CSF-1 receptor/insulin receptor chimera permits CSF-1-dependent differentiation of 3T3-L1 preadipocytes.
A chimeric growth factor receptor (CSF1R/IR) was constructed by splicing cDNA sequences encoding the extracellular ligand binding domain of the human colony stimulating factor-1 (CSF-1) receptor to sequences encoding the transmembrane and cytoplasmic domains of the human insulin receptor. The addition of CSF-1 to cells transfected with the CSF1R/IR chimera cDNA stimulated the tyrosine phosphorylation of a protein that was immunoprecipitated by an antibody directed against the carboxyl terminus of the insulin receptor. Phosphopeptide maps of the 32P-labeled CSF1R/IR protein revealed the same pattern of phosphorylation observed in 32P-labeled insulin receptor beta subunits. CSF-1 stimulated the tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1) and Shc in cells expressing the CSF1R/IR chimera. Lipid accumulation and the expression of a differentiation-specific marker demonstrated that 3T3-L1 preadipocytes undergo CSF-1-dependent differentiation when transfected with the CSF1R/IR chimera cDNA but not when transfected with the expression vector alone. A 12-amino acid deletion within the juxtamembrane region of the CSF1R/IR (CSF1R/IRDelta960) blocked CSF-1-stimulated phosphorylation of IRS-1 and Shc but did not inhibit CSF-1-mediated differentiation of 3T3-L1 preadipocytes. These observations indicate that adipocyte differentiation can be initiated by intracellular pathways that do not require tyrosine phosphorylation of IRS-1 or Shc.
Chaika
O V
OV
Eppley Institute for Research in Cancer and Allied Diseases, University of Nebraska Medical Center, Omaha, Nebraska 68198-6805, USA.
Chaika
N
N
Volle
D J
DJ
Wilden
P A
PA
Pirrucello
S J
SJ
Lewis
R E
RE
D016475:3T3 Cells; D017667:Adipocytes / Q000166:cytology* / Q000187:drug effects / Q000502:physiology; D000818:Animals; D016466:CHO Cells; D002454:Cell Differentiation / Q000187:drug effects*; D003115:Colony-Stimulating Factors / Q000494:pharmacology*; D006224:Cricetinae; D017931:DNA Primers; D006801:Humans; D007700:Kinetics; D051379:Mice; D010449:Peptide Mapping; D010748:Phosphopeptides / Q000737:chemistry / Q000302:isolation & purification; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D011972:Receptor, Insulin / Q000096:biosynthesis / Q000502:physiology*; D016184:Receptors, Colony-Stimulating Factor / Q000096:biosynthesis / Q000502:physiology*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D014162:Transfection
D003115:Colony-Stimulating Factors; D017931:DNA Primers; D010748:Phosphopeptides; D016184:Receptors, Colony-Stimulating Factor; D011993:Recombinant Fusion Proteins; D011972:Receptor, Insulin