Human insulin receptor juxtamembrane domain independent insulin signaling.
The exon 16-encoded juxtamembrane (JM) domain of human insulin receptor (hIR) harbors the NPEY motif which couples the insulin-activated hIR kinase to downstream signal transduction molecules. We sought to determine if signal transduction requires the entire exon 16-encoded 22-amino acid JM domain. Transfected CHO cells were generated stably expressing either the wild-type hIR (hIR-WT) or two mutant hIRs (hIRDeltaEx16 in which the JM domain was deleted, and hIRrosJM in which the deleted segment was replaced by the corresponding domain of v-ros protein). The mutant hIRDeltaEx16 and hIRrosJM exhibited similar insulin-binding as the hIRWT. Insulin internalization and insulin dose-response experiments toward activation of downstream signal transduction molecules demonstrated that: i) the presence of intact hIR-JM domain which harbors the NPEY motif is essential for Shc phosphorylation but not for IRS-1 phosphorylation; ii) insulin signal transduction can occur independent of the JM domain of hIR and without participation of the NPEY motif; iii) engagement of this putative alternative downstream signal transduction is Shc independent and is dependent on insulin concentration; and iv) insulin internalization does not necessarily require the hIR specific aa sequence of the JM domain which can be partially substituted by the JM domain of the v-ros tyrosine kinase.
Sattar
Akm A
AA
Division of Endocrinology, Department of Internal Medicine, Wayne State University School of Medicine, 421 E. Canfield Avenue, Detroit, MI 48201-1928, USA. asattar@med.wayne.edu
Berhanu
Chali
C
Gebreselassie
Surafel
S
Berhanu
Paulos
P
D048868:Adaptor Proteins, Signal Transducing / Q000378:metabolism; D000818:Animals; D015703:Antigens, CD / Q000235:genetics / Q000502:physiology*; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D003412:Cricetulus; D006801:Humans; D007328:Insulin / Q000378:metabolism; D055504:Insulin Receptor Substrate Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011972:Receptor, Insulin / Q000235:genetics / Q000502:physiology*; D055765:Shc Signaling Adaptor Proteins; D015398:Signal Transduction / Q000502:physiology*; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1
D048868:Adaptor Proteins, Signal Transducing; D015703:Antigens, CD; C526292:IRS1 protein, human; D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; C528024:SHC1 protein, human; D055765:Shc Signaling Adaptor Proteins; D000071425:Src Homology 2 Domain-Containing, Transforming Protein 1; C435941:INSR protein, human; D011505:Protein-Tyrosine Kinases; C062333:ROS1 protein, human; D011972:Receptor, Insulin; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3