Association of emerin with nuclear and cytoplasmic actin is regulated in differentiating myoblasts.
Emerin is a nuclear envelope protein whose biological function remains to be elucidated. Mutations of emerin gene cause the Emery-Dreifuss muscular dystrophy, a neuromuscular disorder also linked to mutations of lamin A/C. In this paper, we analyze the interaction between emerin and actin in differentiating mouse myoblasts. We demonstrate that emerin and lamin A/C are bound to actin at the late stages of myotube differentiation and in mature muscle. The interaction involves both nuclear alpha and beta actins and cytoplasmic actin. A serine-threonine phosphatase activity markedly increases emerin-actin binding even in cycling myoblasts. This effect is also observed with purified nuclear fractions in pull-down assay. On the other hand, active protein phosphatase 1, a serine-threonine phosphatase known to associate with lamin A/C, inhibits emerin-actin interaction in myotube extracts. These data provide evidence of a modulation of emerin-actin interaction in muscle cells, possibly through differentiation-related stimuli.
Lattanzi
Giovanna
G
ITOI-CNR, Unit of Bologna, c/o IOR, Via di Barbiano, 1/10, I-40136 Bologna, Italy. lattanzi@jolly.bo.cnr.it
Cenni
Vittoria
V
Marmiroli
Sandra
S
Capanni
Cristina
C
Mattioli
Elisabetta
E
Merlini
Luciano
L
Squarzoni
Stefano
S
Maraldi
Nadir Mario
NM
D000199:Actins / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D066298:In Vitro Techniques; D034904:Lamin Type A / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D032446:Myoblasts / Q000166:cytology* / Q000378:metabolism*; D009687:Nuclear Proteins; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D011485:Protein Binding; D054645:Protein Phosphatase 1; D013946:Thymopoietins / Q000378:metabolism*
D000199:Actins; D034904:Lamin Type A; D008565:Membrane Proteins; D009687:Nuclear Proteins; D013946:Thymopoietins; C092710:emerin; C440308:lamin C; D010749:Phosphoprotein Phosphatases; D054645:Protein Phosphatase 1