BR22, a 26 kDa thyroid transcription factor-1 associated protein (TAP26), is expressed in human lung cells

Eur Respir J. 2003 Jul;22(1):28-34. doi: 10.1183/09031936.03.00117702.

Abstract

The current authors have previously identified BR22, a thyroid transcription factor (TTF)-1 associated protein 26 (TAP26), which interacts with TTF-1 to enhance human surfactant protein (SP)-B promoter activity in transfected 293 cells. However, the expression of TAP26 in the lung cells and its biological relevance to the SP-B production under physiological conditions were not examined. In this study, endogenous co-immunoprecipitation and in situ immunohistochemical staining techniques were employed to explore the presence of TAP26 and TTF-1 complex in the lung epithelial cells. The correlation of TAP26, TTF-1 and SP-B expression was inspected in H441 cells in the presence of dexamethasone, a known positive effector of the SP-B promoter. Monoclonal antibody (mAb) against TAP26 can co-immunoprecipitate both TAP26 and TTF-1 from H441 cells. Using this antibody in in situ staining of human lung sections, the data show that TAP26 is present in the lung alveolar epithelial cells. Reverse transcriptase-polymerase chain reaction and Western blot analyses of type-II cells as well as dexamethasone-treated H441 cells suggest that TAP26 expression is modulated coordinately with SP-B and TTF-1 in these cells. In summary, the current study demonstrates that thyroid transcription factor-1 associated protein 26 is an associated protein of thyroid transcription factor-1 in the lung alveolar epithelial cells where surfactant protein gene expressions take place in vivo.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antibodies, Monoclonal
  • Base Sequence
  • Blotting, Western
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression Regulation
  • Gene Library
  • Humans
  • Immunoenzyme Techniques
  • Mice
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Pulmonary Alveoli / cytology
  • Pulmonary Alveoli / metabolism*
  • Pulmonary Surfactants / metabolism*
  • Sequence Homology, Amino Acid
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • Antibodies, Monoclonal
  • CCDC59 protein, human
  • Nuclear Proteins
  • Pulmonary Surfactants
  • Transcription Factors