PROJECT SUMMARY/ABSTRACT
Skeletal muscle allows for controlled movement and fine-tuned coordination throughout the entire life of an
individual. In all cells, the response to physical forces is critical; however, this is particularly important in skeletal
muscles to facilitate movement, contraction, and force generation. Mechanotransduction allows cells to sense
and respond to the external environment. In muscle cells, forces transmit through the Z-disc which are
interspersed between sarcomeres and anchor actin filaments. In numerous muscular diseases and myopathies,
mechanotransduction is altered and leads to loss of force, muscle wasting, and increased stiffness. At the
molecular level, these pathological alterations are accompanied by extensive transcriptional changes and mis-
regulation of alternative splicing, an RNA processing mechanism that allows single genes to code for multiple
protein isoforms. A unique feature of skeletal muscle is that it exhibits one of the highest levels of tissue-specific
and evolutionarily conserved alternative splicing.
During muscle development, extensive alternative splicing changes occur to facilitate maturation of the
tissue. Interestingly, numerous genes developmentally regulated by splicing encode proteins that are involved
in membrane trafficking and localize to the sarcomere. One of these genes encodes the Capping Actin Protein
of Muscle Z-Line Subunit Beta (CAPZB) protein. Besides its critical function in capping actin, CAPZB plays
unconventional roles in sarcomere organization. Surprisingly, how mechanotransduction and alternative
splicing are interconnected in muscles has not been deeply investigated and can reveal new insights about
muscle diseases. In my proposal, I hypothesize that alternative splicing regulation contributes to the
development of the mechanical properties of skeletal muscle. I will test this hypothesis in two specific aims. In
aim 1, I will identify the role of two splicing regulators, the poly-pyrimidine tract binding protein 1 (PTBP1) and
quaking protein (QK), in controlling the mechanical properties of muscle cells by stretching cells and
investigating effects on mechanosensitive pathways. In aim 2, I will determine how CAPZB and its splice forms
contribute to the mechanosensitivity of muscle cells by using force microscopy and functional studies.
My long-term goal is to be an independent scientific leader who can lead a team. Therefore, the training
I will receive through this fellowship will facilitate my growth in becoming a muscle biologist with expertise in
RNA processing, and solid skills in mentorship, writing and teaching. My sponsor and co-sponsor are experts
in muscle physiology, cell biology, and, alternative splicing and I have recruited collaborators and mentors with
expertise in physics and mechanotransduction to facilitate a multidisciplinary dissertation. All of them are
strongly committed to mentoring and education and will support me during my Ph.D. and as I move forward in
my career. Finally, the University of North Carolina at Chapel Hill has strong communities of RNA Biology,
mechanotransduction, and membrane trafficking that contribute to the collaborative environment I am part of.