Tight co-twin similarity of monozygotic twins for hTERT protein level of T cell subsets, for telomere length and mitochondrial DNA copy number, but not for telomerase activity
Our study analyzed lymphocyte subpopulations of 32 monozygotic twins and compared the level of the catalytic reverse transcriptase protein subunit (hTERT) in T lymphocytes (Tly), helper- (Th), cytotoxic- (Tc) and regulatory T cell (Treg) subgroups. Four variables related to telomere and mitochondrial biology were simultaneously assessed, applying multi-parametric flow cytometry, TRAP-ELISA assay and qPCR standard curve method on peripheral blood mononuclear cell (PBMC) samples of genetically matched individuals. Twin data of telomerase activity (TA), hTERT protein level, telomere length (TL) and mitochondrial DNA copy number (mtDNAcn) were analyzed for co-twin similarity. The present study has provided novel information by demonstrating very high intraclass correlation (ICC) of hTERT protein level in T lymphocytes (0.891) and in both Th (0.896), Treg (0.885) and Tc (0.798) cell subgroups. When comparing results measured from PBMCs, intraclass correlation was also high for telomere length (0.815) and considerable for mtDNA copy number (0.524), and again exceptionally high for the rate-limiting telomerase subunit, hTERT protein level (0.946). In contrast, telomerase activity showed no co-twin similarity (ICC 0). By comparing relative amounts of hTERT protein levels in different lymphocyte subgroups of twin subjects, in Treg cells significantly higher level could be detected compared to Tly, Th or Tc cell subgroups. This is the first study that simultaneously analyzed co-twin similarity in MZ twins for the above four variables and alongside assessed their relationship, whereby positive association was found between TL and mtDNAcn.
KeywordshTERT Telomerase activity Telomere length Mitochondrial DNA copy number T Lymphocytes Regulatory T cells Telomere-independent functions of telomerase Twin studies Epigenetics
The authors are grateful to Ms. Nora Fekete for her assistance throughout the experiments and preparations, to Mrs. Monika Banlaky for her assistance in blood draw and to Viktor Molnar, MD for his assistance in the validation of qPCR results. The authors would also like to thank Marcell Szily for his help in the logistics of sample transports.
Compliance with ethical standards
Conflict of interest
The authors have no conflict of interest to declare.
The study was supported by the grant of Hungarian Pulmonology Foundation (2015).
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