Tetranectin in slow intra- and extrafusal chicken muscle fibers

Tetranectin is a C-type lectin that occurs in the mammalian musculoskeletal system. In the present report we describe the first studies on an avian te tranectin. A full-length chicken tetranectin cDNA was isolated. Comparison of the deduced amino acid sequence of chicken tetranectin with mouse and hu man tetranectin showed an identity of 67 and 68%, respectively. Northern bl ot analysis demonstrated broad expression of chicken tetranectin mRNA, whic h was first detected on embryonic day 4. Tetranectin protein was detected i n chicken serum and egg yolk. Since muscle is one of few tissues in which t etranectin protein is retained, we examined the distribution of tetranectin in various muscle types in chicken. Myofibers strongly positive for tetran ectin were observed in several muscles including m. tibialis ant. and m. sa rtorius (from embryonic day 10 to adult). Using antibodies to fast and slow myosin heavy chains (MHC) and double immunostaining techniques, we found t hat tetranectin was restricted to slow (type I) muscle fibers. Similarly on ly slow intrafusal fibers accumulated tetranectin. The pattern of immunosta ining in chickens differs markedly from that seen in mouse muscles, indicat ing that tetranectin performs a role in muscle that is not associated with a hitherto recognized muscle type or function.