Dihydromyricetin resists inflammation-induced muscle atrophy via ryanodine receptor-CaMKK-AMPK signal pathway.

Skeletal muscle plays a pivotal role in the maintenance of physical and metabolic health. Skeletal muscle atrophy usually results in physical disability, inferior quality of life and higher health care costs. The higher incidence of muscle atrophy in obese and ageing groups is due to increased levels of inflammatory factors during obesity and ageing. Dihydromyricetin, as a bioactive polyphenol, has been used for anti-inflammatory, anti-tumour and improving insulin sensitivity. However, there are no published reports demonstrated the dihydromyricetin effect on inflammation-induced skeletal muscle atrophy. In this study, we first confirmed the role of dihydromyricetin in inflammation-induced skeletal muscle atrophy in vivo and in vitro. Then, we demonstrated that dihydromyricetin resisted inflammation-induced skeletal muscle atrophy by activating Ca2+ -CaMKK-AMPK through signal pathway blockers, Ca2+ probes and immunofluorescence. Finally, we clarified that dihydromyricetin activated Ca2+ -CaMKK-AMPK signalling pathway through interaction with the ryanodine receptor, its target protein, by drug affinity responsive target stability (DARTS). Our results not only demonstrated that dihydromyricetin resisted inflammation-induced muscle atrophy via the ryanodine receptor-CaMKK-AMPK signal pathway but also discovered that the target protein of dihydromyricetin is the ryanodine receptor. Our results provided experimental data for the development of dihydromyricetin as a functional food and new therapeutic strategies for treating or preventing skeletal muscle atrophy.

Dihydromyricetin Ameliorates Inflammation-Induced Insulin Resistance via Phospholipase C-CaMKK-AMPK Signal Pathway.

Patients with metabolic syndrome have a higher risk of type II diabetes and cardiovascular disease. The metabolic syndrome has become an urgent public health problem. Insulin resistance is the common pathophysiological basis of metabolic syndrome. The higher incidence of insulin resistance in obese groups is due to increased levels of inflammatory factors during obesity. Therefore, developing a therapeutic strategy for insulin resistance has great significance for the treatment of the metabolic syndrome. Dihydromyricetin, as a bioactive polyphenol, has been used for anti-inflammatory, antitumor, and improving insulin sensitivity. However, the target of DHM and molecular mechanism of DHM for preventing inflammation-induced insulin resistance is still unclear. In this study, we first confirmed the role of dihydromyricetin in inflammation-induced insulin resistance in vivo and in vitro. Then, we demonstrated that dihydromyricetin resisted inflammation-induced insulin resistance by activating Ca2+-CaMKK-AMPK using signal pathway blockers, Ca2+ probes, and immunofluorescence. Finally, we clarified that dihydromyricetin activated Ca2+-CaMKK-AMPK signaling pathway by interacting with the phospholipase C (PLC), its target protein, using drug affinity responsive target stability (DARTS) assay. Our results not only demonstrated that dihydromyricetin resisted inflammation-induced insulin resistance via the PLC-CaMKK-AMPK signal pathway but also discovered that the target protein of dihydromyricetin is the PLC. Our results provided experimental data for the development of dihydromyricetin as a functional food and new therapeutic strategies for treating or preventing PLC.

Retears and Concomitant Functional Impairments After Rotator Cuff Repair: Shoulder Activity as a Risk Factor.

BACKGROUND: Most patients return successfully to shoulder involving sports or activity after rotator cuff repairs. It has not been decided yet whether postoperative participation in shoulder activity adds to the risk of retear. PURPOSE/HYPOTHESIS: The purpose was to verify whether patients who participate in shoulder activities after rotator cuff repair have a higher risk of structural failure than nonactive patients and to investigate the relationship between postoperative shoulder function and tendon integrity in active and nonactive patients. The hypotheses were that (1) active patients have a higher retear rate than nonactive patients and (2) structural failure is associated with worse functional outcomes in active patients. STUDY DESIGN: Cohort study; Level of evidence, 3. METHODS: A cohort study was performed using 145 patients who underwent arthroscopic rotator cuff repair from 2015 to 2017. Functional assessments and magnetic resonance imaging were performed at least 24 months postoperatively. Shoulder activities since 6 months after surgery were rated in 4 categories (sports, job, activities of daily life, and weight of general lifting) as sedentary, light, moderate, or strenuous. The activity level of each patient was defined by the highest rated category. Patients who were involved in light, moderate, and strenuous activity were identified as active for the present study, and the rest were defined as sedentary. The proportion of retears between groups and the functional conditions between retorn and intact tendons were compared. RESULTS: A total of 48 patients were enrolled in the active group, and 97 were enrolled in the sedentary group. The active group demonstrated a significantly higher retear rate than the sedentary group (27.1% vs 11.3%, respectively; P = .016; risk ratio, 2.39 [95% CI, 1.16-4.93]). In the active group, patients with retears showed higher visual analog scale scores for pain, decreased abduction strength, and lower shoulder functional scores (American Shoulder and Elbow Surgeons score, Fudan University Shoulder Score, and Constant-Murley score) than those with healed tendons, whereas in the sedentary group, functional outcomes were generally similar across patients with and without retears. CONCLUSION: Shoulder activity after the early postoperative period was associated with a high risk of retears in patients who underwent rotator cuff repair. A correlation between inhibited function and structural failure was detected but only in active patients, while sedentary patients with retears retained functional improvements similar to those with intact tendons.

Radiographic Osteoarthritis Prevalence Over Ten Years After Anterior Cruciate Ligament Reconstruction.

The purpose of this study was to conduct an up-to-date systematic review and meta-analysis of radiographic knee osteoarthritis (OA) over minimal ten years after ACL reconstruction. The database of Pubmed and the Ovid was adopted. The radiographic knee OA over minimal ten years after ACL reconstruction was systematically reviewed. Both the ipsilateral and contralateral knees were evaluated referring to the tibiofemoral joint (TFJ), the patellofemoral joint (PFJ), and the overall knee OA prevalence. Nineteen studies were included for review, with nine screened for the meta-analysis. The overall knee OA rate ranged from 8.3-79.2%, meanly 51.6% on the ipsilateral side; ranged from 3.6-35.7%, meanly 15.5% on the contralateral side. Compared to the contralateral side, the RR of developing radiographic OA was 3.73 (P<0.01) for the overall knee, 2.88 (P<0.01) for TFJ, and 2.42 (P<0.01) for PFJ. Ipsilaterally, the RR of developing TFJ radiographic OA was 1.15 (P<0.01) compared to that of the PFJ. Over a minimum of 10 years after surgery, more than half the cases developed overall radiographic OA on the ipsilateral knee, which was nearly four times higher than the contralateral side. On the ipsilateral knee, the TFJ was most affected.

PFN2a Suppresses C2C12 Myogenic Development by Inhibiting Proliferation and Promoting Apoptosis via the p53 Pathway.

Skeletal muscle plays a crucial role in physical activity and in regulating body energy and protein balance. Myoblast proliferation, differentiation, and apoptosis are indispensable processes for myoblast myogenesis. Profilin 2a (PFN2a) is a ubiquitous actin monomer-binding protein and promotes lung cancer growth and metastasis through suppressing the nuclear localization of histone deacetylase 1 (HDAC1). However, how PFN2a regulates myoblast myogenic development is still not clear. We constructed a C2C12 mouse myoblast cell line overexpressing PFN2a. The CRISPR/Cas9 system was used to study the function of PFN2a in C2C12 myogenic development. We find that PFN2a suppresses proliferation and promotes apoptosis and consequentially downregulates C2C12 myogenic development. The suppression of PFN2a also decreases the amount of HDAC1 in the nucleus and increases the protein level of p53 during C2C12 myogenic development. Therefore, we propose that PFN2a suppresses C2C12 myogenic development via the p53 pathway. Si-p53 (siRNA-p53) reverses the PFN2a inhibitory effect on C2C12 proliferation and the PFN2a promotion effect on C2C12 apoptosis, and then attenuates the suppression of PFN2a on myogenic differentiation. Our results expand understanding of PFN2a regulatory mechanisms in myogenic development and suggest potential therapeutic targets for muscle atrophy-related diseases.

MiR-501-3p Forms a Feedback Loop with FOS, MDFI, and MyoD to Regulate C2C12 Myogenesis.

Skeletal muscle plays an essential role in maintaining body energy homeostasis and body flexibility. Loss of muscle mass leads to slower wound healing and recovery from illness, physical disability, poor quality of life, and higher health care costs. So, it is critical for us to understand the mechanism of skeletal muscle myogenic differentiation for maintaining optimal health throughout life. miR-501-3p is a novel muscle-specific miRNA, and its regulation mechanism on myoblast myogenic differentiation is still not clear. We demonstrated that FOS was a direct target gene of miR-501-3p, and MyoD regulated miR-501-3p host gene Clcn5 through bioinformatics prediction. Our previous laboratory experiment found that MDFI overexpression promoted C2C12 myogenic differentiation and MyoD expression. The database also showed there is an FOS binding site in the MDFI promoter region. Therefore, we hypothesize that miR-501-3p formed a feedback loop with FOS, MDFI, and MyoD to regulate myoblast differentiation. To validate our hypothesis, we demonstrated miR-501-3p function in the proliferation and differentiation period of C2C12 cells by transfecting cells with miR-501-3p mimic and inhibitor. Then, we confirmed there is a direct regulatory relationship between miR-501-3p and FOS, MyoD and miR-501-3p, FOS and MDFI through QPCR, dual-luciferase reporter system, and ChIP experiments. Our results not only expand our understanding of the muscle myogenic development mechanism in which miRNA and genes participate in controlling skeletal muscle development, but also provide treatment strategies for skeletal muscle or metabolic-related diseases in the future.

[Effects of electric pulses on liver cancer cells: apoptosis induction and decrease of mitochondrial transmembrane potential].

In order to investigate the effects of electric pulses on cancer cells, we carried out the experiments with exposing HepG2 and L02 to electric pulses (1 kV/cm, l00 micros, 1 Hz) for different lengths of time (8 s, 15 s, 30 s, 60 s). Annexin V-FITC Kit and Flow cytometry were used to study the apoptosis of treated cells. The results showed that the electric pulses of 1 kV/cm, l00 micros, 1 Hz for 8 s could not induce tumor cells apoptosis. Apoptosis was observed when tumor cells were stimulated for 15 s and longer, and the apoptosis percentage increased with the increase of stimulation time. Furthermore, tumor cells were more sensitive than normal cells in response to electrical pulses. Rhodamine 123 and Laser Scanning Confocal Microscope (LSCM) were used to make a real-time study of mitochondrial transmembrane potential (Deltapsim) when the tumor cells were exposed to electric pulses for 60 s. No significant change of Deltapsim was observed within 30 s stimulation. After that, the Deltapsim increased sharply and declined later, suggesting that the mitochondrial pathway may be one of the apoptosis mechanism induced by electric pulses.