Dedifferentiation of Adult Human Myoblasts Induced by Ciliary Neurotrophic Factor In Vitro

Abstract

Ciliary neurotrophic factor (CNTF) is primarily known for its important cellular effects within the nervous system. However, recent studies indicate that its receptor can be highly expressed in denervated skeletal muscle. Here, we investigated the direct effect of CNTF on skeletal myoblasts of adult human. Surprisingly, we found that CNTF induced the myogenic lineage-committed myoblasts at a clonal level to dedifferentiate into multipotent progenitor cells-they not only could proliferate for over 20 passages with the expression absence of myogenic specific factors Myf5 and MyoD, but they were also capable of differentiating into new phenotypes, mainly neurons, glial cells, smooth muscle cells, and adipocytes. These "progenitor cells" retained their myogenic memory and were capable of redifferentiating into myotubes. Furthermore, CNTF could activate the p44/p42 MAPK and down-regulate the expression of myogenic regulatory factors (MRFs). Finally, PD98059, a specific inhibitor of p44/p42 MAPK pathway, was able to abolish the effects of CNTF on both myoblast fate and MRF expression. Our results demonstrate the myogenic lineage-committed human myoblasts can dedifferentiate at a clonal level and CNTF is a novel regulator of skeletal myoblast dedifferentiation via p44/p42 MAPK pathway. INTRODUCTIONAdult skeletal myoblasts have long been considered as myogenic lineage-committed cells with either self-renewing or differentiating into multinucleated myotubes in vitro (Jankowski et al., 2002;Tamaki et al., 2003). Myoblast fate is critically dependent on the myogenic regulatory factors (MRFs): MyoD, Myf5, myogenin, and Mrf4, which have a well-defined role in orchestrating skeletal muscle development and differentiation. Gene targeting in mice has illustrated the essential role for MRFs: Myf5 and MyoD is critical to establishing the myogenic cell lineage and producing committed, undifferentiated myoblasts (Kablar et al., 1999), whereas myogenin has an important role in initiating differentiation (Hasty et al., 1993); Mrf4 regulates terminal differentiation and myofiber maintenance (Patapoutian et al., 1995). Gene targeting in mice has illustrated the essential role for Myf5 and MyoD in myoblast fates. In MyoDϪ/Ϫ and/or Myf5Ϫ/Ϫ knockout mice, muscle precursors acquire nonmuscle cell fates (Kablar et al., 1999) and become multipotential stem cells or a progenitor compartment (Parker et al., 2003). Early histological studies indicated that muscle fibers at the amputation plane of urodele amphibians might dedifferentiate by budding off mononucleate cells from syncytial muscle cells (Echeverri and Tanaka, 2002). Recent studies suggest that dedifferentiation may be also possible in mammalian system (Odelberg et al., 2000;Tsai et al., 2002;Chen et al., 2004). Especially, the recent reports have shown that ectopic expression of msx1 in C2C12 myotubes can induce dedifferentiation of the myotubes to produce multipotent mononucleated cells (Odelberg et al., 2000), and a 2,6-disubstituted purine, reversine, can also induce dedifferentia...

Wnt/β‐catenin signaling is critical for dedifferentiation of aged epidermal cells in vivo and in vitro

“…Dedifferentiation is often associated with carcinogenesis and has been named 'anaplasia', that is, reversion of cells to an immature or a less-differentiated form. Besides tumors (Helm et al, 2005), these cells are found in muscle tissue (Chen et al, 2005), nervous tissue (Harrisingh et al, 2004;Sunico & Moreno-Lopez, 2010), renal tissue (Lluis et al, 2008), myocardial tissue (Jopling et al, 2010), hepatic tissue (Meivar-Levy et al, 2007), chondrocytes (Gustafson & Smith, 2010;Kiesslich et al, 2010), and others. In epidermal tissue, dedifferentiation-derived epidermal stem cell-like cells were found in spinous and granular layers of (Fu et al, 2001;Li et al, 2007).…”

Intravitreal injection of ciliary neurotrophic factor (CNTF) causes peripheral remodeling and does not prevent photoreceptor loss in canine RPGR mutant retina

“…We propose that the loss of these phenotypic markers may represent a form of dedifferentiation. To the best of our knowledge we are unaware of reports of such a process in photoreceptor cells, yet, this is not unexpected since CNTF has recently been shown to induce the dedifferentiation of adult human myoblasts into multipotent progenitor cells (Chen et al, 2005), as well as the transformation of striatal astrocytes toward a more immature and activated phenotype (Escartin et al, 2006). CNTF is known to elicit the formation of new neuritic processes in rodent motor neurons and this process is currently being investigated as a potential approach to treat partial denervation and neuromuscular paralysis (Gurney et al, 1992;Siegel et al, 2000).…”

gp130 receptor ligands as potential therapeutic targets for obesity

“…As a neurotrophic factor it promotes differentiation of sympathetic neurons and glial progenitor cells into astrocytes; supports the survival of sensory, motor, hippocampal, and cerebral neurons; and promotes the maturation of oligodendrocytes (79). However, unlike IL-6, CNTF lacks a signal sequence peptide and is therefore not secreted by neuronal cells (80,81), which has therapeutic implications (see "Using gp130R ligands as therapy: where to now?"). CNTF receptor a (CNTFRa) is most highly expressed within neural tissue, but its expression is ubiquitous, being detected in the adrenal glands, liver, kidney, testis, and skin (79).…”