title: Rapid shortening of telomere length in response to ceramide involves the inhibition of telomere binding activity of nuclear glyceraldehyde-3-phosphate dehydrogenase.
abstract: Ceramide has been demonstrated as one of the upstream regulators of telomerase activity. However, the role for ceramide in the control of telomere length remains unknown. It is shown here that treatment of the A549 human lung adenocarcinoma cells with C(6)-ceramide results in rapid shortening of telomere length. During the examination of ceramide-regulated telomere-binding proteins, nuclear glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was identified to associate with both single- and double-stranded telomeric DNA with high specificity in vitro. The association of nuclear GAPDH with telomeres in interphase nuclei was also demonstrated by co-fluorescence in situ hybridization and chromatin immunoprecipitation analysis. Further data demonstrated that the nuclear localization of GAPDH is regulated by ceramide in a cell cycle-dependent manner parallel with the inhibition of its telomere binding activity in response to ceramide. In addition, the results revealed that nuclear GAPDH is distinct from its cytoplasmic isoform and that telomere binding function of nuclear GAPDH is strikingly higher than the cytoplasmic isoform. More importantly, the functional role for nuclear GAPDH in the maintenance and/or protection of telomeric DNA was identified by partial inhibition of the expression of GAPDH using small interfering RNA, which resulted in rapid shortening of telomeres. In contrast, overexpression of nuclear GAPDH resulted in the protection of telomeric DNA in response to exogenous ceramide as well as in response to anticancer drugs, which have been shown to induce endogenous ceramide levels. Therefore, these results demonstrate a novel function for nuclear GAPDH in the maintenance and/or protection of telomeres and also show that mechanisms of the rapid degradation of telomeres in response to ceramide involve the inhibition of the telomere binding activity of nuclear GAPDH.
authors: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, South Carolina 29425, USA.
authors: Kamala P
authors: KP
authors: Sundararaj
authors: Rachel E
authors: RE
authors: Wood
authors: Suriyan
authors: S
authors: Ponnusamy
authors: Arelis M
authors: AM
authors: Salas
authors: Zdzislaw
authors: Z
authors: Szulc
authors: Alicia
authors: A
authors: Bielawska
authors: Lina M
authors: LM
authors: Obeid
authors: Yusuf A
authors: YA
authors: Hannun
authors: Besim
authors: B
authors: Ogretmen
mesh_terms: D015153:Blotting, Western; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000201:enzymology* / Q000378:metabolism; D002518:Ceramides / Q000737:chemistry* / Q000378:metabolism; D002843:Chromatin / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D005434:Flow Cytometry; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating) / Q000737:chemistry*; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008856:Microscopy, Fluorescence; D010455:Peptides / Q000737:chemistry; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D011485:Protein Binding; D020033:Protein Isoforms; D034741:RNA, Small Interfering / Q000378:metabolism; D016622:Silver Staining; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000737:chemistry / Q000648:ultrastructure; D013997:Time Factors; D014162:Transfection; D014466:Ultraviolet Rays
chemical_list: D002518:Ceramides; D002843:Chromatin; D010455:Peptides; D020033:Protein Isoforms; D034741:RNA, Small Interfering; D024602:Glyceraldehyde-3-Phosphate Dehydrogenase (NADP+)(Phosphorylating); D019098:Telomerase