A MAP kinase‐driven mechanical stress response mediates the hypertrophic response in skeletal muscle

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Cathrine Nordgaard ◽  
Melanie Blasius ◽  
Anna Constance Vind ◽  
Marie Sofie Reinert ◽  
Goda Snieckute ◽  
...  
2013 ◽  
Vol 47 (4) ◽  
pp. 376-381 ◽  
Author(s):  
Mihaela Jurdana ◽  
Maja Cemazar ◽  
Katarina Pegan ◽  
Tomaz Mars

Abstract Background. Long term effects of different doses of ionizing radiation on human skeletal muscle myoblast proliferation, cytokine signalling and stress response capacity were studied in primary cell cultures. Materials and methods. Human skeletal muscle myoblasts obtained from muscle biopsies were cultured and irradiated with a Darpac 2000 X-ray unit at doses of 4, 6 and 8 Gy. Acute effects of radiation were studied by interleukin - 6 (IL-6) release and stress response detected by the heat shock protein (HSP) level, while long term effects were followed by proliferation capacity and cell death. Results. Compared with non-irradiated control and cells treated with inhibitor of cell proliferation Ara C, myoblast proliferation decreased 72 h post-irradiation, this effect was more pronounced with increasing doses. Post-irradiation myoblast survival determined by measurement of released LDH enzyme activity revealed increased activity after exposure to irradiation. The acute response of myoblasts to lower doses of irradiation (4 and 6 Gy) was decreased secretion of constitutive IL-6. Higher doses of irradiation triggered a stress response in myoblasts, determined by increased levels of stress markers (HSPs 27 and 70). Conclusions. Our results show that myoblasts are sensitive to irradiation in terms of their proliferation capacity and capacity to secret IL-6. Since myoblast proliferation and differentiation are a key stage in muscle regeneration, this effect of irradiation needs to be taken in account, particularly in certain clinical conditions.


2020 ◽  
Vol 70 ◽  
pp. 109576 ◽  
Author(s):  
Lisa M. Cooper ◽  
Abby Hanson ◽  
Jack A. Kavanagh ◽  
David S. Waddell

2009 ◽  
Vol 587 (13) ◽  
pp. 3363-3373 ◽  
Author(s):  
Melissa A. Chambers ◽  
Jennifer S. Moylan ◽  
Jeffrey D. Smith ◽  
Laurie J. Goodyear ◽  
Michael B. Reid

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Hui Gong ◽  
Guoliang Jiang ◽  
Chunjie Yang ◽  
Shijun Wang ◽  
Zhidan Chen ◽  
...  

The angiotensin II type 1 receptor (AT1R) has a crucial role in cardiac hypertrophy induced by pressure overload. In the previous study, we found a novel mechanism for mechanical stress-induced AT1R activation without the involvement of Ang II. However, few reports focus on how AT1R senses mechanical stress and translates it into biochemical signals inside the cells to induce cardiomyocyte hypertrophy. Here, we constructed different site-directed mutagenesis of AT1R and transfected them to COS7 cells and ATG–/– (Angiotensinogen knockout) cardiomyocytes, respectively, to observe the activation of downstream signaling to identify functional site of AT1R. The results showed AT1R-WT, AT1R-K199Q, AT1R-L212F,AT1R-Q257A and AT1R-C289A plasmids or adenovirus were overexpressed at high level in plasma membrane of COS7 or cardiomyocytes respectively. There was no obvious difference in subcellular expression of wt-AT1R and all the mut-AT1Rs. The further study revealed that Ang II-induced-phosphorylation of ERK, Jak2 and the redistribution of Gαq11 were dramatically decreased in COS7 cells expressing AT1R-K199Q or AT1R-Q257A, while these effects induced by mechanical stretch were greatly suppressed in COS7 cells expressing AT1R-L212F,AT1R-Q257A or AT1R-C289A compared to these in COS7 cells expressing AT1R-WT. We then transfected the adenovirus of wt-AT1R or different mut-AT1Rs to ATG–/– cardiomyocytes to exclude the influence of endogenous Ang II. The results were consistent with these results in COS7 cells. Moreover, ATG–/– cardiomyocytes overexpressing AT1R-K199Q or AT1R-Q257A parlty abolished hypertrophic response induce by Ang II, while the cardiomyocytes overexpressing AT1R-L212F,AT1R-Q257A or AT1R-C289A greatly inhibited the hypertrophic response induced by mechanical stretch. The present study indicated that Leu212, Gln257 and Cys289 are critical sites for AT1R activation by mechanical stretch without Ang II but Lys199 and Gln257 play important role in AT1R activation with Ang II.


2019 ◽  
Vol 316 (4) ◽  
pp. C567-C581 ◽  
Author(s):  
Ashley N. Haddock ◽  
Sydney A. Labuzan ◽  
Amy E. Haynes ◽  
Caleb S. Hayes ◽  
Karina M. Kakareka ◽  
...  

Skeletal muscle atrophy results from disparate physiological conditions, including denervation, corticosteroid treatment, and aging. The purpose of this study was to describe and characterize the function of dual-specificity phosphatase 4 (Dusp4) in skeletal muscle after it was found to be induced in response to neurogenic atrophy. Quantitative PCR and Western blot analysis revealed that Dusp4 is expressed during myoblast proliferation but rapidly disappears as muscle cells differentiate. The Dusp4 regulatory region was cloned and found to contain a conserved E-box element that negatively regulates Dusp4 reporter gene activity in response to myogenic regulatory factor expression. In addition, the proximal 3′-untranslated region of Dusp4 acts in an inhibitory manner to repress reporter gene activity as muscle cells progress through the differentiation process. To determine potential function, Dusp4 was fused with green fluorescent protein, expressed in C2C12 cells, and found to localize to the nucleus of proliferating myoblasts. Furthermore, Dusp4 overexpression delayed C2C12 muscle cell differentiation and resulted in repression of a MAP kinase signaling pathway reporter gene. Ectopic expression of a Dusp4 dominant negative mutant blocked muscle cell differentiation and attenuated MAP kinase signaling by preferentially targeting the ERK1/2 branch, but not the p38 branch, of the MAP kinase signaling cascade in skeletal muscle cells. The findings presented in this study provide the first description of Dusp4 in skeletal muscle and suggest that Dusp4 may play an important role in the regulation of muscle cell differentiation by regulating MAP kinase signaling.


2019 ◽  
Vol 2019 ◽  
pp. 1-15 ◽  
Author(s):  
Vittoria Cenni ◽  
Snezana Kojic ◽  
Cristina Capanni ◽  
Georgine Faulkner ◽  
Giovanna Lattanzi

Ankrd2 (ankyrin repeats containing domain 2) or Arpp (ankyrin repeat, PEST sequence, and proline-rich region) is a member of the muscle ankyrin repeat protein family. Ankrd2 is mostly expressed in skeletal muscle, where it plays an intriguing role in the transcriptional response to stress induced by mechanical stimulation as well as by cellular reactive oxygen species. Our studies in myoblasts from Emery-Dreifuss muscular dystrophy 2, a LMNA-linked disease affecting skeletal and cardiac muscles, demonstrated that Ankrd2 is a lamin A-binding protein and that mutated lamins found in Emery-Dreifuss muscular dystrophy change the dynamics of Ankrd2 nuclear import, thus affecting oxidative stress response. In this review, besides describing the latest advances related to Ankrd2 studies, including novel discoveries on Ankrd2 isoform-specific functions, we report the main findings on the relationship of Ankrd2 with A-type lamins and discuss known and potential mechanisms involving defective Ankrd2-lamin A interplay in the pathogenesis of muscular laminopathies.


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