Determining the molecular regulatory control of Rho GTPases and their mechanisms of action on skeletal muscle mass and insulin sensitivity

Name of applicant

Lykke Sylow


University of Copenhagen


DKK 4,999,754



Type of grant

Semper Ardens: Accelerate


My project is about how skeletal muscle metabolism and muscle mass is maintained by small molecular switches called Rho GTPases. Skeletal muscle is a key organ for movement, respiration, and mastication and is critically implicated in organismal metabolic control. Evidence is emerging that Rho GTPases play key roles in skeletal muscle mass regulation and insulin sensitivity. With this project, we will identify the molecular mechanisms by which Rho GTPases are activated and inactivated in skeletal muscle. Specifically, we will investigate the role of specific activating GEF proteins and inactivating GAP proteins. Additionally, we will determine how Rho GTPases regulate insulin sensitivity and muscle mass via input to neuromuscular junction formation and the actin cytoskeleton.


Despite their emerging importance, relatively little is known about Rho GTPase regulation and mechanisms of action in skeletal muscle. We also lack a comprehensive knowledge about how insulin sensitivity and muscle mass are maintained and how it is affected in disease. Obtaining basic insights into the regulation of Rho GTPases would improve our understanding of the processes that regulate skeletal muscle function because these small molecules are very little explored. That could generate new knowledge to help tackle the enormous and accelerating burden of aging, diabetes, and cancer in the future and catalyze societal development by providing new strategies to promote skeletal muscle health.


We have identified specific Rho GTPase activating GEFs and inactivating GAPs that we will either introduce or remove to skeletal muscle using recombinant adeno-associated virus (rAAV) progressing from testing in rat myotubes to mouse skeletal muscle. We will measure Rho GTPase activation in response to insulin and muscle contraction (stimuli that we know activate Rho GTPases) in skeletal muscles with the rAAV-induced manipulations of GEFs, GAPs, and GDIα. Using these systems, we will also measure skeletal muscle neuronal innervation and muscle mass regulation and determine the organization of the cortical actin cytoskeleton, all cellular events that are of importance for muscle function and could be regulated by Rho GTPases.

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