Telomerase Reverse Transcriptase Regulates Intracellular Ca(2+) Homeostasis and Mitochondrial Function via the p53/PGC-1α Pathway in HL-1 Cells.

Telomere shortening is strongly associated with cardiovascular aging and disease, and patients with shorter telomeres in peripheral blood leukocytes are at higher risk of cardiovascular diseases such as heart failure and atrial fibrillation (AF). Telomerase reverse transcriptase (TERT) maintains telomere length, and overexpression of TERT has been shown to reduce cardiomyocyte apoptosis and myocardial infarct size, and extend the lifespan of aged mice. However, the specific impact of TERT on the electrophysiology of cardiomyocytes remains to be elucidated. The aims of this study were to evaluate the role of TERT in Ca2+ homeostasis and mitochondrial function in atrial myocytes as well as the underlying mechanisms. TERT overexpressed and silenced HL-1 cells were constructed with lentiviruses, and the respective empty lentiviral vectors were used as negative controls. Then the patch clamp technique was used to record the electrophysiological characteristics such as cell action potential duration (APD) and L-type Ca2+ currents (ICa,L), flow cytometry was used to detect intracellular Ca2+ concentration and mitochondrial membrane potential (MMP), and the Seahorse assay was used to measure the oxygen consumption rate (OCR). TERT silencing led to intracellular Ca2+ overload, shortened APD, decreased ICa,L current density, altered Ca2+ gating mechanism, decreased MMP and OCR, and increased reactive oxygen species (ROS), whereas TERT overexpression led to the reverse effects. Additionally, TERT silencing resulted in intracellular Ca2+ overload with decreased expression of the SERCA2a, CaV1.2, and NCX1.1, whereas TERT overexpression had opposing effects. Furthermore, we discovered that TERT could regulate the expression of p53 and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α). The expression of PGC-1α was downregulated by the p53 agonist Tenovin-6 but upregulated by the p53 inhibitor PFTα. The effects of the PGC-1α inhibitor SR-18292 on intracellular Ca2+ and cell electrophysiology were similar to those of silencing TERT, whereas the PGC-1α agonist ZLN005 produced comparable outcomes to TERT overexpression. TERT silencing-induced Ca2+ overload and mitochondrial dysfunction may be one mechanism of age-related AF. Overexpression of TERT reduced the basis for arrhythmia formation such as AF, suggesting a favorable safety profile for TERT therapy. TERT regulated intracellular Ca2+ homeostasis and mitochondrial function through the p53/PGC-1α pathway. In addition, PGC-1α might be a novel target for AF, suggesting that intervention for AF should be not limited to abnormal cation handling.

Liu C ，Lin K ，Xie Z ，Li D ，Fan J ，Chen Y ，Gao S ，Wang X ，Liu N ，Xue Q ，Li Y ... -  《-》

Telomerase reverse transcriptase protects against diabetic kidney disease by promoting AMPK/PGC-1a-regulated mitochondrial energy homeostasis.

Disordered glucose and lipid metabolism, coupled with disturbed mitochondrial bioenergetics, are pivotal in the initiation and development of diabetic kidney disease (DKD). While the essential role of telomerase reverse transcriptase (TERT) in regulating mitochondrial function in the cardiovascular system has been recognized, its specific function in maintaining mitochondrial homeostasis in DKD remains unclear. This study aimed to explore how TERT regulates mitochondrial function and the underlying mechanisms. In vitro, human renal proximal tubular HK-2 cells exposed to high glucose/high fat (HG/HF) presented significant downregulation of TERT and AMPK dephosphorylation. This led to decreased ATP production, altered NAD+/NADH ratios, reduced mitochondrial complex activities, increased mitochondrial dysfunction, lipid accumulation, and reactive oxygen species (ROS) production. Knockdown of TERT (si-TERT) further exacerbated mitochondrial dysfunction, decreased mitochondrial membrane potential, and lowered levels of cellular oxidative phosphorylation and glycolysis, as determined via a Seahorse X24 flux analyzer. Conversely, mitochondrial dysfunction was significantly alleviated after pcDNA-TERT plasmid transfection and adeno-associated virus (AAV) 9-TERT gene therapy in vivo. Notably, treatment with an AMPK inhibitor, activator, and si-PGC-1a (peroxisome proliferator-activated receptor γ coactivator-1α), resulted in mitochondrial dysfunction and decreased expression of genes related to energy metabolism and mitochondrial biogenesis. Our findings reveal that TERT protects mitochondrial function and homeostasis by partially activating the AMPK/PGC-1a signaling pathway. These results establish a crucial foundation for understanding TERT's critical role inmitochondrial regulation and its protective effect on DKD.

Ma N ，Xu C ，Wang Y ，Cui K ，Kuang H ... -  《-》

BaZiBuShen alleviates cognitive deficits and regulates Sirt6/NRF2/HO-1 and Sirt6/P53-PGC-1α-TERT signaling pathways in aging mice.

BaZiBuShen formula (BZBS) is clinically used to counteract mental fatigue and to retard the aging process. Brain aging echoes in major risks of human sufferings and has become one of the main challenges to our societies and the health-care systems. To investigate the effect and mode of action of BZBS on aging-associated cognitive impairments. BZBS was orally administered to D-galactose and NaNO2-induced aging mice. Premature senescence was assessed using the Morris water maze, step-down type passive avoidance, and pole-climbing tests. Telomere length was examined by qPCR analysis. Telomerase activity was assessed using PCR ELISA assay. Mitochondrial complex IV activity was examined by biochemical test. The levels of redox and immune status were determined by ELISA or biochemical assay. The expressions of sirtuin 6 (Sirt6), peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), P53, telomerase reverse transcriptase (TERT), heme oxygenase-1 (HO-1), phospho(p)-nuclear factor erythroid-2 related factor 2 (NRF2), caspase-3, Bcl-2 associated x (Bax), and B-cell lymphoma-2 (Bcl-2) in the cerebral cortex were examined by Western blot and/or immunohistochemical staining. BZBS intervention ameliorated reduced brain performances in aging mice, including memory, cognitive, and motor functions. In addition, BZBS administration to aging mice preserved redox homeostasis, attenuated immunosenescence, and maintained telomerase activity and telomere length. Moreover, BZBS treatment were associated with a declines in P53, caspase-3, Bax expressions and an increase in Sirt6, p-HO-1, p-NRF2, PGC-1α, and Bcl-2 expressions in the brains of this rapid aging mouse. BZBS attenuates premature senescence possibly via the preservation of redox homeostasis and telomere integrity, and inhibition of apoptosis in rapid aging mouse. The mechanism governing the alterations may be associated with through the activation of Sirt6/NRF2/HO-1 and Sirt6/P53-PGC-1α-TERT signaling pathways. The results suggest that BZBS may provide a novel strategy for confronting aging and age-associated diseases.

Li L ，Zhang H ，Chen B ，Xia B ，Zhu R ，Liu Y ，Dai X ，Ye Z ，Zhao D ，Mo F ，Gao S ，Orekhov AN ，Prentki M ，Wang L ，Guo S ，Zhang D ... -  《-》

Activating the PGC-1α/TERT Pathway by Catalpol Ameliorates Atherosclerosis via Modulating ROS Production, DNA Damage, and Telomere Function: Implications on Mitochondria and Telomere Link.

Zhang Y ，Wang C ，Jin Y ，Yang Q ，Meng Q ，Liu Q ，Dai Y ，Cai L ，Liu Z ，Liu K ，Sun H ... -  《-》

Overexpression of Peroxisome Proliferator-Activated Receptor γ Coactivator 1-α Protects Cardiomyocytes from Lipopolysaccharide-Induced Mitochondrial Damage and Apoptosis.

Zhang T ，Liu CF ，Zhang TN ，Wen R ，Song WL ... -  《-》