Cloning, expression, and promoter analysis of hepatic lipase derived from human hyperplastic adrenals: evidence for alternative mRNA splicing

Cell Biochem Biophys. 2007;47(1):149-58. doi: 10.1385/cbb:47:1:149.

Abstract

Human adrenals contain hepatic lipase (HL) activity, which is thought to facilitate the uptake of plasma cholesterol used in steroidogenesis. We show here that full-length HL mRNA is expressed in hyperplastic adrenals of patients with Cushing's disease. In addition, a splice variant that lacks exon-3 was detected in the human adrenals and hepatoma (HepG2) cells, but not in liver. In CAT-reporter assays using human NCI-H295R adrenocortical cells, the HL(-685/+13) promoter region was transcriptionally active, and its activity was enhanced twofold by cAMP. In rat adrenals, the HL gene is exclusively transcribed from an alternative promoter within intron-2, resulting in a variant mRNA that lacks exons 1 and 2. By reverse-transcription PCR, we found no evidence for expression of such a variant mRNA in human adrenals, liver, or HepG2 cells. The presence of both full length mRNA and enzyme activity in human adrenals suggests that part of the HL activity is locally synthesized.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adrenal Glands / enzymology*
  • Adrenal Glands / pathology
  • Alternative Splicing*
  • Cell Line
  • Cloning, Molecular
  • Exons
  • Gene Expression Regulation*
  • Genetic Variation
  • Humans
  • Hyperplasia / pathology*
  • Introns
  • Lipase / genetics*
  • Pituitary ACTH Hypersecretion / metabolism
  • Promoter Regions, Genetic*
  • RNA, Messenger / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • LIPC protein, human
  • RNA, Messenger
  • Lipase