Sarcolipin expression in human skeletal muscle: Influence of energy balance and exercise

Abstract

Sarcolipin (SLN) is a SERCA uncoupling protein associated with exercise performance and lower adiposity in mice. To determine SLN protein expression in human skeletal muscle and its relationship with adiposity, resting energy expenditure (REE), and performance, SLN was assessed by Western blot in 199 biopsies from two previous studies. In one study, 15 overweight volunteers underwent a pretest followed by 4 days of caloric restriction and exercise (45‐minute one‐arm cranking + 8‐hour walking), and 3 days on a control diet. Muscle biopsies were obtained from the trained and non‐exercised deltoid, and vastus lateralis (VL). In another study, 16 men performed seven sessions of 4‐6 × 30‐sec all‐out sprints on the cycle ergometer with both limbs, and their VL and triceps brachii biopsied pre‐ and post‐training. SLN expression was twofold and 44% higher in the VL than in the deltoids and triceps brachii, respectively. SLN was associated with neither adiposity nor REE, and was not altered by a severe energy deficit (5500 kcal/day). SLN and cortisol changes after the energy deficit were correlated (r = .38, P = .039). SLN was not altered by low‐intensity exercise in the overweight subjects, whereas it was reduced after sprint training in the other group. The changes in SLN with sprint training were inversely associated with the changes in gross efficiency (r = −.59, P = .016). No association was observed between aerobic or anaerobic performance and SLN expression. In conclusion, sarcolipin appears to play no role in regulating the fat mass of men. Sprint training reduces sarcolipin expression, which may improve muscle efficiency.

Role of CaMKII and sarcolipin in muscle adaptations to strength training with different levels of fatigue in the set

“…Since this is the first time that the effects of two different strength training programs on CaMKII isoforms and SLN protein expression in human skeletal muscle have been tested, our findings will need independent confirmation by other researchers. We induced only modest changes in SLN, which were similar to those observed after sprint training 57 ; therefore, it remains unknown whether larger changes in SLN expression could produce adaptations similar to those described in mice overexpressing SLN. In the present investigation, there was a negative association between the changes phospho-Thr 287 -CaMKII δ D and those of SLN suggesting a potential negative feedback loop of phospho-Thr 287 -CaMKII δ D on SLN expression that requires testing in animal and cellular models.…”

Angiotensin‐Converting Enzyme 2 (SARS‐CoV‐2 receptor) expression in human skeletal muscle

“…This is a cross‐sectional study using muscle biopsies obtained from 170 men and 69 women who participated in previous studies, 25–31 including some of the participants in a European research project 32 named METAPREDICT, and some subjects involved in ongoing research projects 33,34 . All subjects were non‐smokers, 105 of them being healthy university students with different physical activity levels and the other 134 were mainly sedentary with overweight or obesity.…”

Physiological and molecular mechanisms of cold-induced improvements in glucose homeostasis in humans beyond brown adipose tissue

“…Hitherto, only SLN protein expression, but not activity, has been measured and compared between metabolically different individuals. In patients with T2DM it was shown that SERCA2 and SLN expression remained unaltered upon prolonged mild cold acclimation [17], and SLN expression was neither significantly different between lean subjects and participants with obesity, nor correlated with body fat percentage or resting metabolic rate [106]. A role for SLN in human skeletal muscle nonshivering thermogenesis thus remains controversial, and should be investigated in more detail.…”