Transcriptional Profiling Reveals Extraordinary Diversity Among Skeletal Muscle Tissues

Skeletal muscles are a diverse family of highly specialized tissues that perform a wide array of physiological activities and maintain whole-body glucose metabolism and energy homeostasis. Functional diversity is a distinctive feature of muscle tissues, which demonstrate remarkable variability in their speed of contraction, metabolic profile, resistance to fatigue, and regenerative capacity. Unsurprisingly, many disorders of skeletal muscle afflict a remarkably specific subset of tissues, including muscular dystrophies, cancer cachexia, aging sarcopenia, and amyotrophic lateral sclerosis. Taken as a whole, these observations indicate that specific genetic programs establish and maintain physiological specialization of muscle tissues. Elucidating these genetic programs is essential to understanding muscle specialization and propensity for disease. Nevertheless, most global profiling studies performed to-date have not directly addressed intrinsic variability between different muscle tissues. This gap in the literature is particularly glaring for more sophisticated mechanisms of gene expression regulation such as circadian control, post-transcriptional regulation and non-coding RNA expression, despite their well-established roles in many disease mechanisms. In an effort to understand the variability present within specific skeletal muscles with respect to gene expression, our lab has performed RNA-Seq on a variety of skeletal muscle tissues.