Growth Hormone Induces Transforming Growth Factor-Beta-Induced Protein in Podocytes: Implications for Podocyte Depletion and Proteinuria.
The glomerular podocytes form a major size selective barrier for the filtration of serum proteins and reduced podocyte number is a critical event in the pathogenesis of proteinuria during diabetic nephropathy (DN). An elevated level of growth hormone (GH) is implicated as a causative factor in the development of nephropathy in patients with type 1 diabetes mellitus. We have previously shown that podocytes express GH receptor and are a target for GH action. To elucidate the molecular basis for the effects of GH on podocyte depletion, we conducted PCR-array analyses for extracellular matrix and adhesion molecules in podocytes. Our studies reveal that GH increases expression of a gene that encodes transforming growth factor-beta-induced protein (TGFBIp) expression. Similarly, microarray data retrieved from the Nephromine database revealed elevation of TGFBIp in patients with DN. Treatment with GH results in increased secretion of extracellular TGFBIp by podocytes. Both GH and TGFBIp induced apoptosis and epithelial mesenchymal transition (EMT) of podocytes. Exposure of podocytes to GH and TGFBIp resulted in increased migration of cells and altered podocyte permeability to albumin across podocyte monolayer. Administration of GH to rats induced EMT and apoptosis in the glomerular fraction of the kidney. Therefore, we conclude that the GH-dependent increase in TGFBIp in the podocyte is one of the mechanisms responsible for podocyte depletion in DN.
National Institute of Nutrition, Hyderabad, India.
P Swathi
PS
Chitra
National Institute of Nutrition, Hyderabad, India.
T
T
Swathi
Osmania General Hospital, Hyderabad, India.
Rakesh
R
Sahay
National Institute of Nutrition, Hyderabad, India.
G Bhanuprakash
GB
Reddy
Pediatric Endocrinology and Molecular and Integrative Physiology, University of Michigan, Ann Arbor, MI.
Ram K
RK
Menon
Department of Biochemistry, University of Hyderabad, Hyderabad, India.
P Anil
PA
Kumar
D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D002465:Cell Movement; D003928:Diabetic Nephropathies / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D004195:Disease Models, Animal; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D013006:Growth Hormone / Q000008:administration & dosage* / Q000494:pharmacology; D006801:Humans; D051379:Mice; D050199:Podocytes / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051381:Rats; D017208:Rats, Wistar; D012709:Serum Albumin / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000235:genetics* / Q000378:metabolism*; D015854:Up-Regulation; D000099222:betaIG-H3 Protein
D016326:Extracellular Matrix Proteins; D013006:Growth Hormone; D012709:Serum Albumin; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein
E-cadherin; TGFBIp; Zeb2; growth hormone; podocytes