The receptor for advanced glycation end products (RAGE), a member of the immunoglobulin superfamily (1), activated by its ligand, HMGB1, stimulates myoblast differentiation (2), and inactivation of RAGE in myoblasts results in reduced differentiation, enhanced proliferation and tumor formation in vivo (3). Also, enforced expression of RAGE in TE671 rhabdomyosarcoma (RMS) cells (that do not express RAGE) results in activation of the myogenic program, increased apoptosis and reduced proliferation, invasiveness and tumor formation (4). Thus, repression of RAGE expression and/or functional inactivation of RAGE at certain stages of myogenesis might contribute to rhabdomyosarcomagenesis. Embryonal RMSs (ERMSs) originate from satellite cells (SCs) and express low levels of myogenin and high levels of Pax7, and upregulated Pax7 has been shown to contribute to ERMS genesis. We show here that: 1) RAGE is rapidly expressed in activated myoblasts in differentiation medium (DM), and its expression is inversely related to the expression of Pax7, a marker of quiescent and proliferating myoblasts/SCs; 2) RAGE activation in these cells and TE671 cells results in downregulation of Pax7 expression via activation of p38 MAPK and induction of myogenin; 3) functional inactivation of RAGE in primary and C2C12 myoblasts and in TE671 cells overexpressing full-length RAGE (TE671/RAGE cells) results in upregulation of Pax7; 4) an inverse relationship is observed between the expression of RAGE and that of Pax7 in a panel of human ERMSs; 5) transient transfection of C2C12 myoblasts with myogenin results in repression of Pax7 expression (mRNA and protein) even in growth medium; and 6) as investigated by chromatin immunoprecipitation, myogenin binds to putative myogenin consensus sequences in the regulatory regions of Pax7 gene both in human TE671 cells and mouse C2C12 cells under conditions in which Pax7 expression is repressed, i.e. in TE671/RAGE cells and C2C12 myoblasts cultivated in DM. We propose that RAGE signaling in myoblasts might downregulate Pax7 via upregulation of myogenin, a mandatory event for the commitment to terminal differentiation, thereby contributing to reduce their proliferation and the probability of their neoplastic transformation, and that forced expression and/or engagement of RAGE in ERMSs might help to reduce their neoplastic potential. Overall, our data suggest that RAGE can be used for diagnostic purposes in histopathology to identify subtypes of ERMSs. 1. Schmidt AM et al (2001) J Clin Invest 108:949-55; 2. Sorci G et al (2004) Mol Cell Biol 24:4880-94; 3. Riuzzi F et al (2006) J Biol Chem 281:8242-53; 4. Riuzzi F et al (2007) Am J Pathol 171:947-61.

RAGE signalling in myoblasts and embryonal rhabdomyosarcoma cells represses Pax7 expression via p38 MAPK-dependent induction of myogenin.

SORCI, Guglielmo;RIUZZI, Francesca;DONATO, Rosario Francesco
2009

Abstract

The receptor for advanced glycation end products (RAGE), a member of the immunoglobulin superfamily (1), activated by its ligand, HMGB1, stimulates myoblast differentiation (2), and inactivation of RAGE in myoblasts results in reduced differentiation, enhanced proliferation and tumor formation in vivo (3). Also, enforced expression of RAGE in TE671 rhabdomyosarcoma (RMS) cells (that do not express RAGE) results in activation of the myogenic program, increased apoptosis and reduced proliferation, invasiveness and tumor formation (4). Thus, repression of RAGE expression and/or functional inactivation of RAGE at certain stages of myogenesis might contribute to rhabdomyosarcomagenesis. Embryonal RMSs (ERMSs) originate from satellite cells (SCs) and express low levels of myogenin and high levels of Pax7, and upregulated Pax7 has been shown to contribute to ERMS genesis. We show here that: 1) RAGE is rapidly expressed in activated myoblasts in differentiation medium (DM), and its expression is inversely related to the expression of Pax7, a marker of quiescent and proliferating myoblasts/SCs; 2) RAGE activation in these cells and TE671 cells results in downregulation of Pax7 expression via activation of p38 MAPK and induction of myogenin; 3) functional inactivation of RAGE in primary and C2C12 myoblasts and in TE671 cells overexpressing full-length RAGE (TE671/RAGE cells) results in upregulation of Pax7; 4) an inverse relationship is observed between the expression of RAGE and that of Pax7 in a panel of human ERMSs; 5) transient transfection of C2C12 myoblasts with myogenin results in repression of Pax7 expression (mRNA and protein) even in growth medium; and 6) as investigated by chromatin immunoprecipitation, myogenin binds to putative myogenin consensus sequences in the regulatory regions of Pax7 gene both in human TE671 cells and mouse C2C12 cells under conditions in which Pax7 expression is repressed, i.e. in TE671/RAGE cells and C2C12 myoblasts cultivated in DM. We propose that RAGE signaling in myoblasts might downregulate Pax7 via upregulation of myogenin, a mandatory event for the commitment to terminal differentiation, thereby contributing to reduce their proliferation and the probability of their neoplastic transformation, and that forced expression and/or engagement of RAGE in ERMSs might help to reduce their neoplastic potential. Overall, our data suggest that RAGE can be used for diagnostic purposes in histopathology to identify subtypes of ERMSs. 1. Schmidt AM et al (2001) J Clin Invest 108:949-55; 2. Sorci G et al (2004) Mol Cell Biol 24:4880-94; 3. Riuzzi F et al (2006) J Biol Chem 281:8242-53; 4. Riuzzi F et al (2007) Am J Pathol 171:947-61.
File in questo prodotto:
Non ci sono file associati a questo prodotto.

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11391/41541
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus ND
  • ???jsp.display-item.citation.isi??? ND
social impact