title: Increasing O-GlcNAcylation level on organ culture of soleus modulates the calcium activation parameters of muscle fibers.
abstract: O-N-acetylglucosaminylation is a reversible post-translational modification which presents a dynamic and highly regulated interplay with phosphorylation. New insights suggest that O-GlcNAcylation might be involved in striated muscle physiology, in particular in contractile properties such as the calcium activation parameters. By the inhibition of O-GlcNAcase, we investigated the effect of the increase of soleus O-GlcNAcylation level on the contractile properties by establishing T/pCa relationships. We increased the O-GlcNAcylation level on soleus biopsies performing an organ culture of soleus treated or not with PUGNAc or Thiamet-G, two O-GlcNAcase inhibitors. The enhancement of O-GlcNAcylation pattern was associated with an increase of calcium affinity on slow soleus skinned fibers. Analysis of the glycoproteins pattern showed that this effect is solely due to O-GlcNAcylation of proteins extracted from skinned biopsies. We also characterized the O-GlcNAcylated contractile proteins using a proteomic approach, and identified among others troponin T and I as being O-GlcNAc modified. We quantified the variation of O-GlcNAc level on all these identified proteins, and showed that several regulatory contractile proteins, predominantly fast isoforms, presented a drastic increase in their O-GlcNAc level. Since the only slow isoform of contractile protein presenting an increase of O-GlcNAc level was MLC2, the effect of enhanced O-GlcNAcylation pattern on calcium activation parameters could involve the O-GlcNAcylation of sMLC2, without excluding that an unidentified O-GlcNAc proteins, such as TnC, could be potentially involved in this mechanism. All these data strongly linked O-GlcNAcylation to the modulation of contractile activity of skeletal muscle.
authors.affiliation: Université Lille Nord de France, Université de Lille 1, Laboratoire Activité Physique, Muscle et Santé, EA4488, IFR114, IRP2B, Villeneuve d'Ascq, France.
authors.forename: Caroline
authors.initials: C
authors.lastname: Cieniewski-Bernard
authors.forename: Valerie
authors.initials: V
authors.lastname: Montel
authors.forename: Serge
authors.initials: S
authors.lastname: Berthoin
authors.forename: Bruno
authors.initials: B
authors.lastname: Bastide
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism*; D009924:Organ Culture Techniques; D051381:Rats
chemical_list: D002118:Calcium; D000117:Acetylglucosamine