title: Retinoic acid induces expression of SLP-76: expression with c-FMS enhances ERK activation and retinoic acid-induced differentiation/G0 arrest of HL-60 cells.
abstract: Retinoic acid (RA) is known to cause MAPK signaling which propels G0 arrest and myeloid differentiation of HL-60 human myeloblastic leukemia cells. The present studies show that RA up-regulated expression of SLP-76 (Src-homology 2 domain-containing leukocyte-specific phospho-protein of 76 kDa), which became a prominent tyrosine-phosphorylated protein in RA-treated cells. SLP-76 is a known adaptor molecule associated with T-cell receptor and MAPK signaling. To characterize functional effects of SLP-76 expression in RA-induced differentiation and G0 arrest, HL-60 cells were stably transfected with SLP-76. Expression of SLP-76 had no discernable effect on RA-induced ERK activation, subsequent functional differentiation, or the rate of RA-induced G0 arrest. To determine the effects of SLP-76 in the presence of a RA-regulated receptor, SLP-76 was stably transfected into HL-60 cells already overexpressing the colony stimulating factor-1 (CSF-1) receptor, c-FMS, from a previous stable transfection. SLP-76 now enhanced RA-induced ERK activation, compared to parental c-FMS transfectants. It also enhanced RA-induced differentiation, evidenced by enhanced paxillin expression, inducible oxidative metabolism and superoxide production. RA-induced RB tumor suppressor protein hypophosphorylation was also enhanced, as was RA-induced G0 cell cycle arrest. A triple Y to F mutant SLP-76 known to be a dominant negative in T-cell receptor signaling failed to enhance RA-induced paxillin expression, but enhanced RA-induced ERK activation, differentiation and G0 arrest essentially as well as wild-type SLP-76. Thus, SLP-76 overexpression in the presence of c-FMS, a RA-induced receptor, had the effect of enhancing RA-induced cell differentiation. This is the first indication to our knowledge that RA induces the expression of an adapter molecule to facilitate induced differentiation via co-operation between c-FMS and SLP-76.
authors.affiliation: Department of Biomedical Sciences, T4-008 VRT, Cornell University, Ithaca, NY 14853, USA. ay13@cornell.edu
authors.forename: Andrew
authors.initials: A
authors.lastname: Yen
authors.forename: Susi
authors.initials: S
authors.lastname: Varvayanis
authors.forename: James L
authors.initials: JL
authors.lastname: Smith
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Lamkin
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D015153:Blotting, Western; D002454:Cell Differentiation / Q000187:drug effects*; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000235:genetics / Q000502:physiology*; D015973:Gene Expression Regulation, Leukemic; D018922:HL-60 Cells; D006801:Humans; D047468:Immunoprecipitation; D015470:Leukemia, Myeloid, Acute / Q000235:genetics / Q000473:pathology / Q000503:physiopathology; D009154:Mutation; D051419:Paxillin / Q000235:genetics / Q000502:physiology; D010750:Phosphoproteins / Q000235:genetics* / Q000502:physiology*; D010766:Phosphorylation; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics / Q000502:physiology*; D011948:Receptors, Antigen, T-Cell / Q000502:physiology; D016192:Resting Phase, Cell Cycle / Q000187:drug effects*; D015398:Signal Transduction; D013481:Superoxides / Q000378:metabolism; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology*; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D051419:Paxillin; D010750:Phosphoproteins; D011948:Receptors, Antigen, T-Cell; C092947:SLP-76 signal Transducing adaptor proteins; D013481:Superoxides; D014212:Tretinoin; D016186:Receptor, Macrophage Colony-Stimulating Factor; D048049:Extracellular Signal-Regulated MAP Kinases