Mechanosignaling pathways alter muscle structure and function by post-translational modification of existing sarcomeric proteins to optimize energy usage

2021 ◽  
Author(s):  
Brenda Russell ◽  
Christopher Solís
Keyword(s):  
Structure And Function ◽  
Sarcomeric Proteins ◽  
Post Translational Modification ◽  
Energy Usage ◽  
Muscle Structure ◽  
And Function

scholarly journals The skeletal muscle circadian clock regulates sarcomere length homeostasis through titin splicing

2021 ◽  
Author(s):  
Lance Riley ◽  
Xiping Zhang ◽  
Joseph Mijares ◽  
David Hammers ◽  
Hailey Olafson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Molecular Clock ◽  
Sarcomere Length ◽  
Structure And Function ◽  
Sarcomeric Proteins ◽  
Muscle Structure ◽  
Splicing Regulator ◽  
And Function ◽  
Ig Domain

Circadian rhythms in skeletal muscle are maintained by a transcriptional-translational feedback loop known as the molecular clock. While previous research suggested a role for the molecular clock in regulating skeletal muscle structure and function, no mechanisms have connected the molecular clock to sarcomeric proteins. Utilizing inducible, skeletal muscle specific, Bmal1 knockout (iMSBmal1-/-) mice, we show that deletion of the skeletal muscle molecular clock alters titin isoform and skeletal muscle sarcomere length. We then use U7 snRNPs in myotubes to directly alter titin splicing in vitro. Truncating the titin proximal Ig domain results in altered sarcomere length. Finally, we identify a mechanism whereby the skeletal muscle molecular clock regulates titin isoform expression through RBM20, a potent splicing regulator of the titin transcript. Our findings demonstrate the importance of the skeletal muscle molecular clock in maintaining sarcomere length homogeneity through its regulation of RBM20 expression. Because circadian rhythm disruption is a feature of many diseases, our results highlight a pathway that could be targeted to maintain skeletal muscle structure and function in a range of pathologies.

scholarly journals Essential Role of Septin 7 in Skeletal Muscle Structure and Function

2020 ◽  
Vol 118 (3) ◽  
pp. 258a
Author(s):  
Laszlo Csernoch ◽  
Mónika Gönczi ◽  
Zsolt Ráduly ◽  
László Szabó ◽  
Nóra Dobrosi ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Essential Role ◽  
Structure And Function ◽  
Muscle Structure ◽  
And Function

scholarly journals Lower leg muscle structure and function are altered in long-distance runners with medial tibial stress syndrome: a case control study

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Joshua Mattock ◽  
Julie R. Steele ◽  
Karen J. Mickle
Keyword(s):  
Lower Leg ◽  
Structure And Function ◽  
Flexor Hallucis Longus ◽  
Plantar Flexor ◽  
Distance Runners ◽  
Long Distance ◽  
Cross Sectional ◽  
Muscle Structure ◽  
Leg Muscle ◽  
And Function

Abstract Background Medial tibial stress syndrome (MTSS) is a common lower leg injury experienced by runners. Although numerous risk factors are reported in the literature, many are non-modifiable and management of the injury remains difficult. Lower leg muscle structure and function are modifiable characteristics that influence tibial loading during foot-ground contact. Therefore, this study aimed to determine whether long-distance runners with MTSS displayed differences in in vivo lower leg muscle structure and function than matched asymptomatic runners. Methods Lower leg structure was assessed using ultrasound and a measure of lower leg circumference to quantify muscle cross-sectional area, thickness and lean lower leg girth. Lower leg function was assessed using a hand-held dynamometer to quantify maximal voluntary isometric contraction strength and a single leg heel raise protocol was used to measure ankle plantar flexor endurance. Outcome variables were compared between the limbs of long-distance runners suffering MTSS (n = 20) and matched asymptomatic controls (n = 20). Means, standard deviations, 95 % confidence intervals, mean differences and Cohen’s d values were calculated for each variable for the MTSS symptomatic and control limbs. Results MTSS symptomatic limbs displayed a significantly smaller flexor hallucis longus cross-sectional area, a smaller soleus thickness but a larger lateral gastrocnemius thickness than the control limbs. However, there was no statistical difference in lean lower leg girth. Compared to the matched control limbs, MTSS symptomatic limbs displayed deficits in maximal voluntary isometric contraction strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles, and reduced ankle plantar flexor endurance capacity. Conclusions Differences in lower leg muscle structure and function likely render MTSS symptomatic individuals less able to withstand the negative tibial bending moment generated during midstance, potentially contributing to the development of MTSS. The clinical implications of these findings suggest that rehabilitation protocols for MTSS symptomatic individuals should aim to improve strength of the flexor hallucis longus, soleus, tibialis anterior and peroneal muscles along with ankle plantar flexor endurance. However, the cross-sectional study design prevents us determining whether between group differences were a cause or effect of MTSS. Therefore, future prospective studies are required to substantiate the study findings.

3D Printed Biodegradable Polyurethaneurea Elastomer Recapitulates Skeletal Muscle Structure and Function

2021 ◽  
Author(s):  
Seyda Gokyer ◽  
Emel Yilgor ◽  
Iskender Yilgor ◽  
Emine Berber ◽  
Engin Vrana ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Structure And Function ◽  
Muscle Structure ◽  
3D Printed ◽  
And Function

Respiratory muscle imaging by ultrasound and MRI in neuromuscular disorders

2021 ◽  
pp. 2100137
Author(s):  
Jeroen L.M. van Doorn ◽  
Francesca Pennati ◽  
Hendrik H.G. Hansen ◽  
Baziel G.M. van Engelen ◽  
Andrea Aliverti ◽  
...  
Keyword(s):  
Respiratory Muscle ◽  
Imaging Techniques ◽  
Neuromuscular Disorders ◽  
Respiratory Muscles ◽  
Daily Practice ◽  
Structure And Function ◽  
Muscle Structure ◽  
Respiratory Management ◽  
Technological Developments ◽  
And Function

Respiratory muscle weakness is common in neuromuscular disorders and leads to significant respiratory difficulties. Therefore, reliable and easy assessment of respiratory muscle structure and function in neuromuscular disorders is crucial. In the last decade, ultrasound and MRI emerged as promising imaging techniques to assess respiratory muscle structure and function. Respiratory muscle imaging directly measures the respiratory muscles and, in contrast to pulmonary function testing, is independent of patient effort. This makes respiratory muscle imaging suitable to use as tool in clinical respiratory management and as outcome parameter in upcoming drug trials for neuromuscular disorders, particularly in children. In this narrative review, we discuss the latest studies and technological developments in imaging of the respiratory muscles by US and MR, and its clinical application and limitations. We aim to increase understanding of respiratory muscle imaging and facilitate its use as outcome measure in daily practice and clinical trials.

scholarly journals Effects of Ovariectomy on Skeletal Muscle Structure and Function in Young Female Rats: Protective Effects of the Flavanol (−)‐Epicatechin

2020 ◽  
Vol 34 (S1) ◽  
pp. 1-1
Author(s):  
Viridiana Navarrrete ◽  
Marcos Ayala ◽  
Antonio Rodriguez ◽  
Francisco Villarreal ◽  
Israel Ramirez-Sanchez
Keyword(s):  
Skeletal Muscle ◽  
Young Female ◽  
Structure And Function ◽  
Female Rats ◽  
Protective Effects ◽  
Muscle Structure ◽  
And Function

The axonemal microtubules of the Chlamydomonas flagellum differ in tubulin isoform content

1998 ◽  
Vol 111 (3) ◽  
pp. 313-320 ◽  
Author(s):  
K.A. Johnson
Keyword(s):  
Structure And Function ◽  
Post Translational Modification ◽  
Immunofluorescence Analysis ◽  
Central Pair ◽  
Alpha Tubulin ◽  
Microtubule Polymerization ◽  
Tubulin Isoforms ◽  
Flagellar Assembly ◽  
Tyrosinated Tubulin ◽  
And Function

Little is known of the molecular basis for the diversity of microtubule structure and function found within the eukaryotic flagellum. Antibodies that discriminate between tyrosinated alpha tubulin and post-translationally detyrosinated alpha tubulin were used to localize these complementary tubulin isoforms in flagella of the single-celled green alga Chlamydomonas reinhardtii. Immunofluorescence analysis of intact axonemes detected both isoforms along most of the lengths of flagella; however, each had a short distal zone rich in tyrosinated tubulin. Localizations on splayed axonemes revealed that the microtubules of the central-pair apparatus were rich in tyrosinated tubulin, while outer doublets contained a mixture of both isoforms. Immunoelectron analysis of individual outer doublets revealed that while tyrosinated tubulin was present in both A and B tubules, detyrosinated tubulin was largely confined to the wall of the B hemi-tubules. The absence of detyrosinated tubulin from the A tubules of the outer doublets and the microtubules of the central pair, both of which extend past the B hemi-tubules of the outer doublets in the flagellar tip, explained the appearance of a tyrosinated tubulin-rich distal zone on intact axonemes. Localizations performed on cells regenerating flagella revealed that flagellar assembly used tyrosinated tubulin; detyrosination of the B tubule occurred during later stages of regeneration, well after microtubule polymerization. The developmental timing of detyrosination, which occurs over a period during which the regrowing flagella begin to beat more effectively, suggests that post-translational modification of the B tubule surface may enhance dynein/B tubule interactions that power flagellar beating.

Muscle structure and function

2010 ◽  
pp. 188-190
Author(s):  
Matthew E. Cross ◽  
Emma V. E. Plunkett
Keyword(s):  
Structure And Function ◽  
Muscle Structure ◽  
And Function

scholarly journals Muscles of mice deficient in α-sarcoglycan maintain large masses and near control force values throughout the life span

2005 ◽  
Vol 22 (2) ◽  
pp. 244-256 ◽  
Author(s):  
Christina M. Consolino ◽  
Franck Duclos ◽  
Jane Lee ◽  
Roger A. Williamson ◽  
Kevin P. Campbell ◽  
...  
Keyword(s):  
Connective Tissue ◽  
Life Span ◽  
Structure And Function ◽  
Null Mouse ◽  
Control Force ◽  
Wild Type ◽  
Cross Sectional ◽  
Muscle Structure ◽  
And Function

α-Sarcoglycan-deficient ( Sgca-null) mice provide potential for elucidating the pathogenesis of limb girdle muscular dystrophy type 2D (LGMD 2D) as well as for studying the effectiveness of therapeutic strategies. Skeletal muscles of Sgca-null mice demonstrate an early onset of extensive fiber necrosis, degeneration, and regeneration, but the progression of the pathology and the effects on muscle structure and function throughout the life span are not known. Thus the phenotypic accuracy of the Sgca-null mouse as a model of LGMD 2D has not been fully established. To investigate skeletal muscle structure and function in the absence of α-sarcoglycan throughout the life span, we analyzed extensor digitorum longus and soleus muscles of male and female Sgca-null and wild-type mice at 3, 6, 12, and 18 mo of age. Maximum isometric forces and powers were measured in vitro at 25°C. Also determined were individual myofiber cross-sectional areas and numbers, water content, and the proportion of the cross section occupied by connective tissue. Muscle masses were 40–100% larger for Sgca-null compared with age- and gender-matched wild-type mice, with the majority of the increased muscle mass for Sgca-null mice attributable to greater connective tissue and water contents. Although the greater mass of muscles in Sgca-null mice was primarily noncontractile material, absolute forces and powers were maintained near control levels at all ages, indicating a successful adaptation to the deficiency in α-sarcoglycan not observed at any age in LGMD 2D patients.

Muscle Structure and Function

2009 ◽  
pp. 1-45 ◽  
Author(s):  
Darl Swartz ◽  
Marion Greaser ◽  
Marie Cantino
Keyword(s):  
Structure And Function ◽  
Muscle Structure ◽  
And Function
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