Diabetic nephropathy (DN) affects around 40% of diabetic patients worldwide and has become a major health concern due to its high morbidity and mortality. The progression of DN is characterized by the thickening of glomerular basement membrane, albuminuria and the development of glomerulosclerosis. Renal function is eventually compromised. Due to various hemodynamic and metabolic changes, especially the elevated blood glucose level in diabetic patients, glomerular mesangial cells have been shown to upregulate transforming growth factor-β1 (TGF-β1) level and signaling, resulting in the excessive production of extracellular matrix (ECM) proteins. The atypical expression of the 78-kDa glucose-regulated protein (GRP78) on the cell surface may be associated with this pro-fibrotic effect through its interaction with the TGF-β1 activation process. However, there is no current literature demonstrating the role of cell surface GRP78 (csGRP78) in the pathogenesis of diabetic renal diseases. The purpose of my MSc project was to determine the role of csGRP78 in TGF-β1 synthesis and activation and thereby in the progression of DN. We hypothesized that the increased expression of csGRP78 in response to high glucose exposure stimulates TGF-β1 upregulation through intracellular signaling, as well as its activation through interaction with the latent complex, which leads to the expansion of mesangial matrix. / Thesis / Master of Science (MSc) / Diabetic kidney disease affects around 40% of diabetic patients worldwide and is a major health concern. A major feature of the disease is glomerulosclerosis, which is the scarring of glomeruli. The glomeruli filter blood passing through blood vessels in the kidneys to remove waste, which will then be excreted into urine. In diabetic patients, high blood glucose causes the fibrosis of glomeruli and damages the filtration barrier. As a result, a large amount of proteins leak from the blood into the urine. It has been discovered that TGF-β1 is one of the key molecules mediating the generation of scar tissue in the glomerulus. It promotes the growth of mesangial cells, a major type of kidney glomerular cells, and stimulates their production of extracellular matrix proteins. Our results showed that GRP78, a protein that is primarily expressed in the endoplasmic reticulum and assists with protein folding, moves from the inside of cells to the surface in response to a high glucose environment. Here, we found that it facilitated TGF-β1 signaling. Based on our studies, we propose that when GRP78 is at the cell surface, it enables the release of latent TGF-β1, increasing TGF-β1 activity and thus promoting the development of disease.
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/23489 |
| Date | January 2018 |
| Creators | Zheng, Mengyu |
| Contributors | Krepinsky, Joan, Medicine |
| Source Sets | McMaster University |
| Language | English |
| Detected Language | English |
| Type | Thesis |
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