagnosis of AR-HSPs. The linkage analysis and exome sequencing were useful for identifying the causative mutation in this family. Supported by: Grant from the Research Committee for Ataxic Diseases (Y.T. and H.S.) of the Ministry of Health, Labor and Welfare, Japan. This work was also supported by Grants-in-Aid from the Research Committee of CNS Degenerative Diseases (I.N. and Y.T.), and the Ministry of Health, Labor and Welfare of Japan, and by a Grant-in-Aid for Scientific Research © (23591253 to H.S.) from The Ministry of Education, Culture, Sports, Science and Technology in Japan. Disclosure: Dr. Shimazaki has nothing to disclose. Dr. Takiyama has nothing to disclose. Dr. Ishiura has nothing to disclose. Dr. Tsuji has nothing to disclose. Dr. Yazaki has nothing to disclose. Dr. Nakano has nothing to disclose.
Haruo Shimazaki - One of the best experts on this subject based on the ideXlab platform.
-
autosomal recessive complicated spastic paraplegia with a novel Lysosomal Trafficking Regulator gene mutation
Journal of Neurology Neurosurgery and Psychiatry, 2014Co-Authors: Haruo Shimazaki, Junko Honda, Tametou Naoi, Michito Namekawa, Imaharu Nakano, Masahide Yazaki, Katsuya Nakamura, Kunihiro Yoshida, Shuichi Ikeda, Hiroyuki IshiuraAbstract:Background Autosomal-recessive hereditary spastic paraplegias (AR-HSP) consist of a genetically diverse group of neurodegenerative diseases characterised by pyramidal tracts dysfunction. The causative genes for many types of AR-HSP remain elusive. We tried to identify the gene mutation for AR-HSP with cerebellar ataxia and neuropathy. Methods This study included two patients in a Japanese family with their parents who are first cousins. Neurological examination and gene analysis were conducted in the two patients and two normal family members. We undertook genome-wide linkage analysis employing single nucleotide polymorphism arrays using the two patients’ DNAs and exome sequencing using one patient9s sample. Results We detected a homozygous missense mutation (c.4189T>G, p.F1397V) in the Lysosomal Trafficking Regulator ( LYST ) gene, which is described as the causative gene for Chediak–Higashi syndrome (CHS). CHS is a rare autosomal-recessive syndrome characterised by hypopigmentation, severe immune deficiency, a bleeding tendency and progressive neurological dysfunction. This mutation was co-segregated with the disease in the family and was located at well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Microscopic observation of peripheral blood in the two patients disclosed large peroxidase-positive granules in both patients’ granulocytes, although they had no symptoms of immune deficiency or bleeding tendency. Conclusions We diagnosed these patients as having adult CHS presenting spastic paraplegia with cerebellar ataxia and neuropathy. The clinical spectrum of CHS is broader than previously recognised. Adult CHS must be considered in the differential diagnosis of AR-HSP.
-
Adult Chediak-Higashi Syndrome Presenting as Spastic Paraplegia, Cerebellar Ataxia and Neuropathy (P06.221)
Neurology, 2013Co-Authors: Haruo Shimazaki, Masahide Yazaki, Hiroyuki Ishiura, Yoshihisa Takiyama, Shoji Tsuji, Imaharu NakanoAbstract:OBJECTIVE: To identify the gene mutation responsible for a family presenting spastic paraplegia, cerebellar ataxia and neuropathy with autosomal recessive transmission. BACKGROUND: Autosomal recessive hereditary spastic paraplegias (AR-HSP) constitute a heterogeneous group of neurodegenerative diseases involving pyramidal tracts dysfunction. The genes responsible for many types of AR-HSPs remain unknown. We attempted to identify the gene responsible for autosomal recessive hereditary spastic paraplegia with cerebellar ataxia and neuropathy. DESIGN/METHODS: The present study included two patients in a Japanese consanguineous family. Their onset of symptoms was 48 and 58 years of age. Neurologic examination and DNA analysis were underwent in two patients and two normal family members. We performed a genomewide linkage analysis employing SNP arrays with two patients9 DNAs and exome sequencing using one patient9s sample. RESULTS: We identified a homozygous missense mutation in the Lysosomal Trafficking Regulator (LYST) gene in the two patients. This mutation co-segregated with the disease in the family, and located at the well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Subsequent hematological analysis in one patient could disclose peroxidase-positive large granules in the patient9s granulocytes, although he had no symptoms according to immunodeficiency or bleeding tendency. CONCLUSIONS: We considered these patients as adult Chediak-Higashi syndrome (CHS) presenting spastic paraplegia with cerebellar ataxia and neuropathy. As far as we know, this family is one of the oldest adult CHS cases in the literatures. Clinical spectrum of CHS is broader than previously recognized. Adult CHS must be considered in the differential diagnosis of AR-HSPs. The linkage analysis and exome sequencing were useful for identifying the causative mutation in this family. Supported by: Grant from the Research Committee for Ataxic Diseases (Y.T. and H.S.) of the Ministry of Health, Labor and Welfare, Japan. This work was also supported by Grants-in-Aid from the Research Committee of CNS Degenerative Diseases (I.N. and Y.T.), and the Ministry of Health, Labor and Welfare of Japan, and by a Grant-in-Aid for Scientific Research © (23591253 to H.S.) from The Ministry of Education, Culture, Sports, Science and Technology in Japan. Disclosure: Dr. Shimazaki has nothing to disclose. Dr. Takiyama has nothing to disclose. Dr. Ishiura has nothing to disclose. Dr. Tsuji has nothing to disclose. Dr. Yazaki has nothing to disclose. Dr. Nakano has nothing to disclose.
Imaharu Nakano - One of the best experts on this subject based on the ideXlab platform.
-
autosomal recessive complicated spastic paraplegia with a novel Lysosomal Trafficking Regulator gene mutation
Journal of Neurology Neurosurgery and Psychiatry, 2014Co-Authors: Haruo Shimazaki, Junko Honda, Tametou Naoi, Michito Namekawa, Imaharu Nakano, Masahide Yazaki, Katsuya Nakamura, Kunihiro Yoshida, Shuichi Ikeda, Hiroyuki IshiuraAbstract:Background Autosomal-recessive hereditary spastic paraplegias (AR-HSP) consist of a genetically diverse group of neurodegenerative diseases characterised by pyramidal tracts dysfunction. The causative genes for many types of AR-HSP remain elusive. We tried to identify the gene mutation for AR-HSP with cerebellar ataxia and neuropathy. Methods This study included two patients in a Japanese family with their parents who are first cousins. Neurological examination and gene analysis were conducted in the two patients and two normal family members. We undertook genome-wide linkage analysis employing single nucleotide polymorphism arrays using the two patients’ DNAs and exome sequencing using one patient9s sample. Results We detected a homozygous missense mutation (c.4189T>G, p.F1397V) in the Lysosomal Trafficking Regulator ( LYST ) gene, which is described as the causative gene for Chediak–Higashi syndrome (CHS). CHS is a rare autosomal-recessive syndrome characterised by hypopigmentation, severe immune deficiency, a bleeding tendency and progressive neurological dysfunction. This mutation was co-segregated with the disease in the family and was located at well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Microscopic observation of peripheral blood in the two patients disclosed large peroxidase-positive granules in both patients’ granulocytes, although they had no symptoms of immune deficiency or bleeding tendency. Conclusions We diagnosed these patients as having adult CHS presenting spastic paraplegia with cerebellar ataxia and neuropathy. The clinical spectrum of CHS is broader than previously recognised. Adult CHS must be considered in the differential diagnosis of AR-HSP.
-
Adult Chediak-Higashi Syndrome Presenting as Spastic Paraplegia, Cerebellar Ataxia and Neuropathy (P06.221)
Neurology, 2013Co-Authors: Haruo Shimazaki, Masahide Yazaki, Hiroyuki Ishiura, Yoshihisa Takiyama, Shoji Tsuji, Imaharu NakanoAbstract:OBJECTIVE: To identify the gene mutation responsible for a family presenting spastic paraplegia, cerebellar ataxia and neuropathy with autosomal recessive transmission. BACKGROUND: Autosomal recessive hereditary spastic paraplegias (AR-HSP) constitute a heterogeneous group of neurodegenerative diseases involving pyramidal tracts dysfunction. The genes responsible for many types of AR-HSPs remain unknown. We attempted to identify the gene responsible for autosomal recessive hereditary spastic paraplegia with cerebellar ataxia and neuropathy. DESIGN/METHODS: The present study included two patients in a Japanese consanguineous family. Their onset of symptoms was 48 and 58 years of age. Neurologic examination and DNA analysis were underwent in two patients and two normal family members. We performed a genomewide linkage analysis employing SNP arrays with two patients9 DNAs and exome sequencing using one patient9s sample. RESULTS: We identified a homozygous missense mutation in the Lysosomal Trafficking Regulator (LYST) gene in the two patients. This mutation co-segregated with the disease in the family, and located at the well-conserved amino acid. This LYST mutation was not found in 200 Japanese control DNAs. Subsequent hematological analysis in one patient could disclose peroxidase-positive large granules in the patient9s granulocytes, although he had no symptoms according to immunodeficiency or bleeding tendency. CONCLUSIONS: We considered these patients as adult Chediak-Higashi syndrome (CHS) presenting spastic paraplegia with cerebellar ataxia and neuropathy. As far as we know, this family is one of the oldest adult CHS cases in the literatures. Clinical spectrum of CHS is broader than previously recognized. Adult CHS must be considered in the differential diagnosis of AR-HSPs. The linkage analysis and exome sequencing were useful for identifying the causative mutation in this family. Supported by: Grant from the Research Committee for Ataxic Diseases (Y.T. and H.S.) of the Ministry of Health, Labor and Welfare, Japan. This work was also supported by Grants-in-Aid from the Research Committee of CNS Degenerative Diseases (I.N. and Y.T.), and the Ministry of Health, Labor and Welfare of Japan, and by a Grant-in-Aid for Scientific Research © (23591253 to H.S.) from The Ministry of Education, Culture, Sports, Science and Technology in Japan. Disclosure: Dr. Shimazaki has nothing to disclose. Dr. Takiyama has nothing to disclose. Dr. Ishiura has nothing to disclose. Dr. Tsuji has nothing to disclose. Dr. Yazaki has nothing to disclose. Dr. Nakano has nothing to disclose.
Peter M. T. Deen - One of the best experts on this subject based on the ideXlab platform.
-
phosphorylation of human aquaporin 2 aqp2 allosterically controls its interaction with the Lysosomal Trafficking protein lip5
Journal of Biological Chemistry, 2017Co-Authors: Jennifer Virginia Roche, Peter M. T. Deen, Sabeen Survery, Stefan Kreida, Veronika Nesverova, Henry Ampahkorsah, Maria Gourdon, Susanna TornrothhorsefieldAbstract:The interaction between the renal water channel aquaporin-2 (AQP2) and the Lysosomal Trafficking Regulator-interacting protein LIP5 targets AQP2 to multivesicular bodies and facilitates Lysosomal degradation. This interaction is part of a process that controls AQP2 apical membrane abundance in a vasopressin-dependent manner, allowing for urine volume adjustment. Vasopressin regulates phosphorylation at four sites within the AQP2 C terminus (Ser256, Ser261, Ser264, and Thr269), of which Ser256 is crucial and sufficient for AQP2 translocation from storage vesicles to the apical membrane. However, whether AQP2 phosphorylation modulates AQP2-LIP5 complex affinity is unknown. Here we used far-Western blot analysis and microscale thermophoresis to show that the AQP2 binds LIP5 in a phosphorylation-dependent manner. We constructed five phospho-mimicking mutants (S256E, S261E, S264E, T269E, and S256E/T269E) and a C-terminal truncation mutant (ΔP242) that lacked all phosphorylation sites but retained a previously suggested LIP5-binding site. CD spectroscopy indicated that wild-type AQP2 and the phospho-mimicking mutants had similar overall structure but displayed differences in melting temperatures possibly arising from C-terminal conformational changes. Non-phosphorylated AQP2 bound LIP5 with the highest affinity, whereas AQP2-ΔP242 had 20-fold lower affinity as determined by microscale thermophoresis. AQP2-S256E, S261E, T269E, and S256E/T269E all had reduced affinity. This effect was most prominent for AQP2-S256E, which fits well with its role in apical membrane targeting. AQP2-S264E had affinity similar to non-phosphorylated AQP2, possibly indicating a role in exosome excretion. Our data suggest that AQP2 phosphorylation allosterically controls its interaction with LIP5, illustrating how altered affinities to interacting proteins form the basis for regulation of AQP2 Trafficking by post-translational modifications.
-
The Lysosomal Trafficking Regulator interacting protein-5 localizes mainly in epithelial cells
Journal of Molecular Histology, 2010Co-Authors: Michelle Boone, Ali Mobasheri, Robert A. Fenton, Bas W. M. Balkom, Ronnie Wismans, Catharina E. E. M. Zee, Peter M. T. DeenAbstract:Endocytosis, subsequent protein sorting into multivesicular bodies (MVBs), and eventual degradation in lysosomes compose an important mechanism for controlling protein expression on the plasma membrane. The Lysosomal Trafficking Regulator interacting protein-5 (LIP5) is part of the complex protein machinery involved in MVB biosynthesis. LIP5 interacts with other players of the ESCRT machinery as well as with two known cargo proteins, AQP2 and EGFR, whose degradation is affected upon reduction of LIP5 expression. To investigate the expression and localization pattern of LIP5, we studied LIP5 protein expression in a mouse tissue panel and subjected various rodent and human tissues to immunohistochemistry. Immunoblotting revealed that, except for jejunum, LIP5 is expressed as a 42 kDa protein in all mouse tissues tested. Alternatively-spliced gene products could not be detected. Immunohistochemical studies revealed that in tissues positive for LIP5, LIP5 is detected in virtually all epithelial cells of the examined rodent and human tissues. The observed LIP5 expression in epithelial tissues suggests that LIP5 is of particular importance in the MVB sorting and degradation of proteins expressed in polarized cells.
-
LIP5 Interacts with Aquaporin 2 and Facilitates Its Lysosomal Degradation
Journal of the American Society of Nephrology : JASN, 2009Co-Authors: Bas W.m. Van Balkom, Michelle Boone, Giel Hendriks, Erik-jan Kamsteeg, Joris H. Robben, H. Christiaan Stronks, Anne Van Der Voorde, Francois Van Herp, Peter Van Der Sluijs, Peter M. T. DeenAbstract:Vasopressin binding to the V2 receptor in renal principal cells leads to activation of protein kinase A, phosphorylation of aquaporin 2 (AQP2) at Ser256, and the translocation of AQP2 to the apical membrane, resulting in concentration of the urine. In contrast, phorbol ester-induced activation of protein kinase C pathway leads to ubiquitination of AQP2 at Lys270 and its internalization to multivesicular bodies, where it is targeted for Lysosomal degradation or stored for recycling. Because little is known about the regulation of AQP2 Trafficking, we used the carboxy-terminal tail of constitutively nonphosphorylated AQP2 (S256A) as a bait for interacting proteins in a yeast two-hybrid assay. We isolated Lysosomal Trafficking Regulator-interacting protein 5 (LIP5) and found that LIP5 interacted with the proximal carboxy-terminal tail (L230-D243) of AQP2 in vitro but not with AQP3 or AQP4, which are also expressed in principal cells. Immunohistochemistry revealed that LIP5 co-localized with AQP2 in principal cells. LIP5 binding occurred independent of the state of Ser256 phosphorylation or Lys270 ubiquitination. LIP5 has been shown to facilitate degradation of the EGF receptor; here, LIP5 seemed to bind this receptor. Knockdown of LIP5 in mouse renal cells (mpkCCD) reduced the phorbol ester-induced degradation of AQP2 approximately two-fold. In summary, LIP5 binds cargo proteins and, considering the role of LIP5 in protein sorting to multivesicular bodies, plays a role in the degradation of AQP2, possibly by reducing the formation of late endosomes.
