Nuclear matrix association of insulin receptor and IRS-1 by insulin in osteoblast-like UMR-106 cells.
In the present study, we explored to determine whether insulin has any effect on the nuclear translocation of insulin receptor and IRS-1 in the nucleus of UMR-106 cells. Following insulin treatment, cells were subjected to subcellular fractionation. Each fraction containing equal amount of protein was subjected to Western blot analysis using antibodies against IR and IRS-1. Significant amounts of insulin receptors and IRS-1 were detected in the nucleus. Insulin receptor and IRS-1 appeared to be translocated to the nucleus in a time dependent manner by insulin whereas Akt levels remained unchanged by insulin treatment. The majority of insulin receptor and IRS-1 translocated to the nucleus appeared to associate with nuclear matrix. Tyrosine phosphorylation of a number of proteins with a molecular mass of 180, 95, 85, or 70 kDa in the nucleus was significantly stimulated by insulin, suggesting insulin signals to the nucleus and could regulate nuclear proteins. Confocal laser scanning microscope (CLSM) analysis also supports the nuclear translocation of insulin receptor and IRS-1. The nuclear insulin signaling may play an important role in the transcription control, differentiation, and growth of osteoblast cells.
Seol
Ki-Cheon
KC
Department of Pharmacology, School of Dentistry, Kyung Hee University, Seoul 130-701, Republic of Korea.
Kim
Sung-Jin
SJ
D021581:Active Transport, Cell Nucleus; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D002455:Cell Division; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D007328:Insulin / Q000378:metabolism*; D055504:Insulin Receptor Substrate Proteins; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D018613:Microscopy, Confocal; D015530:Nuclear Matrix / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism*; D010750:Phosphoproteins / Q000096:biosynthesis*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt; D051381:Rats; D011972:Receptor, Insulin / Q000096:biosynthesis*; D013347:Subcellular Fractions / Q000378:metabolism; D013552:Swine; D013997:Time Factors; D014443:Tyrosine / Q000378:metabolism
D007328:Insulin; D055504:Insulin Receptor Substrate Proteins; C526296:Irs1 protein, rat; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D014443:Tyrosine; D004247:DNA; D007770:L-Lactate Dehydrogenase; D011972:Receptor, Insulin; C494920:Akt1 protein, rat; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt