Human leukocyte antigen CD38, a 45-kD single-chain, transmembrane glycoprotein, is a bifunctional ectoenzyme that participates in signal transduction pathways involved in the regulation of cell growth and differentiation. In this study, we demonstrate the nature of retinoid receptors involved in retinoic acid–induced expression of CD38 protein in the human myeloblastic leukemia cell line HL-60. We used a variant HL-60 cell line, HL-60R, in which retinoid receptor function has been abrogated by a trans-dominant negative mutation. We introduced the normal retinoic acid receptors (RAR)-α, -β, and -γ or retinoid X receptor (RXR)-α into HL-60R cells by retroviral vector-mediated gene transfer. Based on experiments using these cell lines and receptor-specific synthetic retinoids that preferentially bind to one of the RARs or RXRs, we conclude that RAR-α is involved in retinoid-induced CD38 expression in HL-60 cells. Further evidence included our demonstration that blocking of RAR-α with the antagonist Ro 41-5253 completely suppressed the retinoid-induced expression of CD38 mRNA transcript and the production of CD38 protein in HL-60 cells. Various tissues from transgenic mice that expressed an antisense construct of RAR-α lacked or produced very low levels of CD38. As expected, the tissues from transgenic mice contained 50% to 80% reduced levels of RAR-α. These results suggest that regulation of CD38 expression, both in vitro and in vivo, is under the direct control of RAR-α retinoid receptors.
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