Differential expression of mRNA coding for the alpha-2-macroglobulin family and the LRP receptor system in C57BL/6J and C3H/HeJ male mice

Expression of mouse A2M (MAM), murinoglobulin (MUG), the A2M receptor or LD L-Receptor related protein (A2MR/LRP) and the Receptor Associated Protein ( RAP) were measured by northern blotting of mRNA isolated from liver, heart and peritoneal macrophages from C3H/HeJ and C57BL/6J (B6) mice. Marked diff erences between males of the two mouse strains were observed for MAM and MU G mRNA levels in liver, which were reflected in plasma levels of both prote inase inhibitors, as confirmed by immune-electrophoresis. C3H/HeJ mice had higher levels of the MAM and MUG mRNA and their corresponding plasma protei ns than B6 mice. B6 mice expressed higher levels of LRP mRNA relative to C3 H/HeJ mice but had lower levels of RAP mRNA. LRP receptor activity, assayed by fluoresceinated-A2M binding, was higher in B6 cells. The present data c ontribute to the knowledge of genetic background characteristics among male mouse of these two strains, which can take part in many biological events such as lipid metabolism, inflammation and immune response to different inf ectious agents.