Globular CTRP3 promotes mitochondrial biogenesis in cardiomyocytes through AMPK/PGC-1α pathway.

BACKGROUND: Mitochondrial biogenesis is crucial for the maintenance of mitochondrial function and cellular homeostasis. C1q/tumor necrosis factor-related protein-3 (CTRP3) is an adipokine that owns multiple functions on metabolic and cardiovascular diseases. However, whether CTRP3 affects mitochondrial biogenesis in cardiomyocytes remains unknown. METHODS: Neonatal rat ventricular myocytes were cultured and treated with globular CTRP3 (gCTRP3). The expression of mitochondrial biogenesis related genes was measured by real-time PCR and western blot analysis. Mitochondrial morphology was assessed by a transmission electron microscope. ATP content, oxygen consumption rate (OCR), and sirtuin1 activity were measured with commercial kits. RESULTS: gCTRP3 increased the expression of peroxisome proliferators activated receptor-γ co-activator-1α (PGC-1α), nuclear respiratory factor 1 (NRF-1), NRF-2, mitochondrial transcription factor A (TFAM), cytochrome B, and oxidative phosphorylation complexes III and V, and increased mitochondrial cristae components and OCR. Additionally, gCTRP3 enhanced mitochondrial DNA copy number and ATP content, while the induction was inhibited by knockdown of PGC-1α via small interfering RNA. gCTRP3 increased phosphorylation of AMP-activated protein kinase (AMPK), whereas adenine 9-ß-d-arabinofuranoside (AraA), an AMPK inhibitor, attenuated gCTRP3-mediated induction of NRF-1, TFAM, and complexes III and V. gCTRP3 increased both the expression and activity of sirtuin1, whereas inhibition of sirtuin1 by EX-527 attenuated gCTRP3-induced responses. Meanwhile, gCTRP3-mediated activation of sirtuin1 was attenuated by AraA. Moreover, gCTRP3 restored the reduction of sirtuin1, PGC-1α, NRF-1, complex III and ATP content induced by hypoxia-reoxygenation injury. CONCLUSION: CTRP3 promotes mitochondrial biogenesis in cardiomyocytes via AMPK/PGC-1α pathway. GENERAL SIGNIFICANCE: CTRP3 is an endogenous modulator for mitochondrial biogenesis, and may protect cardiomyocytes by ameliorating mitochondrial dysfunction.

[Correlation of large artery stiffness and coronary flow velocity reserve].

OBJECTIVE: Coronary flow velocity reserve (CFVR) is an important indicator of coronary endothelial functions and microcirculation. Pulse wave velocity (PWV) reflects the degree of aortic sclerosis and it is an independent predictor of cardiovascular events. The present study was designed to evaluate the correlation of large artery stiffness and CFVR. METHODS: A total of 101 consecutive subjects were enrolled to measure the brachial-ankle pulse wave velocity (baPWV). According to the presence or absence of higher baPWV (> 1400 cm/s), they were divided into 2 groups. Transthoracic echocardiography was employed to measure coronary flow velocity in coronary left anterior descending (LAD). Then after an intravenous infusion of adenosine triphosphate, the velocity of blood flow was measured when the vessel was in maximal dilation. The ratio of flow velocity of those in maximal dilation to those at rest was CFVR. RESULTS: The subjects with a higher baPWV (> 1400 cm/s) were markedly elder and had higher risks of hypertension and diabetes. Thus age, hypertension and diabetes contributed to arteriosclerosis. More importantly, the subjects with a higher baPWV (> 1400 cm/s) had a much lower level of CFVR (2.66 ± 0.74 vs 2.95 ± 0.76; P < 0.01) than those with a lower baPWV (< 1400 cm/s). Furthermore correlation analysis showed that CFVR and baPWV levels were significantly negatively correlated (r = -0.35, P < 0.01). CONCLUSIONS: A negative correlation exists between artery stiffness and coronary flow velocity reserve. The increased vascular stiffness may impair coronary endothelial function, cause the dysfunction of coronary microcirculation and raise the risks of cardiovascular events.