COREGULATION OF APO A-I, APO C-III AND APO A-IV GENE-EXPRESSION IN HUMAN INTESTINAL BIOPSIES

The apo A-I gene is expressed in the liver and small intestine. In ord er to study the role of human intestinal transcription of the apo A-I gene in determining plasma high-density lipoprotein, (HDL)-cholesterol and apo lipoprotein (ape) A-I concentrations, the authors measured th e relative mRNA levels of apo A-I in human intestinal biopsies. Biopsi es were taken from 50 fasting subjects (25 males and 25 females). At t he same time blood was taken for lipid and lipoprotein analysis. Plasm a HDL-cholesterol correlated linearly with plasma apo A-I protein. No correlation could be demonstrated between intestinal apo A-I mRNA and plasma apo A-I or HDL-cholesterol levels. The apo A-I gene resides in an apolipoprotein cluster with the apo C-III and apo A-IV genes. To as sess whether there is a coordinated expression of this locus, Northern blot analysis of intestinal RNA was performed. The authors have demon strated that under fasting conditions mRNA levels of apo A-I, C-III an d A-IV are co-regulated in the intestine.