scholarly journals Cdc42hs Facilitates Cytoskeletal Reorganization and Neurite Outgrowth by Localizing the 58-Kd Insulin Receptor Substrate to Filamentous Actin

2001 ◽  
Vol 152 (3) ◽  
pp. 579-594 ◽  
Author(s):  
Sheila Govind ◽  
Robert Kozma ◽  
Clinton Monfries ◽  
Louis Lim ◽  
Sohail Ahmed
Keyword(s):  
Insulin Receptor ◽  
Binding Site ◽  
Neurite Outgrowth ◽  
Adaptor Proteins ◽  
Cytoskeletal Reorganization ◽  
Filamentous Actin ◽  
3T3 Cells ◽  
Insulin Receptor Tyrosine Kinase ◽  
Interaction Sites ◽  
Swiss 3T3

Cdc42Hs is involved in cytoskeletal reorganization and is required for neurite outgrowth in N1E-115 cells. To investigate the molecular mechanism by which Cdc42Hs regulates these processes, a search for novel Cdc42Hs protein partners was undertaken by yeast two-hybrid assay. Here, we identify the 58-kD substrate of the insulin receptor tyrosine kinase (IRS-58) as a Cdc42Hs target. IRS-58 is a brain-enriched protein comprising at least four protein–protein interaction sites: a Cdc42Hs binding site, an Src homology (SH)3-binding site, an SH3 domain, and a tryptophan, tyrptophan (WW)-binding domain. Expression of IRS-58 in Swiss 3T3 cells leads to reorganization of the filamentous (F)-actin cytoskeleton, involving loss of stress fibers and formation of filopodia and clusters. In N1E-115 cells IRS-58 induces neurite outgrowth with high complexity. Expression of a deletion mutant of IRS-58, which lacks the SH3- and WW-binding domains, induced neurite extension without complexity in N1E-115 cells. In Swiss 3T3 cells and N1E-115 cells, IRS-58 colocalizes with F-actin in clusters and filopodia. An IRS-581267N mutant unable to bind Cdc42Hs failed to localize with F-actin to induce neurite outgrowth or significant cytoskeletal reorganization. These results suggest that Cdc42Hs facilitates cytoskeletal reorganization and neurite outgrowth by localizing protein complexes via adaptor proteins such as IRS-58 to F-actin.

scholarly journals Novel proliferative effect of phospholipase A2 in Swiss 3T3 cells via specific binding site.

1991 ◽  
Vol 266 (29) ◽  
pp. 19139-19141
Author(s):  
H. Arita ◽  
K. Hanasaki ◽  
T. Nakano ◽  
S. Oka ◽  
H. Teraoka ◽  
...  
Keyword(s):  
Phospholipase A2 ◽  
Binding Site ◽  
Specific Binding ◽  
3T3 Cells ◽  
Proliferative Effect ◽  
Swiss 3T3

Differential effect of pp120 on insulin endocytosis by two variant insulin receptor isoforms

1997 ◽  
Vol 273 (4) ◽  
pp. E801-E808 ◽  
Author(s):  
Sergio Li Calzi ◽  
Curtis V. Choice ◽  
Sonia M. Najjar
Keyword(s):  
Insulin Receptor ◽  
3T3 Cells ◽  
Insulin Receptor Tyrosine Kinase ◽  
Α Subunit ◽  
3T3 Fibroblasts ◽  
Receptor Isoforms ◽  
Insulin Receptor Isoforms ◽  
Exon 11 ◽  
Isoform B ◽  
Nih 3T3

The insulin receptor is expressed as two variably spliced isoforms that differ by the absence (isoform A) or presence (isoform B) of a 12-amino acid sequence encoded by exon 11 at the carboxy terminus of the α-subunit. Coexpression of the A isoform and pp120, a substrate of the insulin receptor tyrosine kinase, in NIH 3T3 fibroblasts increased receptor A-mediated insulin endocytosis and degradation by two- to threefold compared with cells expressing receptors alone. Because B is the predominant isoform in the liver and binds insulin with lower affinity than A, we have examined the effect of pp120 on receptor B-mediated endocytosis. In contrast to isoform A, the effect of pp120 on isoform B-mediated insulin internalization and degradation in stably transfected NIH 3T3 cells was minimal.

scholarly journals Reciprocal feedback regulation of insulin receptor and insulin receptor substrate tyrosine phosphorylation by phosphoinositide 3-kinase in primary adipocytes

2002 ◽  
Vol 368 (3) ◽  
pp. 875-884 ◽  
Author(s):  
Ingeborg HERS ◽  
Christopher J. BELL ◽  
Alastair W. POOLE ◽  
Donyang JIANG ◽  
Richard M. DENTON ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Binding Site ◽  
Tyrosine Phosphorylation ◽  
Binding Sites ◽  
Specific Binding ◽  
Sh2 Domain ◽  
Insulin Receptor Substrate ◽  
Insulin Receptor Tyrosine Kinase ◽  
Irs Proteins ◽  
Phosphoinositide 3 Kinase

Signalling by the insulin receptor substrate (IRS) proteins is critically dependent on the tyrosine phosphorylation of specific binding sites that recruit Src homology 2 (SH2)-domain-containing proteins, such as the p85 subunit of phosphoinositide 3-kinase (PI 3-kinase), the tyrosine phosphatase SHP-2 and the adapter protein Grb2. Here we show that stimulation by insulin of freshly isolated primary adipocytes resulted in the expected rapid tyrosine phosphorylation of the insulin receptor, IRS-1 and IRS-3. Inhibition of PI 3-kinase enhanced the insulin-stimulated phosphorylation of IRS-1 on (i) Tyr612 and Tyr941 (p85 binding sites), concomitant with an increased association of the p85 subunit of PI 3-kinase; (ii) Tyr896 (a Grb2 binding site); and (iii) Tyr1229 (an SHP-2 binding site), although little or no binding of SHP-2 to IRS-1 was detectable under any conditions. In contrast, inhibition of PI 3-kinase led to a decrease in insulin-stimulated p85 binding to IRS-3, but had no effect on SHP-2 binding. Furthermore, insulin-induced insulin receptor tyrosine phosphorylation, phosphorylation of Tyr1158 and insulin receptor tyrosine kinase activity were all reduced by inhibition of PI 3-kinase at later time points (20min). The results demonstrate that, in primary adipocytes, PI 3-kinase feedback control of signalling by the insulin receptor and IRS proteins is multifaceted and reciprocal, illustrating the complexity of predicting the net flux of the insulin signal(s) through the IRS proteins.

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