Meeting Abstract
P2.87 Tuesday, Jan. 5 The Myosin Light Chain 1 Isoform Associated with Masticatory Myosin Heavy Chain in Mammals and Reptiles is Embryonic/atrial MLC1 REISER, PJ*; BICER, S; PATEL, R; AN, Y; CHEN, Q; QUAN, N; Ohio State University; Ohio State University; Ohio State University; Ohio State University; Ohio State University; Ohio State University reiser.17@osu.edu
We recently reported (J Exp Biol 212:2511-2519, 2009) that masticatory myosin heavy chain (MHC-M) is expressed as the exclusive or predominant MHC isoform in masseter and temporalis muscles of several rodent species, contrary to the prevailing dogma that rodents express almost exclusively MHC isoforms that are typically found in fast limb muscles and not masticatory myosin. We also reported that the same rodent species express the embryonic/atrial isoform of MLC1 (MLC1E/A) in jaw-closing muscles and not a unique masticatory MLC1 isoform that others have reported as being expressed in jaw-closing muscles of carnivores that express MHC-M. The objective of this study was to determine whether MLC1E/A is consistently expressed in jaw-closing muscles of other, non-rodent species, including members of Carnivora, which express MHC-M. Jaw-closing muscles and fast and slow limb muscles of nineteen species (six Carnivora species, one Primate species, one Chiroptera species, five marsupial species, alligator and five turtle species) were analyzed using protein gel electrophoresis, immunoblotting, mass spectrometry and RNA sequencing. Gel electrophoresis and immunoblotting indicate that MHC-M is the exclusive or predominant MHC isoform in jaw-closing muscles of each of the studied species. The results from all of the approaches collectively show that MLC1E/A is exclusively or predominantly expressed in jaw-closing muscles of the same species. We conclude that MLC1E/A is the exclusive or predominant MLC1 isoform that is expressed in jaw-closing muscles of vertebrates that express MHC-M, and that a unique masticatory isoform of MLC1 likely does not exist. Supported by the National Science Foundation.
