PKC-dependent stimulation of the human MCT1 promoter involves transcription factor AP2

Seema Saksena, Alka Dwivedi, Ravinder K. Gill, Amika Singla, Waddah A. Alrefai, Jaleh Malakooti, Krishnamurthy Ramaswamy, Pradeep K. Dudeja

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

Monocarboxylate transporter (MCT1) plays an important role in the absorption of short-chain fatty acids (SCFA) such as butyrate in the human colon. Previous studies from our laboratory have demonstrated that phorbol ester, PMA (1 μM, 24 h), upregulates butyrate transport and MCT1 protein expression in human intestinal Caco-2 cells. However, the molecular mechanisms involved in the transcriptional regulation of MCT1 gene expression by PMA in the intestine are not known. In the present study, we showed that PMA (0.1 μM, 24 h) increased the MCT1 promoter activity ( - 871/+91) by approximately fourfold. A corresponding increase in MCT1 mRNA abundance in response to PMA was also observed. PMA-induced stimulation of MCT1 promoter activity was observed as early as 1 h and persisted until 24 h, suggesting that the effects of PMA are attributable to initial PKC activation. Kinase inhibitor and phosphorylation studies indicated that these effects may be mediated through activation of the atypical PKC-ζ isoform. 5'-deletion studies demonstrated that the MCT1 core promoter region (- 229/+ 91) is the PMA-responsive region. Site-directed mutagenesis studies showed the predominant involvement of potential activator protein 2 (AP2) binding site in the activation of MCT1 promoter activity by PMA. In addition, overexpression of AP2 in Caco-2 cells significantly increased MCT1 promoter activity in a dose-dependent manner. These findings showing the regulation of MCT1 promoter by PKC and AP2 are of significant importance for an understanding of the molecular regulation of SCFA absorption in the human intestine.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Volume296
Issue number2
DOIs
StatePublished - Feb 1 2009

Fingerprint

Transcription Factors
Caco-2 Cells
Volatile Fatty Acids
Butyrates
Intestines
Proteins
Gene Expression Regulation
Phorbol Esters
Site-Directed Mutagenesis
Genetic Promoter Regions
Protein Binding
Carrier Proteins
Protein Isoforms
Colon
Phosphotransferases
Up-Regulation
Binding Sites
Phosphorylation
Messenger RNA

Keywords

  • Activator protein 2
  • Human intestine
  • Protein kinase c-ζ
  • Short-chain fatty acid absorption
  • Transcriptional regulation

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

Cite this

PKC-dependent stimulation of the human MCT1 promoter involves transcription factor AP2. / Saksena, Seema; Dwivedi, Alka; Gill, Ravinder K.; Singla, Amika; Alrefai, Waddah A.; Malakooti, Jaleh; Ramaswamy, Krishnamurthy; Dudeja, Pradeep K.

In: American Journal of Physiology - Gastrointestinal and Liver Physiology, Vol. 296, No. 2, 01.02.2009.

Research output: Contribution to journalArticle

Saksena, Seema ; Dwivedi, Alka ; Gill, Ravinder K. ; Singla, Amika ; Alrefai, Waddah A. ; Malakooti, Jaleh ; Ramaswamy, Krishnamurthy ; Dudeja, Pradeep K. / PKC-dependent stimulation of the human MCT1 promoter involves transcription factor AP2. In: American Journal of Physiology - Gastrointestinal and Liver Physiology. 2009 ; Vol. 296, No. 2.
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