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- Lindahl, Emma, et al.
(författare)
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Early transcriptional regulation by C-peptide in freshly isolated rat proximal tubular cells
- 2011
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Ingår i: Diabetes/Metabolism Research Reviews. - : Wiley. - 1520-7552 .- 1520-7560. ; 27:7, s. 697-704
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Clinical studies have shown that proinsulin C-peptide exerts renoprotective effects in type 1 diabetes, although the underlying mechanisms are poorly understood. As C-peptide has been shown to induce several intracellular events and to localize to nuclei, we aimed to determine whether gene transcription is affected in proximal tubular kidney cells, and if so, whether genes with altered transcription include those related to protective mechanisms. METHODS: The effect of C-peptide incubation (2h) on gene expression was investigated in freshly isolated proximal tubular cells from streptozotocin-diabetic Sprague-Dawley rats using global gene expression profiling and RT-qPCR. Protein expression was assayed using western blotting. Different bioinformatic strategies were employed. RESULTS: Gene transcription profiling demonstrated differential transcription of 492 genes (p<0.01) after 2h of C-peptide exposure, with the majority of these genes repressed (83%). RT-qPCR validation supported a trend of several GPCR's being activated, and certain transcription factors to be repressed. Also, C-peptide repressed the transcription of genes associated with pathways of circulatory and inflammatory diseases. CONCLUSIONS: This study shows that C-peptide exerts early effects on gene transcription in proximal tubular cells. The findings also bring further knowledge to the renoprotective mechanisms of C-peptide in type I diabetes, and supports a transcriptional activity for C-peptide. It is suggested that C-peptide may play a regulatory role in the gene expression of proximal tubular cells.
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| 2. |
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| 3. |
- Palm, Fredrik, et al.
(författare)
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Renal oxidative stress, oxygenation and hypertension
- 2011
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 301:5, s. R1229-R1241
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Tidskriftsartikel (refereegranskat)abstract
- Hypertension is closely associated with progressive kidney dysfunction, manifested as glomerulosclerosis, interstitial fibrosis, proteinuria and eventually declining glomerular filtration. The postulated mechanism for development of glomerulosclerosis is barotrauma caused by increased capillary pressure, but the reason for development of interstitial fibrosis and the subsequently reduced kidney function is less clear. However, it has been hypothesized that tissue hypoxia induces fibrogenesis and progressive renal failure. This is very interesting, since recent reports highlight several different mechanisms resulting in altered oxygen handling and availability in the hypertensive kidney. Such mechanisms include decreased renal blood flow due to increased vascular tone induced by angiotensin II that limits oxygen delivery, increased oxidative stress resulting in increased mitochondrial oxygen usage, increased oxygen usage for tubular electrolyte transport and shunting of oxygen from arterial to venous blood in preglomerular vessels. It has been shown in several studies that interventions to prevent oxidative stress and to restore kidney tissue oxygenation prevent progression of kidney dysfunction. Furthermore, inhibition of angiotensin II activity, by either blocking AT(1)-receptors or angiotensin converting enzyme, or by preventing oxidative stress by administration of antioxidants also results in improved blood pressure control. It therefore seems likely that tissue hypoxia in the hypertensive kidney contributes to progression of kidney damage and perhaps also maintaining the high blood pressure.
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| 4. |
- Palm, Fredrik, et al.
(författare)
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Renal tubulointerstitial hypoxia : Cause and consequence of kidney dysfunction
- 2011
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Ingår i: Clinical and experimental pharmacology & physiology. - : Wiley. - 0305-1870 .- 1440-1681. ; 38:7, s. 424-430
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Tidskriftsartikel (refereegranskat)abstract
- 1. Intrarenal oxygen availability is the balance between supply, mainly dependent on renal blood flow, and demand, determined by the basal metabolic demand and the energy-requiring tubular electrolyte transport. Renal blood flow is maintained within close limits in order to sustain stable glomerular filtration, so increased intrarenal oxygen consumption is likely to cause tissue hypoxia.2. The increased oxygen consumption is closely linked to increased oxidative stress, which increases mitochondrial oxygen usage and reduces tubular electrolyte transport efficiency, with both contributing to increased total oxygen consumption.3. Tubulointerstitial hypoxia stimulates the production of collagen I and alpha-smooth muscle actin, indicators of increased fibrogenesis. Furthermore, the hypoxic environment induces epithelial-mesenchymal transdifferentiation and aggravates fibrosis, which results in reduced peritubular blood perfusion and oxygen delivery due to capillary rarefaction.4. Increased oxygen consumption, capillary rarefaction and increased diffusion distance due to the increased fibrosis per se further aggravate the interstitial hypoxia.5. Recently, it has been demonstrated that hypoxia simulates the infiltration and maturation of immune cells, which provides an explanation for the general inflammation commonly associated with the progression of chronic kidney disease. 6. Therapies targeting interstitial hypoxia could potentially reduce the progression of chronic renal failure in millions of patients who are otherwise likely to eventually present with fully developed end-stage renal disease.
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