Temporal Examination of Myoglobin and Myosin Heavy Chain Expression Patterns in Skeletal Muscle Cells


Meeting Abstract

P3-110  Monday, Jan. 6  Temporal Examination of Myoglobin and Myosin Heavy Chain Expression Patterns in Skeletal Muscle Cells LARSON, A M*; KANATOUS, S B; Colorado State University; Colorado State University spashley@rams.colostate.edu

Myoglobin is a hemoprotein expressed in vertebrate muscle that has been shown to ameliorate the effects of tissue ischemia experienced by mammalian divers during diving. Typically, myoglobin expression is known to follow an established slow muscle fiber type. These slow muscle fibers contain a protein called myosin heavy chain I and are found in endurance muscles. Interestingly, recent evidence has shown changes in myoglobin expression without a change in fiber type. This indicates that myoglobin expression may not always be fiber type dependent and could be regulated by different stimulatory pathways. Our lab has shown that mixed lipid supplements, and hypoxia coupled with muscle contraction elevate myoglobin levels in cells from terrestrial and marine mammals, but it is unknown how these supplements affect myoglobin expression relative to the fiber type of the cultured tissue. To investigate, we have cultured and differentiated C2C12 myoblasts in the presence and absence of lipid, hypoxia, and/or caffeine to stimulate contraction. Cells were then harvested each day after differentiation initiation. Western blots were conducted to determine the expression of myoglobin and various myosin heavy chains. With these methods, we have found myoglobin expression prior to that of myosin heavy chain I and IIA. This data reveals conditions under which there are pathways to myoglobin expression independent from slow fiber type expression. Examination of alternate routes of myoglobin expression that are independent of fiber type could yield potential therapeutic benefits to combat ischemic diseases seen in humans and animals.

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