Characterization of human involucrin promoter distal regulatory region transcriptional activator elements-a role for Sp1 and AP1 binding sites.

نویسندگان

  • E B Banks
  • J F Crish
  • J F Welter
  • R L Eckert
چکیده

Human involucrin (hINV) is an important precursor of the keratinocyte cornified envelope that is specifically expressed in the suprabasal layers of stratifying epithelia. Previous truncation and mutagenesis experiments have shown that an activator protein 1 (Ap1) site, AP1-5, located 2100bp upstream of the transcription start site, is required for optimal promoter activity. These previous studies suggest that AP1-5 is part of a distal regulatory region spanning nucleotides -2473 to -2088. In the present report, we study the distal regulatory region (DRR), which surrounds AP1-5. Our studies show that this region contains weak and strong activator elements spanning nucleotides -2473/-2216 and -2140/-2088, respectively. The strong activator element contains AP1-5 and an adjacent specificity protein 1 (Sp1) site. The AP1-5 site is absolutely required for DRR activity, as its mutation reduces transcription to basal levels. Mutagenesis studies of the AP1-5 and Sp1 sites in the presence or absence of the weak activator element indicate that the Sp1 site and the weak activator element synergistically activate the AP1-5 site-dependent transcription. The cooperation between the Sp1 and AP1-5 sites is also observed in the context of the full-length promoter. Gel mobility shift and supershift studies show that Sp1, but not Sp2, Sp3 or Sp4 binds to the Sp1 site. When the Sp1 site is mutated or the distance between the AP1-5 and Sp1 site is increased, the binding of AP1 factors to AP1-5 is markedly reduced. Surprisingly, gel shift studies suggest that activation does not require the formation of a stable AP1/Sp1/DNA ternary complex. These studies suggest that the AP1-5 site is absolutely required for transcriptional activation, that the weak activator element and Sp1 sites serve to enhance this activation, and that the Sp1 site is required for optimal AP1 factor binding at the AP1-5 site.

برای دانلود رایگان متن کامل این مقاله و بیش از 32 میلیون مقاله دیگر ابتدا ثبت نام کنید

ثبت نام

اگر عضو سایت هستید لطفا وارد حساب کاربری خود شوید

منابع مشابه

Transcription factor Sp1 activates involucrin promoter activity in non-epithelial cell types.

The gene for human involucrin (hINV) is selectively expressed in stratifying epithelial cells lining external body surfaces. Previously, we characterized the hINV promoter 5' distal regulatory region (DRR) located between nt -2473 and -2088 upstream of the transcription start site. This region is required for optimal hINV gene expression. The DRR contains weak and strong activator elements. The...

متن کامل

An involucrin promoter AP1 transcription factor binding site is required for expression of involucrin in the corneal epithelium in vivo.

PURPOSE Cell division of corneal limbal stem cells gives rise to transient amplifying cells that ultimately differentiate to form the multilayered corneal epithelium. The mechanisms that regulate changes in gene expression during this process are not well understood. In the present study, the involucrin gene was used as a model to study this regulation. METHODS Regulation of human involucrin ...

متن کامل

Transcriptional control of the human high mobility group A1 gene: basal and oncogenic Ras-regulated expression.

Several studies have already shown that the high mobility group A1 (HMGA1) gene is up-regulated in most common types of cancer and immortalized tissue culture cell lines. HMGA1 expression is also much higher during embryonic development than in adult life. The elevated expression of HMGA1 in cancer thus likely occurs through oncofetal transcriptional mechanisms, which to date have not been well...

متن کامل

Localization of regulatory protein binding sites in the proximal region of human myometrial connexin 43 gene.

Parturition is preceded by a large increase in gap junctions between myometrial smooth muscle cells. Connexin 43 is the major structural protein of myometrial gap junctions. To explore transcriptional regulation of the myometrial Cx43 gene, we used DNase I footprinting, electrophoretic mobility shift and transient transfection assays to examine a 312 bp promoter region (-164 to +148) of the gen...

متن کامل

Arsenite suppression of involucrin transcription through AP1 promoter sites in cultured human keratinocytes.

While preserving keratinocyte proliferative ability, arsenite suppresses cellular differentiation markers by preventing utilization of AP1 transcriptional response elements. In present experiments, arsenite had a dramatic effect in electrophoretic mobility supershift analysis of proteins binding to an involucrin promoter AP1 response element. Without arsenite treatment, binding of JunB and Fra1...

متن کامل

ذخیره در منابع من


  با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید

عنوان ژورنال:
  • The Biochemical journal

دوره 331 ( Pt 1)  شماره 

صفحات  -

تاریخ انتشار 1998