976.3.2.3 Predisposition of Downregulation of DNA Repair Genes
on Compromise of Telomere Shortening
We found CR keeps longer telomeres compared with AL. Surprisingly, it was also
shown that ART, SNP, ARG, or H 2 O 2 enables the elongation/maintenance of telom-
eres in mouse skeletal muscle cells. It is clear that the longest main bands of telomere
restriction fragments (TRF) occur in SNP-treated mice, whereas the shortest main
TRF bands appear in AL mice. Interestingly, treatment of mice by ART, SNP, or ARG
leads to the longer main TRF bands than CR, and CR even gives rise to the shortest
single TRF bands. This is likely because CR mice are older than other treated mice
for 3 months when they were employed for measurement of telomere lengths.
To further validate whether the longer telomeres are originated from the
increased activity of telomerase reverse transcriptase (TERT), we also quantified
Tert mRNA in samples collected from CR and mimetics-treated mice. As results,
while ARG gives rise to a relatively lower Tert mRNA level, other treatments lead
to unchanged levels, suggesting that longer telomeres are likely due to attenuated
DNA damage rather than enhanced telomerase expression.
Nevertheless, it can be expected that a steady-state telomerase activity should
keep the normal telomere lengths. We observed the coordinated downregulation
of Brca1 and Tert mRNAs, and also noticed the coexistence of BRCA1 and TERT
with similar abundance (Wang et al. 2014 ). Overall, it was suggested that longer
telomeres are not related with high-level telomerase, but both Tert mRNA and
TERT protein are downregulated by underlying treatments.
6.3.2.4 Initiation of Dual-Tunnel NO Signaling upon NO-Driven
Enhanced Expression of Mitochondria-Targeted Proteins
Our previous work showed that ART can alkylate hemoproteins including NOS
and CAT by conjugating heme (Zheng and Zhang 2011 ; Zeng et al. 2011 ).
Furthermore, COX is also a kind of hemoprotein within mitochondria, so we
assumed that ART should also inhibit COX activity and block electron transport,
thereby initiating a wide-range responses. Surprisingly, we found that ART can
induce and activate eNOS, which are mirrored by the synchronous accumulations
of both eNOS and phosphorylated eNOS (p-eNOSSer1177). Interestingly, SNP and
ARG can also lead to the coordinated accumulation of eNOS and p-eNOSSer1177,
implying a common signaling pathway for eNOS induction and activation among
ART, SNP, and ARG (Wang et al. 2014 ). These results provided strong support to
our assumption of ART capable of inducing and activating eNOS.
To identify the cascade of ART-initiated signaling, we further evaluated the
impact of ART on the expression and phosphorylation of AMPK and Akt/PKB.
As results, the synchronous accumulations of AMPK and Akt as well as their
phosphorylated forms, p-AMPKThr172 and p-AktSer473, were observed in mouse
skeletal muscles injected with ART. In similar, SNP and ARG also give rise to the
high levels of AMPK/p-AMPKThr172 and Akt/p-AktSer473. Furthermore, we also