Aerobic and resistance training enhances endothelial progenitor cell function via upregulation of caveolin-1 in mice with type 2 diabetes

Free essential amino acid feeding improves endurance during resistance training via DRP1-dependent mitochondrial remodelling

BACKGROUND

Loss of muscle strength and endurance with aging or in various conditions negatively affects quality of life. Resistance exercise training (RET) is the most powerful means to improve muscle mass and strength, but it does not generally lead to improvements in endurance capacity. Free essential amino acids (EAAs) act as precursors and stimuli for synthesis of both mitochondrial and myofibrillar proteins that could potentially confer endurance and strength gains. Thus, we hypothesized that daily consumption of a dietary supplement of nine free EAAs with RET improves endurance in addition to the strength gains by RET.

METHODS

Male C57BL6J mice (9 weeks old) were assigned to control (CON), EAA, RET (ladder climbing, 3 times a week), or combined treatment of EAA and RET (EAA + RET) groups. Physical functions focusing on strength or endurance were assessed before and after the interventions. Several analyses were performed to gain better insight into the mechanisms by which muscle function was improved. We determined cumulative rates of myofibrillar and mitochondrial protein synthesis using 2H2O labelling and mass spectrometry; assessed ex vivo contractile properties and in vitro mitochondrial function, evaluated neuromuscular junction (NMJ) stability, and assessed implicated molecular singling pathways. Furthermore, whole-body and muscle insulin sensitivity along with glucose metabolism, were evaluated using a hyperinsulinaemic-euglycaemic clamp.

RESULTS

EAA + RET increased muscle mass (10%, P < 0.05) and strength (6%, P < 0.05) more than RET alone, due to an enhanced rate of integrated muscle protein synthesis (19%, P < 0.05) with concomitant activation of Akt1/mTORC1 signalling. Muscle quality (muscle strength normalized to mass) was improved by RET (i.e., RET and EAA + RET) compared with sedentary groups (10%, P < 0.05), which was associated with increased AchR cluster size and MuSK activation (P < 0.05). EAA + RET also increased endurance capacity more than RET alone (26%, P < 0.05) by increasing both mitochondrial protein synthesis (53%, P < 0.05) and DRP1 activation (P < 0.05). Maximal respiratory capacity increased (P < 0.05) through activation of the mTORC1-DRP1 signalling axis. These favourable effects were accompanied by an improvement in basal glucose metabolism (i.e., blood glucose concentrations and endogenous glucose production vs. CON, P < 0.05).

CONCLUSIONS

Combined treatment with balanced free EAAs and RET may effectively promote endurance capacity as well as muscle strength through increased muscle protein synthesis, improved NMJ stability, and enhanced mitochondrial dynamics via mTORC1-DRP1 axis activation, ultimately leading to improved basal glucose metabolism.

Oxidized LDL decreases the survival of bone marrow stem cells via inhibition of Bcl-2 expression

Therapy with mesenchymal stem cells (MSCs) is considered an attractive strategy for the repair or regeneration of damaged tissues. However, low survival of MSCs limits their applications clinically. Oxidized low-density lipoprotein (ox-LDL) is significantly increased in patients with hyperlipidemia and decreases the survival of MSCs. Bcl-2 is critically involved in important cell functions including cell membrane integrity and cell survival. The present study was designed to test the hypothesis that ox-LDL attenuate the survival of MSCs via suppression of Bcl-2 expression. Bone marrow MSCs from C57BL/6 mice were cultured with ox-LDL at different concentrations (0-140 μg/ml) for 24 hours with native LDL as control. Ox-LDL treatment substantially decreased the survival of MSCs dose-dependently and enhanced the release of intracellular LDH in association with a significant decrease in Bcl-2 protein level without change in BAX protein expression in MSCs. Bcl-2 overexpression effectively protected MSCs against ox-LDL-induced damages with preserved cell numbers without significant increase in LDH release. Treatment with N-acetylcysteine (NAC) (1 mM) effectively preserved Bcl-2 protein expression in MSCs and significantly attenuated ox-LDL-induced decrease of cell number and increase in the release of intracellular LDH. These data indicated that ox-LDL treatment resulted in a significant damage of cell membrane and dramatically decreased the survival of MSCs dose-dependently through inhibition of Bcl-2 expression. NAC treatment significantly protected MSCs against the damage of cell membrane by ox-LDL and promoted the survival of MSCs in association with preserved Bcl-2 expression.

Resistance exercise preconditioning prevents disuse muscle atrophy by inhibiting apoptosis and protein degradation via SESN2 in C57BL/6J mice

AIM

To compare the effects of different exercise preconditioning in the context of skeletal muscle atrophy and to investigate the potential involvement of Sestrin2 (SESN2), a stress-inducible protein that can be regulated by exercise, in exercise preconditioning on preventing disuse muscle atrophy.

METHODS

Eight-week-old male C57BL/6J mice were randomly assigned to sedentary groups (SD), aerobic exercise groups (AE), resistance exercise groups (RE), and combined exercise groups (CE) with or without 7 days of immobilization. The duration of the exercise intervention was 10 weeks. The effects of different exercise preconditioning to prevent muscle atrophy were analyzed by evaluating skeletal muscle function and mass. Additionally, to investigate the potential underlying mechanism of exercise-induced protection of skeletal muscle, wild-type and SESN2--/-- mice were randomly divided into sedentary group and resistance exercise preconditioning group. C2C12 cells were treated with SESN2 adenoviruses and MK2206 (an AKT inhibitor) for 48 h to elucidate the underlined mechanism.

RESULTS

RE was more effective in preserving skeletal muscle function, muscle mass and maintaining skeletal muscle protein homeostasis than AE and CE under immobilized condition. Importantly, exercise performance, muscle mass to body weight ratio, and the cross-sectional area of muscle fibers were significantly lower in SESN2-/- mice than wild-type mice after resistance exercise preconditioning. Mechanistically, the absence of SESN2 led to activation of the ubiquitin-proteasome system and induction of apoptosis. In vitro experiments showed that MK2206 treatment mitigated the regulatory effects of overexpression-SESN2 on protein hydrolysis and apoptosis.

CONCLUSION

RE was more effective than AE or CE in preventing disuse muscle atrophy. SESN2 mediated the protective effects of resistance exercise preconditioning on skeletal muscle atrophy.

A Combined Western and Bead-Based Multiplex Platform to Characterize Extracellular Vesicles

In regenerative medicine, extracellular vesicles (EVs) are considered as a promising cell-free approach. EVs are lipid bilayer-enclosed vesicles secreted by cells and are key players in intercellular communication. EV-based therapeutic approaches have unique advantages over the use of cell-based therapies, such as a high biological, but low immunogenic and tumorigenic potential. To analyze the purity and biochemical composition of EV preparations, the International Society for Extracellular Vesicles (ISEV) has prepared guidelines recommending the analysis of multiple (EV) markers, as well as proteins coisolated/recovered with EVs. Traditional methods for EV characterization, such as Western blotting, require a relatively high EV sample/protein input for the analysis of one protein. We here evaluate a combined Western and bead-based multiplex platform, called DigiWest, for its ability to detect simultaneously multiple EV markers in an EV-containing sample with inherent low protein input. DigiWest analysis was performed on EVs from various sources and species, including mesenchymal stromal cells, notochordal cells, and milk, from human, pig, and dog. The study established a panel of nine antibodies that can be used as cross-species for the detection of general EV markers and coisolates in accordance with the ISEV guidelines. This optimized panel facilitates the parallel evaluation of EV-containing samples, allowing for a comprehensive characterization and assessment of their purity. The total protein input for marker analysis with DigiWest was 1 μg for all nine antibodies, compared with ∼10 μg protein input required for traditional Western blotting for one antibody. These findings demonstrate the potential of the DigiWest technique for characterizing various types of EVs in the regenerative medicine field.

miR-221/222 Promote Endothelial Differentiation of Adipose-Derived Stem Cells by Regulation of PTEN/PI3K/AKT/mTOR Pathway

Adipose-derived stem cells (ADSCs) are a type of adult mesenchymal stem cell that show a repair effect on ischemic tissues owing to their capacity for endothelial differentiation. MicroRNA-221/222 (miR-221/222) has been extensively studied in endothelial cells (ECs). However, the mechanism that regulates ADSCs differentiation into ECs remains unknown. In this study, we investigated the effects of miR-221/222-overexpression/silence in ADSCs on endothelial differentiation by constructing lentiviral vectors. Differentiation capacity was assessed by measuring the expression of endothelial markers (CD31, CD34, and CD144). In addition, low-density lipoprotein (LDL) uptake and tube-like formation were performed for evaluation of functional characterization. The PTEN/PI3K/AKT/mTOR signaling pathway was investigated using western blotting to clarify the action mechanism of this gene. The revascularization of miR-221/222-transfeted ADSCs was further verified in a rat hind limb ischemia model. The results confirmed that transfection with miR-221/222 promoted the expression of endothelial markers, LDL uptake, and tube-like formation. As expected, the PI3K/AKT signaling pathway was effectively activated when ADSCs showed high expression of miR-221/222 during endothelial differentiation. Furthermore, injection of miR-221/222 transfected ADSCs significantly improved rat hindlimb ischemia, as evidenced by increased blood flow and structural integrity and reduce inflammatory infiltration. The results of this study suggest that miR-221/222 is essential for endothelial differentiation of ADSCs and provides a novel strategy for modulating vascular formation and ischemic tissue regeneration.

Exercise-Based Cancer Rehabilitation Program Improves Phase Angle in Breast Cancer Survivors

Phase angle (PhA) is an index of cell membrane integrity and prognostic indicator of survival and quality of life in cancer survivors. The efficacy of exercise-based cancer rehabilitation programs (ExCR) on PhA is unknown. To assess the effect of ExCR on PhA in breast cancer survivors. Fifty-nine female breast cancer survivors (61 ± 9 years) were referred to the ExCR by their oncologist and participated in one-on-one exercise-based training for 90 minutes, 3 times a week, for 12 weeks. Training sessions included 45 minutes of resistance training at intensities between 40-85% of 1-repetition maximum with a rate of perceived exertion (RPE) between 3-8, 30 minutes of cardiorespiratory training at intensities between 40-85% of heart rate reserve with an RPE between 3-8, and 15 minutes of flexibility training. Participants completed pre- and post-measurements of body composition, cardiorespiratory endurance, flexibility, muscular endurance, muscular strength, and PhA (Inbody 770). PhA significantly increased (p < 0.05) after ExCR (PhA_pre = 4.56; PhA_post = 4.64; Δ = 1.8%). Changes in measures of muscular strength have a weak but significant positive relationship (r = 0.20-0.39; p < 0.05) with changes in PhA. There was no relationship between changes in PhA and changes in cardiorespiratory endurance or muscular endurance. A 12-week ExCR significantly improves PhA in breast cancer survivors. Training muscular strength may be an integral component of ExCR with the objective of improving PhA.

Effects of Whey Peptide Supplementation on Sarcopenic Obesity in High-Fat Diet-Fed Mice

The incidence of sarcopenic obesity gradually increased in parallel with the aged population. This research examined the effects of whey peptide (WP) supplementation with/without resistant exercise (RE) on sarcopenic obesity. Male 8-month-old C57BL/6J mice were fed a control diet (10 kcal% fat) or a high-fat diet (60 kcal% fat) for 8 weeks. High-fat diet-fed mice were randomly divided into four groups: obesity control group (OB), RE (RE only), WP (WP only), and WPE (RE and WP). WP supplementation (1500 mg/day/kg B.W.) gavage and RE (ladder climbing, five times weekly, 8−10 repetitions, 10−20% B.W. load) were conducted for an additional 8 weeks. Protein and mRNA levels of markers related to energy, protein, and lipid metabolism were analyzed in skeletal muscle and adipose tissue by one-way analysis of variance (ANOVA). WP supplementation regardless of RE significantly suppressed the increasing fat mass (p = 0.016) and decreasing lean mass (p = 0.014) and alleviated abnormal morphological changes in skeletal muscle and adipose tissue (p < 0.001). In adipose tissue, WP supplementation regardless of RE ameliorated dysregulated energy metabolism and contributed to the reduction in adipocyte differentiation (PPAR-γ (p = 0.017), C/EBPα (p = 0.034)). In skeletal muscle, WP supplementation regardless of RE alleviated energy metabolism dysregulation and resulted in down-regulated protein degradation (Atrogin-1 (p = 0.003), MuRF1 (p = 0.006)) and apoptosis (Bax) (p = 0.004). Taken together, the current study elucidated that WP supplementation regardless of RE has potential anti-obesity and anti-sarcopenic effects in sarcopenic obesity.

Potential Effects of Resistant Exercise on Cognitive and Muscle Functions Mediated by Myokines in Sarcopenic Obese Mice

Recently, it has been demonstrated that in sarcopenic obesity (SO), physical activity could improve cognitive functions. Moreover, previous studies suggested that muscle contraction could influence cognitive function via myokines. This study investigated the potential effects of resistant exercise on cognitive and muscle functions in SO. SO was induced by a high-fat diet treatment for 8 weeks in 8-month-old male C57BL/6J mice. Then, resistant exercise (ladder climbing) for 8 weeks was performed. Muscle and cognitive function tests and morphological analysis were conducted. The protein levels of myokines were investigated in muscle, plasma, and the hippocampus in sarcopenic obese mice. Muscle and cognitive functions were significantly elevated in the obesity-exercise group (EX) compared to the obesity-control group (OB). Interestingly, muscle function was positively correlated with cognitive function. Abnormal morphological changes in the hippocampus were ameliorated in EX compared to OB, but not in the muscle. Protein levels of cognitive function-related myokines and energy metabolism-related markers in EX were significantly elevated in both muscle and hippocampus compared to those in OB. Interestingly, the protein level of brain-derived neurotrophic factor (BDNF) in EX was simultaneously increased in all tissues including muscle, plasma, and hippocampus compared to that in OB. In conclusion, modulation of muscle-derived cognitive function-related myokines in various pathological conditions via a resistant exercise could be a possible way of relieving muscle and cognitive dysfunction.

Microarray meta-analysis reveals IL6 and p38β/MAPK11 as potential targets of hsa-miR-124 in endothelial progenitor cells: Implications for stent re-endothelization in diabetic patients

Circulating endothelial progenitor cells (EPCs) play an important role in the repair processes of damaged vessels, favoring re-endothelization of stented vessels to minimize restenosis. EPCs number and function is diminished in patients with type 2 diabetes, a known risk factor for restenosis. Considering the impact of EPCs in vascular injury repair, we conducted a meta-analysis of microarray to assess the transcriptomic profile and determine target genes during the differentiation process of EPCs into mature ECs. Five microarray datasets, including 13 EPC and 12 EC samples were analyzed, using the online tool ExpressAnalyst. Differentially expressed genes (DEGs) analysis was done by Limma method, with an | log2FC| &gt; 1 and FDR &lt; 0.05. Combined p-value by Fisher exact method was computed for the intersection of datasets. There were 3,267 DEGs, 1,539 up-regulated and 1,728 down-regulated in EPCs, with 407 common DEGs in at least four datasets. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis showed enrichment for terms related to “AGE-RAGE signaling pathway in diabetic complications.” Intersection of common DEGs, KEGG pathways genes and genes in protein-protein interaction network (PPI) identified four key genes, two up-regulated (IL1B and STAT5A) and two down-regulated (IL6 and MAPK11). MicroRNA enrichment analysis of common DEGs depicted five hub microRNA targeting 175 DEGs, including STAT5A, IL6 and MAPK11, with hsa-miR-124 as common regulator. This group of genes and microRNAs could serve as biomarkers of EPCs differentiation during coronary stenting as well as potential therapeutic targets to improve stent re-endothelization, especially in diabetic patients.

Caveolin1: its roles in normal and cancer stem cells

PURPOSE

Stem cells are characterized by the capability of self-renewal and multi-differentiation. Normal stem cells, which are important for tissue repair and tissue regeneration, can be divided into embryonic stem cells (ESCs) and somatic stem cells (SSCs) depending on their origin. As a subpopulation of cells within cancer, cancer stem cells (CSCs) are at the root of therapeutic resistance. Tumor-initiating cells (TICs) are necessary for tumor initiation. Caveolin1 (Cav1), a membrane protein located at the caveolae, participates in cell lipid transport, cell migration, cell proliferation, and cell signal transduction. The purpose of this review was to explore the relationship between Cav1 and stem cells.

RESULTS

In ESCs, Cav1 is beneficial for self-renewal, proliferation, and migration. In SSCs, Cav1 exhibits positive or/and negative effects on stem cell self-renewal, differentiation, proliferation, migration, and angiogenic capacity. Cav1 deficiency impairs normal stem cell-based tissue repair. In CSCs, Cav1 inhibits or/and promotes CSC self-renewal, differentiation, invasion, migration, tumorigenicity ability, and CSC formation. And suppressing Cav1 promotes chemo-sensitivity in CSCs and TICs.

CONCLUSION

Cav1 shows dual roles in stem cell biology. Targeting the Cav1-stem cell axis would be a new way for tissue repair and cancer drug resistance.

Caveolin-1, a novel player in cognitive decline

Cognitive decline (CD), which related to vascular dementia, Alzheimer's disease, Parkinson's disease, Huntington's disease, amyotrophic lateral sclerosis and diabetes mellitus, is a growing health concern that has a great impact on the patients' quality of life. Although extensive efforts, the mechanisms of CD are still far from being clarified, not to mention the effective treatment and prevention strategies. Caveolin-1 (Cav-1), a trans-membrane protein, is a major component of the caveolae structure and scaffolding proteins. Recently, ample evidence depicts a strong correlation between Cav-1 and CD, however, the specific role of Cav-1 in CD has not been clearly examined and how they might be connected have yet to be identified. This review seeks to provide a comprehensive overview about how Cav-1 modulates pathogeneses of CD-associated diseases. In summary, Cav-1 can promote structural and functional plasticity of neurons, improve neurogenesis, relieve mitochondrial dysfunction, inhibit inflammation and suppress oxidative stress, which have shed light on the idea that Cav-1 may be an efficacious therapeutic target to treat CD.

Endothelial Progenitor Cells Dysfunctions and Cardiometabolic Disorders: From Mechanisms to Therapeutic Approaches

Metabolic syndrome (MetS) is a cluster of several disorders, such as hypertension, central obesity, dyslipidemia, hyperglycemia, insulin resistance and non-alcoholic fatty liver disease. Despite health policies based on the promotion of physical exercise, the reduction of calorie intake and the consumption of healthy food, there is still a global rise in the incidence and prevalence of MetS in the world. This phenomenon can partly be explained by the fact that adverse events in the perinatal period can increase the susceptibility to develop cardiometabolic diseases in adulthood. Individuals born after intrauterine growth restriction (IUGR) are particularly at risk of developing cardiovascular diseases (CVD) and metabolic disorders later in life. It has been shown that alterations in the structural and functional integrity of the endothelium can lead to the development of cardiometabolic diseases. The endothelial progenitor cells (EPCs) are circulating components of the endothelium playing a major role in vascular homeostasis. An association has been found between the maintenance of endothelial structure and function by EPCs and their ability to differentiate and repair damaged endothelial tissue. In this narrative review, we explore the alterations of EPCs observed in individuals with cardiometabolic disorders, describe some mechanisms related to such dysfunction and propose some therapeutical approaches to reverse the EPCs dysfunction.