Proteinuria is associated with progressive chronic kidney disease. It is well known that exposure of proximal tubular epithelial (PTEC) cells to large amounts of albumin leads to the development of tubular atrophy and fibrosis. However, the possible pathogenic role of albumin in this process has not been fully elucidated. Development of new therapeutic tools to prevent or slow the progression of proteinuric chronic kidney disease requires clear understanding of the effect of proteinuria on tubular cell function. We propose that exposure of PTEC to albumin inhibits autophagy, a critical cellular function responsible for turnover of cellular macromolecules and organelles, including dysfunctional mitochondria. Our hypothesis is that albumin impairs autophagy by one of the following mechanisms: (a) stimulating albumin receptor-mediated signaling events; (b) up-regulating mTOR, a potent autophagy inhibitor; or (c) causing lysosomal dysfunction or inhibition of autophagosomal-lysosomal fusion which, in turn, inhibits autophagy. We hypothesize that experimental inhibition of autophagy by albumin overload or by knockdown of crucial autophagic proteins will result in accumulation of dysfunctional mitochondria leading to increased production of reactive oxygen species. The resulting oxidative damage increases the permeability and depolarization of the mitochondrial membrane and facilitates the leakage of intramitochondrial components such as cytochrome c and AIF, pro-apoptotic proteins that promote cell death. In in vivo experiments, proteinuria will be correlated with autophagy, ROS production, PTEC apoptosis, tubular atrophy, fibrosis and organ function. We will use Ins2Akita/+, a diabetic mouse model that develops proteinuria, interstitial fibrosis, tubular dysfunction and atrophy. We will also test if pharmacologic up-regulation of autophagy ameliorates proteinuria-induced changes in the proximal tubule. By investigating the possible signal transduction cascades that impair autophagy, this proposal will improve our understanding of the pathogenic role of albumin in proteinuric states, an established cause of progressive chronic kidney disease, and will investigate the novel role of autophagy stimulators in ameliorating progressive organ failure. Mastering the new principles and techniques presented in this proposal is essential for my scientific development and future research productivity. They will complement my previous experiences in the lab, permit me to lay down the foundation of a unique area of research and help me make a significant contribution to the depth and breadth of research in the field of proteinuric kidney diseases. I believe that this NIH mentored award will promote my scientific maturity and allow me to transition to a level that will make me competitive for independent research support.

Public Health Relevance

Proteinuria is associated with progressive chronic kidney disease which affects more that 20 million Americans. Exposure of renal proximal tubular epithelial cells to large amounts of albumin leads to the development of tubular atrophy and fibrosis which in turn results in end stage renal failure; however, the possible pathogenic role of albumin in this process is not fully elucidated. Exploring the presently unknown pathophysiologic processes in proteinuric kidney disease can lead to the development of new therapeutic tools to prevent or slow the progression to chronic kidney failure.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Clinical Investigator Award (CIA) (K08)
Project #
5K08DK090143-05
Application #
8848810
Study Section
Diabetes, Endocrinology and Metabolic Diseases B Subcommittee (DDK)
Program Officer
Rankin, Tracy L
Project Start
2011-07-15
Project End
2016-04-30
Budget Start
2015-05-01
Budget End
2016-04-30
Support Year
5
Fiscal Year
2015
Total Cost
$149,278
Indirect Cost
$11,058
Name
Boston Medical Center
Department
Type
DUNS #
005492160
City
Boston
State
MA
Country
United States
Zip Code
02118
Havasi, Andrea; Doros, Gheorghe; Sanchorawala, Vaishali (2018) Predictive value of the new renal response criteria in AL amyloidosis treated with high dose melphalan and stem cell transplantation. Am J Hematol 93:E129-E132
Prokaeva, Tatiana; Akar, Harun; Spencer, Brian et al. (2017) Hereditary Renal Amyloidosis Associated With a Novel Apolipoprotein A-II Variant. Kidney Int Rep 2:1223-1232
Havasi, Andrea; Lu, Weining; Cohen, Herbert T et al. (2017) Blocking peptides and molecular mimicry as treatment for kidney disease. Am J Physiol Renal Physiol 312:F1016-F1025
Nolin, Angela C; Mulhern, Ryan M; Panchenko, Maria V et al. (2016) Proteinuria causes dysfunctional autophagy in the proximal tubule. Am J Physiol Renal Physiol 311:F1271-F1279
Menn-Josephy, Hanni; Lee, Carol S; Nolin, Angela et al. (2016) Renal Interstitial Fibrosis: An Imperfect Predictor of Kidney Disease Progression in Some Patient Cohorts. Am J Nephrol 44:289-299
Havasi, Andrea; Dong, Zheng (2016) Autophagy and Tubular Cell Death in the Kidney. Semin Nephrol 36:174-88
Havasi, Andrea; Stern, Lauren; Lo, Stephen et al. (2016) Validation of new renal staging system in AL amyloidosis treated with high dose melphalan and stem cell transplantation. Am J Hematol 91:E458-60
Stern, Lauren; Havasi, Andrea (2015) Renal transplantation in amyloidosis and MIDD. Front Biosci (Elite Ed) 7:149-57
Gall, Jonathan M; Wang, Zhiyong; Bonegio, Ramon G et al. (2015) Conditional knockout of proximal tubule mitofusin 2 accelerates recovery and improves survival after renal ischemia. J Am Soc Nephrol 26:1092-102
Siriwardana, Nirodhini S; Meyer, Rosana; Havasi, Andrea et al. (2014) Cell cycle-dependent chromatin shuttling of HBO1-JADE1 histone acetyl transferase (HAT) complex. Cell Cycle 13:1885-901

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