Working Party report: defecation disorders.
Explore the source record for details and available documents.
Constipation↗
Biomedical subjects
H Kuijpers
Publications and source records attributed to H Kuijpers.
Nuclear A-type lamins are differentially expressed in human lung cancer subtypes.
Nuclear A-type and B-type lamin expression was investigated in the major human lung cancer subtypes: small cell lung cancer (SCLC), squamous cell carcinomas, and adenocarcinomas (both non-SCLC). Twenty-two human lung cancer cell lines and 46 fresh frozen human lung cancer specimens were examined. Expression of B-type lamins was found in all the different cell lines. A-type lamins were expressed in all non-SCLC cell lines but were absent or only weakly expressed in 14 out of 16 SCLC cell lines. The immunocytochemical results were confirmed by immunoblotting and Northern blot analyses. In sections of SCLCs and non-SCLCs, B-type lamins were found to be expressed in all tumors. However, in some non-SCLCs, particularly in adenocarcinomas, a considerable proportion of the tumor cells were negative for B-type lamins. A-type lamin expression in SCLCs was weakly positive or negative in 14 out of 15 cases. In contrast, all non-SCLCs displayed A-type lamins, but in several of these samples, both cytoplasmic and nuclear staining was observed.
Adenocarcinoma↗
Association of mRNA and eIF-2 alpha with the cytoskeleton in cells lacking vimentin.
The human bladder carcinoma cell lines RT4 and T24 and the human breast adenocarcinoma cell line MCF-7 were found to be negative for vimentin when studied by means of immunofluorescence and immunoblotting. Northern blot analysis revealed that these cells lacked detectable levels of vimentin mRNA with the exception of T24, which contains trace amounts of vimentin mRNA compared to the RNA level in vimentin-containing HeLa cells. CAT assays performed on these cells showed that a hamster vimentin promoter is inactive in RT4 and MCF-7 cells. In the vimentin-lacking cells, the binding of polyribosomes, specific mRNAs, and translation factor eIF-2 alpha to the cytoskeletal fraction was examined. Our results indicate that the presence of a vimentin network is not crucial for the association of the translation machinery with the cytoskeleton. Furthermore, in these vimentin-negative cell lines the immunofluorescence staining pattern of eIF-2 alpha shows a fibro-granular structure that has no resemblance to the cytokeratin or actin cytoskeleton present in these cells.
Actins↗
Protein composition of nuclear matrix preparations from HeLa cells: an immunochemical approach.
Procedures for the isolation of HeLa S3 nuclear matrices were re-examined with special emphasis on the use of various nucleases and detergents as well as on the ionic strength of the final salt extraction. The protein composition of the resulting nuclear matrix preparations was analysed by one- and two-dimensional gel electrophoresis and found to be extremely reproducible. By means of co-electrophoresis several typical cytoskeletal proteins (actin, vimentin and cytokeratins) and heterogeneous nuclear RNA (hnRNA)-associated core proteins (hnRNP) were shown to be present in such nuclear matrix preparations. The nature of some other protein components was elucidated using two-dimensional immunoblotting and immunofluorescence. For this purpose mouse monoclonal antibodies to cytoskeletal components (vimentin, cytokeratins), small nuclear RNP (70 X 10(3) Mr protein of U1-RNP), hnRNP (C1/C2) and the pore-complex lamina (lamins A, B and C) were used next to human autoimmune sera obtained from patients with connective tissue diseases and directed against the residual nucleoli and the internal fibrillar mass. These antibodies enabled us to identify a number of proteins present specifically in the nuclear matrix and to show that part of the cytoskeletal proteins are still present in the isolated structures.
Cell Nucleus↗
Distribution of the 70K U1 RNA-associated protein during interphase and mitosis. Correlation with other U RNP particles and proteins of the nuclear matrix.
Earlier studies suggested that the 70K (70 X 10(3) Mr) polypeptide is a nuclear matrix (associated) protein since it is the only U1 RNP-associated antigen that is not released from the nucleus after treatment of the cell with, successively, detergents, DNase I and/or RNase A and high salt. The possibility that the 70K protein functions in the binding of U1 RNP to the nuclear matrix is now further substantiated by the finding that U1 RNP particles that did or did not contain the 70K protein could be isolated, depending on the method of isolation. When U1 RNP particles were obtained by means of sonic disruption of the nucleus they contained the 70K polypeptide, whereas particles that were isolated by extraction at room temperature and a slightly alkaline pH lacked the 70K protein but contained the intact U1 RNA and the other U1 RNA-associated proteins. During interphase the localization of the 70K protein is restricted to the nucleus, giving a dot-like distribution pattern with exclusion of the nucleoli. During prophase to late anaphase the protein is dispersed throughout the entire cytoplasm with the exception of the chromatin regions. Immunofluorescence studies, using a monoclonal anti-70K antibody in combination with human autoimmune sera that react with U1 RNA-associated proteins, demonstrate that the 70K protein is localized in those areas of the cell where other U RNP proteins occur, also during mitosis. Topoisomerase I and nuclear lamins, typical nuclear matrix proteins, show completely different distribution patterns in all phases of the cell cycle. Assembly of the nuclear envelope is attended by the re-formation of the clustered appearance of the 70K antigen. These results suggest that, although associated with the nuclear matrix fraction in interphase cells, the 70K protein remains associated with the U1 RNP particles during cell division.
Animals↗