Tenascin-Y, a component of distinctive connective tissues, supports musclecell growth

Chicken tenascin-Y is an extracellular matrix protein most closely related to the mammalian tenascin-X. It is highly expressed in the connective tissu e of skeletal muscle (C. Hagios, M. Koch, J. Spring, M. Chiquet, and R. Chi quet-Ehrismann, 1996, J. Cell Biol. 134, 1499-1512). Here we demonstrate th e presence of tenascin-Y in specific areas of the connective tissues in dev eloping lung, kidney, and skin. In skin tenascin-Y shows a complementary ex pression pattern to tenascin-C, whereas in the lung and kidney the sites of expression are partly overlapping. Tenascin-Y is also present in embryonic skeletal muscle where it is expressed in the developing connective tissue in between the muscle fibers. This connective tissue is also the major site of alpha 5 integrin expression. We purified recombinantly expressed tenasc in-Y and tested its effect on cell adhesion and its influence on muscle cel l growth and differentiation. C2C12 myoblasts were able to adhere to tenasc in-Y and showed extensive formation of actin-rich processes without generat ion of stress fibers. Furthermore, we found that tenascin-Y influenced cell morphology of chick embryo fibroblasts over prolonged times in culture and that it supports primary muscle cell growth and restricts muscle cell diff erentiation. (C) 1999 Academic Press.