Both emerin and lamin C depend on lamin A for localization at the nuclear envelope.
Physical interactions between lamins and emerin were investigated by co-immunoprecipitation of in vitro translated proteins. Emerin interacted with in vitro translated lamins A, B1 and C in co-immunprecipitation reactions. Competition reactions revealed a clear preference for interactions between emerin and lamin C. Structural associations between lamins and emerin were investigated in four human cell lines displaying abnormal expression and/or localisation of lamins A and C. In each cell line absence of lamins A and C from the nuclear envelope (NE) was correlated with mis-localisation of endogenous and exogenous emerin to the ER. In two cell lines that did not express lamin A but did express lamin C, lamin C as well as emerin was mis-localised. When GFP-lamin A was expressed in SW13 cells (which normally express only very low levels of endogenous lamin A and mis-localise endogenous emerin and lamin C), all three proteins became associated with the NE. When GFP-lamin C was expressed in SW13 cells neither the endogenous nor the exogenous lamin C was localised to the NE and emerin remained in the ER. Finally, lamins A and C were selectively eliminated from the NE of HeLa cells using a dominant negative mutant of lamin B1. Elimination of these lamins from the lamina led to the accumulation of emerin as aggregates within the ER. Our data suggest that lamin A is essential for anchorage of emerin to the inner nuclear membrane and of lamin C to the lamina.
Vaughan
A
A
Department of Biological Sciences, The University of Durham, UK.
Alvarez-Reyes
M
M
Bridger
J M
JM
Broers
J L
JL
Ramaekers
F C
FC
Wehnert
M
M
Morris
G E
GE
Whitfield WGF
Hutchison
C J
CJ
D000306:Adrenal Cortex Neoplasms; D018268:Adrenocortical Carcinoma; D000818:Animals; D000906:Antibodies; D002051:Burkitt Lymphoma; D018288:Carcinoma, Small Cell; D002461:Cell Line, Transformed; D003594:Cytoplasmic Granules / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D015870:Gene Expression / Q000502:physiology; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D066298:In Vitro Techniques; D007202:Indicators and Reagents / Q000378:metabolism; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D008164:Luminescent Proteins / Q000235:genetics; D008175:Lung Neoplasms; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D020389:Muscular Dystrophy, Emery-Dreifuss / Q000378:metabolism; D016296:Mutagenesis / Q000502:physiology; D009685:Nuclear Envelope / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011817:Rabbits; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D013946:Thymopoietins / Q000235:genetics / Q000378:metabolism*
D000906:Antibodies; D007202:Indicators and Reagents; D034904:Lamin Type A; D034921:Lamin Type B; D034882:Lamins; D008164:Luminescent Proteins; D008565:Membrane Proteins; D009687:Nuclear Proteins; D011993:Recombinant Fusion Proteins; D013946:Thymopoietins; C092710:emerin; C440308:lamin C; D049452:Green Fluorescent Proteins