Uptake of leptin and albumin via separate pathways in proximal tubule cells |
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| Institution: | 1. Centre For Chronic Disease, College of Health and Biomedicine, Victoria University, St. Albans, VIC 3021, Australia;2. Department of Physiology, The University of Melbourne, Parkville, Melbourne, VIC 3010, Australia;3. School of Medical Sciences, The Bosch Institute, The University of Sydney, NSW 2006, Australia;1. Department of Pharmacy and Pharmacology, Faculty of Health Sciences, University of the Witwatersrand, 7 York Road, Parktown, 2193, South Africa;2. Department of Pharmaceutical Sciences, Faculty of Sciences, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa;3. Department of Pharmaceutical Sciences, SAMRC Herbal Drugs Research Unit, Tshwane University of Technology, Private Bag X680, Pretoria, 0001, South Africa;1. Department of Transplantation Medicine, Nephrology and Internal Medicine, Medical University of Warsaw, Warsaw, Poland;2. Department of Nephrology, Kidney Transplantation, and Arterial Hypertension, Children''s Memorial Health Institute, Warsaw, Poland;3. Department of General and Endocrinological Surgery, Medical University of Warsaw, Warsaw, Poland;4. Department of General, Vascular and Transplant Surgery, Medical University of Warsaw, Warsaw, Poland;1. Laboratoire de Génétique Moléculaire Humaine, Faculté de Médecine de Sfax, Université de Sfax, Tunisia;2. ISBS (Institut Supérieur de Biotechnologie de Sfax), Sfax, Tunisia;3. CBS (Centre de Biotechnologie de Sfax), Sfax, Tunisia |
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| Abstract: | The adipokine leptin and oncotic protein albumin are endocytosed in the proximal tubule via the scavenger receptor megalin. Leptin reduces megalin expression and activates cell signalling pathways that upregulate fibrotic protein expression. The aim of this study was to investigate if leptin uptake in proximal tubule cells was via the albumin-megalin endocytic complex. In immortalised proximal tubule Opossum kidney cells (OK) fluorescent leptin and albumin co-localised following 5 min exposure, however there was no co-localisation at 10, 20 and 30 min exposure. In OK cells, acute exposure to leptin for 2 h did not alter NHE3, ClC-5, NHERF1 and NHERF2 mRNA. However, acute leptin exposure increased NHERF2 protein expression in proximal tubule cells. In OK cells, immunoprecipitation experimentation indicated leptin did not bind to ClC-5. Leptin uptake in OK cells was enhanced by bafilomycin and ammonium chloride treatment, demonstrating that uptake was not dependent on lysosomal pH. Thus, it is likely that two pools of megalin exist in proximal tubule cells to facilitate separate uptake of leptin and albumin by endocytosis. |
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| Keywords: | Leptin Albumin Proximal tubule Megalin NHERF2 |
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