Functional block for 1 alpha,25-dihydroxyvitamin D3-mediated gene regulation in human B lymphocytes.
Elements necessary for the steroid hormone 1 alpha,25-dihydroxyvitamin D3 (1 alpha,25-(OH)2D3) to induce a biological response include the presence of specific intracellular receptors (vitamin D3 receptors (VDR)) and modulation of gene expression via hormone-activated receptor binding to regulatory regions of target genes. These parameters were examined in normal and Epstein-Barr virus-immortalized human B cells and compared with 1 alpha,25-(OH)2D3-responsive cells of the T and monocytic lineages. Although resting tonsillar B cells did not express VDR mRNA, activation of these cells with interleukin-4 induced VDR in the absence of exogenously supplemented 1 alpha,25-(OH)2D3. As indicators of hormone-mediated gene regulation we analyzed modulation of CD23, a common B cell/monocyte surface antigen, and 24-hydroxylase. 1 alpha,25-(OH)2D3 inhibited CD23 expression in U937 cells, yet failed to modulate CD23 expression in B cells. Furthermore, 1 alpha,25-(OH)2D3 induced 24-hydroxylase mRNA expression and metabolic activity in both U937 cells and lectin-activated T cells, yet failed to induce 24-hydroxylase mRNA or its metabolic activity in B cells. These findings suggest that although human B lymphocytes can express VDR mRNA and protein, they exhibit a functional block for vitamin D-dependent gene regulation.
Morgan
J W
JW
Department of Pathology, Roger Williams Cancer/Medical Center, Brown University, Providence, Rhode Island 02908.
Reddy
G S
GS
Uskokovic
M R
MR
May
B K
BK
Omdahl
J L
JL
Maizel
A L
AL
Sharma
S
S
D001402:B-Lymphocytes / Q000378:metabolism*; D001483:Base Sequence; D002117:Calcitriol / Q000502:physiology*; D002461:Cell Line, Transformed; D005786:Gene Expression Regulation / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D014066:Palatine Tonsil / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D018167:Receptors, Calcitriol / Q000235:genetics / Q000378:metabolism; D017455:Receptors, IgE / Q000235:genetics
D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D018167:Receptors, Calcitriol; D017455:Receptors, IgE; D002117:Calcitriol