Cloning and Functional Analysis of a Family of Nuclear Matrix Transcription Factors (NP/NMP4) that Regulate Type I Collagen Expression in Osteoblasts

• Published in: Journal of bone and mineral research 2001-01, Vol.16 (1), p.10-23
• Main Authors: Thunyakitpisal, Pasutha, Alvarez, Marta, Tokunaga, Kunihiko, Onyia, Jude E., Hock, Janet, Ohashi, Naoko, Feister, Hilary, Rhodes, Simon J., Bidwell, Joseph P.
• Format: Article
• Language: English
• Subjects: Alternative Splicing - genetics; Amino Acid Sequence; Animals; Antigens, Nuclear; architectural transcription factors; Biological and medical sciences; bone; Bone and Bones - cytology; Bone and Bones - metabolism; Bone Development - genetics; Cell Line; Cloning, Molecular; collagen; Collagen - genetics; Collagen - metabolism; DNA-Binding Proteins - chemistry; DNA-Binding Proteins - genetics; DNA-Binding Proteins - immunology; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Regulation; Genes, Reporter; In Situ Hybridization; Male; Molecular Sequence Data; Mutation - genetics; NP/NMP4/CIZ; nuclear matrix; Nuclear Matrix - chemistry; nuclear matrix proteins; Nuclear Matrix-Associated Proteins; Nuclear Proteins - chemistry; Nuclear Proteins - genetics; Nuclear Proteins - immunology; Nuclear Proteins - metabolism; osteoblasts; Osteoblasts - metabolism; Promoter Regions, Genetic - genetics; Protein Binding; Protein Isoforms - chemistry; Protein Isoforms - genetics; Protein Isoforms - metabolism; Rats; Rats, Sprague-Dawley; Response Elements - genetics; RNA, Messenger - analysis; RNA, Messenger - genetics; Sequence Alignment; Skeleton and joints; Transcription Factors - chemistry; Transcription Factors - genetics; Transcription Factors - immunology; Transcription Factors - metabolism; Vertebrates: osteoarticular system, musculoskeletal system; Zinc Fingers - genetics
• ISSN: 0884-0431; 1523-4681
• DOI: 10.1359/jbmr.2001.16.1.10

Collagen expression is coupled to cell structure in connective tissue. We propose that nuclear matrix architectural transcription factors link cell shape with collagen promoter geometry and activity. We previously indicated that nuclear matrix proteins (NP/NMP4) interact with the rat type I collagen α1(I) polypeptide chain (COL1A1) promoter at two poly(dT) sequences (sites A and B) and bend the DNA. Here, our objective was to determine whether NP/NMP4‐COL1A1 binding influences promoter activity and to clone NP/NMP4. Promoter‐reporter constructs containing 3.5 kilobases (kb) of COL1A1 5′ flanking sequence were fused to a reporter gene. Mutation of site A or site B increased promoter activity in rat UMR‐106 osteoblast‐like cells. Several full‐length complementary DNAs (cDNAs) were isolated from an expression library using site B as a probe. These clones expressed proteins with molecular weights and COL1A1 binding activity similar to NP/NMP4. Antibodies to these proteins disrupted native NP/NMP4‐COL1A1 binding activity. Overexpression of specific clones in UMR‐106 cells repressed COL1A1 promoter activity. The isolated cDNAs encode isoforms of Cys2His2 zinc finger proteins that contain an AT‐hook, a motif found in architectural transcription factors. Some of these isoforms recently have been identified as Cas‐interacting zinc finger proteins (CIZ) that localize to fibroblast focal adhesions and enhance metalloproteinase gene expression. We observed NP/NMP4/CIZ expression in osteocytes, osteoblasts, and chondrocytes in rat bone. We conclude that NP/NMP4/CIZ is a novel family of nuclear matrix transcription factors that may be part of a general mechanical pathway that couples cell structure and function during extracellular matrix remodeling.