Work

Regulation of parathyroid hormone-related protein (PTHrP) gene expression. Sp1 binds through an inverted CACCC motif and regulates promoter activity in cooperation with Ets1.

Year: 1994

Type: article

Abstract: W e have previously shown that mutations in the GGAA core motif of the Etsl binding site, EBSI, or deletion of EBSI, reduced basal and Tax, transactivation of the PTHrP P2 promoter.Here we demonstrate that, in addition to EBSI, a CACCC-like motif located between -53 and -58 is required for full basal activity of this promoter in Jurkat T-cells.Site-specific mutations in the CACCC motif decreased promoter activity approximately 5-fold.In an effort to identify transcription factors that bind to the CACCC element, we found that purified human Spl, as well as Spl in HeLa nuclear extract, can specifically bind to a DNA probe that corresponds to the PTHrP-specific sequence between -94 and -34.Gel shift competition studies and DNase I footprinting analyses revealed that Spl specifically interacts with the CACCC motif.In the presence of Etsl, the mobility of the Spl-specific gel shift complex with the PTHrP DNA decreased.DNase I footprint analysis of this gel shift complex showed an extended footprint over both the Spl and the Etsl binding site, demonstrating that Spl and Etsl form a ternary complex with the PTHrP DNA.Cotransfection of an Etsl and Spl expression vector into Drosophila Schneider cells demonstrated that Spl can functionally cooperate with Etsl to transactivate the PTHrP promoter.W e conclude from these data that Etsl and Spl can cooperatively regulate PTHrP P2 promoter activity.The parathyroid hormone-related protein (PTHrP)' was originally identified as a humoral factor associated with the humoral hypercalcemia of malignancy (1, 2 j.PTHrP has calcium-mobilizing activity by mimicking PTH action (3, 4).It is expressed at low levels in normal fetal and adult tissues (5, 6).Overexpression and secretion of PTHrP by tumor cells, like adult T-cell leukemia (ATL) cells transformed by the human T-cell lymphotropic virus I (HTLV-I), leads to the humoral hypercalcemia of malignancy (1, 2, 7).In addition to its PTH-like activity, PTHrP has been reported to have growth-stimulating as well as growth-inhibiting properties (6, 8-13).

Source: Journal of Biological Chemistry

DOI: 10.1016/s0021-9258(17)31821-5

Authors: J. Dittmer, A. Gégonne, S.D. Gitlin, J. Ghysdael, J.N. Brady

Institutions: National Institutes of Health, University of Michigan, Michigan Medicine, National Cancer Institute, Institut Curie

Language: English

Topic: Genomics and Chromatin Dynamics

Subfield: Molecular Biology

Field: Biochemistry, Genetics and Molecular Biology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: hybrid

Estimated APC paid: $3,430