Abnormal A-type lamin organization in a human lung carcinoma cell line.
We have studied the expression of lamins A and C (A-type lamins) in a lung carcinoma cell line using type-specific monoclonal antibodies. Using immunofluorescence and immunoblotting studies it was noted that several irregularities in lamin expression exist in the cell line GLC-A1, derived from an adenocarcinoma. First, the expression of the A-type lamins was lower than in other adenocarcinoma cell lines of the lung. Also the ratio between lamins A and C proteins was 1:8 instead of the 1:1 ratio seen in the other cell lines. Northern blotting confirmed the altered level of A-type lamin expression. Secondly, an abnormal localization of lamin A was observed. Intensely fluorescing lamin A aggregates were observed in the nucleus, rather than the typical perinuclear staining pattern. Confocal scanning laser microscopy revealed that the lamin A aggregates were indeed present throughout the internal nucleus. When these cells were extracted with Triton X-100 the nucleoplasmic aggregates disappeared, which indicates that the A-type lamins are not properly incorporated into the lamina. The A-type lamins in other cell lines derived from adenocarcinomas remained present in the nuclear periphery after extraction with the non-ionic detergent. Immunoblotting studies of the Triton X-100 soluble and insoluble fractions showed that lamin A and an apparently truncated product, which was detected with the lamin A antibody, were present in the insoluble fraction of GLC-A1. This truncated product is partly Triton X-100 soluble since it was also detected in the detergent soluble fraction.(ABSTRACT TRUNCATED AT 250 WORDS)
Machiels
B M
BM
Department of Molecular Cell Biology & Genetics, University of Limburg, Maastricht, The Netherlands.
Broers
J L
JL
Raymond
Y
Y
de Ley
L
L
Kuijpers
H J
HJ
Caberg
N E
NE
Ramaekers
F C
FC
D000230:Adenocarcinoma / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D015151:Immunoblotting; D034904:Lamin Type A; D034882:Lamins; D008175:Lung Neoplasms / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D012995:Solubility; D014407:Tumor Cells, Cultured
D034904:Lamin Type A; D034882:Lamins; D009687:Nuclear Proteins; D012333:RNA, Messenger