Vol. 185, No. 1, 1992 May 29, 1992 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS Pages 27]-275 MOUSE AND HUMAN HEMOPOIETIC CELL LINES OF ERYTHROID LINEAGE EXPRESS LAMINS A,B AND C Alberto M. Martelli °, Anna Maria Billi, R. Stewart Gilmour*, Lucia Manzoli +, Roberto Di Primio + and Lucio Cocco Istituto di Anatomia Umana Normale, via Irnerio, 48, 40126 Bologna, Italy *Institute of Animal Physiology and Genetics Research, AFRC, Babraham, UK + Istituto di Morfologia Umana Normale, Chieti, Italy Received April 13, 1992 Using monoclonal antibodies, we have studied the expression of lamins A,B,C and vimentin in mouse and human erythroleukemia cells . We have found that in contrast with previous reports these cells have all three lamins. Mouse cells lack vimentin, whereas human cells express it. Lamins B and C are the most abundant lamins, whereas considerably less lamin A is detectable. Our results argue that some mouse and human hemopoietic cells can express all three lamins and that production of vimentin does not necessarily precede that of lamins A/C, as other reports have suggested in the past. The data also show that the absence of a salt resistant inner nuclear matrix is not always related with the lack of lamins A/C and vimentin, as recently proposed. ~ 1992 Academic Pr .... Inc. The nuclear lamina is a fibrous meshwork located underneath the inner nuclear membrane (1-2).The main constituents of the lamina are lamins A,B and C, polypeptides with molecular weights between 70 and 62 kDa , although additional minor components have been identified (3).Lamin B is connected to the nuclear membrane by means of its interaction with a specific integral protein (4), whilst lamins A/C are DNA-binding proteins (5-6).While lamin B is expressed throughout the development, lamins A/C are absent from several embryonic tissues and they cannot also be detected in cells from immune and hemopoietic systems (7-12).1t is generally thought that the expression of lamins A/C is closely related to that of intermediate filament proteins such as vimentin, with which lamins A/C share sequence homologies (13). In this report we show that mouse and human erythroleukemia cell lines express all three lamins. We also demonstrate that while mouse cells do not produce any detectable vimentin, human cells express such a protein. o To whom correspondence should be addressed. 271 0006-291X/92 $4.00 Copyright © 1992 by Academic Press, Inc. All rights of reproduction in any form reserved.