Congratulations Evan Webber for successfully defending your Master's Degree Thesis!

Evan Webber

Master’s Degree Candidate
Dr. Chris Phiel's Lab
CU Denver Department of Integrative Biology

Date: Wednesday, April 3rd, 2024, 10:00am - 12:00pm
Where: Science Building, Room 1067

Tropomyosin Directs Myogenesis by Regulating Actin Dynamics

Through the process of muscle development (myogenesis), muscle progenitor cells become mature muscles. Key stages in this process are myotube elongation and myoblast fusion, which are crucial for proper muscle function. However, the pathways that direct myotube elongation and myoblast fusion remain largely unknown. Tropomyosin, more commonly known for regulating contraction in mature muscles, plays a role in elongation and fusion, as evidenced by its ability to rescue both processes when overexpressed in mutant embryos. Additionally, mutations in human Tropomyosins produce serious congenital myopathies that are similar to elongation defects observed in mutant embryos.

I utilized the fruit fly (Drosophila melanogaster) as a model for muscle development. I performed genetic interaction experiments in order to understand how Tropomyosin regulates elongation, fusion, and filopodial dynamics. Through analysis of muscle defects in embryos containing mutant alleles for Tropomyosin and genes regulating actin dynamics, genetic interactions were identified in myotube elongation. These interactions indicated that Tropomyosin has roles in stabilizing the actin filament and regulating other actin binding proteins. Analysis of filopodia in live-imaged embryos also suggested that Tropomyosin increases filopodial longevity, which may implicate a role in myotube pathfinding and environmental sensing. These effects appear to be limited to myotube elongation, as no interactions occurred between Tropomyosin and regulators of actin dynamics during myoblast fusion. This disparity suggests that different pathways govern elongation and fusion.