Atrophy In Mice Research Articles

Abstract 16995: Inhibition of lncRNA MAAT Contributes to Multiple Types of Muscle Atrophy

Background: Skeletal muscle atrophy is the consequence of many diseases, such as denervation, long-term inactivity, excessive fasting, ageing, and heart failure. Recently, increasing studies have shown that long noncoding RNAs (lncRNAs) play an important role in myogenesis and adult skeletal muscle regeneration. However, if lncRNAs are responsible for muscle atrophy remains largely unclear. Hypothesis: We aimed to select and investigate the role of lncRNAs in muscle atrophy. Methods and Results: LncRNA arrays indicated that several lncRNA transcripts were changed during denervation-induced muscle atrophy in mice. After detecting the expression of lncRNAs in multiple types of muscle atrophy in vivo (denervation, Angiotensin II and fasting induced muscle atrophy) and in vitro (Angiotensin II, H 2 O 2 and TNFα induced muscle atrophy) by qRT-PCRs, we identified that MAAT (Muscle Atrophy-Associated Transcript) was down-regulated in multiple types of muscle atrophy. Then lentivirus of shRNA and overexpression of MAAT were further used to study the role of MAAT in muscle atrophy in vitro and in vivo . We found that knockdown of MAAT promoted muscle atrophy, whereas upregulating MAAT prevented multiple types of muscle atrophy. Mechanistically, we found that MAAT negatively regulated the transcription of microRNA-29b through SOX6, and that MAAT influenced the expression of neighbor gene-MBNL by a cis-regulatory module. Conclusions: Inhibition of LncRNA MAAT contributes to muscle atrophy by increasing miR-29b and repressing MBNL. Overexpressing MAAT might be a novel approach to counteract muscle atrophy.

Systemic bone loss, impaired osteogenic activity and type I muscle fiber atrophy in mice with elastase-induced pulmonary emphysema: Establishment of a COPD-related osteoporosis mouse model.

Although it is suggested that chronic obstructive pulmonary disease (COPD) and bone are related, almost all of the pathological mechanisms of COPD-related osteoporosis remain unknown. There is a mouse model showing a deterioration of bone quality after cigarette smoke exposure; however, in smoking exposure models, various factors exist that affect bone metabolism, such as smoking and body weight loss (muscle and fat mass loss). We considered it appropriate to use an elastase-induced emphysema model to exclude factors influencing bone metabolism and to investigate the influence of pulmonary emphysema on bone metabolism. The purpose of this study was to establish a COPD/emphysema-related osteoporosis mouse model by using the elastase-induced emphysema model. The lumbar vertebrae and femurs/tibiae exhibited trabecular bone loss and impaired osteogenic activity in 24-week-old male elastase-induced emphysema model mice. In addition, the model mice showed atrophy of type I muscle fibers without atrophy of type II muscle fibers. We believe that the mice described in this experimental protocol will be accepted as a COPD/emphysema-related osteoporosis mouse model and contribute to further investigations.

Dexamethasone exacerbates cisplatin-induced muscle atrophy.

Dexamethasone for antiemetic therapy is typically administered with anticancer drugs such as cisplatin. We previously reported that cisplatin upregulates the muscle-specific E3 ubiquitin ligase genes, namely muscle ring-finger protein 1 (MuRF1) and atrophy gene-1 (atrogin-1), and promotes muscle atrophy in mice. It is well known that dexamethasone causes upregulation of MuRF1 and Atrogin-1 expression in skeletal muscles. Although it is speculated that a combination of dexamethasone and cisplatin worsens muscle atrophy, there are no reports based on research. We thereby investigated the effects of cisplatin and dexamethasone, alone or in combination, on the expression of MuRF1 and Atrogin-1 in murine skeletal muscles and C2C12 myotubes. Mice were intraperitoneally injected with cisplatin or the vehicle control once daily for 4days. Dexamethasone or the vehicle control was subcutaneously administered 30minutes prior to the administration of cisplatin. Dexamethasone enhanced MuRF1 and Atrogin-1 gene expression upregulated by cisplatin in murine quadriceps muscles and C2C12 myotubes. Cisplatin-caused upregulation of myostatin and downregulation of IGF-1 gene expression were also enhanced by co-administration of dexamethasone in murine quadriceps muscles and C2C12 myotubes. This study shows that the combination treatment of cisplatin and dexamethasone exacerbated muscle atrophy in mice. Therefore, this treatment regimen might exacerbate muscle atrophy in cancer patients.

Exogenous Delta-Like 1 Homolog (DLK1)-Fc Treatment Attenuates Muscle Atrophy in Both Dexamethasone and High-Fat Diet–Induced Obesity Mice Models

Skeletal muscle degeneration is accelerated in elderly patients with diabetes and the imbalance between muscle growth and wasting can lead to metabolic dysfunction. DLK1 is a member of the EGF-like family and essential for skeletal muscle development and regeneration. To identify whether exogenous DLK1 treatment can prevent muscle wasting, we assessed muscle mass as well as muscle differentiation and atrophy markers in two different models: dexamethasone and high fat diet (HFD)-induced obesity mice models (n=7-8 per each group). In the dexamethasone model, mice were divided into (1) control, (2) dexamethasone treatment (1mg/Kg, 2 weeks), and (3) DLK1 (0.8mg/Kg, 2 weeks) and dexamethasone treatment groups. In the HFD model, mice were divided into (1) control, (2) HFD (60% calories from fat, 8 weeks), and (3) HFD with DLK1 treatment (0.8mg/Kg, 8 weeks) groups. The expressions of genes related to muscle differentiation and atrophy were determined using RT-PCR. We observed that dexamethasone reduced muscle mass and markedly increased atrophy makers including atrogin-1 and murf-1. DLK1 treatment attenuated these degenerative changes. Furthermore, the level of myostatin, which inhibits muscle cell growth, was reduced in DLK1 treatment group compared to dexamethasone group. Additionally, compared to HFD group, DLK1 inhibited muscle atrophy by increasing the differentiation marker: myoD, and decreasing the atrophy markers: mysotatin, atrogin-1, and murf-1. Taken together, these results suggest that DLK1 attenuates both dexamethasone and HFD-induced muscle atrophy in mice by suppressing the downstream signaling of myostatin/atrogin-1/murf-1 pathway. The increased expression of myoD indicates that DLK1 treatment can also improve the quality of muscle formation. Our study implies that DLK1 could be a promising candidate in the treatment of aging or diabetes-related sarcopenia, characterized by muscle atrophy and dysfunction. Disclosure J. Lee: None. M. Lee: None. H. Jung: None. J. Lee: None. Y. Cho: None. J. Bae: None. Y. Lee: None. B. Lee: None. E. Kang: None. B. Cha: None.

AMP-activated kinase (AMPK) promotes innate immunity and antiviral defense against Zika virus induced ocular infection

Abstract Purpose We recently reported that Zika Virus infected multiple retinal cell types and caused chorioretinal atrophy in mouse eyes. In this study, we investigated the potential role of AMPK, a master regulator of cellular metabolism, in pathogenesis of ocular ZIKV infection. Methods Primary human RPE cells were infected with ZIKV for various time points and AMPK phosphorylation was detected Western blotting (WB). AMPK activity was modulated by pharmacological activators (AICAR and Metformin) and inhibitors (Compound C) of AMPK. ZIKV replication was assessed by immunofluorscence staining for 4G2 and western blot detection of NS3 proteins. For in vivo studies B6 mice eye were challenged with ZIKV with or without AICAR treatment and disease progression were measured by fundus imaging. Activation of innate immune and antiviral response genes was assessed by qPCR. Results ZIKV challenge upregulated the AMPK phosphorylation in Pr. RPE cells in a time-dependent fashion. Our results indicate that AMPK deficient mouse embryonic fibroblast (MEF) cells were more permissive to ZIKV replication as compared to WT MEFs. AMPK activation using AICAR and Metformin restricted ZIKV replication in Pr. RPE cells and presence of Compound C reversed the effect of AICAR/Metformin. In vivo AICAR treatment ameliorated ZIKV-induced chorioretinal atrophy in mice with increased antiviral responses. ZIKV infection leads to activation of MEK pathways and an MEK pathways inhibitor, U0126, attenuated ZIKV replication. Conclusion Collectively, these findings indicate the AMPK activation evokes antiviral innate responses and restricts ZIKV replication. Hence, targeting AMPK signaling can be explored to develop anti-viral therapy against ZIKV infection.

High‐fat diet augments muscle atrophy by changes of muscle atrophy‐related genes in mice

IntroductionRecently, it has been reported that obesity accelerates muscle atrophy and protein degradation induced by 14‐days denervation in mice. Muscle atrophy primarily results from accelerated protein degradation and is associated with increased expression of two muscle‐specific ubiquitin ligases: MuRF1 and atrogin‐1. PGC1α is the master transcription regulator that stimulates mitochondrial biogenesis, and expression level of PGC1α was reduced in obesity and muscle atrophy. However, the expression level of these genes in response to muscle atrophy on obesity is still unclear. The purpose of this study was to investigate the expression level of MuRF1, atrogin‐1 and PGC1α during muscle atrophy in mice fed a high‐fat diet.MethodsThis study was approved by the Juntendo University Animal Care Committee (H28‐14). Fifty‐two male C57BL/6J mice (6 weeks old) were randomly divided into two groups: 1) normal diet (ND, n=26), 2) high‐fat diet (HFD, n=26). HFD were fed a high‐fat diet (60% calories from fat) for 16 weeks, while ND received a chow diet (10% calories from fat). Following 16 weeks of each experimental diet intake, all mice were lightly anaesthetized with the inhalant isoflurane and one hindlimb was immobilized in the plantar flexion position with casting tape. After immobilization for 1, 3, and 7 days, the soleus and plantaris muscles were removed. Statistical significance was analyzed by using two‐way (diet and time) analysis of variance (ANOVA). Statistical significant level was set at P < 0.05.ResultsBody weight and epididymal fat pad mass were significantly higher in the HFD group compared with the ND group. In the 7 days, the HFD significantly augmented loss of mass rate as compared with ND. The expression level of MuRF1 mRNA 3d in soleus and plantaris muscles was significantly higher in the HFD group compared with the ND group. The expression level of atrogin‐1 mRNA was significantly increased in response to immobilization, but no changes in ND and HFD. The expression level of PGC1α mRNA was significantly reduced in response to immobilization and was lower in HFD compared with ND in soleus and plantaris muscle.ConclusionHFD augments muscle atrophy by immobilization, at least in part by increasing the expression level of MuRF1 mRNA.Support or Funding InformationThis study was supported in part by Japan Society for the Promotion of Science KAKENHI Grant (16H07182), President's Grant for Interfaculty Collaboration, Juntendo University (Goto A: K1613, K1708) and MEXT‐Supported Program for the Strategic Research Foundation at Private Universities.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

A novel mechanism of tumor-induced thymic atrophy in mice bearing H22 hepatocellular carcinoma

BackgroundThymic atrophy was discovered in tumor-bearing mice in recent years.MethodsFlow cytometry was carried out including Annexin V-FITC/PI double staining, PI staining, Terminal dUTP nick-end labeling, CD3-FITC/CD19-PE and CD8-FITC/CD4-PE double staining. Enzyme-linked immunosorbent assay and polymerase chain reaction were also investigated.ResultsAccording to our experiments, we demonstrated that no signs of apoptosis in thymocytes were found in H22-bearing mice, while the proportions of CD4+ T cells and CD8+ T cells in thymuses were remarkably increased, the opposite tendency was found in peripheral bloods, and only CD3+CD8+ T cells were discovered in H22 solid tumors. We further discovered that the level of thymosin alpha 1 (Tα1) and the expression of Wnt4 in thymus of H22-bearing mice were significantly improved than control, which indicated the active proliferation and differentiation of thymocytes. Our study revealed that CD8+ T cells could not effectively eliminate H22 cells independently when CD4+ T cells were suppressed by tumors, while the body would only enhance the differentiation and maturation of T cells in thymuses and release them to solid tumor to reinforce antitumor immunocompetence, leading to a vicious cycle which finally led to thymic atrophy.ConclusionOur data propose a novel mechanism of tumor-induced thymic atrophy regulated by abnormal immunoreaction and may provide new ideas for the immunotherapy of tumors.

Cell-Specific Deletion of PGC-1α from Medium Spiny Neurons Causes Transcriptional Alterations and Age-Related Motor Impairment.

Multiple lines of evidence indicate that a reduction in the expression and function of the transcriptional coactivator peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) is associated with neurodegeneration in diseases such as Huntington's disease (HD). Polymorphisms in the PGC-1α gene modify HD progression and PGC-1α expression is reduced in striatal medium spiny neurons (MSNs) of HD patients and mouse models. However, neither the MSN-specific function of PGC-1α nor the contribution of PGC-1α deficiency to motor dysfunction is known. We identified novel, PGC-1α-dependent transcripts involved in RNA processing, signal transduction, and neuronal morphology and confirmed reductions in these transcripts in male and female mice lacking PGC-1α specifically in MSNs, indicating a cell-autonomous effect in this population. MSN-specific PGC-1α deletion caused reductions in previously identified neuronal and metabolic PGC-1α-dependent genes without causing striatal vacuolizations. Interestingly, these mice exhibited a hypoactivity with age, similar to several HD animal models. However, these newly identified PGC-1α-dependent genes were upregulated with disease severity and age in knock-in HD mouse models independent of changes in PGC-1α transcript, contrary to what would be predicted from a loss-of-function etiological mechanism. These data indicate that PGC-1α is necessary for MSN transcriptional homeostasis and function with age and that, whereas PGC-1α loss in MSNs does not replicate an HD-like phenocopy, its downstream genes are altered in a repeat-length and age-dependent fashion. Understanding the additive effects of PGC-1α gene functional variation and mutant huntingtin on transcription in this cell type may provide insight into the selective vulnerability of MSNs in HD.SIGNIFICANCE STATEMENT Reductions in peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α)-mediated transcription have been implicated in the pathogenesis of Huntington's disease (HD). We show that, although PGC-1α-dependent transcription is necessary to maintain medium spiny neuron (MSN) function with age, its loss is insufficient to cause striatal atrophy in mice. We also highlight a set of genes that can serve as proxies for PGC-1α functional activity in the striatum for target engagement studies. Furthermore, we demonstrate that PGC-1α-dependent genes are upregulated in a dose- and age-dependent fashion in HD mouse models, contrary to what would be predicted from a loss-of-function etiological mechanism. However, given this role for PGC-1α in MSN transcriptional homeostasis, it is important to consider how genetic variation in PGC-1α could contribute to mutant-huntingtin-induced cell death and disease progression.

Allopurinol partially prevents disuse muscle atrophy in mice and humans

Disuse muscle wasting will likely affect everyone in his or her lifetime in response to pathologies such as joint immobilization, inactivity or bed rest. There are no good therapies to treat it. We previously found that allopurinol, a drug widely used to treat gout, protects muscle damage after exhaustive exercise and results in functional gains in old individuals. Thus, we decided to test its effect in the prevention of soleus muscle atrophy after two weeks of hindlimb unloading in mice, and lower leg immobilization following ankle sprain in humans (EudraCT: 2011-003541-17). Our results show that allopurinol partially protects against muscle atrophy in both mice and humans. The protective effect of allopurinol is similar to that of resistance exercise which is the best-known way to prevent muscle mass loss in disuse human models. We report that allopurinol protects against the loss of muscle mass by inhibiting the expression of ubiquitin ligases. Our results suggest that the ubiquitin-proteasome pathway is an appropriate therapeutic target to inhibit muscle wasting and emphasizes the role of allopurinol as a non-hormonal intervention to treat disuse muscle atrophy.

Prenylation enhances the biological activity of dietary flavonoids by altering their bioavailability.

Flavonoids are distributed across the plant kingdom and have attracted substantial attention owing to their potential benefits for human health. Several studies have demonstrated that flavonoids prenylation enhances various biological activities, suggesting an attractive tool for developing functional foods. This review provides an overview of the current knowledge on how prenylation influences the biological activity and bioavailability of flavonoids. The enhancement effect of prenylation on the biological activities of dietary flavonoids in mammals was demonstrated by comparing the effect of 8-prenyl naringenin (8PN) with that of parent naringenin in the prevention of disuse muscle atrophy in mice. This enhancement results from higher muscular accumulation of 8PN than naringenin. As to bioavailability, despite the lower absorption of 8-prenyl quercetin (8PQ) compared with quercetin, higher 8PQ accumulation was found in the liver and kidney. These data imply that prenylation interferes with the elimination of flavonoids from tissues.

Dermatoporosis: a further step to recognition.

Skin ageing has long been considered only as a cosmetic issue. However, with increasing lifespan, we experience a functional dimension of skin ageing which extends beyond cosmetics and appearance. Ten years ago, we proposed the neologism dermatoporosis to cover different characteristics of a chronic cutaneous insufficiency/fragility syndrome, to understand underlying molecular mechanisms and to develop preventative or therapeutic strategies.

Disuse skeletal muscle atrophy in humans. Proteomic and molecular adaptations

Disuse skeletal muscle atrophy in humans. Proteomic and molecular adaptations

Deletion of NAD(P)H Oxidase 2 Prevents Angiotensin II-Induced Skeletal Muscle Atrophy.

Skeletal muscle atrophy is induced by an imbalance between protein synthesis and degradation. Our previous studies reported that angiotensin II (AII) directly induced muscle atrophy in mice. This study investigated the role of NAD(P)H oxidase 2 (Nox2) activation by AII in the induction of skeletal muscle atrophy. For 4 weeks, either saline (vehicle: V) or AII (1000 ng kg−1 min−1) was infused into male wild-type (WT) and Nox2 knockout (KO) mice via osmotic minipumps. Experiments were performed in the following 4 groups: WT + V, KO + V, WT + AII, and KO + AII. Body weight, muscle weight, and myocyte cross-sectional area were significantly decreased in WT + AII compared to WT + V mice, and these changes were not observed in KO + AII mice. Akt phosphorylation of Ser473 and p70S6K of Thr389 was decreased, gene expression levels of MuRF-1 and atrogin-1 were increased in WT + AII compared to WT + V, and these changes were significantly attenuated in KO + AII mice. The deletion of Nox2 prevented AII-induced skeletal muscle atrophy via improving the balance between protein synthesis and degradation. Therefore, Nox2 may be a therapeutic target for AII-induced skeletal muscle atrophy.

Extracellular polysaccharides purified from Aureobasidium pullulans SM‑2001 (Polycan) inhibit dexamethasone‑induced muscle atrophy in mice.

The present study assessed the beneficial skeletal muscle-preserving effects of extracellular polysaccharides from Aureobasidium pullulans SM-2001 (Polycan) (EAP) on dexamethasone (DEXA)-induced catabolic muscle atrophy in mice. To investigate whether EAP prevented catabolic DEXA-induced muscle atrophy, and to examine its mechanisms of action, EAP (100, 200 and 400 mg/kg) was administered orally, once a day for 24 days. EAP treatment was initiated 2 weeks prior to DEXA treatment (1 mg/kg, once a day for 10 days) in mice. Body weight alterations, serum biochemistry, calf thickness, calf muscle strength, gastrocnemius muscle thickness and weight, gastrocnemius muscle antioxidant defense parameters, gastrocnemius muscle mRNA expression, histology and histomorphometry were subsequently assessed. After 24 days, DEXA control mice exhibited muscle atrophy according to all criteria indices. However, these muscle atrophy symptoms were significantly inhibited by oral treatment with all three doses of EAP. Regarding possible mechanisms of action, EAP exhibited favorable ameliorating effects on DEXA-induced catabolic muscle atrophy via antioxidant and anti-inflammatory effects; these effects were mediated by modulation of the expression of genes involved in muscle protein synthesis (AKT serine/threonine kinase 1, phosphatidylinositol 3-kinase, adenosine A1 receptor and transient receptor potential cation channel subfamily V member 4) and degradation (atrogin-1, muscle RING-finger protein-1, myostatin and sirtuin 1). Therefore, these results indicated that EAP may be helpful in improving muscle atrophies of various etiologies. EAP at 400 mg/kg exhibited favorable muscle protective effects against DEXA-induced catabolic muscle atrophy, comparable with the effects of oxymetholone (50 mg/kg), which has been used to treat various muscle disorders.

50 - Inducible motor neuron specific deletion of CuZn Superoxide dismutase accelerates muscle atrophy in mice

Age-associated loss of muscle mass and function has a profound effect on the quality of life in elderly people, yet the mechanisms are unknown and treatments are lacking. Our previous studies have shown that absence of CuZn superoxide dismutase in mice (Sod1KO mice) is associated with a number of characteristics of the sarcopenia phenotype including elevated oxidative stress, mitochondrial dysfunction, accelerated age-associated muscle atrophy and weakness and neuromuscular denervation suggesting oxidative stress and loss of innervation play a key role in initiating muscle atrophy and weakness in aging. Interestingly, neuron specific rescue of CuZnSOD in Sod1KO mice rescued these phenotypes supporting an important role for motor neuron deficits in the etiology of sarcopenia. Here we hypothesized that motor neuron-specific reduction of Sod1 would be sufficient to induce muscle atrophy. To test this, we generated inducible motor neuron-specific Sod1 knock out mice (i-mnSod1KO mice) using motor neuron specific SlickH Cre mice bred to mice carrying a floxed Sod1 allele. Mice were injected at 4 months of age with tamoxifen (2.5 mg/kg body weight) for 3 days and sacrificed at ten months of age. The i-mnSod1KO mice showed a reduction in CuZnSOD protein expression in brain (61.4%), spinal cord (73.4%) and sciatic nerve (60%), but skeletal muscle CuZnSOD expression was not changed. Motor neuron number (28%) and area (48.1%) and protein expression of choline acetyl transferase (ChAT) are reduced in sciatic nerve of i-mnSod1KO mice and neuromuscular junctions showed increased NMJ fragmentation (31%). Gastrocnemius muscle showed markers of muscle denervation (acetylcholine alpha, delta, GADD45 alpha, and RUNX) and muscle atrophy (MURF1) in i-mnSod1KO mice and muscle mass was reduced approximately 23.3% (p>0.004). In contrast to our previous findings in the Sod1KO mice, mitochondrial function is not altered in gastrocnemius muscle in response to the neuronal deletion of Sod1. In summary, our findings suggest that elevated oxidative stress in the motor neuron alone can cause muscle atrophy in mice and point to neuronal deficits as causal in age related loss of muscle mass.

Fermented Rice Germ Extract Alleviates Morphological and Functional Damage to Murine Gastrocnemius Muscle by Inactivation of AMP-Activated Protein Kinase.

Sarcopenia, loss of muscle mass and function, is mainly observed in elderly people. In this study, we investigated whether fermented rice germ extract (FRGE) has some effects on the mouse gastrocnemius muscle by using behavioral and morphological analyses, Western blotting, and a murine model of immobilization-induced muscle atrophy. Daily oral FRGE administration increased muscle weight and strength. In addition, myofiber size in gastrocnemius muscle of FRGE-treated mice was increased as revealed by morphological quantification. Activation of AMP-activated protein kinase (AMPK) signaling, which inhibits protein synthesis and stimulates protein degradation in gastrocnemius muscle, was significantly attenuated in the FRGE-treated mice compared with control mice. Expression level of forkhead box 3a (FOXO3a) protein was also significantly decreased in the FRGE-treated group. Moreover, the decrease in mean myofiber cross-sectional area in immobilized hindlimb in vehicle-treated mice was inhibited by FRGE treatment in histological analysis. In conclusion, FRGE increased the strength and weight of gastrocnemius muscle and myofiber size, and reduced immobilization-induced muscle atrophy in mice. These findings indicated that FRGE might be beneficial in preventing motor dysfunction in a range of conditions, including sarcopenia.

P.354 - Nuclear PABPN1 aggregates in OPMD: correlation study and therapy

Oculopharyngeal muscular dystrophy (OPMD) is a rare late onset genetic disease manifested primarily by progressive weakness of the eyelid and pharyngeal muscles, leading to ptosis and dysphagia. A short abnormal triplet expansion in the polyA-binding protein nuclear 1 (PABPN1) gene leads to the accumulation of nuclear insoluble aggregates in muscles of OPMD patients. While the roles of PABPN1 in post-transcriptional gene regulation are established, the molecular basis of OPMD and the exact contribution of these PABPN1 aggregates remain poorly understood. We are currently investigating the role they might have in the pathology, searching triggers that induce their formation, and testing drugs to remove them. Using a large collection of OPMD patient's muscle biopsies, we are evaluating the percentage, size and characteristics of these aggregates using immunofluorescent and electronic microscopy. Any potential correlation of these parameters with age and genotype is carefully monitored. Results obtained so far suggest an increase in the percentage of nuclear aggregates together with age. Although there are controversies regarding the role of aggregates in OPMD, it is commonly accepted that aggregates and/or the early oligomeric species are toxic (Abu-Baker et al., 2013; Davies et al., 2006). Decreasing their number in OPMD models greatly ameliorate the muscle phenotype. Within the frame of an European OPMD network, we are testing drugs to reduce aggregate formation. Among them, guanabenz acetate (GA) has been identified as a good candidate in drosophila OPMD model (Barbezier et al., 2011). Here we show that GA is also efficient in cell and mouse OPMD models: treatment with GA decreases the percentage of nuclear aggregates and ameliorates muscle strength and atrophy in mice. Altogether these studies will shed light on the exact contribution of aggregate in OPMD and help design potential therapeutic targets.

Human polyclonal antibodies produced in transchromosomal cattle prevent lethal Zika virus infection and testicular atrophy in mice

Zika virus (ZIKV) is rapidly spreading throughout the Americas and is associated with significant fetal complications, most notably microcephaly. Treatment with polyclonal antibodies for pregnant women at risk of ZIKV-related complications could be a safe alternative to vaccination. We found that large quantities of human polyclonal antibodies could be rapidly produced in transchromosomal bovines (TcB) and successfully used to protect mice from lethal infection. Additionally, antibody treatment eliminated ZIKV induced tissue damage in immunologically privileged sites such as the brain and testes and protected against testicular atrophy. These data indicate that rapid development and deployment of human polyclonal antibodies could be a viable countermeasure against ZIKV.

TRPC3-Nox2 complex mediates doxorubicin-induced myocardial atrophy.

Myocardial atrophy is a wasting of cardiac muscle due to hemodynamic unloading. Doxorubicin is a highly effective anticancer agent but also induces myocardial atrophy through a largely unknown mechanism. Here, we demonstrate that inhibiting transient receptor potential canonical 3 (TRPC3) channels abolishes doxorubicin-induced myocardial atrophy in mice. Doxorubicin increased production of ROS in rodent cardiomyocytes through hypoxic stress-mediated upregulation of NADPH oxidase 2 (Nox2), which formed a stable complex with TRPC3. Cardiomyocyte-specific expression of TRPC3 C-terminal minipeptide inhibited TRPC3-Nox2 coupling and suppressed doxorubicin-induced reduction of myocardial cell size and left ventricular (LV) dysfunction, along with its upregulation of Nox2 and oxidative stress, without reducing hypoxic stress. Voluntary exercise, an effective treatment to prevent doxorubicin-induced cardiotoxicity, also downregulated the TRPC3-Nox2 complex and promoted volume load-induced LV compliance, as demonstrated in TRPC3-deficient hearts. These results illustrate the impact of TRPC3 on LV compliance and flexibility and, focusing on the TRPC3-Nox2 complex, provide a strategy for prevention of doxorubicin-induced cardiomyopathy.

Long-term cigarette smoke exposure inhibits histone deacetylase 2 expression and enhances the nuclear factor-κB activation in skeletal muscle of mice.

Long-term cigarette smoke induces lung inflammatory injury and chronic obstructive pulmonary disease (COPD), associated with skeletal muscle inflammation. This study aimed at investigating how cigarette smoke promotes skeletal muscle inflammation and its molecular pathogenesis. Mice were exposed to air or cigarette smoke for 12 or 24 weeks, and C2C12 cells were stimulated with cigarette smoke extract (CSE). The mass and function, myotube formation, inflammatory cytokine production, histone deacetylase 2 (HDAC2) and nuclear factor-κB (NF-κB) p65 expression were detected in the gastrocnemius muscles of mice and C2C12 cells. In comparison with the control mice, cigarette smoke significantly damaged the lung and reduced the gastrocnemius muscle mass and body weights in mice. Cigarette smoke significantly down-regulated myosin heavy chain (MHC)-IIβ and HDAC2 expression, but enhanced NF-κBp65, keratinocyte chemoattractant (KC) and tumor necrosis factor (TNF)-α expression in the gastrocnemius muscles. CSE stimulation significantly inhibited the myotube formation, MyoD and HDAC2 expression, but enhanced NF-κBp65 expression, KC and TNF-α production in C2C12 cells, which were enhanced by HDAC2 knockdown and abrogated by a NF-κB inhibitor. CSE significantly inhibited the interaction of HDAC2 with NF-κBp65, and increased the levels of acetyl-NF-κBp65 in C2C12 cells. These data indicated that cigarette smoke inhibited HDAC2 expression and its interaction with NF-κBp65 to stimulate inflammation, contributing to the pathogenesis of COPD-related skeletal muscle atrophy in mice.