caa a22 4500 606234748 CHVBK 20210128101239.0 cr unu---uuuuu 210128e20151101xx s 000 0 eng 10.1007/s11010-015-2507-y doi (NATIONALLICENCE)springer-10.1007/s11010-015-2507-y Nahálková Jarmila Department of Medical Biochemistry and Microbiology (IMBIM), BMC, Uppsala University, Box 582, 751 23, Uppsala, Sweden aut Novel protein-protein interactions of TPPII, p53, and SIRT7 [Elektronische Daten] [Jarmila Nahálková] Novel protein-protein interactions of TPPII, SIRT7, and p53 were detected by co-immunoprecipitation using both HeLa cell lysates and the cytoplasmic fraction prepared by fractionation of mouse liver tissue. The interactions were further verified in vivo by in situ proximity ligation assay (PLA) within control HEK293 cells transformed with empty vector, highactTPPII HEK293 cells over-expressing murine TPPII displaying high specific enzymatic activity and in lowactTPPII HEK293 cells over-expressing human TPPII having low specific activity of the enzyme. Besides an abundant cytoplasmic localization of TPPII-p53 interaction signal, the nuclear interactions were also demonstrated. The cytoplasmic interactions were likewise detected between TPPII and SIRT7 in control HEK293 and lowactTPPII HEK293 cells. The interactions of SIRT7 with p53 were confirmed in three HEK293 cell transformants as well. The cytoplasmic occurrence of SIRT7 protein was demonstrated by immunofluorescence, when both nucleolar and cytoplasmic signals were identified within HEK293 cells and primary human fibroblasts. The unique cytoplasmic localization of SIRT7 protein was discussed based on an epitope specificity of N-terminus specific SIRT7 antibodies utilized in the present study compared with C-terminus specific antibodies previously used for nuclear detection of SIRT7 by other authors. The epitope sequence of N-terminal antibodies is occurring in all three splicing variants of SIRT7 compared to the epitope of C-terminal antibody, which is specific exclusively to the splicing variant 1. The cytoplasmic localization of p53 detected by immunofluorescence supported the results from its interactions with TPPII and SIRT7 observed by in situ PLA within model cells. Novel interactions of TPPII, p53, and SIRT7 presented in this study might contribute to the knowledge of the regulatory effects of these proteins on apoptotic pathways and to the understanding mechanisms of aging and lifespan regulation. Springer Science+Business Media New York, 2015 TPPII nationallicence SIRT7 nationallicence p53 nationallicence Apoptosis nationallicence Cellular senescence nationallicence Aging nationallicence Molecular and Cellular Biochemistry Springer US; http://www.springer-ny.com 409/1-2(2015-11-01), 13-22 0300-8177 409:1-2<13 2015 409 11010 https://doi.org/10.1007/s11010-015-2507-y text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s11010-015-2507-y text/html Onlinezugriff via DOI NATIONALLICENCE 100 1- Nahálková Jarmila Department of Medical Biochemistry and Microbiology (IMBIM), BMC, Uppsala University, Box 582, 751 23, Uppsala, Sweden aut NATIONALLICENCE 773 0- Molecular and Cellular Biochemistry Springer US; http://www.springer-ny.com 409/1-2(2015-11-01), 13-22 0300-8177 409:1-2<13 2015 409 11010