Nmp4/CIZ regulation of matrix metalloproteinase 13 (MMP-13) response to parathyroid hormone in osteoblasts.
Parathyroid hormone (PTH) regulation of matrix metalloproteinase-13 (MMP-13) expression in osteoblasts contributes to normal bone turnover. The PTH response region of the rat MMP-13 gene spans nucleotides (nt) -148 to -38 and supports binding of numerous transcription factors, including Runx2, necessary for osteoblast differentiation, c-Fos/c-Jun, and Ets-1. These trans-acting proteins mediate hormone induction via incompletely defined combinatorial interactions. Within this region, adjacent to the distal Runx2 site, is a homopolymeric(dA:dT) element (-119/-110 nt) that conforms to the consensus site for the novel transcription factor nuclear matrix protein-4/cas interacting zinc finger protein (Nmp4/CIZ). This protein regulates bone cell expression of type I collagen and suppresses BMP2-enhanced osteoblast differentiation. The aim of this study was to determine whether Nmp4/CIZ contributes to MMP-13 basal transcription and PTH responsiveness in osteoblasts. Electrophoretic mobility shift analysis confirms Nmp4/CIZ binding within the MMP-13 PTH response region. Mutation of the Nmp4/CIZ element decreases basal activity of an MMP-13 promoter-reporter construct containing the first 1329 nt of the 5'-regulatory region, and overexpression of Nmp4/CIZ protein enhances the activity of the wild-type promoter. The same mutation of the homopolymeric(dA:dT) element enhances the MMP-13 response to PTH and PGE(2). Overexpression of Nmp4/CIZ diminishes hormone induction. Mutation of both the homopolymeric(dA:dT) element and the adjacent Runx2 site further augments the PTH response. On the basis of these data and previous studies, we propose that Nmp4/CIZ is a component of a multiprotein assemblage or enhanceosome within the MMP-13 PTH response region and that, within this context, Nmp4/CIZ promotes both basal expression and hormonal synergy.
Shah
Rita
R
Department of Anatomy, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Alvarez
Marta
M
Jones
Daniel R
DR
Torrungruang
Kitti
K
Watt
Andrew J
AJ
Selvamurugan
Nagarajan
N
Partridge
Nicola C
NC
Quinn
Cheryl O
CO
Pavalko
Fred M
FM
Rhodes
Simon J
SJ
Bidwell
Joseph P
JP
D016475:3T3 Cells; D000818:Animals; D017364:Collagenases / Q000235:genetics / Q000378:metabolism*; D004742:Enhancer Elements, Genetic / Q000235:genetics / Q000502:physiology; D005786:Gene Expression Regulation; D053509:Matrix Metalloproteinase 13; D051379:Mice; D034521:Nuclear Matrix-Associated Proteins / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D010281:Parathyroid Hormone / Q000502:physiology*; D011401:Promoter Regions, Genetic; D051381:Rats; D020218:Response Elements / Q000235:genetics / Q000502:physiology; D015534:Trans-Activators / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology; D014407:Tumor Cells, Cultured; D016335:Zinc Fingers / Q000502:physiology
D034521:Nuclear Matrix-Associated Proteins; D010281:Parathyroid Hormone; D015534:Trans-Activators; D014157:Transcription Factors; C499081:Zfp384 protein, mouse; C440548:Zfp384 protein, rat; D017364:Collagenases; D053509:Matrix Metalloproteinase 13; C507081:Mmp13 protein, mouse; C507083:Mmp13 protein, rat