Peroxisomal proliferator-activated receptor gamma co-activator-1 alpha gene expression increases above the lactate threshold in human skeletal muscle

AIM

Peroxisomal proliferator-activated receptor gamma co-activator-1 alpha (PGC-1α) plays a role not only as an activator of mitochondrial biogenesis, but also as a suppressor of inflammatory cytokines, which induce chronic diseases. Therefore, increasing PGC-1α expression can be one of the important factors for preventing chronic diseases. PGC-1α expression is activated by adenosine monophosphate-activated protein kinase (AMPK) and cAMP dependent kinase. The activity of these enzymes depends on the exercise intensity. Therefore, this study compared the effects of two different exercise intensities (above lactate threshold (LT) and below LT) with an equal amount of energy expenditure on PGC-1α gene expression in human skeletal muscle.

METHODS

Six young men participated in this study. They performed exercise at 120% and 80% LT intensity. The duration of the 120% LT exercise was 60 minutes and the duration of the session performed at 80% LT was calculated to yield equal energy expenditure as the 120% LT intensity exercise. Skeletal muscle was obtained after 1 hour of exercise.

RESULTS

The working rate, % peak VO2 and HR during exercise were significantly higher in at 120% LT than at 80% LT. PGC-1α gene expression was not significantly different between control (0.087; 0.026-0.284 (the median; inter quartile range)) and 80% LT (0.171; 0.030-0.484). However, PGC-1α gene expression after 120% LT (0.441; 0.121-4.643) was significantly higher than in the control.

CONCLUSION

The findings of this study suggest that PGC-1α gene expression depends on exercise intensity.

Regulation of muscle genes by moderate exercise

Moderate-intensity exercise at the lactate threshold (LT) is considered to be a safe and effective training regimen for improving metabolic syndrome. The aim of the current study was to investigate the effects of moderate exercise performed at the LT on skeletal muscle gene expression. 6 healthy men participated in cycle ergometer training at LT, 60 min/d, 5 d/wk for 12 wks. Muscle samples were collected after 5 d of training, and then 2 d after training at wks 6 and 12. Quantitative real-time PCR analysis revealed that the expression of peroxisome proliferator activated receptor co-activated 1alpha was significantly increased at 1 h after the training session on day 5. Moreover, using serial analysis gene expression, we found that moderate training for 6 and 12 wks simultaneously induced the expression of a number of metabolic genes involved in the TCA cycle, beta-oxidation, and electron transport. Furthermore, several genes encoding antioxidant enzymes and contractile apparatus were induced. The expression levels of 233 novel transcripts were also altered in response to moderate exercise. Thus, moderate training at the LT is a sufficient stimulus to induce the expression of numerous genes implicated in the development of metabolic syndrome, transcripts involved in the contractile apparatus, and novel transcripts.

Physical function is weakly associated with angiotensin-converting enzyme gene I/D polymorphism in elderly Japanese subjects

BACKGROUND

The turning point in the deterioration of physical function seems to occur between the ages of 70 and 80 years. In particular, muscle strength may decline even more in subjects older than 75. A recent study found that the angiotensin-converting enzyme (ACE) genotype also affects physiological left ventricular hypertrophy. A very limited number of papers have examined genetic differences in resistance and endurance forms of a single sporting discipline.

OBJECTIVE

The purpose of this study was to evaluate the relationship between ACE genotype and physical function by controlling the known confounding factors including dental status.

METHODS

We selected 431 subjects who were aged 76 years and did not require special care for their daily activities. We conducted a medical examination, followed by 5 physical function tests, as follows: (1) maximum hand grip strength, (2) maximal isometric knee extensor strength, (3) maximal stepping rate for 10 s, (4) one-leg standing time with eyes open and (5) 10-meter maximum walking speed. Subjects were genotyped for the ACE intron 16 Alu insertion. In addition, serum concentrations of total cholesterol, total protein, IgA and IgG were measured at a commercial laboratory. The Eichner index was used as an indicator of occlusal condition. Multiple linear regression analysis was performed to evaluate the relationship between the ACE gene insertion/deletion (I/D) polymorphism and physical function considering confounding factors.

RESULTS

The ACE gene I/D polymorphism was positively associated with hand grip strength and 10-meter maximum walking speed. Betas of hand grip strength were 0.09 for I/D (p = 0.022) and 0.12 for insertion/insertion (I/I; p = 0.004). Betas of 10-meter walking speed were -0.11 for I/D (p = 0.093) and -0.14 for I/I (p = 0.039). Dental status such as Eichner index class C was significantly associated with one-leg standing time with eyes open (beta -0.11; p = 0.028).

CONCLUSION

This study suggests that there is a significant relationship between ACE genotype and physical function. In particular, subjects with the ACE deletion/deletion genotype were associated with upper extremities.