DOWNSTREAM ACTIVATION OF A TATA-LESS PROMOTER BY OCT-2, BOB1, AND NF-KAPPA-B DIRECTS EXPRESSION OF THE HOMING RECEPTOR BLR1 TO MATURE B-CELLS

The chemokine receptor, BLR1, is a major regulator of the microenviron mental homing of B cells in lymphoid organs. In vitro studies identify three essential elements of the TATA-less blr1 core promoter that con fer cell type- and differentiation-specific expression in the B cells of both humans and mice, a functional promoter region (-36 with respec t to the transcription start site), a NF-kappa B motif (+44), and a no ncanonical octamer motif (+157), The importance of these sites was con firmed by in vivo studies in gene-targeted mice deficient of either Oc t-2, Bob1, or both NF-kappa B subunits p50 and p52, In all of these an imals, the expression of BLR1 was reduced or absent. In mice deficient only of p52/NF-KB, BLR1 expression was unaffected. Thus our data demo nstrate that BLR1 is a target gene for Oct-2, Bob1, and members of the NF-kappa B/Rel family and provides a link to the impaired B cell func tions in mice deficient for these factors.