The tissue-specific nuclear matrix protein, NMP-2, is a member of the AML/CBF/PEBP2/runt domain transcription factor family: interactions with the osteocalcin gene promoter

Biochemistry. 1995 Oct 10;34(40):13125-32. doi: 10.1021/bi00040a025.

Abstract

The nuclear matrix protein, NMP-2, was originally identified as an osteoblast-specific DNA-binding complex localized exclusively to the nuclear matrix. NMP-2 was shown to recognize two binding sites, site A (nt-605 to -599) and site B (nt -441 to -435), in the rat bone-specific osteocalcin gene promoter. This study shows that the NMP-2 binding sites A and B as well as a third NMP-2 binding site (nt -135 to -130) constitute a consensus sequence, ATGCTGGT, and represent an AML-1 recognition motif. AML-1 is a member of the AML transcription factor family which is associated with acute myelogenous leukemia and binds to the sequence TGCTGGT via its DNA-binding runt domain. Electrophoretic mobility shift assays reveal that a component of NMP-2 is a member of the AML/PEBP2/runt domain transcription factor family based on cross-competition with AML-1 consensus oligonucleotide. Limited immunoreactivity of NMP-2 with a polyclonal N-terminal AML-1 antibody and inability of the AML-1 partner protein CBF-beta to form complexes with NMP-2 indicate that NMP-2 is not identical to AML-1 but represents a variant AML/PEBP2/runt domain protein. Western and Northern blots reveal the presence of multiple AML-related proteins and AML-1 transcripts in several osseous cell lines. Furthermore, our results indicate that AML family members may selectively partition between nuclear matrix and nonmatrix compartments. Because proteins that contain a runt domain are implicated in tissue-specific transcriptional regulation, our results support the concept that the nuclear matrix mediates osteoblast-specific expression of the osteocalcin gene.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Consensus Sequence
  • DNA-Binding Proteins / metabolism*
  • Gene Expression Regulation
  • In Vitro Techniques
  • Molecular Sequence Data
  • Nuclear Matrix / metabolism*
  • Nuclear Proteins / metabolism*
  • Oligodeoxyribonucleotides / chemistry
  • Osteocalcin / genetics*
  • Promoter Regions, Genetic
  • Rats
  • Transcription Factors / metabolism*
  • Tumor Cells, Cultured

Substances

  • DNA-Binding Proteins
  • Nuclear Proteins
  • Oligodeoxyribonucleotides
  • Transcription Factors
  • nuclear matrix protein 2
  • Osteocalcin