Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2018-2019)

The overarching theme of our NSERC program is to unravel the role of the AP-1 transcription complex in the control of skeletal muscle gene regulation during developmental and adult myogenesis . Recently, we have made the important observation that AP-1 is expressed in the resident stem cells (called satellite cells) in adult skeletal muscle. Satellite cells are crucial for the maintenance of muscle mass and also repair in all mammals. In the proposed studies we plan to further assess the requirement for AP-1 in skeletal muscle development during embryogenesis and during adult muscle regeneration. Towards this goal, we will address the following objectives in the next funding cycle:

1) To determine if AP-1 is a competence factor for Notch signaling and pax 7 expression in myogenic progenitor cells and satellite cells.
2) To assess the effect of conditional cJun/Fra2 deletion on embryonic myogenesis and post-natal muscle regeneration.
3) To characterize the AP-1 interactome in response to growth factor signaling in myogenic progenitor cells.

To address aim 1 we will use gain and loss of function studies of AP-1 to assess how this influences components and downstream targets of Notch signalling in primary myoblast cultures and single fiber cultures. We will particularly utilize state of the art confocal live cell imaging technology for this aim.
To address aim 2 we will use conditional Cre mediated excision of Floxed cJun and Fra2 in mice and then assess embryonic muscle formation and also post-natal muscle regeneration. We have a pax7 Cre mouse to excise floxed Fra2 and cJun alleles.
To address aim 3 we will continue to define the signalling pathway regulated control of Fra2 activity by characterizing the Fra2 protein interactions in myogenic cells using an affinity purification- mass spectrometry based approach that we have now perfected (AP-LC MS/MS). Protein interactions will then be interrogated for their role in myogenic cells.
These questions are all based on extensive data that we have generated over several funding cycles of NSERC support for this research initiative. Personnel, reagents and experience position us to address these questions with high feasibility and excellent impact.