The Experts below are selected from a list of 5358 Experts worldwide ranked by ideXlab platform
Michael R Eccles - One of the best experts on this subject based on the ideXlab platform.
-
PAX2 is an antiapoptotic molecule with deregulated expression in medulloblastoma.
International Journal of Oncology, 2012Co-Authors: Michael C. Burger, Michael R Eccles, Thomas Klingebiel, Peter Baumgarten, Daniel P. Brucker, Michael W. Ronellenfitsch, Christina Wanka, Martin Hasselblatt, Michael Weller, Johannes RiegerAbstract:: PAX2 is a paired box transcription factor possessing a fundamental role in the embryogenesis of hindbrain and urinary tract. PAX genes are proto-oncogenes, PAX2 expression may contribute to the pathogenesis of renal cell carcinoma. Because of the expression of PAX2 in the developing hindbrain and its essential role in cerebellar development, it has been hypothesized that PAX2 may also be involved in medulloblastoma tumorigenesis. We investigated the expression pattern of PAX2 and various genes of the neuronal lineage in medulloblastoma and glioma cell lines. We found high expression of PAX2 mRNA and PAX2 protein in medulloblastoma cells and some glioma cell lines independent of their neuronal lineage gene expression signature. Gene suppression of PAX2 decreased the expression of the PAX2 transcriptional target GDNF in Daoy cells and had a profound cytotoxic effect in vitro on Daoy medulloblastoma and T98G glioma cells. Expression of PAX2 was then assessed in two separate medulloblastoma tissue microarrays with a total of 61 patient samples by immunohistochemistry. PAX2 expression was detected in the majority of medulloblastoma samples and correlated with less differentiated histology. Therefore, PAX2 is a biomarker for a more aggressive medulloblastoma phenotype and may represent a novel therapeutic target.
-
PAX2 gene dosage influences cystogenesis in autosomal dominant polycystic kidney disease
Human Molecular Genetics, 2006Co-Authors: Cherie Stayner, Paul Goodyer, Diana M Iglesias, Lana Ellis, G. G. Germino, Jing Zhou, Michael R EcclesAbstract:Mutations in PKD1 cause dominant polycystic kidney disease (PKD), characterized by large fluid-filled kidney cysts in adult life, but the molecular mechanism of cystogenesis remains obscure. Ostrom et al .[ Dev. Biol., 219, 250‐258 (2000)] showed that reduced dosage of PAX2 caused increased apoptosis, and ameliorated cystogenesis in Cpk mutant mice with recessive PKD. PAX2 is expressed in condensing metanephrogenic mesenchyme and arborizing ureteric bud, and plays an important role in kidney development. Transient PAX2 expression during fetal kidney mesenchyme-to-epithelial transition, as well as in nascent tubules, is followed by marked down-regulation of PAX2 expression. Here, we show that in humans with PKD, as well as in Pkd1 del34/del34 mutant mice, PAX2 was expressed in cyst epithelial cells, and facilitated cyst growth in Pkd1 del34/del34 mutant mice. In Pkd1 del34/del34 mutant kidneys, the expression of PAX2 persisted in nascent collecting ducts. In contrast, homozygous Pkd1 del34/del34 fetal mice carrying mutant PAX2 exhibited ameliorated cyst growth, although reduced cystogenesis was not associated with increased apoptosis. PAX2 expression was attenuated in nascent collecting ducts and absent from remnant cysts of Pkd1 del34/del34 /PAX2 1Neu/1 mutant mice. To investigate whether the Pkd1 gene product, Polycystin-1, regulates PAX2 ,M DCK cells were engineered constitutively expressing wild-type Pkd1; PAX2 protein levels and promoter activity were both repressed in MDCK cells over-expressing Pkd1, but not in cells without transgenic Pkd1. These data suggest that polycystin-1-deficient tubular epithelia persistently express PAX2 in ADPKD, and that PAX2 or its pathway may be an appropriate target for the development of novel therapies for ADPKD.
-
PAX2 activates wnt4 expression during mammalian kidney development
Journal of Biological Chemistry, 2006Co-Authors: Elena Torban, Michael R Eccles, Alison Dziarmaga, Diana M Iglesias, Tatiana Vassilieva, Melissa H Little, Maria Teresa Discenza, Jerry Pelletier, Paul GoodyerAbstract:The transcription factor PAX2 is expressed during normal kidney development and is thought to influence outgrowth and branching of the ureteric bud. Mice with homozygous null PAX2 mutations have developmental defects of the midbrain-hindbrain region, optic nerve, and ear and are anephric. During nephrogenesis, PAX2 is also expressed by mesenchymal cells as they cluster and reorganize to form proximal elements of each nephron, but the function of PAX2 in these cells is unknown. In this study we hypothesized that PAX2 activates expression of WNT4, a secreted glycoprotein known to be critical for successful nephrogenesis. PAX2 protein was identified in distal portions of the S-shaped body, and the protein persists in the emerging proximal tubules of murine fetal kidney. PAX2 activated WNT4 promoter activity 5-fold in co-transfection assays with JTC12 cells derived from the proximal tubule. Inspection of the 5'-flanking sequence of the human WNT4 gene identified three novel PAX2 recognition motifs; each exhibited specific PAX2 protein binding in electromobility shift assays. Two motifs were contained within a completely duplicated 0.66-kb cassette. Transfection of JTC12 cells with a PAX2 expression vector was associated with a 7-fold increase in endogenous WNT4 mRNA. In contrast, Wnt4 mRNA was decreased by 60% in mesenchymal cell condensates of fetal kidney from mice with a heterozygous PAX2 mutation. We speculated that a key function of PAX2 is to activate WNT4 gene expression in metanephric mesenchymal cells as they differentiate to form elements of the renal tubules.
-
PAX2 inactivation enhances cisplatin induced apoptosis in renal carcinoma cells
Kidney International, 2006Co-Authors: Pierrealain Hueber, Michael R Eccles, Paula J Waters, P Clarke, Paul GoodyerAbstract:Renal cell carcinoma (RCC) is the most common kidney malignancy and has a poor prognosis owing to its resistance to chemotherapy. RCC cells overexpress the transcription factor, PAX2, normally expressed in fetal kidney but downregulated at birth. Since PAX2 suppresses apoptosis during renal development, we reasoned that PAX2 may confer resistance to cisplatin-induced apoptosis in RCC. Here, we show that PAX2 confers resistance to cisplatin-induced apoptosis in normal kidney cells and fetal kidney explants. Human embryonic kidney 293 cells transfected with a PAX2 expression vector and exposed to cisplatin (40 μ M) exhibited 45±15% as much caspase-3 cleavage compared to control cells. Conversely, murine collecting duct cells stably transfected with PAX2 antisense cDNA had twofold increase in cisplatin-induced apoptosis. Murine fetal (embryonic day 15) kidney explants from PAX2 1Neu +/- mice exposed to cisplatin (25 μ M × 24 h) had 50% increased apoptosis (terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling staining). We then show that RCC cells (CAKI-1 (human, Caucasian, kidney, carcinoma) and ACHN (human, Caucasian, kidney, adenocarcinoma)) express PAX2 protein. PAX2-small interfering RNA (100 nM) reduces endogenous PAX2 protein (10% of baseline) and induces apoptosis (Annexin-V staining). PAX2 knockdown sensitized RCC cells to cisplatin-induced apoptosis, killing 50–60% of cisplatin-resistant ACHN and CAKI-1 cells. These findings suggest that PAX2 confers resistance to cisplatin-induced apoptosis in non-transformed kidney cells and fetal kidney explants. Similarly, PAX2 overexpression in RCC cells contributes to cisplatin resistance. Conceivably, a therapeutic strategy that inactivates PAX2 in vivo might enhance the efficacy of conventional cytotoxic drugs against RCC.
-
PAX2 suppresses apoptosis in renal collecting duct cells
American Journal of Pathology, 2000Co-Authors: Elena Torban, Michael R Eccles, Jack Favor, Paul GoodyerAbstract:PAX2 is a transcription factor belonging to the evolutionarily conserved paired box family and is required during development of the central nervous system and genitourinary axis. Mutations in the PAX2 gene cause a rare autosomal dominant renal-coloboma syndrome, characterized by optic nerve colobomas and renal hypoplasia. Recent analysis of a spontaneous PAX2 mutant mouse model (1Neu) revealed that the major cause of renal hypoplasia is reduced branching of the ureteric bud (UB) and fewer nephrons. We have observed that this abnormality is associated with a striking increase in the number of UB cells undergoing programmed cell death during nephrogenesis. To ascertain whether apoptosis is directly linked to the level of PAX2 expression, we have studied the role of PAX2 in cultured renal cells. We show that mIMCD-3 cells, a murine collecting duct cell line with high endogenous PAX2 expression, undergo apoptosis when transfected with anti-sense PAX2. In contrast, HEK293 cells expressing exogenous PAX2 are protected against apoptotic death induced by caspase-2. PAX2 has no effect on proliferation of embryonic kidney or in cultured kidney cells. Our observations imply a direct role for PAX2 in survival of ureteric bud cells.
Frederic G Barr - One of the best experts on this subject based on the ideXlab platform.
-
correlation between histology and pax fkhr fusion status in alveolar rhabdomyosarcoma a report from the children s oncology group
The American Journal of Surgical Pathology, 2007Co-Authors: David M Parham, Frederic G Barr, Stephen J Qualman, Timothy J Triche, Poul H Sorensen, Lisa A Teot, Raphaella Morotti, William H MeyerAbstract:At the molecular level, alveolar rhabdomyosarcomas (ARMS) are characterized by 3 mutually exclusive PAX/FKHR conditions: PAX3/FKHR fusion (present in 60% of cases), PAX7/FKHR fusion (present in 20%), and PAX/FKHR fusion-negativity (present in 20%). The possibility of morphologic variation among thes
-
Analysis of genetic events that modulate the oncogenic and growth suppressive activities of the PAX3-FKHR fusion oncoprotein
Laboratory Investigation, 2007Co-Authors: Prerna Rajput, Donna M Strzelecki, Frederic G BarrAbstract:Alveolar rhabdomyosarcoma (ARMS) is associated with chromosomal translocations that generate PAX3-FKHR and PAX7-FKHR fusion oncoproteins. Based on studies demonstrating that high PAX3-FKHR expression causes growth suppression, the hypothesis is proposed that, during ARMS tumorigenesis, the translocations cause low oncoprotein expression and are followed by collaborating events that block growth suppression pathways and permit upregulation of oncoprotein expression. To investigate oncogenic function at low expression levels, PAX3-FKHR was introduced into NIH3T3 cells in the pBabe retroviral vector. Compared to high expression systems, PAX3-FKHR expression from pBabe was lower and did not suppress growth, but showed transforming activity in the soft agar assay. As a possible collaborating event, PAX3-FKHR paired box mutations were previously shown in high expression systems to reverse growth suppressive effects. In the low expression system, the paired box mutation enhanced transformation in soft agar and focus formation assays. Although these mutations are candidate collaborating events, sequencing of paired box regions in ARMS tumors did not identify mutations. Finally, genes from known genetic alterations in ARMS were introduced, alone or combined, into NIH3T3 cells with high PAX3-FKHR expression and did not rescue growth suppression. In summary, these studies provide a model for an event in ARMS tumorigenesis that enhances PAX3-FKHR oncogenicity and abrogates growth suppression, but do not demonstrate a known event occurring in ARMS tumors that fulfills these criteria.
-
use of a novel fish assay on paraffin embedded tissues as an adjunct to diagnosis of alveolar rhabdomyosarcoma
Laboratory Investigation, 2006Co-Authors: Jun Nishio, Frederic G Barr, Stephen J Qualman, Ming Zhou, David M Parham, Lisa A Teot, Pamela A Althof, Jacqueline M Bailey, James R Neff, Julia A BridgeAbstract:A valuable diagnostic adjunct and important prognostic parameter in alveolar rhabdomyosarcoma (ARMS) is the identification of translocations t(2;13)(q35;q14) and t(1;13)(p36;q14), and the associated PAX3-FKHR and PAX7-FKHR fusion transcripts, respectively. Most RMS fusion gene type studies have been based on reverse transcriptase-polymerase chain reaction (RT-PCR) detection of the fusion transcript, a technique limited by RNA quality and failure of devised primer sets to detect unusual variants. As an alternative approach, we developed a fluorescence in situ hybridization (FISH) assay that can: (1) distinguish between the two most common ARMS-associated fusion genes; (2) identify potential unusual variant translocations; (3) assess histologic components in mixed alveolar/embryonal RMS; and (4) be performed on paraffinized tissue. FISH analyses of 75 specimens (40 ARMS, 16 ERMS, 8 mixed ARMS/ERMS, and 11 non-RMS tumors) using selected cosmid clone, bacterial, P1-derived, and yeast artificial chromosome probe sets were successful in all but two cases. Among specimens with informative results for both FISH and RT-PCR or standard karyotyping, PAX/FKHR classification results were concordant in 94.6% (53/56). The three discordant cases included one exhibiting a t(2;13) by FISH that was subsequently confirmed by repeat RT-PCR, a second showing a rearrangement of the PAX3 locus only (consistent with the presence of a PAX3 variant translocation), and a third revealing a t(2;13) by FISH that lacked this translocation cytogenetically. Both alveolar and embryonal components of the mixed ARMS/ERMS subtype were negative for PAX3, PAX7, and FKHR rearrangements, a surprising finding confirmed by RT-PCR and/or conventional karyotyping. These data demonstrate that FISH with newly designed probe sets is a reliable and highly specific method of detecting t(1;13) and t(2;13) in routinely processed tissue and may be useful in differentiating ARMS from other small round cell tumors. The findings also suggest that FISH may be a more sensitive assay than RT-PCR in some settings, capable of revealing variant translocations.
-
examination of gene fusion status in archival samples of alveolar rhabdomyosarcoma entered on the intergroup rhabdomyosarcoma study iii trial a report from the children s oncology group
The Journal of Molecular Diagnostics, 2006Co-Authors: Frederic G Barr, Stephen J Qualman, Donna Strzelecki, James C Lynch, David M Parham, Lynette M Smith, Philip P BreitfeldAbstract:Alveolar rhabdomyosarcoma (ARMS) is a soft tissue cancer in which chromosomal translocations generate PAX3-FKHR and PAX7-FKHR gene fusions. To improve the approach for fusion detection in archival samples, we developed a real-time reverse transcrip-tase-polymerase chain reaction assay for these fusion transcripts. By incorporating consensus primers and gene-specific probes, both presence and subtype of the fusion were determined in one assay. We applied this approach to a convenience sample of 78 formalin-fixed, paraffin-embedded ARMS tumors from the Intergroup Rhabdomyosarcoma Study (IRS)-III clinical trial and obtained satisfactory results in 59 (76%) cases. The distribution of fusion types was 35 (59%) PAX3-FKHR, 11 (19%) PAX7-FKHR, and 13 fusionnegative (22%). In a subsequent clinical analysis, we found that IRS-III ARMS cases analyzed for fusion status had a significantly improved outcome compared to IRS-III ARMS cases that were not available for fusion analysis. The basis of this outcome could not be explained by known prognostic clinical factors, and multivariate analysis confirmed that our convenience sample was not representative of the whole IRS-III cohort. In conclusion, although these robust assays provide new opportunities for correlative studies of archival material, our first application illustrates an important limitation of using a convenience sample for molecular-clinical correlative studies.
-
genetic heterogeneity in the alveolar rhabdomyosarcoma subset without typical gene fusions
Cancer Research, 2002Co-Authors: Frederic G Barr, Julia A Bridge, Stephen J Qualman, Michele H Macris, Natalya Melnyk, Elizabeth R Lawlor, Donna Strzelecki, Timothy J Triche, Poul H SorensenAbstract:Previous studies of the PAX3-FKHR and PAX7-FKHR gene fusions in alveolar rhabdomyosarcoma (ARMS) indicated that the corresponding fusiontranscripts are not detectable in 20% of ARMS cases. To investigate the genetic features of this ARMS subset, we identified 23 ARMS cases in which PAX3-FKHR and PAX7-FKHR transcripts were not detected by a standard sensitivity reverse transcription-PCR (RT-PCR) assay. Subsequent analysis with a high sensitivity RT-PCR assay identified low-level expression of PAX3-FKHR or PAX7-FKHR in three cases. Analysis with a Southern blot assay for PAX3 and PAX7 rearrangements and a fluorescence in situ hybridization assay for FKHR rearrangements identified three cases with variant fusions in which PAX3 or PAX7 is postulated to be joined to novel genomic loci. In one such case, RT-PCR analysis of candidate partners identified a fusion of PAX3 to AFX , which is highly similar in structure and function to FKHR . Additional fluorescence in situ hybridization analysis identified two cases in which a PAX3-FKHR or PAX7-FKHR genomic fusion is present but is not associated with a fusion transcript detectable by RT-PCR. Finally, our analyses of the PAX3 , PAX7 , and FKHR loci did not identify rearrangements in >50% of cases, consistent with the possibility that there is a true fusion-negative subset. In summary, our analysis of ARMS cases without characteristic PAX3-FKHR or PAX7-FKHR transcripts identified several genetically distinct subsets including low expression or atypical presentation of standard fusions, variant fusions with other genes, and possibly true fusion-negative cases.
Luan D Truong - One of the best experts on this subject based on the ideXlab platform.
-
PAX2 and PAX8: useful markers for metastatic effusions.
Acta Cytologica, 2013Co-Authors: Lindsay L. Waters, Luan D Truong, Suzanne M. Crumley, Dina R. Mody, Donna CoffeyAbstract:Objective: It was the aim of this study to determine the utility of PAX2 and PAX8 in cytology effusions with metastatic tumor. Study Design:
-
flat pattern of nephrogenic adenoma previously unrecognized pattern unveiled using PAX2 and pax8 immunohistochemistry
Modern Pathology, 2013Co-Authors: Sergio Pinaoviedo, Steven S Shen, Luan D Truong, Jae Y Ro, Alberto G AyalaAbstract:Flat pattern of nephrogenic adenoma: previously unrecognized pattern unveiled using PAX2 and PAX8 immunohistochemistry
-
PAX2 and pax8 expression in primary and metastatic renal tumors a comprehensive comparison
Archives of Pathology & Laboratory Medicine, 2012Co-Authors: Ayhan Ozcan, Steven S Shen, Gustavo De La Roza, Jae Y Ro, Luan D TruongAbstract:Context.—The diagnosis of renal cell carcinoma (RCC) remains problematic, especially in the context of metastasis or small-needle biopsies. PAX2 and PAX8 transcription factors are known to be expressed by several histologic types of renal neoplasms. Objective.—To evaluate the diagnostic utility of PAX2 and PAX8 relative to one another, which has not been studied. Design.—Consecutive tissue sections from the archival samples of 243 primary and 99 metastatic renal neoplasms were submitted to PAX2 and PAX8 immunostain. Results.—Within the primary neoplasms, PAX2 versus PAX8 expression was noted in 90 of 95 (95%) versus 92 of 95 (97%) for clear cell RCC, 29 of 38 (76%) versus 38 of 38 (100%) for papillary RCC, 14 of 25 (56%) versus 22 of 25 (88%) for chromophobe RCC, 3 of 7 (43%) versus 5 of 7 (71%) for collecting duct RCC, 6 of 8 (75%) versus 8 of 8 (100%) for acquired cystic kidney disease–related RCC, and 7 of 13 (54%) versus 11 of 13 (85%) for oncocytoma. Regardless of histologic subtype, PAX8 staining wa...
-
PAX2 and pax8 expression in primary and metastatic mullerian epithelial tumors a comprehensive comparison
The American Journal of Surgical Pathology, 2011Co-Authors: Ayhan Ozcan, Nathan Liles, Donna Coffey, Steven S Shen, Luan D TruongAbstract:: PAX2 and PAX8 are transcription factors that are essential in embryonic development of mullerian organs. They may also play a role in tumor development in these organs. The diagnostic utility of PAX2 and PAX8 relative to one another has not been comprehensively studied. Archival tissue samples for normal or non-neoplastic tissue (251), primary epithelial neoplasms (316 for PAX2 and 357 for PAX8), and metastatic epithelial neoplasms (16), all of mullerian origin, were subjected to PAX2 and PAX8 immunostaining. The staining frequency, extent, and intensity for these markers were compared. Virtually identical PAX2 and PAX8 expressions were noted in non-neoplastic tissue. They were constantly seen in most epithelial cells (but not in stromal cells) of the endocervix, endometrium, fallopian tube, paratubal cyst, endosalpingiosis, endometriosis, and endometrial polyp. Within the primary epithelial neoplasms, PAX2 and PAX8 expression was noted in 55% and 98% of serous tumors, 25% and 94% of endometrioid tumors, 19% and 100% of clear cell tumors, 11% and 67% of transitional/undifferentiated tumors, and 10% and 22% of mucinous tumors, respectively. Regardless of histologic subtypes, PAX2 staining was noted in fewer cells and with less staining intensity compared with PAX8. No tumor showed only PAX2 staining. Within the metastatic carcinomas, PAX2 and PAX8 expression was noted in 38% and 98% of cases, respectively, with a diffuse and strong staining for PAX8, contrasting with a patchy and weak PAX2 expression. PAX2 and PAX8 are constantly expressed in normal or non-neoplastic tissue of mullerian origin. For primary and metastatic mullerian epithelial tumors, PAX8 shows strong and diffuse staining in most cases of all histologic subtypes, except in mucinous tumors. In contrast, PAX2 expression is always less than PAX8, and exclusive staining for PAX2 is not seen. PAX8 supersedes PAX2 as probably the best epithelial marker hitherto for primary or metastatic mullerian epithelial tumors.
Gregory R. Dressler - One of the best experts on this subject based on the ideXlab platform.
-
PAX2 and pax8 proteins regulate urea transporters and aquaporins to control urine concentration in the adult kidney
Journal of The American Society of Nephrology, 2020Co-Authors: Ann M Laszczyk, Atsuko Y Higashi, Sanjeevkumar R Patel, Craig N Johnson, Abdul Soofi, Saji Abraham, Gregory R. DresslerAbstract:BACKGROUND: As the glomerular filtrate passes through the nephron and into the renal medulla, electrolytes, water, and urea are reabsorbed through the concerted actions of solute carrier channels and aquaporins at various positions along the nephron and in the outer and inner medulla. Proliferating stem cells expressing the nuclear transcription factor PAX2 give rise to renal epithelial cells. PAX2 expression ends once the epithelial cells differentiate into mature proximal and distal tubules, whereas expression of the related Pax8 protein continues. The collecting tubules and renal medulla are derived from PAX2-positive ureteric bud epithelia that continue to express PAX2 and Pax8 in adult kidneys. Despite the crucial role of PAX2 in renal development, functions for PAX2 or Pax8 in adult renal epithelia have not been established. METHODS: To examine the roles of PAX2 and Pax8 in the adult mouse kidney, we deleted either PAX2, Pax8, or both genes in adult mice and examined the resulting phenotypes and changes in gene expression patterns. We also explored the mechanism of Pax8-mediated activation of potential target genes in inner medullary collecting duct cells. RESULTS: Mice with induced deletions of both PAX2 and Pax8 exhibit severe polyuria that can be attributed to significant changes in the expression of solute carriers, such as the urea transporters encoded by Slc14a2, as well as aquaporins within the inner and outer medulla. Furthermore, Pax8 expression is induced by high-salt levels in collecting duct cells and activates the Slc14a2 gene by recruiting a histone methyltransferase complex to the promoter. CONCLUSIONS: These data reveal novel functions for Pax proteins in adult renal epithelia that are essential for retaining water and concentrating urine.
-
regulation of c ret in the developing kidney is responsive to PAX2 gene dosage
Human Molecular Genetics, 2006Co-Authors: Jason Clarke, Gregory R. Dressler, Sanjeevkumar R Patel, Richard M Raymond, Scott D Andrew, Bruce G Robinson, Patrick D BrophyAbstract:During kidney development, PAX2 and Pax8 are expressed very early in the mammalian nephric duct and both precede the expression of receptor tyrosine kinase, c-Ret. However, in PAX2 -/- mutant mice, expression of c-Ret is lost after embryonic day 10.5. As the Ret/Gdnf pathway is necessary for renal development and there is a temporal and spatial relationship of PAX2 and c-Ret expression in the developing genito-urinary system, we postulate that PAX2 is necessary for c-Ret expression in the developing kidney. In vitro, PAX2 protein is capable of physically interacting with a c-RET promoter, and both PAX2 and Pax8 can activate the expression of a reporter gene driven by the c-RET promoter. Compound heterozygous null mice (PAX2 +/- : Ret +/- ) display an increased incidence of unilateral and bilateral renal agenesis, and smaller kidneys with fewer nephrons. Furthermore, the expression of Gdnf is reduced 2-3-fold, whereas c-Ret expression is reduced 9-47-fold in PAX2 heterozygous embryonic kidneys as detected by real-time quantitative RT (QRT)-PCR. The data demonstrate that PAX2 plays an integral role in the initiation and maintenance of the Ret/Gdnf pathway by not only activating the ligand of the pathway, but by also enhancing the expression of the pathway receptor Ret. The effects of reduced PAX2 gene dosage are thus amplified resulting in a haploinsufficient phenotype.
-
the secreted frizzled related protein 2 sfrp2 gene is a target of the PAX2 transcription factor
Journal of Biological Chemistry, 2003Co-Authors: Patrick D Brophy, Katherine M Lang, Gregory R. DresslerAbstract:Abstract Despite their essential role in vertebrate development, the function of Pax proteins in gene regulation is not well understood. To identify potential genes regulated by the PAX2 protein, we screened embryonic kidney cells transformed with PAX2-expressing retroviruses for genes activated in response to PAX2 expression. In this system, the gene encoding the secreted frizzled related protein, Sfrp2, was strongly activated in all PAX2b-expressing cells. This activation of Sfrp2 expression correlated with changes in chromatin structure at the Sfrp2 locus, particularly in and around regions of PAX2 binding. Although the amount of PAX2-dependent transactivation was low in transient assays, the data suggests that local alterations of chromatin structure by Pax proteins can greatly enhance expression when presented in the right cellular context.
-
the hmg i y related protein p8 binds to p300 and PAX2 trans activation domain interacting protein to regulate the trans activation activity of the PAX2a and PAX2b transcription factors on the glucagon gene promoter
Journal of Biological Chemistry, 2002Co-Authors: Albrecht Hoffmeister, Gregory R. Dressler, Alejandro Ropolo, Sophie Vasseur, Gustavo V Mallo, Hans Bodeker, Beate Ritzlaser, Maria Ines Vaccaro, Jean Charles Dagorn, Silvia N J MorenoAbstract:Abstract p8 is a nuclear DNA-binding protein, which was identified because its expression is strongly activated in response to several stresses. Biochemical and biophysical studies revealed that despite a weak sequence homology p8 is an HMG-I/Y-like protein, suggesting that p8 may be involved in transcription regulation. Results reported here strongly support this hypothesis. Using a pull-down approach, we found that p8 interacts with the general co-activator p300. We also found that, similar to the HMG proteins, p300 was able to acetylate recombinant p8in vitro, although the significance of such modification remains to be determined. Then a screening by the two-hybrid system, using p8 as bait, allowed us to identify the PAX2trans-activation domain-interacting protein (PTIP) as another partner of p8. Transient transfection studies revealed that PTIP is a strong inhibitor of the trans-activation activities of PAX2A and PAX2B on the glucagon gene promoter, which was chosen as a model because it is a target of the PAX2A and PAX2B transcription factors. This effect is completely abolished by co-transfection of p8 in glucagon-producing InRIG9 cells, indicating that p8 binding to PTIP prevents inhibition of the glucagon gene promoter. This was not observed in NIH3T3 fibroblasts that do not express glucagon. Finally, expression of p8 enhances the effect of p300 on PAX2A and PAX2B trans-activation of the glucagon gene promoter. These observations suggest that in glucagon-producing cells p8 is a positive cofactor of the activation of the glucagon gene promoter by PAX2A and PAX2B, both by recruiting the p300 cofactor to increase the PAX2A and PAX2B activities and by binding the PAX2-interacting protein PTIP to suppress its inhibition.
-
PAX2/5 and Pax6 subdivide the early neural tube into three domains.
Mechanisms of Development, 1999Co-Authors: Martin K. Schwarz, Gonzalo Alvarez-bolado, Gregory R. Dressler, Pavel Urbánek, Meinrad Busslinger, Peter GrussAbstract:Abstract The nested expression patterns of the paired-box containing transcription factors PAX2/5 and Pax6 demarcate the midbrain and forebrain primordium at the neural plate stage. We demonstrate that, in PAX2/5 deficient mice, the mesencephalon/metencephalon primordium is completely missing, resulting in a fusion of the forebrain to the hindbrain. Morphologically, in the alar plate the deletion is characterized by the substitution of the tectum (dorsal midbrain) and cerebellum (dorsal metencephalon) by the caudal diencephalon and in the basal plate by the replacement of the midbrain tegmentum by the ventral metencephalon (pons). Molecularly, the loss of the tectum is demonstrated by an expanded expression of Pax6, (the molecular determinant of posterior commissure), and a rostral shift of the territory of expression of Gbx2 and Otp (markers for the pons), towards the caudal diencephalon. Our results suggest that an intact territory of expression of PAX2/5 in the neural plate, nested between the rostral and caudal territories of expression of Pax6, is necessary for defining the midbrain vesicle.
Meinrad Busslinger - One of the best experts on this subject based on the ideXlab platform.
-
PAX2 and pax8 cooperate in mouse inner ear morphogenesis and innervation
BMC Developmental Biology, 2010Co-Authors: Maxime Bouchard, Meinrad Busslinger, Pinxian Xu, Dominique Crapon De Caprona, Bernd FritzschAbstract:Background PAX2;5;8 transcription factors play diverse roles in vertebrate and invertebrate organogenesis, including the development of the inner ear. Past research has suggested various cochlear defects and some vestibular defects in PAX2 null mice but the details of the cochlear defects and the interaction with other Pax family members in ear development remain unclear.
-
PAX2 8 regulated gata3 expression is necessary for morphogenesis and guidance of the nephric duct in the developing kidney
Development, 2006Co-Authors: David Grote, Meinrad Busslinger, Abdallah Souabni, Maxime BouchardAbstract:The mammalian pro- and mesonephros are transient embryonic kidneys essential for urogenital system development. The nephric (Wolffian) duct, which is a central constituent of both structures, elongates caudally along a stereotypical path to reach the hindlimb level where it induces metanephros (adult kidney) formation, while the remaining duct gives rise to the male genital tract (epidydimis, vas deferens). The transcription factors PAX2 and Pax8 are essential for the initiation of pro- and mesonephros development. In a cDNA microarray screen for genes specifically expressed in the pro/mesonephros and regulated by Pax proteins, we identified Gata3, a transcription factor gene associated with hypoparathyroidism, deafness and renal anomaly (HDR) syndrome. Gata3 is already expressed in the pronephric anlage, together with PAX2 and Pax8, suggesting that it may be a direct PAX2/8 target gene. Inactivation of Gata3 by insertion of an Ires-GFP reporter gene resulted in a massive increase in nephric duct cellularity, which was accompanied by enhanced cell proliferation and aberrant elongation of the nephric duct. Interestingly, however, the nephrogenic cord extended, with delayed kinetics, along the entire caudal path up to the level of the hindlimb bud, indicating that extension of the nephric duct and cord is controlled by different guidance cues. At the molecular level, the nephric duct of Gata3-/- embryos is characterized by the loss of Ret expression and signaling, which may contribute to the guidance defect of the nephric duct. Together, these results define Gata3 as a key regulator of nephric duct morphogenesis and guidance in the pro/mesonephric kidney.
-
Nephric lineage specification by PAX2 and Pax8
Genes & Development, 2002Co-Authors: Maxime Bouchard, Abdallah Souabni, Markus Mandler, Annette Neubuser, Meinrad BusslingerAbstract:Kidney development in mammals and birds proceeds in three successive steps that are all characterized by the mesenchymal-to-epithelial transformation of intermediate mesoderm cells. The development of the first kidney, the transient pronephros, is initiated by signals from the somite and surface ectoderm that induce cells in the intermediate mesoderm to undergo the transition to epithelial cells forming the nephric duct (Obara-Ishihara et al. 1999; Mauch et al. 2000). The caudal migration of the nephric duct subsequently induces the adjacent nephrogenic mesoderm to aggregate and form the tubules of the mesonephros, the second embryonic kidney. On further extension, the nephric duct reaches the metanephrogenic mesenchyme at the level of the developing hindlimb, where the ureteric bud evaginates from the nephric duct and invades the surrounding mesenchyme. Both the ureter and mesenchyme subsequently undergo reciprocal inductive interactions to form the nephrons and collecting ducts of the metanephros, the third and adult kidney. Ultimately, the development of the metanephros therefore depends on the proper formation of the nephric duct during pronephros induction (for review, see Saxen 1987; Vainio and Muller 1997). Targeted mutagenesis in the mouse has identified a multitude of genes that are important for normal kidney development (for review, see Kuure et al. 2000; Davies and Brandli 2002). The majority of these genes are essential for proper morphogenesis of the metanephros with the most severe phenotypes being caused by the inactivation of the transcription factor genes Lim1 (Shawlot and Behringer 1995), WT1 (Kreidberg et al. 1993), and PAX2 (Torres et al. 1995; Favor et al. 1996). Lim1 mutant embryos fail to develop a metanephros and gonads (Shawlot and Behringer 1995), although a nephric duct is initially formed, but then degenerates in the posterior part of the mesonephros (Tsang et al. 2000). The Wilms' tumor suppressor gene WT1 is also necessary for metanephros and gonad development, as the metanephric mesenchyme is unresponsive to inductive signals and undergoes apoptosis in the absence of WT1 function (Kreidberg et al. 1993). The mesonephros, however, still develops in WT1-deficient embryos, although its most caudal tubules fail to form (Sainio et al. 1997). Interestingly, the PAX2 gene is still expressed in the mesonephros of both Lim1 and WT1 mutant embryos (Donovan et al. 1999; Tsang et al. 2000), suggesting that PAX2 acts upstream of these two transcription factors in kidney development. PAX2 is the first known kidney-specific gene to be expressed in the pronephros of the mouse embryo (Bouchard et al. 2000). Despite this early expression, the mesonephric duct is still formed in PAX2-deficient embryos, but then fails to extend to the metanephrogenic mesenchyme because of its rapid degeneration (Torres et al. 1995). As a consequence, the metanephros and genital tracts never develop in PAX2 mutant mice (Torres et al. 1995; Favor et al. 1996). Importantly, however, none of the known gene mutations—including PAX2—interferes with the earliest phase of kidney development, that is, the initial formation of the pro- and mesonephros. Pax8, another member of the PAX2/5/8 family, is also expressed during pro-, meso-, and metanephros development (Plachov et al. 1990; Pfeffer et al. 1998). Surprisingly, kidney organogenesis is normal in Pax8 mutant mice that die postnatally of a defect in thyroid gland development (Mansouri et al. 1998). By gene replacement in the mouse, we have shown recently that the proteins of the PAX2/5/8 family can substitute for each other in development because of their equivalent biochemical function (Bouchard et al. 2000). By analyzing PAX2,Pax8 double-mutant embryos, we now demonstrate that these two transcription factors have redundant functions in kidney development. PAX2 and Pax8 together are required for the formation of the pro- and mesonephros, as the intermediate mesoderm of PAX2−/−Pax8−/− embryos was unable to undergo the initial mesenchymal-epithelial transitions and to express the early kidney-specific genes c-ret and Lim1. In complementary experiments, the retroviral misexpression of PAX2 was sufficient to induce ectopic nephric structures in the intermediate mesoderm and genital ridge of chick embryos. Together, these data demonstrate that PAX2 and Pax8 are both necessary and sufficient for specifying the nephric lineage.
-
nephric lineage specification by PAX2 and pax8
Genes & Development, 2002Co-Authors: Maxime Bouchard, Abdallah Souabni, Markus Mandler, Annette Neubuser, Meinrad BusslingerAbstract:The mammalian kidney develops in three successive steps from the initial pronephros via the mesonephros to the adult metanephros. Although the nephric lineage is specified during pronephros induction, no single regulator, including the transcription factor PAX2 or Pax8, has yet been identified to control this initial phase of kidney development. In this paper, we demonstrate that mouse embryos lacking both PAX2 and Pax8 are unable to form the pronephros or any later nephric structures. In these double-mutant embryos, the intermediate mesoderm does not undergo the mesenchymal-epithelial transitions required for nephric duct formation, fails to initiate the kidney-specific expression of Lim1 and c-Ret, and is lost by apoptosis 1 d after failed pronephric induction. Conversely, retroviral misexpression of PAX2 was sufficient to induce ectopic nephric structures in the intermediate mesoderm and genital ridge of chick embryos. Together, these data identify PAX2 and Pax8 as critical regulators that specify the nephric lineage.
-
functional equivalence of the transcription factors PAX2 and pax5 in mouse development
Development, 2000Co-Authors: Maxime Bouchard, Peter Pfeffer, Meinrad BusslingerAbstract:PAX2 and Pax5 arose by gene duplication at the onset of vertebrate evolution and have since diverged in their developmental expression patterns. They are expressed in different organs of the mouse embryo except for their coexpression at the midbrain-hindbrain boundary (MHB), which functions as an organizing center to control midbrain and cerebellum development. During MHB development, PAX2 expression is initiated prior to Pax5 transcription, and PAX2(−/−) embryos fail to generate the posterior midbrain and cerebellum, whereas Pax5(−/−) mice exhibit only minor patterning defects in the same brain regions. To investigate whether these contrasting phenotypes are caused by differences in the temporal expression or biochemical activity of these two transcription factors, we have generated a knock-in (ki) mouse, which expresses a Pax5 minigene under the control of the PAX2 locus. Midbrain and cerebellum development was entirely rescued in PAX2(5ki/5ki) embryos. Pax5 could furthermore completely substitute for the PAX2 function during morphogenesis of the inner ear and genital tracts, despite the fact that the Pax5 transcript of the PAX2(5ki)allele was expressed only at a fivefold lower level than the wild-type PAX2 mRNA. As a consequence, the PAX2(5ki)allele was able to rescue most but not all PAX2 mutant defects in the developing eye and kidney, both of which are known to be highly sensitive to PAX2 protein dosage. Together these data demonstrate that the transcription factors PAX2 and Pax5 have maintained equivalent biochemical functions since their divergence early in vertebrate evolution.
