title: ATRA-induced HL-60 myeloid leukemia cell differentiation depends on the CD38 cytosolic tail needed for membrane localization, but CD38 enzymatic activity is unnecessary.
abstract: Leukocyte antigen CD38 expression is an early marker of all-trans retinoic acid (ATRA) stimulated differentiation in the leukemic cell line HL-60. It promotes induced myeloid maturation when overexpressed, whereas knocking it down is inhibitory. It is a type II membrane protein with an extracellular C-terminal enzymatic domain with NADase/NADPase and ADPR cyclase activity and a short cytoplasmic N-terminal tail. Here we determined whether CD38 enzymatic activity or the cytoplasmic tail is required for ATRA-induced differentiation. Neither a specific CD38 ectoenzyme inhibitor nor a point mutation that cripples enzymatic activity (CD38 E226Q) diminishes ATRA-induced differentiation or G1/0 arrest. In contrast a cytosolic deletion mutation (CD38 Δ11-20) prevents membrane expression and inhibits differentiation and G1/0 arrest. These results may be consistent with disrupting the function of critical molecules necessary for membrane-expressed CD38 signal transduction. One candidate molecule is the Src family kinase Fgr, which failed to undergo ATRA-induced upregulation in CD38 Δ11-20 expressing cells. Another is Vav1, which also showed only basal expression after ATRA treatment in CD38 Δ11-20 expressing cells. Therefore, the ability of CD38 to propel ATRA-induced myeloid differentiation and G1/0 arrest is unimpaired by loss of its ectoenzyme activity. However a cytosolic tail deletion mutation disrupted membrane localization and inhibited differentiation. ATRA-induced differentiation thus does not require the CD38 ectoenzyme function, but is dependent on a membrane receptor function.
authors.affiliation: Department of Biomedical Sciences, Veterinary Research Tower, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Johanna
authors.initials: J
authors.lastname: Congleton
authors.forename: Hong
authors.initials: H
authors.lastname: Jiang
authors.forename: Fabio
authors.initials: F
authors.lastname: Malavasi
authors.forename: Hening
authors.initials: H
authors.lastname: Lin
authors.forename: Andrew
authors.initials: A
authors.lastname: Yen
mesh_terms: D051997:ADP-ribosyl Cyclase 1 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D015415:Biomarkers / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects*; D002462:Cell Membrane / Q000378:metabolism*; D018922:HL-60 Cells / Q000187:drug effects* / Q000502:physiology*; D006801:Humans; D015398:Signal Transduction / Q000187:drug effects; D014212:Tretinoin / Q000494:pharmacology*
chemical_list: D015415:Biomarkers; D014212:Tretinoin; D051997:ADP-ribosyl Cyclase 1