BACKGROUND: Glomerular epithelial protein 1 (GLEPP1) is a receptor-like membrane protein tyrosine phosphatase (RPTP) with a large ectodomain consisting of multiple fibronectin type III repeats, a single transmembrane segment, and a single cytoplasmic phosphatase active site sequence. In adult human and rabbit kidneys, GLEPP1 is found exclusively on apical membranes of podocytes and especially on surfaces of foot processes. Although neither ligand nor function for this protein is known, other RPTPs with similar topologies have been implicated in mediating adherence behavior of cells. METHODS: To evaluate potential roles of GLEPP1 further, we cloned the full-length mouse GLEPP1 cDNA and examined its expression patterns in developing kidney by Northern blot analysis, in situ hybridization, and immunofluorescence microscopy. RESULTS: Nucleotide sequencing showed that mouse GLEPP1 was approximately 80% identical to rabbit and human GLEPP1 and approximately 91% identical at the amino acid level. The membrane-spanning and phosphatase domains of mouse GLEPP1 shared> 99% homology with PTPphi, a murine macrophage cytoplasmic phosphatase. Northern analysis identified a single GLEPP1 transcript of approximately 5.5 kb in fetal kidney that became approximately threefold more abundant in adults. In situ hybridization of newborn mouse kidney revealed GLEPP1 mRNA in visceral epithelial cells (developing podocytes) of comma- and S-shaped nephric figures, and expression increased in capillary loop and maturing stage glomeruli. Beginning on embryonic day 14, GLEPP1 protein was first observed on cuboidal podocytes of capillary loop stage glomeruli, but nascent podocytes of earlier comma- and S-shaped nephric figures were negative. At later stages of glomerular maturation, where foot process elongation and interdigitation occurs, GLEPP1 immunolabeling intensified on podocytes and then persisted at high levels in fully developed glomeruli. CONCLUSION: Our findings are consistent with a role for GLEPP1 in mediating and maintaining podocyte differentiation specifically.
BACKGROUND:Glomerular epithelial protein 1 (GLEPP1) is a receptor-like membrane protein tyrosine phosphatase (RPTP) with a large ectodomain consisting of multiple fibronectin type III repeats, a single transmembrane segment, and a single cytoplasmic phosphatase active site sequence. In adult human and rabbit kidneys, GLEPP1 is found exclusively on apical membranes of podocytes and especially on surfaces of foot processes. Although neither ligand nor function for this protein is known, other RPTPs with similar topologies have been implicated in mediating adherence behavior of cells. METHODS: To evaluate potential roles of GLEPP1 further, we cloned the full-length mouseGLEPP1 cDNA and examined its expression patterns in developing kidney by Northern blot analysis, in situ hybridization, and immunofluorescence microscopy. RESULTS: Nucleotide sequencing showed that mouseGLEPP1 was approximately 80% identical to rabbit and humanGLEPP1 and approximately 91% identical at the amino acid level. The membrane-spanning and phosphatase domains of mouseGLEPP1 shared> 99% homology with PTPphi, a murine macrophage cytoplasmic phosphatase. Northern analysis identified a single GLEPP1 transcript of approximately 5.5 kb in fetal kidney that became approximately threefold more abundant in adults. In situ hybridization of newborn mouse kidney revealed GLEPP1 mRNA in visceral epithelial cells (developing podocytes) of comma- and S-shaped nephric figures, and expression increased in capillary loop and maturing stage glomeruli. Beginning on embryonic day 14, GLEPP1 protein was first observed on cuboidal podocytes of capillary loop stage glomeruli, but nascent podocytes of earlier comma- and S-shaped nephric figures were negative. At later stages of glomerular maturation, where foot process elongation and interdigitation occurs, GLEPP1 immunolabeling intensified on podocytes and then persisted at high levels in fully developed glomeruli. CONCLUSION: Our findings are consistent with a role for GLEPP1 in mediating and maintaining podocyte differentiation specifically.
Authors: Dale R Abrahamson; Billy G Hudson; Larysa Stroganova; Dorin-Bogdan Borza; Patricia L St John Journal: J Am Soc Nephrol Date: 2009-05-07 Impact factor: 10.121
Authors: Amy K Mottl; Suma Vupputuri; Shelley A Cole; Laura Almasy; Harald H H Göring; Vincent P Diego; Sandra Laston; Nora Franceschini; Nawar M Shara; Elisa T Lee; Lyle G Best; Richard R Fabsitz; Jean W MacCluer; Jason G Umans; Kari E North Journal: Kidney Int Date: 2008-08-13 Impact factor: 10.612
Authors: Deane S Charba; Roger C Wiggins; Meera Goyal; Bryan L Wharram; Jocelyn E Wiggins; Ellen T McCarthy; Ram Sharma; Mukut Sharma; Virginia J Savin Journal: Am J Physiol Renal Physiol Date: 2009-04-29
Authors: Brooke M Steenhard; Roberto Vanacore; David Friedman; Adrian Zelenchuk; Larysa Stroganova; Kathryn Isom; Patricia L St John; Billy G Hudson; Dale R Abrahamson Journal: PLoS One Date: 2012-12-07 Impact factor: 3.240