title: Transforming growth factor-beta1 and bone morphogenetic protein-2 downregulate CaV3.1 channel expression in mouse C2C12 myoblasts.
abstract: In the developing skeletal muscle, fusion of myoblasts and myotube formation is a process that involves Ca2+ influx through T-type (CaV3) channels. Treatment of myoblasts with transforming growth factor-beta1 (TGF-beta1) and bone morphogenetic protein-2 (BMP-2) decreases the number of CaV3 channels in the plasma membrane and reduces myotube formation. In the current report, we examined whether the inhibitory actions of TGF-beta1 and BMP-2 involve alterations in CaV3 mRNA expression in the myoblast C2C12 cell line. Using RT-PCR, we found that CaV3.1 but not CaV3.2 and CaV3.3 transcripts are present in either undifferentiated or fusion competent C2C12 myoblasts. Semi-quantitative analysis revealed a significant decrease of CaV3.1 mRNA expression in cells treated with TGF-beta1 and BMP-2. In contrast, patch-clamp recordings on HEK-293 cells stably expressing recombinant CaV3.1 channels showed that T-type currents were not affected by chronic exposure to the growth factors. These results suggest that muscle T-channel downregulation by TGF-beta1 and BMP-2 may be mediated by reduced transcription rather than through post-transcriptional modifications of CaV3.1 channels.
authors.affiliation: Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies of the National Polytechnic Institute (Cinvestav-IPN), Mexico City, Mexico.
authors.forename: Traudy
authors.initials: T
authors.lastname: Avila
authors.forename: Arturo
authors.initials: A
authors.lastname: Andrade
authors.forename: Ricardo
authors.initials: R
authors.lastname: Felix
mesh_terms: D000818:Animals; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins / Q000494:pharmacology*; D020747:Calcium Channels, T-Type / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D018076:DNA, Complementary / Q000378:metabolism; D015536:Down-Regulation / Q000187:drug effects*; D006801:Humans; D051379:Mice; D032446:Myoblasts / Q000187:drug effects*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D015203:Reproducibility of Results; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016212:Transforming Growth Factor beta / Q000494:pharmacology*; D053773:Transforming Growth Factor beta1
chemical_list: C525718:BMP2 protein, human; C525719:Bmp2 protein, mouse; D055396:Bone Morphogenetic Protein 2; D019485:Bone Morphogenetic Proteins; C498197:Cacna1g protein, mouse; D020747:Calcium Channels, T-Type; D018076:DNA, Complementary; D012333:RNA, Messenger; D011994:Recombinant Proteins; C508960:TGFB1 protein, human; C508961:Tgfb1 protein, mouse; D016212:Transforming Growth Factor beta; D053773:Transforming Growth Factor beta1