Alport syndrome is a common disorder that results in progressive kidney disease, and is occasionally associated with hearing loss and eye defects. The most common form of Alport syndrome is inherited as an X-linked trait (XAS), and is due to mutations in the alpha5 chain, one of six genetically distinct isoforms of type IV collagen. Rare autosomal recessive forms of the disease also exist, and are due to mutations in the alpha3 or alpha4 chains of type IV collagen. Type IV collagen is a major component of the glomerular basement membrane (GBM) and is predominantly composed of alpha3, alpha4 and alpha5 isoforms of type IV collagen. Mutations in any one of these isoforms in Alport syndrome leads to an absence of all three isoforms from the GBM of these patients, making their membranes more susceptible to breakdown by proteases. These results suggest a molecular association between the three isoforms in the kidney GBM. In the first part of this proposal we plan to study the relationship between the structure of GBM type IV collagen and the turnover of this membrane in Alport syndrome, using human Alport kidneys and kidneys from mice with Alport-like disease. These studies will determine the structural organization of type IV collagen in the human GBM and how such organized networks are altered by mutations in Alport syndrome. In the second part of this proposal, we will identify specific populations of NC1 hexamer in the human GBM and how mutations in Alport syndrome effect their assembly. We will use recombinant NC1 domains of alpha3, alpha4 and alpha5 chains produced in NIH 3T3 cells for in vitro hexamer assembly experiments. The role of mutated alpha3 chain in the in vivo assembly of GBM type IV collagen will be evaluated in transgenic mice. Lastly, the role of alpha5 chain (X-linked Alport gene) will be studied in mice, made deficient for this gene by gene targeting technology. These mice will be valuable in understanding the molecular events leading to defects in the Alport GBM due to mutations in the alpha5 chain. Successful completion of this project will determine the role of type IV collagen in the GBM turnover and identify molecular parameters for the assembly of type IV collagen NC1 hexamer which turns defective in Alport syndrome. A consideration of the differential sensitivity of GBM in XAS to degradation might perhaps at some point lead to therapeutic trials with new generation protease inhibitors now emerging for clinical use.

National Institute of Health (NIH)
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Research Project (R01)
Project #
Application #
Study Section
General Medicine B Study Section (GMB)
Program Officer
Hirschman, Gladys H
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Beth Israel Deaconess Medical Center
United States
Zip Code
Cleland, Timothy P; Schroeter, Elena R; Zamdborg, Leonid et al. (2015) Mass Spectrometry and Antibody-Based Characterization of Blood Vessels from Brachylophosaurus canadensis. J Proteome Res 14:5252-62
Lovisa, Sara; LeBleu, Valerie S; Tampe, Björn et al. (2015) Epithelial-to-mesenchymal transition induces cell cycle arrest and parenchymal damage in renal fibrosis. Nat Med 21:998-1009
Zeisberg, Michael; Tampe, Björn; LeBleu, Valerie et al. (2014) Thrombospondin-1 deficiency causes a shift from fibroproliferative to inflammatory kidney disease and delays onset of renal failure. Am J Pathol 184:2687-98
Özdemir, Berna C; Pentcheva-Hoang, Tsvetelina; Carstens, Julienne L et al. (2014) Depletion of carcinoma-associated fibroblasts and fibrosis induces immunosuppression and accelerates pancreas cancer with reduced survival. Cancer Cell 25:719-34
Kahlert, Christoph; Melo, Sonia A; Protopopov, Alexei et al. (2014) Identification of double-stranded genomic DNA spanning all chromosomes with mutated KRAS and p53 DNA in the serum exosomes of patients with pancreatic cancer. J Biol Chem 289:3869-75
Melo, Sonia A; Sugimoto, Hikaru; O'Connell, Joyce T et al. (2014) Cancer exosomes perform cell-independent microRNA biogenesis and promote tumorigenesis. Cancer Cell 26:707-21
Charytan, David M; Padera, Robert; Helfand, Alexander M et al. (2014) Increased concentration of circulating angiogenesis and nitric oxide inhibitors induces endothelial to mesenchymal transition and myocardial fibrosis in patients with chronic kidney disease. Int J Cardiol 176:99-109
Carstens, Julienne L; Lovisa, Sara; Kalluri, Raghu (2014) Microenvironment-dependent cues trigger miRNA-regulated feedback loop to facilitate the EMT/MET switch. J Clin Invest 124:1458-60
Ayala de la Peña, Francisco; Kanasaki, Keizo; Kanasaki, Megumi et al. (2014) Specific activation of K-RasG12D allele in the bladder urothelium results in lung alveolar and vascular defects. PLoS One 9:e95888
Tampe, Björn; Tampe, Desiree; Müller, Claudia A et al. (2014) Tet3-mediated hydroxymethylation of epigenetically silenced genes contributes to bone morphogenic protein 7-induced reversal of kidney fibrosis. J Am Soc Nephrol 25:905-12

Showing the most recent 10 out of 122 publications