title: Nuclear Raf-1 kinase regulates the CXCR5 promoter by associating with NFATc3 to drive retinoic acid-induced leukemic cell differentiation.
abstract: Novel functions of signaling molecules have been revealed in studies of cancer stem cells. Retinoic acid (RA) is an embryonic morphogen and stem cell regulator that controls the differentiation of a patient-derived leukemic cell line, HL-60, which is composed of progenitor cells with bipotent myelo-monocytic differentiation capability. RA treatment of HL-60 cells causes unusually long-lasting mitogen-activated protein kinase signaling, with the cells exhibiting the beginning of G0 cell cycle arrest and functional differentiation by 48 h after treatment with RA. This event coincides with the nuclear translocation of Raf-1, phosphorylated at serine 621. The present study shows how the novel localization of Raf-1 to the nucleus results in transcriptional changes that contribute to the differentiation of HL-60 cells induced by RA. We find that nuclear pS621 Raf-1 associates with NFATc3 near its cognate binding site in the promoter of CXCR5, a gene that must be up-regulated to drive RA-induced differentiation. NFATc3 becomes immunoprecipitable with anti-phosphoserine serum, and CXCR5 is transcriptionally up-regulated upon RA-induced differentiation. Inhibiting the pS621 Raf-1/NFATc3 association with PD98059 inhibits these processes and cripples RA-induced differentiation. In this novel paradigm for Raf-1 and RA function, Raf-1 has a role in driving the nuclear signaling of RA-induced differentiation of leukemic progenitor cells.
authors: Department of Biomedical Sciences, Cornell University, Ithaca, NY, USA.
authors: Wendy M
authors: WM
authors: Geil
authors: Andrew
authors: A
authors: Yen
mesh_terms: D002454:Cell Differentiation / Q000187:drug effects*; D005419:Flavonoids / Q000494:pharmacology; D018922:HL-60 Cells; D006801:Humans; D050778:NFATC Transcription Factors / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects*; D011401:Promoter Regions, Genetic / Q000235:genetics*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D054380:Receptors, CXCR5 / Q000235:genetics*; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: C095085:CXCR5 protein, human; D005419:Flavonoids; D050778:NFATC Transcription Factors; C494008:NFATC3 protein, human; D054380:Receptors, CXCR5; D014212:Tretinoin; D019908:Proto-Oncogene Proteins c-raf; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one
keywords: CXCR5; NFATc3; Raf-1; differentiation; retinoic acid