Tissue-specific regulation of the alpha-myosin heavy chain gene promoter in transgenic mice.

TLDR

The intergenic region between mouse alpha‑MHC and beta‑MHC genes has been shown to drive tissue‑specific and developmental stage‑specific expression of a reporter gene. This study examined whether that intergenic region can direct gene expression in transgenic mice. Transgenic mice were generated with deletions of the intergenic region, including an alpha‑3 deletion lacking the distal 2.5 kb and a minimal 138‑bp construct, and expression was assessed by reporter activity and in situ hybridization of alpha‑MHC transcripts. Expression was low in lung tissue, with alpha‑MHC transcripts detected by PCR and localized by in situ hybridization to the thick intimal wall of veins and venules.

Abstract

The intergenic region between the mouse alpha-myosin heavy chain (MHC) and beta-MHC genes was analyzed in terms of its ability to drive gene expression in transgenic mice. Earlier, we reported that the entire intergenic region was sufficient to direct expression of the bacterial chloramphenicol acetyl transferase reporter gene in a tissue-specific and developmental stage-specific manner. Additional transgenic lines have been generated which include two deletions. The first deletion, alpha-3, which lacks the distal 2.5 kilobase pairs of the upstream region, is competent to direct tissue- and developmental-specific expression of the transgene. A larger deletion, in which only 138 base pairs upstream of the transcriptional start site remain, shows no chloramphenicol acetyltransferase activity in either muscle or non-muscle tissue. Tissue surveys of transgene expression indicated low levels of activity in the lung, and analyses via the polymerase chain reaction confirmed the presence of the endogenous alpha-MHC gene transcripts in this tissue. Subsequently, an alpha-MHC gene-specific riboprobe was used to detect the cognate transcripts in lung sections by in situ hybridization. The data show that, in the lung, the transcripts are localized to the thick intimal wall of the veins and venules.