Identification of a cDNA clone for mouse apoprotein A-1 (apo A-1) and its use in characterization of apo A-1 mRNA expression in liver and small intestine.

A cDNA clone for mouse apoprotein A-1 (apo A-1), the major apoprotein of plasma high density lipoproteins, has been identified. In addition to structural and physiological evidence, a genetic polymorphism for mouse plasma apo A-1 has been used to confirm that this DNA sequence corresponds to the apo A-1 gene. Use of this clone in molecular hybridization studies has shown that the concentration of apo A-1 mRNA is similar in liver and small intestine and is constant along the entire length of the small intestine. We provide evidence that the same apo A-1 gene is expressed in both liver and small intestine. Apo A-1 mRNA is also present in the stomach and esophagus at 10-15% the concentration found in small intestine but is undetectable in other tissues (such as large intestine, pancreas, heart, kidney, spleen, and brain). Finally, we show that there is a differential effect of a diet high in saturated fat and cholesterol on apo A-1 mRNA levels in liver and small intestine.