Dynamic expression patterns of leucine-rich repeat containing protein 10 in the heart.

Leucine-rich repeat containing protein 10 (LRRC10) is a heart-specific factor whose function remains unknown. Examination of the intracellular location of the gene products is a critical step in determining the biological functions of the protein. Our expression analyses in mice indicate that LRRC10 is exclusively expressed from the precardiac region in early embryos to the adult heart. LRRC10 expression is markedly elevated upon birth, suggesting its role in the embryonic as well as adult hearts. Of interest, LRRC10 exhibits dynamic intracellular expression patterns in cardiomyocytes. Cardiomyocytes from embryos and newborns show diffuse cytoplasmic and nuclear staining of LRRC10. In contrast, striking striations are observed in adult cardiomyocytes, which are colocalized with the markers for the Z-line, sarcoplasmic reticulum (SR), and transverse (T)-tubule by double immunostaining. Further investigation by electron micrographs places LRRC10 in a diad region where the SR interacts with the T-tubule that locates along the Z-line.