Mouse brain and muscle tissues constitutively express high levels of Homerproteins

In order to characterize expression of Homers in mouse brain and peripheral tissues we have developed a coupled reverse transcription (RT)-PCR/restric tion digestion approach. This has allowed us to determine the molecular com position and relative levels of the constitutive expression of the Homer-1, -2 and -3 mRNAs across mouse tissues. We report here that mammalian brain constitutively expresses high levels of the Homer-1, -2 and -3 mRNAs. Expre ssion of thr Homer-1 mRNAs reaches 66% of the brain total Homer mRNAs expre ssion, followed by Homer-3 mRNA (22%) and Homer-2 mRNAs (12%). Quantitative RT-PCR analysis and the Western blotting using pan-Homer antibody revealed that mouse heart, skeletal muscle and diaphragm constitutively express hig h levels of the Homer proteins and their mRNAs, We have shown that the mole cular profile of expression of Homer-1, -2 and -3 mRNAs in muscle containin g tissues resembles that obtained for mammalian brain.