E-Newsletter No. 45

Newsletter # 41 described the pharmacokinetics and morphological effects of Myoplex^® at the cellular level. Myoplex^® also interacts with the immune system to induce the cytokine (a chemical messenger secreted from cells), interlukin-4 (Il-4), adding to the repertoire of actions of this novel monoclonal antibody (Mab).

In the 16 May, 2003, issue of Cell, Horsley, et al. showed that among its other effects on the immune system, Il-4 builds up muscle by promoting the fusion of myoblasts (an embryonic cell which becomes a cell of the muscle fiber). Myoblast fusion creates the long syncitial myotubes (a multinucleate mass of protoplasm produced by the merging of cells) that comprise the skeletal muscle fibers.

This sharing of nuclei builds up muscle cell size during development, maintenance, and repair. The investigators found that removing Il-4 or its receptor from muscle cells reduced their size during development and the number of nuclei. It seems that Il-4 acts after an initial phase in which a subset of myoblasts fuses together to form nascent (just born; just coming into existence) myotubes with a limited number of nuclei. Il-4 is expressed from a subset of these myotubes and recruits more mononuclear cells in the syncitia.

Il-4 seemed to be induced by the downregulation/suppression of myostatin (MSTN) gene to recruit a member of a transcription factor family (separate biochemical pathways within cells that transmit signals received from receptors on the outer cell wall membrane in order to direct functions inside the cell) that also turns on Il-4 in macrophages (large mononuclear, wandering, secretory cell that ingests microorganism, or other cells and foreign particles, and which originates in the tissues): nuclear factor of activated T cells (NFAT). Thus, we now understood both the genetic and the immune effects of the Myoplex^® Mab.

Click here to learn more about myostatin

In simpler terms, Myoplex^®, a proprietary monoclonal antibody, is a powerful muscle builder. Its safety and efficacy studies show interactions between genetic and hormonal effects on the brain (the neuroendocrine system), extracellular chemical messengers (the immune system), and intracellular signaling (signal transcription/transduction) mechanism.

Also see:

Big Blue Double-Muscle Syndrome

Sarcopenia -- The Role of Mitochondrial DNA (mt DNA) Deletion Mutation

Myoplex^® Effectiveness For Sarcopenia of Aging

Definition of Myostatin

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