Expression of synemin in the mouse spinal cord.

beta-Synemin was previously identified as an alpha-dystrobrevin-interacting protein in muscle. To better understand its function in neural tissue, in situ and immunohistochemical analyses were performed to identify where the synemin isoforms are expressed in the spinal cord of C57BL/6 and dystrophin-deficient (mdx) C57BL/10 mice. These analyses show that synemin transcript and its encoded protein colocalize in the anterior horn cells and that no differences in synemin expression were found in nerve tissue from C57BL/6 or mdx mice. The expression of synemin mRNA and protein predominantly in the anterior horn cells suggests that synemin performs an essential function in those cells. Because synemin is more highly expressed in the midbrain and pons, its function in neurological cells was further pursued by identifying coexpressed proteins in cells from those regions of the brain. These results show that neurons that express synemin also express tryptophan hydroxylase-1, a marker of serotoninergic nerve fibers. Muscle Nerve, 2009.