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. 2013 Jan 14;2(1):57-66.
doi: 10.3390/cells2010057.

Functional Assessment of Pharmacological Telomerase Activators in Human T Cells

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Free PMC article

Functional Assessment of Pharmacological Telomerase Activators in Human T Cells

Brenda Molgora et al. Cells. .
Free PMC article

Abstract

Telomeres are structures at the ends of chromosomes that shorten during cell division and eventually signal an irreversible state of growth arrest known as cellular senescence. To delay this cellular aging, human T cells, which are critical in the immune control over infections and cancer, activate the enzyme telomerase, which binds and extends the telomeres. Several different extracts from the Astragalus membranaceus root have been documented to activate telomerase activity in human T cells. The objective of this research was to compare two extracts from Astragalus membranaceus, TA-65 and HTA, for their effects on both telomerase and proliferative activity of human CD4 and CD8 T cells. Our results demonstrate that, TA-65 increased telomerase activity significantly (1.3 to 3.3-fold relative to controls) in T cell cultures from six donors tested, whereas HTA only increased telomerase levels in two out of six donors. We also demonstrate that TA-65 activates telomerase by a MAPK- specific pathway. Finally, we determine that during a three-day culture period, only the T cells treated with the TA-65 extract showed a statistically significant increase in proliferative activity. Our results underscore the importance of comparing multiple telomerase activators within the same experiment, and of including functional assays in addition to measuring telomerase activity.

Figures

Figure 1
Figure 1
TA-65 and HTA treatment of CD4 T cells increases telomerase activity in response to primary (A) and secondary (B) cell stimulations. This figure shows representative results for cultures of purified CD4 T cells from a single donor that were exposed to either TA-65, HTA or DMSO (triplicate cultures for each condition). Top portion of Figure 1A,B illustrate the band products of telomerase activity indicated as TPG (TPG is total product generate, a measure of telomerase activity). Dark bands indicate high telomerase activity. The bottom portions of panels A and B represent quantization bar graph values for the enzyme activity. The average DMSO TPG was used to normalize telomerase activity between treatments. The total dilution of compounds in grams/mL is indicated above the lanes and below the bar graphs. Statistical significance was determined by student paired t test (p < 0.05).
Figure 2
Figure 2
Average telomerase activity for a primary stimulation for (A) CD4 (n = 6) and (B) CD8 (n = 6) T cells. TPG is total product generated for telomerase activity. DMSO treated samples were used to normalized the TPG between the donors, which allow direct donor’s variability comparisons.
Figure 3
Figure 3
TA-65 activates telomerase via MAPK pathway. CD8 T cells stimulated for a second time and treated with MAPK inhibitor (as described in materials and methods) blocked the increase telomerase activity from TA-65, but no significant inhibition was observed using AKT inhibitors. Statistical significance was determined by student paired t-test (p < 0.05).
Figure 4
Figure 4
Proliferation effects of TA-65 and HTA: Cell counts were determined on day 3 after stimulation. A, represents results for CD4 T cells and B represents results for CD8 T cells (concentrations are 106/mL). A and B top, represents actual cell concentration after first T cell stimulation, A and B bottom represents total cell concentration after second stimulation. Statistical significance was determined by student paired t test (p < 0.05).

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References

    1. de Lange T. Shelterin: The protein complex that shapes and safeguards human telomeres. Gene Dev. 2005;19:2100–2110. doi: 10.1101/gad.1346005. - DOI - PubMed
    1. Artandi S.E., DePinho R.A. Telomeres and telomerase in cancer. Carcinogenesis. 2010;31:9–18. doi: 10.1093/carcin/bgp268. - DOI - PMC - PubMed
    1. Counter C.M., Avilion A.A., LeFeuvre C.E., Stewart N.G., Greider C.W., Harley C.B., Bacchetti S. Telomere shortening associated with chromosome instability is arrested in inmortal cells which express telomerase activity. EMBO J. 1992;11:1921–1929. - PMC - PubMed
    1. Price C. M. Centromeres and telomeres. Curr Opin Cell Biol. 1992;4:379–84. doi: 10.1016/0955-0674(92)90002-T. - DOI - PubMed
    1. Monteiro J., Batliwalla F., Ostrer H., Gregersen P.K. Shortened telomeres in clonally expanded CD28-CD8+ T cells imply a replicative history that is distinct from their CD28+CD8+ counterparts. J. Immunol. 1996;156:3587–3590. - PubMed
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