Regulation of Megalin Expression in Cultured Proximal Tubule Cells by Angiotensin II Type 1A Receptor- and Insulin-Mediated Signaling Cross Talk
| Autor: | Hideyuki Kabasawa, Keiko Yamamoto, Ryohei Kaseda, Tetsuro Takeda, Asako Kobayashi, Hiroyoshi Sato, Thomas J. Thekkumkara, Michihiro Hosojima, Yoshiki Suzuki, Kenji Ikuyama, Noriaki Iino, Aya Takeyama, Taeko Soma, Akiyo Suzuki, Fumitake Gejyo, Akihiko Saito, Akira Nishiyama |
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| Rok vydání: | 2009 |
| Předmět: |
MAPK/ERK pathway
medicine.medical_specialty Angiotensin receptor Insulin Receptor Substrate Proteins urologic and male genital diseases Models Biological Receptor Angiotensin Type 1 Kidney Tubules Proximal Phosphatidylinositol 3-Kinases Endocrinology Internal medicine Insulin receptor substrate medicine Animals Insulin RNA Messenger Extracellular Signal-Regulated MAP Kinases Cells Cultured biology Chemistry Angiotensin II Receptor Cross-Talk LRP2 Endocytosis Rats Low Density Lipoprotein Receptor-Related Protein-2 Insulin receptor Gene Expression Regulation biology.protein Signal transduction Signal Transduction |
| Zdroj: | Endocrinology. 150:871-878 |
| ISSN: | 1945-7170 0013-7227 |
| Popis: | Impairment of proximal tubular endocytosis of glomerular-filtered proteins including albumin results in the development of proteinuria/albuminuria in patients with chronic kidney disease. However, the mechanisms regulating the proximal tubular function are largely unknown. This study aimed to investigate the role of angiotensin II type 1A receptor (AT1AR)- and insulin-mediated signaling pathways in regulating the expression of megalin, a multiligand endocytic receptor in proximal tubule cells (PTCs). Opossum kidney PTC-derived OK cells that stably express rat AT1AR but are deficient in endogenous angiotensin II receptors (AT1AR-OK cells) were used for this study. Treatment of the cells with angiotensin II suppressed mRNA and protein expression of megalin at 3- and 24-h incubation time points, respectively. Cellular uptake and degradation of albumin and receptor-associated protein, megalin’s endocytic ligands were suppressed 24 h after angiotensin II treatment. The AT1AR-mediated decrease in megalin expression was partially prevented by ERK inhibitors. Insulin competed with the AT1AR-mediated ERK activation and decrease in megalin expression. Inhibitors of phosphatidylinositol 3-kinase (PI3K), a major component of insulin signaling, also suppressed megalin expression, and activation of the insulin receptor substrate (IRS)/PI3K system was prevented by angiotensin II. Collectively the AT1AR-mediated ERK signaling is involved in suppressing megalin expression in the OK cell line, and insulin competes with this pathway. Conversely, the insulin-IRS/PI3K signaling, with which angiotensin II competes, tends to stimulate megalin expression. In conclusion, there is AT1AR- and insulin-mediated competitive signaling cross talk to regulate megalin expression in cultured PTCs.Angiotensin II type 1A receptor- and insulin-mediated competitive signaling cross-talk regulates the expression of megalin, a multi-ligand endocytic receptor, in cultured proximal tubule cells. |
| Databáze: | OpenAIRE |
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