Title of project

RhoA and YAP: regulators and new targets in skeletal muscle insulin sensitivity

Abstract

In patients with type 2 diabetes (T2D), skeletal muscle insulin resistance is a primary defect that leads to hyperglycaemia, metabolic dysregulation, and severe complications. Thus, drugs that target skeletal muscle insulin resistance are needed.

To that end, a basic understanding of the molecular mechanisms regulating insulin-stimulated glucose uptake in skeletal muscle could reveal new treatment opportunities. RhoA, part of the Rho GTPase family of molecular switches, is an intriguing candidate. Given the known and critical roles of another Rho GTPase, Rac1, in insulin-mediated glucose uptake, the role of RhoA in the context of muscle insulin resistance is likely.

Based on multi-omics human datasets, spatiotemporal localization data, and a glucose transporter assay,
RhoA is a strong candidate for controlling insulin sensitivity. My exciting preliminary data obtained using live cell imaging of muscle cells and ex vivo muscle fibers suggested that RhoA mediates cytoskeletal reorganization, which is critical for insulin-mediated glucose uptake, and co-localizes with the glucose transporter GLUT4. Insulin-sensitive YAP activation was indicated by translocation to the nucleus.

The specific aims of this project are to i) determine whether RhoA and its downstream target YAP regulate insulin-stimulated glucose uptake in skeletal muscle in mice and human muscle cells and ii) uncover the
therapeutic potential of RhoA and YAP in improving glucose metabolism in a preclinical T2D model.

RhoA and YAP will be deleted or overexpressed in human skeletal muscle cells, and the skeletal muscle of humanized lean or diabetic db/db mice using recombinant adeno-associated virus-driven technology, either in a single muscle, or in all the muscle of the mouse. Insulin-stimulated glucose uptake (using isotopic tracers), insulin signalling, and 4D spatiotemporal molecular interactions will be utilized to determine the role for RhoA and YAP and their therapeutic potential.

Obtaining basic insights into mechanisms of action of RhoA in skeletal muscle insulin sensitivity could change the current treatment paradigm of T2D to include treatment options for skeletal muscle insulin resistance. Our generated new knowledge could thereby help tackle the enormous and accelerating burden of T2D.