Meeting Abstract
P2.99 Wednesday, Jan. 5 Expression of Akirin Isoforms During Muscle Regeneration in Response to Muscle Injury in Rainbow Trout (Oncorhynchus mykiss) BILLING, Samantha R.*; BIGA, Peggy R.; North Dakota State University, Fargo; North Dakota State University, Fargo samantha.billing@ndsu.edu
After muscle tissue undergoes injury, a series of events take place to repair or replace the injured myofibers. Akirin, a novel gene found to be a downstream target of myostatin, is a promyogenic factor in proliferating and differentiating muscle cells. Rainbow trout express eight akirin isoforms that are fairly constitutively expressed. These isoforms potentially have differing effects on muscle regeneration. Rainbow trout display indeterminate muscle growth, where muscle cells in adult fish can undergo both hypertrophy and hyperplasia. We propose that muscle injury will decrease local myostatin expression with a subsequent increase in akirin2 expression and differential expression of the akirin1 isoforms. This hypothesis was tested by inflicting a mechanical injury on the muscle tissue above the lateral line using a scalpel and leaving the right side uninjured as a control. Fish were then sampled at different time points following the injury at 1, 3, 7, 14 and 28 days. An absolute control that was not exposed to any kind of injury was also included in the experimental design. Injured and non-injured muscle tissue was analyzed for differential gene expression of myostatin and akirin isoforms using quantitative PCR. In addition, localization of differential gene expression was analyzed by in situ hybridization. Akirin1(2a and 2b) and akirin2 (2a and 2b) exhibit higher expression in red muscle than white muscle. Akirin isoforms were upregulated in injured versus non-injured muscle tissue, however the isoforms exhibited differential expression pattern across isoforms and genes. These results suggest a complex regulatory system and potential differential functions of the akirin isoforms that warrants better understanding.
