Effects of general receptor for phosphoinositides 1 on insulin and insulin-like growth factor I-induced cytoskeletal rearrangement, glucose transporter-4 translocation, and deoxyribonucleic acid synthesis

Martin Clodi, Peter Vollenweider, Jes Klarlund, Naoki Nakashima, Stuart Martin, Michael P. Czech, Jerrold M. Olefsky

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

We investigated the effects of general receptor for phosphoinositides-1 (GRP1), a recently cloned protein that binds 3,4,5-phosphatidylinositol [PtdIns(3,4,5)P3] with high affinity, but not PtdIns(3,4)P2 nor PtdIns(3)P, on insulin and insulin-like growth factor I (IGF-I)-induced cytoskeletal rearrangement, glucose transporter-4 (GLUT4) translocation, and DNA synthesis. GRP1 consists of an NH2-terminally located coiled coil domain followed by a Sec7 domain and a COOH-terminal pleckstrin homology (PH) domain that is required for PtdIns binding. We used microinjection of glutathione- S-transferase fusion proteins containing residues 239-399 (PH domain), residues 52-260 (Sec7 domain), residues 5-71 (N-terminal domain), full- length GRP1, and an antibody (AB) raised against full-length GRP1 coupled with immunofluorescent detection of actin filament rearrangement, GLUT4 translocation, and 3'-bromo-5'-deoxyuridine incorporation. Microinjection of these constructs and the AB had no effect on insulin-induced GLUT4 translocation or DNA synthesis. However, microinjection of the GRP1-PH and the GRP1-Sec7 domain as well as the α-GRP1-AB significantly inhibited insulin- and IGF-I-stimulated actin rearrangement in an insulin receptor- overexpressing cell line (HIRcB) compared with that in control experiments. Coinjection of GRP1-Sec7 along with constitutively active Rac (Q67L) did not inhibit Rac-induced actin rearrangement. Furthermore, GRP1 is not able to bind and act as a nucleotide exchange factor for the small GTP-binding proteins of the Rho family. As GRP1 acts as a guanine nucleotide exchange factor for ARF6 proteins, we propose a signaling pathway distinct from the small GTP-binding protein Rac, connecting PtdIns(3,4,5)P3 via GRP1 to ARF6, leading to insulin- and IGF-I-induced actin rearrangement.

Original languageEnglish
Pages (from-to)4984-4990
Number of pages7
JournalEndocrinology
Volume139
Issue number12
DOIs
Publication statusPublished - Jan 1 1998
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Endocrinology

Fingerprint Dive into the research topics of 'Effects of general receptor for phosphoinositides 1 on insulin and insulin-like growth factor I-induced cytoskeletal rearrangement, glucose transporter-4 translocation, and deoxyribonucleic acid synthesis'. Together they form a unique fingerprint.

  • Cite this