0000000000113166
AUTHOR
Sira Karvinen
showing 15 related works from this author
Branched-Chain Amino Acid Deprivation Decreases Lipid Oxidation and Lipogenesis in C2C12 Myotubes
2022
Impaired lipid metabolism is a common risk factor underlying several metabolic diseases such as metabolic syndrome and type 2 diabetes. Branched-chain amino acids (BCAAs) that include valine, leucine and isoleucine have been proven to share a role in lipid metabolism and hence in maintaining metabolic health. We have previously introduced a hypothesis suggesting that BCAA degradation mechanistically connects to lipid oxidation and storage in skeletal muscle. To test our hypothesis, the present study examined the effects of BCAA deprivation and supplementation on lipid oxidation, lipogenesis and lipid droplet characteristics in murine C2C12 myotubes. In addition, the role of myotube contract…
Lifespan and skeletal muscle properties the effects of genetic background, physical activity and aging
2016
Obesity and metabolic disorders have become a notable world-wide epidemic. The pathogenesis of metabolic diseases, such as metabolic syndrome and type 2 diabetes, has begun to negatively affect life expectancy of current generations. Low aerobic capacity has shown to be a strong predictor of mortality both in rodents and humans. Exercise is known to increase an individual’s aerobic capacity; interestingly, recent studies have suggested that genetic background may play a significant role in the physical activity level of an individual. The purpose of this study was to investigate the role of genetic background and physical activity on skeletal muscle properties, metabolism and lifespan. The …
Extracellular vesicles and high‐density lipoproteins: Exercise and oestrogen‐responsive small RNA carriers
2023
Decreased systemic oestrogen levels (i.e., menopause) affect metabolic health. However, the detailed mechanisms underlying this process remain unclear. Both oestrogens and exercise have been shown to improve metabolic health, which may be partly mediated by circulating microRNA (c-miR) signalling. In recent years, extracellular vesicles (EV) have increased interest in the field of tissue crosstalk. However, in many studies on EV-carried miRs, the co-isolation of high-density lipoprotein (HDL) particles with EVs has not been considered, potentially affecting the results. Here, we demonstrate that EV and HDL particles have distinct small RNA (sRNA) content, including both host and nonhost sRN…
Estrogenic regulation of skeletal muscle proteome : a study of premenopausal women and postmenopausal MZ cotwins discordant for hormonal therapy
2017
Female middle age is characterized by a decline in skeletal muscle mass and performance, predisposing women to sarcopenia, functional limitations, and metabolic dysfunction as they age. Menopausal loss of ovarian function leading to low circulating level of 17b-estradiol has been suggested as a contributing factor to aging-related muscle deterioration. However, the underlying molecular mechanisms remain largely unknown and thus far androgens have been considered as a major anabolic hormone for skeletal muscle. We utilized muscle samples from 24 pre- and postmenopausal women to establish proteome-wide profiles, associated with the difference in age (30–34 years old vs. 54– 62 years old), men…
Age affects myosin relaxation states in skeletal muscle fibers of female but not male mice
2018
The recent discovery that myosin has two distinct states in relaxed muscle–disordered relaxed (DRX) and super-relaxed (SRX)–provides another factor to consider in our fundamental understanding of the aging mechanism in skeletal muscle, since myosin is thought to be a potential contributor to dynapenia (age-associated loss of muscle strength independent of atrophy). The primary goal of this study was to determine the effects of age on DRX and SRX states and to examine their sex specificity. We have used quantitative fluorescence microscopy of the fluorescent nucleotide analog 2′/3′-O-(N-methylanthraniloyl) ATP (mantATP) to measure single-nucleotide turnover kinetics of myosin in skinned skel…
Effects of intrinsic aerobic capacity, aging and voluntary running on skeletal muscle sirtuins and heat shock proteins
2016
Aim Sirtuins are proteins that connect energy metabolism, oxidative stress and aging. Expression of heat shock proteins (Hsps) is regulated by heat shock factors (HSFs) in response to various environmental and physiological stresses, such as oxidative stress. Oxidative stress accumulates during aging which makes cells more prone to DNA damage. Although many experimental animal models have been designed to study the effects of knockdown or overexpression of sirtuins, HSFs and Hsps, little is known about how aging per se affects their expression. Here we study the impact of intrinsic aerobic capacity, aging and voluntary exercise on the levels of sirtuins, HSFs and Hsps in skeletal muscle. Me…
Interactive effects of aging and aerobic capacity on energy metabolism-related metabolites of serum, skeletal muscle, and white adipose tissue
2021
ABSTRACTAerobic capacity is a strong predictor of longevity. With aging, aerobic capacity decreases concomitantly with changes in whole body metabolism leading to increased disease risk. To address the role of aerobic capacity, aging and their interaction on metabolism, we utilized rat models of low and high intrinsic aerobic capacity (LCRs/HCRs) and assessed the metabolomics of serum, muscle, and white adipose tissue (WAT). We compared LCRs and HCRs at two time points: Young rats were sacrificed at 9 months, and old rats were sacrificed at 21 months. Targeted and semi-quantitative metabolomics analysis was performed on ultra-pressure Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS)…
Xylo-Oligosaccharides in Prevention of Hepatic Steatosis and Adipose Tissue Inflammation: Associating Taxonomic and Metabolomic Patterns in Fecal Mic…
2021
We have shown that prebiotic xylo-oligosaccharides (XOS) increased beneficial gut microbiota (GM) and prevented high fat diet-induced hepatic steatosis, but the mechanisms associated with these effects are not clear. We studied whether XOS affects adipose tissue inflammation and insulin signaling, and whether the GM and fecal metabolome explain associated patterns. XOS was supplemented or not with high (HFD) or low (LFD) fat diet for 12 weeks in male Wistar rats (n = 10/group). Previously analyzed GM and fecal metabolites were biclustered to reduce data dimensionality and identify interpretable groups of co-occurring genera and metabolites. Based on our findings, biclustering provides a use…
Physical activity in adulthood: genes and mortality.
2015
AbstractObservational studies report a strong inverse relationship between leisure-time physical activity and all-cause mortality. Despite suggestive evidence from population-based associations, scientists have not been able to show a beneficial effect of physical activity on the risk of death in controlled intervention studies among individuals who have been healthy at baseline. On the other hand, high cardiorespiratory fitness is known to be a strong predictor of reduced mortality, even more robust than physical activity level itself. Here, in both animals and/or human twins, we show that the same genetic factors influence physical activity levels, cardiorespiratory fitness and risk of de…
Estradiol deficiency and skeletal muscle apoptosis: Possible contribution of microRNAs.
2020
Background Menopause leads to estradiol (E2) deficiency that is associated with decreases in muscle mass and strength. Here we studied the effect of E2 deficiency on miR-signaling that targets apoptotic pathways. Methods C57BL6 mice were divided into control (normal estrous cycle, n = 8), OVX (E2 deficiency, n = 7) and OVX + E2 groups (E2-pellet, n = 4). Six weeks following the OVX surgery, mice were sacrificed and RNA isolated from gastrocnemius muscles. miR-profiles were studied with Next-generation sequencing (NGS) and candidate miRs verified using qPCR. The target proteins of the miRs were found using in silico analysis and measured at mRNA (qPCR) and protein levels (Western blot). Resu…
Metabolic health, menopause, and physical activity : a 4-year follow-up study
2022
Background In women, metabolic health deteriorates after menopause, and the role of physical activity (PA) in mitigating the change is not completely understood. This study investigates the changes in indicators of metabolic health around menopause and evaluates whether PA modulates these changes. Methods Longitudinal data of 298 women aged 48–55 years at baseline participating in the ERMA and EsmiRs studies was used. Mean follow-up time was 3.8 (SD 0.1) years. Studied indicators of metabolic health were total and android fat mass, waist circumference, waist-to-hip ratio (WHR), systolic (SBP) and diastolic (DBP) blood pressure, blood glucose, triglycerides, serum total cholesterol, and high…
MicroRNAs in Extracellular Vesicles in Sweat Change in Response to Endurance Exercise
2020
Background: To date, microRNAs (miRs) carried in extracellular vesicles (EVs) in response to exercise have been studied in blood but not in non-invasively collectable body fluids. In the present study, we examined whether six exercise–responsive miRs, miRs-21, -26, -126, -146, -221, and -222, respond to acute endurance exercise stimuli of different intensities in sweat. Methods: We investigated the response of miRs isolated from sweat and serum EVs to three endurance exercise protocols: (1) maximal aerobic capacity (VO2max), (2) anaerobic threshold (AnaT), and (3) aerobic threshold (AerT) tests. Sauna bathing was used as a control test to induce sweating through increased body temperature i…
Menopausal Status and Physical Activity Are Independently Associated With Cardiovascular Risk Factors of Healthy Middle-Aged Women: Cross-Sectional a…
2019
Cardiovascular disease (CVD) is the primary cause of mortality in women in developed countries. CVD risk rises with age, yet for women there is a rapid increase in CVD risk that occurs after the onset of menopause. This observation suggests the presence of factors in the middle-aged women that accelerate the progression of CVD independent of chronological aging. Leisure time physical activity (LTPA) is a well-established protective factor against CVD. However, its role in attenuating atherogenic lipid profile changes and CVD risk in post-menopausal women has not been well-established. The present study is part of the Estrogenic Regulation of Muscle Apoptosis (ERMA) study, a population-based…
Total and regional body adiposity increases during menopause : evidence from a follow‐up study
2022
For women, menopausal transition is a time of significant hormonal changes, which may contribute to altered body composition and regional adipose tissue accumulation. Excess adiposity, and especially adipose tissue accumulation in the central body region, increases women's risk of cardiovascular and metabolic conditions and affects physical functioning. We investigated the associations between menopausal progression and total and regional body adiposity measured with dual-energy X-ray absorptiometry and computed tomography in two longitudinal cohort studies of women aged 47–55 (n = 230 and 148, mean follow-up times 1.3 ± 0.7 and 3.9 ± 0.2 years, mean baseline BMI 25.5 kg/m2). We also examin…
Role of Menopausal Transition and Physical Activity in Loss of Lean and Muscle Mass : A Follow-Up Study in Middle-Aged Finnish Women
2020
In midlife, women experience hormonal changes due to menopausal transition. A decrease especially in estradiol has been hypothesized to cause loss of muscle mass. This study investigated the effect of menopausal transition on changes in lean and muscle mass, from the total body to the muscle fiber level, among 47–55-year-old women. Data were used from the Estrogenic Regulation of Muscle Apoptosis (ERMA) study, where 234 women were followed from perimenopause to early postmenopause. Hormone levels (estradiol and follicle stimulating hormone), total and regional body composition (dual-energy X-ray absorptiometry (DXA) and computed tomography (CT) scans), physical activity level (self-reported…