Microtubule-based transport is essential to distribute RNA and nascent protein in skeletal muscle

AbstractWhile the importance of RNA localization in highly differentiated cells is well appreciated, basic principles of RNA localization in skeletal muscle remain poorly characterized. Here, we develop a method to detect and quantify single molecule RNA localization patterns in skeletal myofibers, and uncover a critical role for directed transport of RNPs in muscle. We find that RNAs localize and are translated along sarcomere Z-disks, dispersing tens of microns from progenitor nuclei, regardless of encoded protein function. We find that directed transport along the lattice-like microtubule network of myofibers becomes essential to achieve this localization pattern as muscle development progresses; disruption of this network leads to extreme accumulation of RNPs and nascent protein around myonuclei. Our observations suggest that global active RNP transport may be required to distribute RNAs in highly differentiated cells and reveal fundamental mechanisms of gene regulation, with consequences for myopathies caused by perturbations to RNPs or microtubules.

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Microtubule-based Transport is Essential to Distribute RNA and Nascent Protein in Skeletal Muscle

10.1101/2021.02.26.433059 ◽

2021 ◽

Author(s):

Lance T. Denes ◽

Chase P. Kelley ◽

Eric T. Wang

Keyword(s):

Skeletal Muscle ◽

Protein Synthesis ◽

Nuclear Envelope ◽

Muscle Development ◽

Rna Localization ◽

Microtubule Network ◽

Basic Principles ◽

General Role ◽

Rna Molecules ◽

Differentiated Cells

SUMMARYWhile the importance of RNA localization in highly differentiated cells is well appreciated, basic principles of RNA localization in skeletal muscle remain poorly characterized. Here, we develop a method to detect single RNA molecules and quantify localization patterns in skeletal myofibers, and we uncover a critical and general role for directed transport of RNPs in muscle. We find that RNAs are localized and translated along cytoskeletal filaments, and we identify the Z-disk as a biological hub for RNA localization and protein synthesis. We show that muscle development triggers complete reliance on the lattice-like microtubule network to transport RNAs and that disruption of microtubules leads to striking accumulation of RNPs and nascent protein around myonuclei. Our observations suggest that active transport may be globally required to distribute RNAs in highly differentiated cells and reveal fundamental mechanisms relevant to myopathies caused by perturbations to RNPs, microtubules, and the nuclear envelope.Abstract Figure

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Zfp422 promotes skeletal muscle differentiation by regulating EphA7 to induce appropriate myoblast apoptosis

Cell Death and Differentiation ◽

10.1038/s41418-019-0448-9 ◽

2019 ◽

Vol 27 (5) ◽

pp. 1644-1659 ◽

Cited By ~ 1

Author(s):

Yaping Nie ◽

Shufang Cai ◽

Renqiang Yuan ◽

Suying Ding ◽

Xumeng Zhang ◽

...

Keyword(s):

Skeletal Muscle ◽

Zinc Finger ◽

Muscle Development ◽

Zinc Finger Protein ◽

Critical Role ◽

Muscle Differentiation ◽

C2c12 Cells ◽

Myoblast Differentiation ◽

Skeletal Muscle Differentiation ◽

Finger Protein

Abstract Zinc finger protein 422 (Zfp422) is a widely expressed zinc finger protein that serves as a transcriptional factor to regulate downstream gene expression, but until now, little is known about its roles in myogenesis. We found here that Zfp422 plays a critical role in skeletal muscle development and regeneration. It highly expresses in mouse skeletal muscle during embryonic development. Specific knockout of Zfp422 in skeletal muscle impaired embryonic muscle formation. Satellite cell-specific Zfp422 deletion severely inhibited muscle regeneration. Myoblast differentiation and myotube formation were suppressed in Zfp422-deleted C2C12 cells, isolated primary myoblasts, and satellite cells. Chromatin Immunoprecipitation Sequencing (ChIP-Seq) revealed that Zfp422 regulated ephrin type-A receptor 7 (EphA7) expression by binding an upstream 169-bp DNA sequence, which was proved to be an enhancer of EphA7. Knocking EphA7 down in C2C12 cells or deleting Zfp422 in myoblasts will inhibit cell apoptosis which is required for myoblast differentiation. These results indicate that Zfp422 is essential for skeletal muscle differentiation and fusion, through regulating EphA7 expression to maintain proper apoptosis.

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HDAC4 Regulates the Proliferation, Differentiation and Apoptosis of Chicken Skeletal Muscle Satellite Cells

Animals ◽

10.3390/ani10010084 ◽

2020 ◽

Vol 10 (1) ◽

pp. 84 ◽

Cited By ~ 3

Author(s):

Jing Zhao ◽

Xiaoxu Shen ◽

Xinao Cao ◽

Haorong He ◽

Shunshun Han ◽

...

Keyword(s):

Skeletal Muscle ◽

Satellite Cells ◽

Muscle Development ◽

Critical Role ◽

Muscle Growth ◽

Positive Role ◽

Muscle Satellite Cells ◽

Skeletal Muscle Satellite Cells ◽

Chicken Skeletal Muscle

The development of skeletal muscle satellite cells (SMSCs) is a complex process that could be regulated by many genes. Previous studies have shown that Histone Deacetylase 4 (HDAC4) plays a critical role in cell proliferation, differentiation, and apoptosis in mouse. However, the function of HDAC4 in chicken muscle development is still unknown. Given that chicken is a very important meat-producing animal that is also an ideal model to study skeletal muscle development, we explored the functions of HDAC4 in chicken SMSCs after the interference of HDAC4. The results showed that HDAC4 was enriched in embryonic skeletal muscle, and it was highly expressed in embryonic muscle than in postnatal muscles. Meanwhile, knockdown of HDAC4 could significantly inhibit the proliferation and differentiation of chicken SMSCs but had no effect on the apoptosis of SMSCs as observed in a series of experiment conducted in vitro. These results indicated that HDAC4 might play a positive role in chicken skeletal muscle growth and development.

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Dyrk1b is a key Regulatory Kinase Integrating Fgf, Shh and mTORC1 signaling in Skeletal Muscle Development and Homeostasis

10.1101/2020.04.22.055947 ◽

2020 ◽

Author(s):

Neha Bhat ◽

Anand Narayanan ◽

Mohsen Fathzadeh ◽

Anup Srivastava ◽

Arya Mani

Keyword(s):

Skeletal Muscle ◽

Muscle Development ◽

Human Genetics ◽

Critical Role ◽

The Novel ◽

Skeletal Muscle Development ◽

Kinase Activation ◽

Transcriptional Suppression ◽

Mtorc1 Signaling ◽

Feedback Inhibitor

ABSTRACTThe advent of human genetics has provided unprecedented opportunities for discovery of novel disease pathways. Mutations in DYRK1B have been associated with metabolic syndrome and sarcopenic obesity in humans, underscoring the critical role of the encoded protein in skeletal muscle development and homeostasis. By the novel creation of Dyrk1b knockout zebrafish models we demonstrate that Dyrk1b kinase activity is critical for specification of the paraxial myoD. Mechanistically, Dyrk1b mediates and amplifies Fgf signaling in the paraxial domain by the transcriptional suppression of its negative feedback inhibitor sprouty1. In the adaxial myoD domain, Dyrk1b amplifies Shh signaling and partially rescues defects caused by its disruption. The investigations of C2C12 terminal differentiation revealed that Dyrk1b also plays a critical role in myofiber fusion. Combined biochemical and proteomic analysis of C2C12 myoblasts undergoing differentiation showed that Dyrk1b kinase activation is induced by shh inhibition, and triggers differentiation by inhibiting mTOR, subsequent upregulation of 4e-bp1 and induction of autophagy. In conclusion, we demonstrate that Dyrk1b plays a critical role in sustaining myocyte specification and differentiation by integrating Fgf, Shh and mTORC1 signaling pathways.

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The ABCs of IGF-I isoforms: impact on muscle hypertrophy and implications for repair

Applied Physiology Nutrition and Metabolism ◽

10.1139/h06-054 ◽

2006 ◽

Vol 31 (6) ◽

pp. 791-797 ◽

Cited By ~ 87

Author(s):

Elisabeth R. Barton

Keyword(s):

Skeletal Muscle ◽

Muscle Hypertrophy ◽

Muscle Development ◽

Critical Role ◽

The Body ◽

Skeletal Muscle Development ◽

Active Peptides ◽

Igf I ◽

Physiological Impact

Insulin-like growth factor I (IGF-I) plays a critical role in the growth and development of many tissues in the body. It is a key regulator of skeletal muscle development, and continues to enhance the ability for muscle to grow and undergo repair throughout life. Although the focus of research has been on the molecular actions and physiological impact of IGF-I, there has also been a growing undercurrent of studies geared toward the characterization of additional potentially active peptides produced by the igf1 gene. Alternative splicing of the gene results in multiple isoforms that retain the identical sequence for mature IGF-I, but also give rise to divergent C-terminal peptides. The peptides might modulate the actions, stability, or bioavailability of IGF-I, or they might have independent activity. These possibilities have gained the attention of the skeletal muscle field, where novel actions of IGF-I could have significant impact on muscle mass, strength, and repair.

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Disruption of the MyoD/p21 Pathway in Rhabdomyosarcoma

Sarcoma ◽

10.1080/13577149778218 ◽

1997 ◽

Vol 1 (3-4) ◽

pp. 135-141 ◽

Cited By ~ 6

Author(s):

Michael Weintraub ◽

Thea Kalebic ◽

Lee J. Helman ◽

Kishor G. Bhatia

Keyword(s):

Cell Cycle ◽

Skeletal Muscle ◽

Cell Line ◽

Muscle Development ◽

Kinase Inhibitor ◽

Critical Role ◽

Inverse Correlation ◽

Single Strand Conformation Polymorphism ◽

Coding Region ◽

Cyclin Dependent Kinase Inhibitor

Purpose. Rhabdomyosarcoma (RMS) is an embryonal tumor thought to arise from skeletal muscle cells that fail to differentiate terminally. The majority of RMSs express MyoD, a protein essential to the differentiation of skeletal muscle. It was recently shown that during myogenesis, MyoD activates the expression of the cyclin-dependent kinase inhibitor (CDKi), p21, which itself plays a critical role in normal muscle development. To investigate the integrity of the MyoD/p21 pathway in RMS, we analyzed p21 and its relationship to MyoD expression in RMS.Methods. A panel of RMS samples was assembled from primary biopsies and from cell lines. Integrity of p21 was analyzed by single-strand conformation polymorphism (SSCP) and sequencing. Expression of p21 and MyoD was determined by Northern blot analysis, and the ability of exogenous p21 to arrest the cell cycle of RMS cell line was determined by transfection studies.Results. Our analysis indicates that although p21 is wild type in RMS, there is an inverse correlation between the levels of p21 and MyoD in these tumors. Tumors that express significant amounts of MyoD fail to express p21. This does not appear to be the result of mutations within the potential CACGTG sites present in the p21 promoter region or in the coding region of p21. An additional group of RMSs express very high levels of p21 but express little, if any, MyoD. Furthermore, RD, a RMS cell line which expresses high levels of endogenous p21, undergoes withdrawal from the cell cycle following forced expression of p21, suggesting that the pathway which would lead to G1arrest from endogenous p21 activity is defective.Discussion. These data suggest that the interaction between p21 and MyoD is defective in RMS although the precise nature of the defect remains to be elucidated.

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Follistatin-mediated skeletal muscle hypertrophy is regulated by Smad3 and mTOR independently of myostatin

The Journal of Cell Biology ◽

10.1083/jcb.201109091 ◽

2012 ◽

Vol 197 (7) ◽

pp. 997-1008 ◽

Cited By ~ 103

Author(s):

Catherine E. Winbanks ◽

Kate L. Weeks ◽

Rachel E. Thomson ◽

Patricio V. Sepulveda ◽

Claudia Beyer ◽

...

Keyword(s):

Skeletal Muscle ◽

Intracellular Signaling ◽

Muscle Development ◽

Viral Vector ◽

Critical Role ◽

Muscle Growth ◽

Mammalian Target Of Rapamycin ◽

Mtor Signaling ◽

Mediated Effects

Follistatin is essential for skeletal muscle development and growth, but the intracellular signaling networks that regulate follistatin-mediated effects are not well defined. We show here that the administration of an adeno-associated viral vector expressing follistatin-288aa (rAAV6:Fst-288) markedly increased muscle mass and force-producing capacity concomitant with increased protein synthesis and mammalian target of rapamycin (mTOR) activation. These effects were attenuated by inhibition of mTOR or deletion of S6K1/2. Furthermore, we identify Smad3 as the critical intracellular link that mediates the effects of follistatin on mTOR signaling. Expression of constitutively active Smad3 not only markedly prevented skeletal muscle growth induced by follistatin but also potently suppressed follistatin-induced Akt/mTOR/S6K signaling. Importantly, the regulation of Smad3- and mTOR-dependent events by follistatin occurred independently of overexpression or knockout of myostatin, a key repressor of muscle development that can regulate Smad3 and mTOR signaling and that is itself inhibited by follistatin. These findings identify a critical role of Smad3/Akt/mTOR/S6K/S6RP signaling in follistatin-mediated muscle growth that operates independently of myostatin-driven mechanisms.

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LMNA Mutations G232E and R482L Cause Dysregulation of Skeletal Muscle Differentiation, Bioenergetics, and Metabolic Gene Expression Profile

Genes ◽

10.3390/genes11091057 ◽

2020 ◽

Vol 11 (9) ◽

pp. 1057

Author(s):

Elena V. Ignatieva ◽

Oksana A. Ivanova ◽

Margarita Y. Komarova ◽

Natalia V. Khromova ◽

Dmitrii E. Polev ◽

...

Keyword(s):

Skeletal Muscle ◽

Muscle Development ◽

Neuromuscular Disorders ◽

Control Cell ◽

Muscle Differentiation ◽

Mitochondrial Uncoupling ◽

Partial Lipodystrophy ◽

Differentiated Cells ◽

Wide Range

Laminopathies are a family of monogenic multi-system diseases resulting from mutations in the LMNA gene which include a wide range of neuromuscular disorders. Although lamins are expressed in most types of differentiated cells, LMNA mutations selectively affect only specific tissues by mechanisms that remain largely unknown. We have employed the combination of functional in vitro experiments and transcriptome analysis in order to determine how two LMNA mutations associated with different phenotypes affect skeletal muscle development and metabolism. We used a muscle differentiation model based on C2C12 mouse myoblasts genetically modified with lentivirus constructs bearing wild-type human LMNA (WT-LMNA) or R482L-LMNA/G232E-LMNA mutations, linked to familial partial lipodystrophy of the Dunnigan type and muscular dystrophy phenotype accordingly. We have shown that both G232E/R482L-LMNA mutations cause dysregulation in coordination of pathways that control cell cycle dynamics and muscle differentiation. We have also found that R482/G232E-LMNA mutations induce mitochondrial uncoupling and a decrease in glycolytic activity in differentiated myotubes. Both types of alterations may contribute to mutation-induced muscle tissue pathology.

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Alterations in Ultrastructure of Skeletal Muscle From Newborn Guinea Pigs Following in Utero Exposure to Ethanol

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120126 ◽

1985 ◽

Vol 43 ◽

pp. 686-687

Author(s):

C. Uphoff ◽

C. Nyquist-Battie ◽

T.B. Cole

Keyword(s):

Skeletal Muscle ◽

Guinea Pigs ◽

Muscle Development ◽

In Utero ◽

Ethanol Exposure ◽

Prenatally Exposed ◽

Chronic Alcoholic ◽

Test Kit ◽

Food And Water Intake ◽

Post Intubation

Ultrastructural alterations of skeletal muscle have been observed in adult chronic alcoholic patients. However, no such study has been performed on individuals prenatally exposed to ethanol. In order to determine if ethanol exposure in utero in the latter stages of muscle development was deleterious, skeletal muscle was obtained from newborn guinea pigs treated in the following manner. Six Hartly strain pregnant guinea pigs were randomly assigned to either the ethanol or the pair-intubated groups. Twice daily the 3 ethanol-treated animals were intubated with Ensure (Ross Laboratories) liquid diet containing 30% ethanol (6g/Kg pre-pregnant body weight per day) from day 35 of gestation until parturition at day 70±1 day. Serum ethanol levels were determined at 1 hour post-intubation by the Sigma alcohol test kit. For pair-intubation the Ensure diet contained sucrose substituted isocalorically for ethanol. Both food and water intake were monitored.

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Coaction of Electrostatic and Hydrophobic Interactions: Dynamic Constraints on Disordered TrkA Juxtamembrane Domain

10.26434/chemrxiv.9847190 ◽

2019 ◽

Author(s):

Zichen Wang ◽

Huaxun Fan ◽

Xiao Hu ◽

John Khamo ◽

Jiajie Diao ◽

...

Keyword(s):

Single Molecule ◽

Protein Function ◽

Hydrophobic Interactions ◽

Transmembrane Helix ◽

Point Mutations ◽

Salt Bridge ◽

Receptor Activation ◽

Membrane Dynamics ◽

Juxtamembrane Domain ◽

Joint Work

<p>The receptor tyrosine kinase family transmits signals into cell via a single transmembrane helix and a flexible juxtamembrane domain (JMD). Membrane dynamics makes it challenging to study the structural mechanism of receptor activation experimentally. In this study, we employ all-atom molecular dynamics with Highly Mobile Membrane-Mimetic to capture membrane interactions with the JMD of tropomyosin receptor kinase A (TrkA). We find that PIP<sub>2 </sub>lipids engage in lasting binding to multiple basic residues and compete with salt bridge within the peptide. We discover three residues insertion into the membrane, and perturb it through computationally designed point mutations. Single-molecule experiments indicate the contribution from hydrophobic insertion is comparable to electrostatic binding, and in-cell experiments show that enhanced TrkA-JMD insertion promotes receptor ubiquitination. Our joint work points to a scenario where basic and hydrophobic residues on disordered domains interact with lipid headgroups and tails, respectively, to restrain flexibility and potentially modulate protein function.</p>

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