Cigarette smoking inhibits myoblast regeneration by promoting proteasomal degradation of NPAT protein and hindering cell cycle progression.

Cigarette smoking (CS) causes skeletal muscle dysfunction, leading to sarcopenia and worse prognosis of patients with diverse systemic diseases. Here, we found that CS exposure prevented C2C12 myoblasts proliferation in a dose-dependent manner. Immunoblotting assays verified that CS exposure promoted the expression of cell cycle suppressor protein p21. Furthermore, CS exposure significantly inhibited replication-dependent (RD) histone transcription and caused S phase arrest in the cell cycle during C2C12 proliferation. Mechanistically, CS deregulated the expression levels of Nuclear Protein Ataxia-Telangiectasia Locus (NPAT/p220). Notably, the proteasome inhibitor MG132 was able to reverse the expression of NPAT in myoblasts, implying that the degradation of CS-mediated NPAT is proteasome-dependent. Overexpression of NPAT also rescued the defective proliferation phenotype induced by CS in C2C12 myoblasts. Taken together, we suggest that CS exposure induces NPAT degradation in C2C12 myoblasts and impairs myogenic proliferation through NPAT associated proteasomal-dependent mechanisms. As an application of the proteasome inhibitor MG132 or overexpression of NPAT could reverse the impaired proliferation of myoblasts induced by CS, the recovery of myoblast proliferation may be potential strategies to treat CS-related skeletal muscle dysfunction.

Anthocyanin improves kidney function in diabetic kidney disease by regulating amino acid metabolism.

BACKGROUND: Diabetic kidney disease (DKD) is among the most important causes for chronic kidney disease. Anthocyanins (ANT) are polyphenolic compounds present in various food and play an important role in ameliorating hyperglycemia and insulin sensitivity. However, the effects of ANT in DKD are still poorly understood. This study aimed to investigate the effect of ANT (cyanidin-3-O-glucoside [C3G]) on the renal function of DKD, and whether the anti-DKD effect of ANT is related to metabolic pathways. METHODS: To explore the role of ANT in DKD, we performed the examination of blood glucose, renal function, and histopathology. As for the mechanism, we designed the label-free quantification proteomics and nontargeted metabolomics analysis for kidney and serum. Subsequently, we revealed the anti-DKD effect of ANT through the bioinformatic analysis. RESULTS: We showed that the fasting blood glucose level (- 6.1 mmol/L, P = 0.037), perimeter of glomerular lesions (- 24.1 µm, P = 0.030), fibrosis score of glomerular (- 8.8%, P = 0.002), and kidney function (Cystatin C: - 701.4 pg/mL, P = 0.043; urine creatinine: - 701.4 mmol/L, P = 0.032) were significantly alleviated in DKD mice after ANT treatment compared to untreated in the 20th week. Further, proteins and metabolites in the kidneys of DKD mice were observed to be dramatically altered due to changes in amino acid metabolism with ANT treatment; mainly, taurine and hypotaurine metabolism pathway was upregulated (P = 0.0001, t value = 5.97). Furthermore, upregulated tryptophan metabolism (P < 0.0001, t value = 5.94) and tyrosine metabolism (P = 0.0037, t value = 2.91) pathways had effects on serum of DKD mice as responsed ANT regulating. CONCLUSIONS: Our results suggested that prevention of the progression of DKD by ANT could be related to the regulation of amino acid metabolism. The use of dietary ANT may be one of the dietary strategies to prevent and treat DKD.

Phase separation of insulin receptor substrate 1 drives the formation of insulin/IGF-1 signalosomes.

As a critical node for insulin/IGF signaling, insulin receptor substrate 1 (IRS-1) is essential for metabolic regulation. A long and unstructured C-terminal region of IRS-1 recruits downstream effectors for promoting insulin/IGF signals. However, the underlying molecular basis for this remains elusive. Here, we found that the C-terminus of IRS-1 undergoes liquid-liquid phase separation (LLPS). Both electrostatic and hydrophobic interactions were seen to drive IRS-1 LLPS. Self-association of IRS-1, which was mainly mediated by the 301-600 region, drives IRS-1 LLPS to form insulin/IGF-1 signalosomes. Moreover, tyrosine residues of YXXM motifs, which recruit downstream effectors, also contributed to IRS-1 self-association and LLPS. Impairment of IRS-1 LLPS attenuated its positive effects on insulin/IGF-1 signaling. The metabolic disease-associated G972R mutation impaired the self-association and LLPS of IRS-1. Our findings delineate a mechanism in which LLPS of IRS-1-mediated signalosomes serves as an organizing center for insulin/IGF-1 signaling and implicate the role of aberrant IRS-1 LLPS in metabolic diseases.

Benzo[a]pyrene inhibits myoblast differentiation through downregulating the Hsp70-MK2-p38MAPK complex.

Cigarette smoking causes skeletal muscle dysfunction and worse prognosis for patients with diverse systemic diseases. Benzo[a]pyrene (BaP), one major constituent that is inhaled during smoking, is particularly known for its ability to impair neurodevelopment, impede reproductivity, or reduce birth weight. Here, we found that BaP exposure led to the inhibition of C2C12 myoblasts differentiation in a dose-dependent manner and reduced the expression of both early and late myogenic differentiation markers. BaP exposure significantly decreased the expression of p38 mitogen-activated protein kinase (p38MAPK), but not AKT, which are both critical during myogenic differentiation. Mechanistically, BaP downregulated the expression levels of MAPK-activated protein kinase 2 (MK2) and heat shock protein 70 (Hsp70), both of which stabilize p38MAPK. Interestingly, treatment of proteasome inhibitor MG132 was able to reverse BaP-induced degradation of Hsp70/ MK2 and p38MAPK in myoblasts, implying BaP-mediated p38MAPK degradation is proteasome-dependent. Overexpression of p38MAPK also rescued the defective differentiation phenotype of C2C12 induced by BaP. Taken together, we suggest that BaP exposure induces MK2/Hsp70/p38MAPK complex degradation in C2C12 myoblasts and impairs myogenic differentiation by proteasomal-dependent mechanisms. As application of the proteasome inhibitor MG132 or overexpression of p38MAPK could reverse impaired differentiation of myoblasts induced by BaP, this may suggest potential related strategies for preventing tobacco-related skeletal muscle diseases or for respiratory rehabilitation.

Brominated flame retardant TBPH induced oxidative damage and reduced the expression of memory-related proteins in mice, with no discernable impairment of learning and memory.

Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate (TBPH) is one of the new brominated flame retardants with adverse neurobehavioral potential. These flame retardants are often added to household furnishings where children would come into contact with them. This study explores whether oral exposure to TBPH for 28 days would impair neurobehavioral function in mice and the role of curcumin (CUR) in this process. CUR is a natural antioxidant and is thought to be of use in the treatment of neurological toxicity due to its neuroprotective effects. Learning and memory of mice exposed to TBPH was investigated using the Morris water maze. Levels of malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione (GSH) were determined to assess oxidative damage. Western blot was used to detect the expression of glucose-regulated protein 78-kDa (GRP78), PKR-like ER kinase (PERK), and C/EBP homologous protein (CHOP) in the hippocampus. End-point effects were evaluated through observing post-synaptic density protein-95 (PSD-95), brain-derived neurotrophic factor (BDNF), and phosphorylated cAMP response element binding protein (p-CREB). Although TBPH exposure alone does not impair learning and memory, oxidative stress markers and endoplasmic reticulum stress-associated proteins were adversely affected in exposed mice. TBPH could significantly decrease the levels of BDNF, p-CREB, and PSD-95 in the hippocampus, and these TBPH-induced neurotoxic effects were attenuated by CUR. These findings provide further understanding of the neurotoxic effects of TBPH and the protective effect of CUR on TBPH exposure.

Toripalimab plus chemotherapy as second-line treatment in previously EGFR-TKI treated patients with EGFR-mutant-advanced NSCLC: a multicenter phase-II trial.

This multicenter phase-II trial aimed to investigate the efficacy, safety, and predictive biomarkers of toripalimab plus chemotherapy as second-line treatment in patients with EGFR-mutant-advanced NSCLC. Patients who failed from first-line EGFR-TKIs and did not harbor T790M mutation were enrolled. Toripalimab plus carboplatin and pemetrexed were administrated every three weeks for up to six cycles, followed by the maintenance of toripalimab and pemetrexed. The primary endpoint was objective-response rate (ORR). Integrated biomarker analysis of PD-L1 expression, tumor mutational burden (TMB), CD8 + tumor-infiltrating lymphocyte (TIL) density, whole-exome, and transcriptome sequencing on tumor biopsies were also conducted. Forty patients were enrolled with an overall ORR of 50.0% and disease-control rate (DCR) of 87.5%. The median progression free survival (PFS) and overall survival were 7.0 and 23.5 months, respectively. The most common treatment-related adverse effects were leukopenia, neutropenia, anemia, ALT/AST elevation, and nausea. Biomarker analysis showed that none of PD-L1 expression, TMB level, and CD8 + TIL density could serve as a predictive biomarker. Integrated analysis of whole-exome and transcriptome sequencing data revealed that patients with DSPP mutation had a decreased M2 macrophage infiltration and associated with longer PFS than those of wild type. Toripalimab plus chemotherapy showed a promising anti-tumor activity with acceptable safety profiles as the second-line setting in patients with EGFR-mutant NSCLC. DSPP mutation might serve as a potential biomarker for this combination. A phase-III trial to compare toripalimab versus placebo in combination with chemotherapy in this setting is ongoing (NCT03924050).

Culture-Related Health Disparities in Quality of Life: Assessment of Instrument Dimensions Among Chinese.

Background: Health-related quality of life (HRQoL) is one of the major focuses of primary care. However, HRQoL instruments used in China are mainly developed from Western countries. Such instruments may not cover all important health concepts valued by the Chinese as health is a culture-specific concept. Objectives: The objectives of this study are to identify culture-specific health dimensions and culture-related health disparities in primary care that are considered important by Chinese living in China. Methods: A purposive sample of 164 adult Chinese (67 healthy persons and 97 patients) were interviewed face to face. In-depth open-ended questions were asked to elicit culture-specific dimensions of quality of life in primary care settings in China. Results: Twelve health dimensions were identified. Five most frequently mentioned dimensions were: mood (N = 52, 31.71%), physical activities (N = 48, 29.27%), work (N = 40, 24.39%), diet (N = 32, 19.51%), and vitality (N = 28, 17.07%). Significantly more healthy persons reported mood (49.25 vs. 19.59%, P < 0.001), mindset (16.42 vs. 0.00%, P < 0.001), and self-care (11.94 vs. 2.06%, P = 0.016) characterizing good HRQoL, while more patients emphasized on work (4.48 vs. 38.14%, P < 0.001). Diet and vitality appeared to be culture-specific dimensions related to health among Chinese. Conclusions: To better adapt or develop HRQoL instruments for Chinese, dimensions or items regarding diet might be included and disparities in the meaning of vitality between Chinese and Western cultures should be considered.

Blood tumor mutation burden can predict the clinical response to immune checkpoint inhibitors in advanced non-small cell lung cancer patients.

BACKGROUND: Tissue tumor mutation burden (tTMB) assessed by whole-exome sequencing (WES), which has been regarded as the gold standard method of tTMB measurement, can predict the clinical benefits of immune checkpoint inhibitors (ICIs). Multiple studies have investigated the feasibility of utilizing large panels to evaluate TMB but have obtained conflicting results. Furthermore, whether blood TMB (bTMB) can also be a predictive biomarker in NSCLC has not been determined. METHODS: Fifty-six advanced NSCLC patients treated with ICIs were enrolled, including an exploratory cohort (n = 42) and a small independent validation cohort (n = 14). Next-generation sequencing was performed on tumor and plasma samples collected prior to ICI treatment using a panel consisting of 520 cancer-related genes (OncoScreen) to evaluate tTMB/bTMB. WES was also performed on tumor samples to serve as references. RESULTS: A positive correlation between tTMB derived from WES and OncoScreen was observed. OncoScreen-derived tTMB showed a positive correlation with OncoScreen-derived bTMB. Patients with OncoScreen-derived tTMB [Formula: see text] 7 mutations/Mb (p = 0.003) or bTMB [Formula: see text] 11 mutations/Mb (p = 0.0029) had superior progression-free survival (PFS). In the small validation cohort, patients with OncoScreen-derived bTMB [Formula: see text] 11 mutations/Mb exhibited longer PFS (p = 0.192) with a nonsignificant difference. In all 42 patients who had available bTMB and PFS, patients with bTMB [Formula: see text] 11 mutations/Mb had significantly longer PFS (p = 0.011) than those with bTMB [Formula: see text] 11 mutations/Mb. CONCLUSION: Our study confirmed the feasibility of using large panels to estimate TMB. We also demonstrated that bTMB can serve as a potential biomarker for predicting the efficacy of ICIs in NSCLC.

Gastrodin Regulates the Notch Signaling Pathway and Sirt3 in Activated Microglia in Cerebral Hypoxic-Ischemia Neonatal Rats and in Activated BV-2 Microglia.

In response to hypoxic-ischemic brain damage (HIBD), microglia activation and its mediated inflammation contribute to neuronal damage. Inhibition of over-activated microglia is deemed to be a potential therapeutic strategy. Our previous studies showed that gastrodin efficiently depressed the neuroinflammation mediated by activated microglia in HIBD neonatal rats. The underlying mechanisms through which gastrodin acts on activated microglia have not been fully elucidated. This study is designed to determine whether gastrodin would regulate the Notch signaling pathway and Sirtuin3 (Sirt3), which are implicated in regulating microglia activation. The present results showed that gastrodin markedly suppressed the expression of members of Notch signaling pathway (Notch-1, NICD, RBP-JK and Hes-1) in activated microglia both in vivo and in vitro. Conversely, Sirt3 expression was enhanced. In BV-2 microglia treated with a γ-secretase inhibitor of Notch pathway- DAPT, the expression of RBP-JK, Hes-1, and NICD was suppressed in activated microglia. Treatment with DAPT and gastrodin further decreased NICD and Hes-1 expression. Sirt3 expression was also decreased after DAPT treatment. However, Sirt3 expression in activated BV-2 microglia given a combined DAPT and gastrodin treatment was not further increased. In addition, combination of DAPT and Gastrodin cumulatively decreased tumor necrosis factor-α (TNF-α) expression. The results suggest that gastrodin regulates microglia activation via the Notch signaling pathway and Sirt3. More importantly, interference of the Notch signaling pathway inhibited Sirt3 expression, indicating that Sirt3 is a downstream gene of the Notch signaling pathway. It is suggested that Notch and Sirt3 synergistically regulate microglia activation such as in TNF-α production.

[Biomechanical study on the treatment of intertrochanteric fracture of A3.3 type with medial sustainable nail and proximal femoral anti-rotation nail].

OBJECTIVE: A3 intertrochanteric fracture is an extremely unstable fracture, which is often treated with intramedullary nail, but the implant failure is common due to the posterior medial fragment cannot be reconstructed. A new medial sustainable nail (MSN-Ⅱ) which can reconstruct the femoral medial support by sustainable screw was introduced in this study. The mechanical effect was verified by biomechanical experiment. METHODS: The loss medial support model of intertrochanteric fracture (A3) was made by artificial Sawbones model, fixed with MSN-Ⅱ and PFNA-Ⅱ, underwent axial loading and axial failure tests. The axial stiffness, yield load, displacement of head-neck fragment and torsional angle of fracture site of these nails were recorded and compared for biomechanical differences. The effect of early reconstruction of medial support with MSN-Ⅱ was determined. RESULTS: The axial stiffness, yield load, the displacement of head and neck fragment when the axial load was 1 800 N and torsional angle of the fracture site after the axial failure test of MSN-Ⅱ were (222.76 ±62.46) N /mm, (4 241.71 ±847.42) N, (11.51 ±0.62) mm, (1.71 ±0.10)° respectively, while the PFNA -Ⅱ was (184.58±40.59) N /mm, (3 058.76±379.63) N, (16.15±1.36) mm, (2.52±0.26)°respectively. The difference between the two groups was statistically significant. CONCLUSION: The axial stiffness of MSN-Ⅱ is better than that of PFNA-Ⅱ. The MSN-Ⅱ can bear more loads when fixed A3.3 intertrochanteric fracture and has greater axial and rotational stability. It is an effective means to reconstruct the medial support of A3 intertrochanteric fracture.

SARS-CoV-2: characteristics and current advances in research.

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 infection has spread rapidly across the world and become an international public health emergency. Both SARS-CoV-2 and SARS-CoV belong to subfamily Coronavirinae in the family Coronaviridae of the order Nidovirales and they are classified as the SARS-like species while belong to different cluster. Besides, viral structure, epidemiology characteristics and pathological characteristics are also different. We present a comprehensive survey of the latest coronavirus-SARS-CoV-2-from investigating its origin and evolution alongside SARS-CoV. Meanwhile, pathogenesis, cardiovascular disease in COVID-19 patients, myocardial injury and venous thromboembolism induced by SARS-CoV-2 as well as the treatment methods are summarized in this review.

Triptolide induces atrophy of myotubes by triggering IRS-1 degradation and activating the FoxO3 pathway.

Triptolide is an active ingredient isolated from an ancient Chinese herb (Tripterygium wilfordii Hook. f) for inflammatory and immune disorders. It has been shown to inhibit the proliferation of skeletal muscle; however, mechanisms of this effect remain unclear. We used mouse C2C12 myotubes as an in vitro model to investigate the effects of triptolide on skeletal muscle. Triptolide markedly inhibited the expression of myosin heavy chain and upregulated the expression of muscle atrophy-related proteins, leading to atrophy of the myotubes. Triptolide dose-dependently decreased the phosphorylation of Forkhead box O3 (FoxO3) and activated FoxO3 transcription activity, which regulates the expression of muscle atrophy-related proteins. Furthermore, triptolide inhibited the phosphorylation of Akt on the site of S473 and T308, and decreased the phosphorylation of insulin receptor substrate-1 (IRS-1) on the site of S302. In addition, triptolide reduced the protein level, but not mRNA level of IRS-1, whereas other upstream regulators of the Akt signaling pathway were not affected. Finally, a time-course experiment showed that the triptolide-induced degradation of IRS-1 in myotubes occurred 12 h prior to both inhibition of Akt activity and the activation of FoxO3. These data indicate that triptolide triggers IRS-1 degradation to promote FoxO3 activation, which subsequently led to atrophy of myotubes, providing us a potential target to prevent triptolide-induced skeletal muscle atrophy.

Hsp90ß interacts with MDM2 to suppress p53-dependent senescence during skeletal muscle regeneration.

Cellular senescence plays both beneficial and detrimental roles in embryonic development and tissue regeneration, while the underlying mechanism remains elusive. Recent studies disclosed the emerging roles of heat-shock proteins in regulating muscle regeneration and homeostasis. Here, we found that Hsp90ß, but not Hsp90α isoform, was significantly upregulated during muscle regeneration. RNA-seq analysis disclosed a transcriptional elevation of p21 in Hsp90ß-depleted myoblasts, which is due to the upregulation of p53. Moreover, knockdown of Hsp90ß in myoblasts resulted in p53-dependent cellular senescence. In contrast to the notion that Hsp90 interacts with and protects mutant p53 in cancer, Hsp90ß preferentially bound to wild-type p53 and modulated its degradation via a proteasome-dependent manner. Moreover, Hsp90ß interacted with MDM2, the chief E3 ligase of p53, to regulate the stability of p53. In line with these in vitro studies, the expression level of p53-p21 axis was negatively correlated with Hsp90ß in aged mice muscle. Consistently, administration of 17-AAG, a Hsp90 inhibitor under clinical trial, impaired muscle regeneration by enhancing injury-induced senescence in vivo. Taken together, our finding revealed a previously unappreciated role of Hsp90ß in regulating p53 stability to suppress senescence both in vitro and in vivo.

[Surveillance of Anopheles populations in different periods in Suizhou City].

OBJECTIVE: To evaluate the effect of malaria vector control measures so as to provide the evidence for consolidating the control effectiveness of malaria and carrying out the vector surveillance in Suizhou City. METHODS: The distributions of Anopheles sinensis and An. anthropophagus were investigated by the combination of retrospective review and field survey. The changes of density and population of mosquito vectors were investigated and compared among various years. RESULTS: From 1985 to 1996, both An. sinensis and An. anthropophagus were found in 18 towns, and An. anthropophagus mosquitoes accounted for 52.3% of the total Anopheles mosquitoes. Only An. sinensis mosquitoes were found in other 26 towns. In 2003 and 2004, An. anthropophagus mosquitoes were found in the original 18 towns, and they accounted for 47.0% and 38.1% respectively, but in 2005, An. anthropophagus mosquitoes were not found in this city. However, the density of An. sinensis presented an upward trend. CONCLUSIONS: An. anthropophagus population has gradually disappeared in Suizhou City, and currently, An. sinensis is the main Anopheles population, which might be the malaria vector in suitable conditions. Therefore, the surveillance and control of Anophe les vector should be strengthened in order to consolidate the achievements of malaria elimination.

Template-ready PCR method for detection of human telomerase reverse transcriptase mRNA in sputum.

Human telomerase reverse transcriptase (hTERT) mRNA in tissue is a biomarker of lung cancer, but hTERT mRNA in sputum had not been successfully detected with conventional reverse transcription PCR methods. Here, we developed a novel PCR protocol: Template-Ready PCR (TRPCR), to detect sputum hTERT mRNA, in which probes serve as templates of amplification. While free probes and dsDNA were removed in template preparation through aspiration and restriction digestion, probes that formed into heterocomplex with target RNA remained intact for PCR amplification. By fishing out the heterocomplex and amplifying the probes, TRPCR achieved sensitivity higher than reverse transcription-quantitative PCR (RT-qPCR). ROC curve of sputum hTERT mRNA by TRPCR assay showed the discrimination in high sensitivity and specificity between patients with lung cancer and lung cancer-free donors at the PCR Ct cutoff of 33. We further validated this approach through TRPCR assay of sputum from 858 lung cancer patients and 480 non-malignant pulmonary disease patients. 722 (84.2%) cases from 858 with lung cancer patients were detected as positive, whereas 461 (96.0%) cases from 480 non-malignant pulmonary disease patients were detected as negative, suggesting that TRPCR assay of sputum hTERT mRNA can serve as a non-invasive molecular diagnosis of lung cancer.

A preclinical method for evaluating the kinematics of knee prostheses.

The primary intent of anatomical knee implants is to replicate the motions of a normal knee joint. In developing such designs, a preclinical evaluation of kinematic behavior is needed. This study introduces an in vitro testing method for recording movements of the knee joint. A novel testing jig was developed and incorporated into a knee simulator setup alongside a motion capture system to directly track the medial and lateral movements of a knee prosthesis. The test system developed in this study required a number of factors to be validated; (i) gait inputs to the knee simulator (result: 0.37-1.575% error), (ii) validity of global coordinate system in the motion capture system, (iii) the position of flexion facet centers (FFCs) detected by the motion capture system (result: a maximum error of 0.08 mm in AP direction and 0.3 mm in SI direction), (iv) local coordinate system in the motion capture system (result: 1.09% error for the measurement of flexion angle), (v) that FFC results were in good agreement with inputs. In conclusion, the system developed in this study for recording FFC is a direct and reliable in vitro test method for analyzing the kinematics of a knee prosthesis.

Honokiol induces apoptosis of lung squamous cell carcinoma by targeting FGF2-FGFR1 autocrine loop.

Lung squamous cell carcinoma (SCC) accounts for a considerable proportion of lung cancer cases, but there is still a lack of effective therapies. FGFR1 amplification is generally considered a promising therapeutic target. Honokiol is a chemical compound that has been proven to be effective against various malignancies and whose analog has been reported to target the mitogen-activated protein kinase family, members of a downstream signaling pathway of FGFR1. This was an explorative study to determine the mechanism of honokiol in lung SCC. We found that honokiol induced apoptosis and cell cycle arrest in lung SCC cell lines in a time- and dose-dependent manner. Honokiol also restricted cell migration in lung SCC cell lines. Moreover, the expression of FGF2 and the activation of FGFR1 were both downregulated by honokiol. Pharmacological inhibition and siRNA knockdown of FGFR1 induced apoptosis in lung SCC cells. Our in vivo study indicated that honokiol could suppress the growth of xenograft tumors, and this effect was associated with the inhibition of the FGF2-FGFR1 signaling pathway. In conclusion, honokiol induced cell apoptosis in lung SCC by targeting the FGF2-FGFR1 autocrine loop.

Hsp70 Interacts with Mitogen-Activated Protein Kinase (MAPK)-Activated Protein Kinase 2 To Regulate p38MAPK Stability and Myoblast Differentiation during Skeletal Muscle Regeneration.

The regenerative process of injured muscle is dependent on the fusion and differentiation of myoblasts derived from muscle stem cells. Hsp70 is important for maintaining skeletal muscle homeostasis and regeneration, but the precise cellular mechanism remains elusive. In this study, we found that Hsp70 was upregulated during myoblast differentiation. Depletion or inhibition of Hsp70/Hsc70 impaired myoblast differentiation. Importantly, overexpression of p38 mitogen-activated protein kinase α (p38MAPKα) but not AKT1 rescued the impairment of myogenic differentiation in Hsp70- or Hsc70-depleted myoblasts. Moreover, Hsp70 interacted with MK2, a substrate of p38MAPK, to regulate the stability of p38MAPK. Knockdown of Hsp70 also led to downregulation of both MK2 and p38MAPK in intact muscles and during cardiotoxin-induced muscle regeneration. Hsp70 bound MK2 to regulate MK2-p38MAPK interaction in myoblasts. We subsequently identified the essential regions required for Hsp70-MK2 interaction. Functional analyses showed that MK2 is essential for both myoblast differentiation and skeletal muscle regeneration. Taken together, our findings reveal a novel role of Hsp70 in regulating myoblast differentiation by interacting with MK2 to stabilize p38MAPK.

Activation of G protein coupled estrogen receptor (GPER) promotes the migration of renal cell carcinoma via the PI3K/AKT/MMP-9 signals.

Renal cell carcinoma (RCC) is the third most frequent malignancy within urological oncology. However, the mechanisms responsible for RCC metastasis are still needed further illustration. Our present study revealed that a seven-transmembrane receptor G-protein coupled estrogen receptor (GPER) was highly detected in various RCC cell lines such as ACHN, OS-RC-2 and SW839. The activation of GPER by its specific agonist G-1 significantly promoted the in vitro migration and invasion of ACHN and OS-RC-2 cells. G-1 also up regulated the expression of matrix metalloproteinase-2 (MMP-2) and MMP-9. The inhibitor of MMP-9 (Cat-444278), but not MMP-2 (Sc-204092), abolished G-1 induced cell migration, which suggested that MMP-9 is the key molecule mediating G-1 induced RCC progression. Further, G-1 treatment resulted in phosphorylation of AKT and ERK in RCC cells. PI3K/AKT inhibitor (LY294002), while not ERK inhibitor (PD98059), significantly abolished G-1 induced up regulation of MMP-9 in both AHCN and OS-RC-2 cells. Generally, our data revealed that activation of GPER by its specific agonist G-1 promoted the metastasis of RCC cells through PI3K/AKT/MMP-9 signals, which might be a promising new target for drug discovery of RCC patients.