CARM1 and skeletal muscle atrophy / Coactivator-associated arginine methyltransferase 1 (CARM1) is emerging as an important player in skeletal muscle biology. We sought to elucidate the role of CARM1 in mediating muscle mass and function, as well as in the induction and progression of the muscle atrophy program. To this end, we engineered CARM1 skeletal muscle-specific knockout (mKO) mice and employed distinct, but complementary models of muscle atrophy, including neurogenic muscle disuse, food deprivation, and the sarcopenia of aging. CARM1 mKO resulted in reduced muscle mass and myofiber cross-sectional area concomitant with dysregulated autophagic and atrophic signaling, which indicates the requirement of CARM1 for the maintenance of muscle biology. Interestingly, CARM1 deletion mitigated the progression of both denervation- and fasting-induced skeletal muscle atrophy as compared to wild-type (WT) mice. Key mechanistic findings revealed that CARM1 interacts with the master neuromuscular regulator AMPK and attenuates the expression and activity of its downstream autophagy and atrophy networks. Surprisingly, both male and female mKO mice have a significantly shorter lifespan versus their WT littermates, revealed by a ~50% reduction in survival at 22-months-old, which is equivalent to ~70 years-old in humans. As such, we observed significantly reduced functional outcomes of integrative physiology in old mKO mice compared to old WT animals, such as strength and motor performance. Taken together, these results indicate that skeletal muscle CARM1 is indispensable for maintaining muscle mass, function, and lifespan. Targeting the interplay between CARM1 and AMPK may offer a viable therapeutic strategy for combating life-limiting muscle wasting conditions. / Thesis / Doctor of Philosophy (PhD) / While muscle wasting and weakness remains a widespread issue, the mechanisms that control muscle atrophy are not entirely understood. Previous evidence suggests that coactivator-associated arginine methyltransferase 1 (CARM1) regulates skeletal muscle remodeling. However, the role of CARM1 during muscle atrophy is unknown. Therefore, the purpose of this work was to investigate the function of CARM1 during muscle wasting. We generated mice with CARM1 deleted in skeletal muscle and studied the impact of CARM1 deficiency on the loss of skeletal muscle mass during muscle disuse, food deprivation, and aging. We found that CARM1 is required to maintain muscle mass under basal conditions. Interestingly, knocking out CARM1 in muscle attenuated the progression of denervation- and fasting-induced atrophy. However, CARM1 deletion in muscle resulted in lower muscle strength and a reduced lifespan. CARM1 deficiency did not prevent aging-induced muscle loss. Overall, these findings advance our understanding of CARM1 in skeletal muscle biology.

名古屋大学博士学位論文 学位の種類:博士（医療技術学）（課程）学位授与年月日:平成21年3月25日

国立情報学研究所で電子化したコンテンツを使用している。

No description available.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2005. / Härtill 5 uppsatser.

Rotator cuff injury is a debilitating condition and when injury cannot be managed through non-operative procedures, surgery is required. To determine explanations for the failure of surgery to restore joint function, human muscle biopsies of supraspinatus were studied compared to deltoid. Histology showed atrophy and a tendency toward fibrosis/fatty infiltration in injured supraspinatus. Findings from AChR-subunit western blot and Sema3A localization around satellite cells suggest supraspinatus denervation. Nucleotide incorporation to quantify satellite cell activation in culture showed a significant increase in BrdU+(active) satellite cells in supraspinatus treated with a nitric oxide-donor drug, but not deltoid muscle. The application of principal component analysis to these data extracted components that suggest variables assaying muscle atrophy, satellite cell activity, and fibrosis contribute strongly to the observed variability. The results suggest supraspinatus muscle of the injured rotator cuff is atrophic, denervated, possibly subject to fibro-fatty infiltration, and support the idea that treatment could promote growth in atrophic supraspinatus to improve functional outcomes. / October 2015

Submitted by Edineia Teixeira (edineia.teixeira@unioeste.br) on 2017-11-27T18:31:17Z No. of bitstreams: 2 MARCELA LEITE2017.pdf: 2527004 bytes, checksum: 37310bebca45bcc15d56cfda1b505434 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-11-27T18:31:17Z (GMT). No. of bitstreams: 2 MARCELA LEITE2017.pdf: 2527004 bytes, checksum: 37310bebca45bcc15d56cfda1b505434 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-01-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Objective: To evaluate whether periodontal disease, through systemic inflammation, can potentiates the deleterious effects of immobilization of the skeletal striated muscle, contributing to the development of muscle atrophy due to disuse. Methods: Forty Wistar rats were divided into four groups: 1) Control Group (CG), 2) Periodontal Disease (GPD) 3) Immobilized (IG) and 4) Immobilized with Periodontal Disease (IPDG). Periodontal disease was induced for 30 days, with ligature method, and the immobilization of the right pelvic limb was performed with cast bandage for 15 days. Prior to euthanasia, the nociceptive threshold and muscular grasping force were evaluated. Afterwards, the soleus muscle was dissected and processed for sarcomere counting and morphological and morphometric analysis. For analysis of the data, the one-way ANOVA followed by the Tukey post test, with p < 0.05. Results: The IG and IPDG groups presented lower muscle weight, lower muscular grip strength and less number of sarcomeres compared to CG. The PDG showed reduction of muscle strength and nociceptive threshold after 15 days of periodontal disease and increase of connective tissue compared to CG. The IPDG presented lower muscle length and nociceptive threshold compared to the other groups. The IG presented a reduction in the cross-sectional area and a smaller diameter, an increase in the number of nuclei and a nucleus/fiber ratio, a decrease in the number of capillaries and a capillary/fiber ratio, with an increase in connective tissue. In the IPDG group, there were significant results for increased nucleus/fiber ratio, decreased capillaries and increased connective tissue when compared to the IG group. The IPDG group presented greater muscle tissue degeneration and increased inflammatory cells when compared to the other groups. Conclusion: Periodontal disease potentiated the deleterious effects of immobilization of the skeletal striated muscle, through intense destruction of muscle tissue, with significant increase of connective tissue, nucleus/fiber ratio and inflammatory infiltrate, significant reduction of vascularization and reduction of muscle length, with consequent reduction of muscle strength and nociceptive threshold. / Objetivo: Avaliar se a doença periodontal, por meio da inflamação sistêmica, potencializa os efeitos deletérios da imobilização do músculo estriado esquelético, colaborando para o desenvolvimento da atrofia muscular por desuso. Metodologia: Foram utilizados 40 ratos Wistar, divididos em quatro grupos: 1) Grupo Controle (GC); 2) Doença Periodontal (GDP); 3) Imobilizado (GI); 4) Doença Periodontal Imobilizado (GDPI). A doença periodontal foi induzida pelo método de ligadura, durante 30 dias e a imobilização do membro pélvico direito foi realizada com atadura gessada, por 15 dias. Antes da eutanásia, foram avaliados o limiar nociceptivo e força muscular de preensão. Após, o músculo sóleo foi dissecado e processado para contagem de sarcômeros e análise morfológica e morfométrica. Para análise dos dados, foi utilizado o teste ANOVA de uma via seguida do post test Tukey, com p<0,05. Resultados: Os grupos GI e GDPI apresentaram menor peso muscular, força muscular de preensão e número de sarcômeros comparados ao GC. O GDP apresentou redução da força muscular e do limiar nociceptivo após 15 dias de doença periodontal e aumento de tecido conjuntivo comparado ao GC. O GDPI apresentou menor comprimento muscular e limiar nociceptivo comparados aos demais grupos. O GI apresentou redução da área de secção transversa e menor diâmetro, aumento no número de núcleos e razão núcleo/fibra, diminuição no número de capilares e razão capilar/fibra, com aumento de tecido conjuntivo. No grupo GDPI, houve resultados significativos para aumento da razão núcleo/fibra, diminuição de capilares e aumento de tecido conjuntivo quando comparado ao grupo GI. O grupo GDPI apresentou maior degeneração do tecido muscular e aumento de células inflamatórias quando comparado aos outros grupos. Conclusão: A doença periodontal potencializou os efeitos deletérios da imobilização do músculo estriado esquelético, por meio da intensa destruição do tecido muscular, com significativo aumento do tecido conjuntivo, da razão núcleo/fibra e infiltrado inflamatório, significativa diminuição da vascularização e redução do comprimento muscular, com consequente redução da força muscular e limiar nociceptivo.

Critically ill patients admitted to the intensive care unit (ICU) commonly develop severe muscle wasting and weakness and consequently impaired muscle function. This not only delays respirator weaning and ICU discharge, but has deleterious effects on morbidity, mortality, financial costs, and quality of life of survivors. Acute Quadriplegic Myopathy (AQM) is one of the most common neuromuscular disorders underlying ICU muscle wasting and paralysis, and is a consequence of modern intensive care interventions, although the exact causes remain unclear. Muscle gene/protein expression, intracellular signalling, post-translational modifications, muscle membrane excitability, and contractile properties at the single muscle fibre level were explored in order to unravel the mechanisms underlying the muscle wasting and weakness associated with AQM and how this can be counteracted by specific intervention strategies. A unique experimental rat ICU model was used to address the mechanistic and therapeutic aspects of this condition, allowing time-resolved studies for a period of two weeks. Subsequently, the findings obtained from this model were translated into a clinical study. The obtained results showed that the mechanical silencing of skeletal muscle, i.e., absence of external strain (weight bearing) and internal strain (myosin-actin activation) due to the pharmacological paralysis or sedation associated with the ICU intervention, is likely to be the primary mechanism triggering the preferential myosin loss and muscle wasting, features specifically characteristic of AQM. Moreover, mechanical silencing induces a specific gene expression pattern as well as post-translational modifications in the motor domain of myosin that may be critical for both function and for triggering proteolysis. The higher nNOS expression found in the ICU patients and its cytoplasmic dislocation are indicated as a probable mechanism underlying these highly specific modifications. This work also demonstrated that passive mechanical loading is able to attenuate the oxidative stress associated with the mechanical silencing and induces positive effects on muscle function, i.e., alleviates the loss of force-generating capacity that underlie the ICU intervention, supporting the importance of early physical therapy in immobilized, sedated, and mechanically ventilated ICU patients.

A perda muscular ou atrofia é uma condição associada a importantes doenças sistêmicas humanas, incluindo diabetes, câncer e insuficiência renal. Há diversos estudos de perfis transcricionais mostrando que um conjunto comum de genes, denominados atrogenes, é modulado nos músculos atrofiados. No entanto, as alterações transcricionais que desencadeiam a reversão ou atenuação da atrofia muscular ainda não foram caracterizadas a nível molecular até o momento. Para identificar os principais genes envolvidos na recuperação da massa muscular esquelética, utilizamos a técnica de microarray e RT-PCR para investigar genes diferencialmente expressos durante a reversão da atrofia do músculo Elevador do ânus (EA) sensível a andrógeno, no modelo de castração e reposição de testosterona. Como esperado, a maioria dos genes expressos de maneira diferencial comportam-se como atrogenes e respondem à atrofia induzida pela castração. Porém, observou-se pela primeira vez um grupo de sete genes (APLN, DUSP5, IGF1, PIK3IP1, KLHL38, PI15 e MKL1) que não responderam à castração, mas exclusivamente à reposição de testosterona. Considerando que quase todas as proteínas codificadas por esses genes estão associadas à reversão da atrofia e podem funcionar como reguladores da proliferação/crescimento celular, nossos resultados abrem novas perspectivas sobre a existência de anti-atrogenes / Muscle wasting or atrophy is a condition associated with major human systemic diseases including diabetes, cancer, and kidney failure. There is accumulating evidence from transcriptional profiles showing that a common set of genes, termed atrogenes, is modulated in atrophying muscles. However, transcriptional changes that trigger reversion or attenuation of muscle atrophy have not been characterized at the molecular level until now. To identify key genes involved in the recovery of skeletal muscle mass, we have used cDNA microarrays and RT-PCR to investigate genes differentially expressed during the atrophy reversion of the androgen-sensitive Levator ani muscle (LA), in the well-established model of castration and testosterone replacement. As expected, most of the differential expressed genes behave as atrogenes and responded to castration-induced atrophy. Strikingly, seven genes (APLN, DUSP5, IGF1, PIK3IP1, KLHL38, PI15, and MKL1) did not respond to castration but exclusively to the testosterone replacement. Considering that almost all proteins encoded by these genes are associated to reversion of atrophy and may function as regulators of cell proliferation/growth, our results open new perspectives on the existence of a new group of genes, determined anti-atrogenes

Neste estudo, testamos dois novos moduladores seletivos do receptor de glicocorticóide, nomeados L5 e L7, em comparação com o dexametasona, sobre aspectos estruturais, funcionais e moleculares no músculo sóleo. Ratos Wistar foram tratados com doses progressivas de dexametasona, L5 e L7 em 1 ou 7 dias. A massa corporal e a ingestão alimentar apresentaram queda após o tratamento com dexametasona em todas as doses; os tratamentos com L5/L7 mostraram resposta semelhante aos controles. O peso do músculo foi diminuído pelo dexametasona, efeito não observado nos tratamentos com L5/L7. Apenas o tratamento com dexametasona causou uma diminuição na área de secção transversa dos tipos de fibra muscular analisada. A força tetânica do sóleo foi diminuída pela dexametasona, nos tratamentos com L5/L7 este parâmetro também não foi afetado. A expressão gênica de MAFbx/Atrogin-1 e MuRF-1 foi elevada pela dexametasona; por outro lado, L5/L7 não elevaram a expressão destes genes. Concluímos que o L5/L7, em contraste com o dexametasona, preveniu o músculo esquelético da atrofia. / In this study, we have tested two new selective modulators named L5 and L7 along with dexamethasone in skeletal muscle structural, functional and molecular aspects. Male Wistar rats were treated with progressive doses of dexamethasone, L5 and L7 for 1 and 7 days. While body weight and food intake were decreased by the dexamethasone treatment in all doses, L5/L7 treatments induced gain in body weight similarly to controls. Muscle weight was decreased by dexamethasone, while L5/L7 were ineffective. Only the dexamethasone treatment caused a decrease in the analyzed cross sectional area of the skeletal muscle fiber types. Soleus tetanic force was decreased by the dexamethasone treatment, while L5/L7 treatments did not alter this parameter. MAFbx/Atrogin-1 and MuRF-1 gene expressions were elevated by dexamethasone; on the other hand, L5/L7 did not modulate any expression of those genes. We conclude that L5/L7, in contrast to dexamethasone, spare skeletal muscle from structural and functional loss, and molecular changes, reinforcing their role as a therapeutic device.