Poster abstracts

Poster number 55 submitted by Melissa Siebert

Regulation of myoblast migration by Eph-Ephrin signaling

Melissa Siebert (OSBP), Denis Guttridge (Molecular Virology, Immunology and Medical Genetics)

Abstract:
After birth, the largest increase in neonatal mass comes from skeletal muscle growth and this growth is necessary to gain motility and posture. Although, neonatal growth depends on myoblast precursor cells fusion to the ends of muscle fibers, our laboratory was the first to give a mechanism explaining this phenomenon. We found NG2 interstitial cells promotes the migration of myoblasts to the ends of muscle fibers through the production of a newly discovered NF-kappaB target gene, EphrinA5. The aim in this project will be to identify the Ephrin receptor (Eph) on myoblasts that interacts with the EphrinA5. 1 I have found that of the six known receptors that can bind EphrinA5; only EphA3, EphA4 and EphB2 RNA is expressed in C2C12 cells and primary myoblasts. EphA3 and EphB2 protein is also expressed on myoblasts although EphA4 protein is barely detectable in primary myoblasts. Similarly, in P7 EDL muscle, Pax7 positive interstitial cells co-stain with EphA3 and EphB2 but not EphA4. Based on these preliminary results, I hypothesize EphA3 and/or EphB2 are binding to EphrinA5 to promote myoblast migration. To test this hypothesis I will measure whether EphrinA5 can promote the migration of EphA3 and EphB2 knockout C2C12 myoblasts. Currently I have knocked out EphB2 from C2C12 cells using CRISPR-Cas9. After I knockout EphA3 from C2C12 cells, I will measure the relative migration of the knockout C2C12 cells through a boyden chamber compared to wild type C2C12 cells in the presence of EphrinA5. This work will give us a more complete understanding of how EphrinA5 promotes myoblast migration.

References:
1. Gu, J.-M. et al. An NF-κB - EphrinA5-Dependent Communication between NG2+ Interstitial Cells and Myoblasts Promotes Muscle Growth in Neonates. Dev. Cell 36, 215–224 (2016).

Keywords: Ephrin-Eph Signaling, Muscle Development