Modulation of human Niemann-Pick C1-like 1 gene expression by sterol: Role of sterol regulatory element binding protein 2

Waddah A. Alrefai, Fadi Annaba, Zaheer Sarwar, Alka Dwivedi, Seema Saksena, Amika Singla, Pradeep K. Dudeja, Ravinder K. Gill

Research output: Contribution to journalArticle

79 Scopus citations


Niemann-Pick C1-like 1 (NPC1L1) is an essential intestinal component of cholesterol absorption. However, little is known about the molecular regulation of intestinal NPC1L1 expression and promoter activity. We demonstrated that human NPC1L1 mRNA expression was significantly decreased by 25- hydroxycholesterol but increased in response to cellular cholesterol depletion achieved by incubation with Mevinolin (an inhibitor of 3-hydroxy-3- methylglutaryl-CoA reductase) in human intestinal Caco-2 cells. We also showed that a -1741/+56 fragment of the NPC1L1 gene demonstrated high promoter activity in Caco-2 cells that was reduced by 25-hydroxycholesterol and stimulated by cholesterol depletion. Interestingly, we showed that the NPC1L1 promoter is remarkably transactivated by the overexpression of sterol regulatory element (SRE) binding protein (SREBP)-2, suggesting its involvement in the sterol-induced alteration in NPC1L1 promoter activity. Finally, we identified two putative SREs in the human NPC1L1 promoter and established their essential roles in mediating the effects of cholesterol on promoter activity. Our study demonstrated the modulation of human NPC1L1 expression and promoter activity by cholesterol in a SREBP-2-dependent mechanism.

Original languageEnglish (US)
Pages (from-to)G369-G376
JournalAmerican Journal of Physiology - Gastrointestinal and Liver Physiology
Issue number1
StatePublished - Jan 1 2007



  • Intestinal cholesterol absorption
  • Oxysterols

ASJC Scopus subject areas

  • Physiology
  • Hepatology
  • Gastroenterology
  • Physiology (medical)

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