| First Author | Charó NL | Year | 2018 |
| Journal | Biochim Biophys Acta | Volume | 1865 |
| Issue | 2 | Pages | 432-443 |
| PubMed ID | 29208528 | Mgi Jnum | J:257469 |
| Mgi Id | MGI:6119202 | Doi | 10.1016/j.bbamcr.2017.11.015 |
| Citation | Charo NL, et al. (2018) Heterochromatin protein (HP)1gamma is not only in the nucleus but also in the cytoplasm interacting with actin in both cell compartments. Biochim Biophys Acta 1865(2):432-443 |
| abstractText | Confocal and electron microscopy images, and WB analysis of cellular fractions revealed that HP1gamma is in the nucleus but also in the cytoplasm of C2C12 myoblasts, myotubes, skeletal and cardiac muscles, N2a, HeLa and HEK293T cells. Signal specificity was tested with different antibodies and by HP1gamma knockdown. Leptomycin B treatment of myoblasts increased nuclear HP1gamma, suggesting that its nuclear export is Crm-1-dependent. HP1gamma exhibited a filamentous pattern of staining partially co-localizing with actin in the cytoplasm of myotubes and myofibrils. Immunoelectron microscopic analysis showed high-density immunogold particles that correspond to HP1gamma localized to the Z-disk and A-band of the sarcomere of skeletal muscle. HP1gamma partially co-localized with actin in C2C12 myotubes and murine myofibrils. Importantly, actin co-immunoprecipitated with HP1gamma in the nuclear and cytosolic fractions of myoblasts. Actin co-immunoprecipitated with HP1gamma in myoblasts incubated in the absence or presence of the actin depolymerizing agent cytochalasin D, suggesting that HP1gamma may interact with G-and F-actin. In the cytoplasm, HP1gamma was associated to the perinuclear actin cap that controls nuclear shape and position. In the nucleus, re-ChIP assays showed that HP1gamma-actin associates to the promoter and transcribed regions of the house keeping gene GAPDH, suggesting that HP1gamma may function as a scaffold protein for the recruitment of actin to control gene expression. When HP1gamma was knocked-down, myoblasts were unable to differentiate or originated thin myotubes. In summary, HP1gamma is present in the nucleus and the cytoplasm interacting with actin, a protein complex that may exert different functions depending on its subcellular localization. |
