Rin1 regulates insulin receptor signal transduction pathways

• Published in: Experimental cell research Vol. 312; no. 7; pp. 1106 - 1118
• Main Authors: Hunker, C.M., Giambini, H., Galvis, A., Hall, J., Kruk, I., Veisaga, M.L., Barbieri, M.A.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 15-04-2006; Elsevier BV
• Subjects: Cell Line; Cell Proliferation; Consensus Sequence; Endocytosis - physiology; Extracellular Signal-Regulated MAP Kinases - metabolism; Genetic Vectors; Humans; Insulin receptor; Intracellular Signaling Peptides and Proteins - genetics; Intracellular Signaling Peptides and Proteins - physiology; Proto-Oncogene Proteins c-akt - metabolism; Ras; Receptor, Insulin - metabolism; Retroviridae; Rin1; Signal transduction; Signal Transduction - physiology; Transduction, Genetic; Erk1/2; IGF-I; Ras; EGF; p38k; JNK; GEF; IR; IRS; GFP; Signal transduction; PI3K; Rin1; Insulin receptor
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1016/j.yexcr.2005.12.021

Rin1 is a multifunctional protein containing several domains, including Ras binding and Rab5 GEF domains. The role of Rin1 in insulin receptor internalization and signaling was examined by expressing Rin1 and deletion mutants in cells utilizing a retrovirus system. Here, we show that insulin-receptor-mediated endocystosis and fluid phase insulin-stimulated endocytosis are enhanced in cells expressing the Rin1:wild type and the Rin1:C deletion mutant, which contain both the Rab5-GEF and GTP-bound Ras binding domains. However, the Rin1:N deletion mutant, which contains both the SH
2 and proline-rich domains, blocked insulin-stimulated receptor-mediated and insulin-stimulated fluid phase endocytosis. In addition, the expression of Rin1:Δ (429–490), a natural occurring splice variant, also blocked both receptor-mediated and fluid phase endocystosis. Furthermore, association of the Rin1 SH
2 domain with the insulin receptor was dependent on tyrosine phosphorylation of the insulin receptor. Morphological analysis indicates that Rin1 co-localizes with insulin receptor both at the cell surface and in endosomes upon insulin stimulation. Interestingly, the expression of Rin1:wild type and both deletion mutants blocks the activation of Erk1/2 and Akt1 kinase activities without affecting either JN or p38 kinase activities. DNA synthesis and Elk-1 activation are also altered by the expression of Rin1:wild type and the Rin1:C deletion mutant. In contrast, the expression of Rin1:Δ stimulates both Erk1/2 and Akt1 activation, DNA synthesis and Elk-1 activation. These results demonstrate that Rin1 plays an important role in both insulin receptor membrane trafficking and signaling.