Differentiation of C2C12 myoblasts expressing lamin A mutated at a site responsible for Emery-Dreifuss muscular dystrophy is improved by inhibition of the MEK-ERK pathway and stimulation of the PI3-kinase pathway.
Mutation R453W in A-type lamins, that are major nuclear envelope proteins, generates Emery-Dreifuss muscular dystrophy. We previously showed that mouse myoblasts expressing R453W-lamin A incompletely exit the cell cycle and differentiate into myocytes with a low level of multinucleation. Here we attempted to improve differentiation by treating these cells with a mixture of PD98059, an extracellular-regulated kinase (ERK) kinase (also known as mitogen-activated kinase, MEK) inhibitor, and insulin-like growth factor-II, an activator of phosphoinositide 3-kinase. We show that mouse myoblasts expressing R453W-lamin A were sensitive to the drug treatment as shown by (i) an increase in multinucleation, (ii) downregulation of proliferation markers (cyclin D1, hyperphosphorylated Rb), (iii) upregulation of myogenin, and (iv) sustained activation of p21 and cyclin D3. However, nuclear matrix anchorage of p21 and cyclin D3 in a complex with hypophosphorylated Rb that is critical to trigger cell cycle arrest and myogenin induction was deficient and incompletely restored by drug treatment. As the turn-over of R453W-lamin A at the nuclear envelope was greatly enhanced, we propose that R453W-lamin A impairs the capacity of the nuclear lamina to serve as scaffold for substrates of the MEK-ERK pathway and for MyoD-induced proteins that play a role in the differentiation process.
Favreau
Catherine
C
Institut Jacques Monod, UMR7592, CNRS et Universités Paris 6 et 7, Paris Cedex 05, France.
Delbarre
Erwan
E
Courvalin
Jean-Claude
JC
Buendia
Brigitte
B
D000818:Animals; D018949:Antigens, CD1 / Q000378:metabolism; D017252:CD3 Complex / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000378:metabolism; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000494:pharmacology; D034904:Lamin Type A / Q000378:metabolism*; D051379:Mice; D020929:Mitogen-Activated Protein Kinase Kinases / Q000037:antagonists & inhibitors; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors*; D020389:Muscular Dystrophy, Emery-Dreifuss / Q000201:enzymology* / Q000473:pathology; D050505:Mutant Proteins / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D032446:Myoblasts / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D018008:Myogenin / Q000378:metabolism; D034881:Nuclear Lamina / Q000187:drug effects / Q000378:metabolism; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D016160:Retinoblastoma Protein / Q000378:metabolism
D018949:Antigens, CD1; D017252:CD3 Complex; D050759:Cyclin-Dependent Kinase Inhibitor p21; D034904:Lamin Type A; D050505:Mutant Proteins; D018008:Myogenin; D047428:Protein Kinase Inhibitors; D016160:Retinoblastoma Protein; D049452:Green Fluorescent Proteins; D007335:Insulin-Like Growth Factor II; D019869:Phosphatidylinositol 3-Kinases; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D020929:Mitogen-Activated Protein Kinase Kinases