Grant: Operating Grant

Mechanical force is an important physiological signal. In living tissues, mechanical force is transmitted to cells through extracellular matrix, which serves as a structural scaffold for cells to adhere, migrate and differentiate. Tenascins are an important family of extracellular matrix proteins and play important roles in modulating cell-matrix interactions. Tenascins are expressed in adult tissues that are subject to heavy tensile loading or undergo remodeling. Deficiency and mutations in tenascin-X were found to link directly to one recessive form of Ehler-Danlos Syndrome, which is characterized by abnormal mechanical properties of skin tissues and joints. However, little is known about the molecular basis of tenascin mechanics and mechanotransduction. The long term goal of this proposal is to determine the molecular basis of the fine-tuned nanomechanics of tenascins and understand how tenascins function in mechanotransduction in connective tissues. Towards this goal, we will combine the state-of-the-art single molecule atomic force microscopy, protein engineering and cell biology techniques to investigate the mechanical architecture and design of tenascins. We will focus our studies on tenascin-C and tenascin-X. We will examine the mechanical phenotype of disease-causing point mutants of FnIII domains, and explore the possible mechanism linking point mutations to connective tissue disorder. We will examine the mechanical effect of the binding of various receptors and/or ligands to tenascins to test various hypotheses on the roles of tenascins in tissue modeling and connective tissue disorder. We will also develop novel tools to quantitatively probe the force experienced by tenascins in living cells. These proposed experiments will provide insights into molecular basis of tenascin mechanics and the role of tenascin-X in biomechanics of connective tissues. These insights will also offer useful information for tissue engineering strategies in skeletal repair.