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Thesis Format

Alternative Format

Degree

Master of Science

Program

Biology

Collaborative Specialization

Developmental Biology

Supervisor

Kelly, Gregory

Abstract

Myogenesis is defined as the formation of skeletal muscle tissue during embryonic development and involves a multitude of cellular signalling pathways. Among these include the Sonic hedgehog (Shh) signalling pathway which must be deactivated for differentiation into muscle cells to occur. However, less is known regarding the pathways operation during cell differentiation and whether Suppressor of Fused (SUFU), the protein inhibitor of Shh signalling, plays a role. To address this, mouse C2C12 myoblast cells were utilized as a model and differentiated into muscle cells to identify the presence of SUFU during this time. Experiments in qRT-PCR show a decrease in Shh responsive gene transcripts after induced differentiation thus confirming the deactivation of the pathway during this time. Alongside this, immunoblotting results show the absence of SUFU during proliferation of the cells and its presence throughout differentiation. These results postulate a role for SUFU as an inhibitor during Shh mediated myogenesis.

Summary for Lay Audience

During embryonic development, the structures and organs of the eventual adult body are built through differentiating cells. Cell differentiation is defined as the process whereby cells transform into that of a more specialized type with unique properties such as that of a muscle cell. For this process to occur, cells must receive a message in the form of a molecule or protein which binds to their surface. Upon successful delivery of this message, a chain reaction occurs within the cell whereby proteins pass along the newly delivered message to each other. The final protein in this chain then activates cell type specific genes needed for differentiation to occur such as genes involved in building the architecture of a muscle cell with the ability to contract. This successive passing of information is known as a cellular signalling pathway which exists in many different forms, each of which can signal cells to perform different actions.

The process in which undifferentiated cells transform into muscle cells is known as myogenesis. Many different signalling pathways participate in this process including the Sonic hedgehog (Shh) signalling pathway which must be deactivated for differentiation to occur. However, little is known regarding how this specific pathway is regulated during this time. Of particular interest to this thesis is the presence of the protein Suppressor of Fused (SUFU) during myogenesis which acts as an inhibitor to Shh signalling.

To identify the presence of SUFU during myogenesis, the C2C12 cell line was used as a cellular model for the experiments of this study to replicate differentiation as it occurs during development. These cells were originally isolated from mice and consist of myoblasts, the precursor to muscle cells. In this study, once C2C12 myoblast cell differentiation was induced, samples of the cells were collected at each day of differentiation and used in experimentation to determine the activation/deactivation of Shh signalling and presence of SUFU. Shh signalling was found to decrease throughout differentiation while SUFU was found to be present during this time. These results postulate that SUFU may play a role in the inhibition of Shh signalling during myogenesis.

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