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This Article Full Text Full Text (PDF) All Versions of this Article: 35/1/86    most recent 00232.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Evans, M. Articles by Barton, E. R. PubMed PubMed Citation Articles by Evans, M. Articles by Barton, E. R.

Expression profiling reveals heightened apoptosis and supports fiber size economy in the murine muscles of mastication

¹ Department of Anatomy and Cell Biology, School of Dental Medicine, Philadelphia, Pennsylvania
² Department of Physiology, School of Medicine, Philadelphia, Pennsylvania
³ Pennsylvania Muscle Institute, University of Pennsylvania, Philadelphia, Pennsylvania

Distinctions between craniofacial and axial muscles exist from the onset of development and throughout adulthood. The masticatory muscles are a specialized group of craniofacial muscles that retain embryonic fiber properties in the adult, suggesting that the developmental origin of these muscles may govern a pattern of expression that differs from limb muscles. To determine the extent of these differences, expression profiling of total RNA isolated from the masseter and tibialis anterior (TA) muscles of adult female mice was performed, which identified transcriptional changes in unanticipated functional classes of genes in addition to those attributable to fiber type. In particular, the masseters displayed a reduction of transcripts associated with contractile and cytoskeletal load-sensing and anabolic processes, and heightened expression of genes associated with stress. Associated with these observations was a significantly smaller fiber cross-sectional area in masseters, significantly elevated load-sensing signaling (phosphorylated focal adhesion kinase), and increased apoptotic index in masseters compared with TA muscles. Based on these results, we hypothesize that masticatory muscles may have a fundamentally different strategy for muscle design, compared with axial muscles. Specifically there are small diameter fibers that have an attenuated ability to hypertrophy, but an increased propensity to undergo apoptosis. These results may provide insight into the molecular basis for specific muscle-related pathologies associated with masticatory muscles.

caspase-12; focal adhesion complex; endoplasmic reticulum-stress apoptosis; myosin heavy chain