Extracellular Matrix and Gelatinases in Disuse-induced Skeletal Muscle Atrophy

+Liu, X.; Lee, D., Natsuhara K., Kim, H. +University of California, San Francisco, CA, Veterans Affairs Medical Center, San Francisco, CA Senior author: [email protected] INTRODUCTION: Extracellular matrix (ECM) plays a critical role in maintaining normal structure and function of skeletal muscle. Muscle basement membrane serves as an interface between cells and the rest of matrix. It is also thought to be responsible for force transmission within the muscle [1]. Interruption of the integrity of basement membrane is thought to play a critical role in muscle degradation [2]. Our previous work has demonstrated degradation of type IV collagen and laminin, two major components of basement membrane in skeletal muscle after disuse [3]. Gelatinases are ECM remodeling enzymes, which are thought to be responsible for basement membrane degradation especially. In our previous work, we demonstrated a critical role of gelatinase A (also known as matrix metalloproteinase 2, MMP-2) in disuse-induced muscle atrophy [4]. However, it remains unknown that if the other member of gelatinases—gelatinase B (also known as MMP-9) plays an equally critical role in disuse-induced muscle atrophy. In this study, we investigated the role of gelatinase B (MMP-9) in disuse-induced skeletal muscle atrophy using MMP-9 null mice. We hypothesize that deleting gelatinase B gene will preserve muscle mass after disuse.