Autism-associated SHANK3 mutations impair maturation of neuromuscular junctions and striated muscles

Heterozygous mutations of the gene encoding the postsynaptic protein SHANK3 are associated with syndromic forms of autism spectrum disorders (ASDs). One of the earliest clinical symptoms in SHANK3-associated ASD is neonatal skeletal muscle hypotonia. This symptom can be critical for the early diagnosis of affected children; however, the mechanism mediating hypotonia in ASD is not completely understood. Here, we used a combination of patient-derived human induced pluripotent stem cells (hiPSCs), Shank3Δ11(−/−) mice, and Phelan-McDermid syndrome (PMDS) muscle biopsies from patients of different ages to analyze the role of SHANK3 on motor unit development. Our results suggest that the hypotonia in SHANK3 deficiency might be caused by dysfunctions in all elements of the voluntary motor system: motoneurons, neuromuscular junctions (NMJs), and striated muscles. We found that SHANK3 localizes in Z-discs in the skeletal muscle sarcomere and co-immunoprecipitates with α-ACTININ. SHANK3 deficiency lead to shortened Z-discs and severe impairment of acetylcholine receptor clustering in hiPSC-derived myotubes and in muscle from Shank3Δ11(−/−) mice and patients with PMDS, indicating a crucial role for SHANK3 in the maturation of NMJs and striated muscle. Functional motor defects in Shank3Δ11(−/−) mice could be rescued with the troponin activator Tirasemtiv that sensitizes muscle fibers to calcium. Our observations give insight into the function of SHANK3 besides the central nervous system and imply potential treatment strategies for SHANK3-associated ASD.

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A distinct cardiopharyngeal mesoderm genetic hierarchy establishes antero-posterior patterning of esophagus striated muscle

eLife ◽

10.7554/elife.47460 ◽

2019 ◽

Vol 8 ◽

Cited By ~ 4

Author(s):

Glenda Comai ◽

Eglantine Heude ◽

Sebastian Mella ◽

Sylvain Paisant ◽

Francesca Pala ◽

...

Keyword(s):

Skeletal Muscle ◽

Striated Muscle ◽

Striated Muscles ◽

Food Ingestion ◽

Loss Of Function ◽

Pharmacological Studies ◽

Posterior Migration ◽

Functional Relevance ◽

Genetic Signatures ◽

Genetic Hierarchy

In most vertebrates, the upper digestive tract is composed of muscularized jaws linked to the esophagus that permits food ingestion and swallowing. Masticatory and esophagus striated muscles (ESM) share a common cardiopharyngeal mesoderm (CPM) origin, however ESM are unusual among striated muscles as they are established in the absence of a primary skeletal muscle scaffold. Using mouse chimeras, we show that the transcription factors Tbx1 and Isl1 are required cell-autonomously for myogenic specification of ESM progenitors. Further, genetic loss-of-function and pharmacological studies point to MET/HGF signaling for antero-posterior migration of esophagus muscle progenitors, where Hgf ligand is expressed in adjacent smooth muscle cells. These observations highlight the functional relevance of a smooth and striated muscle progenitor dialogue for ESM patterning. Our findings establish a Tbx1-Isl1-Met genetic hierarchy that uniquely regulates esophagus myogenesis and identify distinct genetic signatures that can be used as framework to interpret pathologies arising within CPM derivatives.

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Increased Ca2+ signaling in NRXN1α+/− neurons derived from ASD induced pluripotent stem cells

Molecular Autism ◽

10.1186/s13229-019-0303-3 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 7

Author(s):

Sahar Avazzadeh ◽

Katya McDonagh ◽

Jamie Reilly ◽

Yanqin Wang ◽

Stephanie D. Boomkamp ◽

...

Keyword(s):

Clinical Symptoms ◽

Neurodevelopmental Disorder ◽

Autism Spectrum ◽

Healthy Donors ◽

Human Neurons ◽

Co Morbidity ◽

Functional Consequences ◽

Skin Biopsies ◽

Screening Assays ◽

Induced Pluripotent

Abstract Background Autism spectrum disorder (ASD) is a neurodevelopmental disorder with a high co-morbidity of epilepsy and associated with hundreds of rare risk factors. NRXN1 deletion is among the commonest rare genetic factors shared by ASD, schizophrenia, intellectual disability, epilepsy, and developmental delay. However, how NRXN1 deletions lead to different clinical symptoms is unknown. Patient-derived cells are essential to investigate the functional consequences of NRXN1 lesions to human neurons in different diseases. Methods Skin biopsies were donated by five healthy donors and three ASD patients carrying NRXN1α+/− deletions. Seven control and six NRXN1α+/− iPSC lines were derived and differentiated into day 100 cortical excitatory neurons using dual SMAD inhibition. Calcium (Ca2+) imaging was performed using Fluo4-AM, and the properties of Ca2+ transients were compared between two groups of neurons. Transcriptome analysis was carried out to undercover molecular pathways associated with NRXN1α+/− neurons. Results NRXN1α+/− neurons were found to display altered calcium dynamics, with significantly increased frequency, duration, and amplitude of Ca2+ transients. Whole genome RNA sequencing also revealed altered ion transport and transporter activity, with upregulated voltage-gated calcium channels as one of the most significant pathways in NRXN1α+/− neurons identified by STRING and GSEA analyses. Conclusions This is the first report to show that human NRXN1α+/− neurons derived from ASD patients’ iPSCs present novel phenotypes of upregulated VGCCs and increased Ca2+ transients, which may facilitate the development of drug screening assays for the treatment of ASD.

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THE ULTRASTRUCTURE OF FROG VENTRICULAR CARDIAC MUSCLE AND ITS RELATIONSHIP TO MECHANISMS OF EXCITATION-CONTRACTION COUPLING

The Journal of Cell Biology ◽

10.1083/jcb.38.1.99 ◽

1968 ◽

Vol 38 (1) ◽

pp. 99-114 ◽

Cited By ~ 112

Author(s):

Nancy A. Staley ◽

Ellis S. Benson

Keyword(s):

Skeletal Muscle ◽

Cardiac Muscle ◽

Striated Muscle ◽

Structural Features ◽

Mammalian Skeletal Muscle ◽

Striated Muscles ◽

Thin Filaments ◽

Excitation Contraction Coupling ◽

Contraction Coupling ◽

Dense Granules

Frog ventricular cardiac muscle has structural features which set it apart from frog and mammalian skeletal muscle and mammalian cardiac muscle. In describing these differences, our attention focused chiefly on the distribution of cellular membranes. Abundant inter cellular clefts, the absence of tranverse tubules, and the paucity of sarcotubules, together with exceedingly small cell diameters (less than 5 µ), support the suggestion that the mechanism of excitation-contraction coupling differs in these muscle cells from that now thought to be characteristic of striated muscle such as skeletal muscle and mammalian cardiac muscle. These structural dissimilarities also imply that the mechanism of relaxation in frog ventricular muscle differs from that considered typical of other striated muscles. Additional ultrastructural features of frog ventricular heart muscle include spherical electron-opaque bodies on thin filaments, inconstantly present, forming a rank across the I band about 150 mµ from the Z line, and membrane-bounded dense granules resembling neurosecretory granules. The functional significance of these features is not yet clear.

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Troponin Variants as Markers of Skeletal Muscle Health and Diseases

Frontiers in Physiology ◽

10.3389/fphys.2021.747214 ◽

2021 ◽

Vol 12 ◽

Author(s):

Monica Rasmussen ◽

Jian-Ping Jin

Keyword(s):

Skeletal Muscle ◽

Troponin I ◽

Striated Muscle ◽

Troponin T ◽

Muscle Quality ◽

Striated Muscles ◽

Thin Filaments ◽

Age Related ◽

Development And Aging ◽

Regulation Of Muscle Contraction

Ca2+-regulated contractility is a key determinant of the quality of muscles. The sarcomeric myofilament proteins are essential players in the contraction of striated muscles. The troponin complex in the actin thin filaments plays a central role in the Ca2+-regulation of muscle contraction and relaxation. Among the three subunits of troponin, the Ca2+-binding subunit troponin C (TnC) is a member of the calmodulin super family whereas troponin I (TnI, the inhibitory subunit) and troponin T (TnT, the tropomyosin-binding and thin filament anchoring subunit) are striated muscle-specific regulatory proteins. Muscle type-specific isoforms of troponin subunits are expressed in fast and slow twitch fibers and are regulated during development and aging, and in adaptation to exercise or disuse. TnT also evolved with various alternative splice forms as an added capacity of muscle functional diversity. Mutations of troponin subunits cause myopathies. Owing to their physiological and pathological importance, troponin variants can be used as specific markers to define muscle quality. In this focused review, we will explore the use of troponin variants as markers for the fiber contents, developmental and differentiation states, contractile functions, and physiological or pathophysiological adaptations of skeletal muscle. As protein structure defines function, profile of troponin variants illustrates how changes at the myofilament level confer functional qualities at the fiber level. Moreover, understanding of the role of troponin modifications and mutants in determining muscle contractility in age-related decline of muscle function and in myopathies informs an approach to improve human health.

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Contractile Properties of Esophageal Striated Muscle: Comparison with Cardiac and Skeletal Muscles in Rats

Journal of Biomedicine and Biotechnology ◽

10.1155/2010/459789 ◽

2010 ◽

Vol 2010 ◽

pp. 1-7 ◽

Cited By ~ 2

Author(s):

Takahiko Shiina ◽

Takeshi Shima ◽

Kazuaki Masuda ◽

Haruko Hirayama ◽

Momoe Iwami ◽

...

Keyword(s):

Skeletal Muscle ◽

Striated Muscle ◽

Electrical Field Stimulation ◽

Muscle Layer ◽

Contractile Properties ◽

High Frequency Stimulation ◽

Striated Muscles ◽

High Potassium ◽

Contractile Responses ◽

Esophageal Muscle

The external muscle layer of the mammalian esophagus consists of striated muscles. We investigated the contractile properties of esophageal striated muscle by comparison with those of skeletal and cardiac muscles. Electrical field stimulation with single pulses evoked twitch-like contractile responses in esophageal muscle, similar to those in skeletal muscle in duration and similar to those in cardiac muscle in amplitude. The contractions of esophageal muscle were not affected by an inhibitor of gap junctions. Contractile responses induced by high potassium or caffeine in esophageal muscle were analogous to those in skeletal muscle. High-frequency stimulation induced a transient summation of contractions followed by sustained contractions with amplitudes similar to those of twitch-like contractions, although a large summation was observed in skeletal muscle. The results demonstrate that esophageal muscle has properties similar but not identical to those of skeletal muscle and that some specific properties may be beneficial for esophageal peristalsis.

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A Cultured Sensorimotor Organoid Model Forms Human Neuromuscular Junctions

10.1101/2021.03.03.433128 ◽

2021 ◽

Author(s):

João D. Pereira ◽

Daniel M. DuBreuil ◽

Anna-Claire Devlin ◽

Aaron Held ◽

Yechiam Sapir ◽

...

Keyword(s):

Skeletal Muscle ◽

Sensory Neurons ◽

Motor Neurons ◽

Pluripotent Stem Cells ◽

Disease Modeling ◽

Neuromuscular Junctions ◽

Familial Als ◽

Induced Pluripotent ◽

Lateral Sclerosis ◽

Individual Human

AbstractHuman induced pluripotent stem cells (iPSCs) hold promise for modeling diseases in individual human genetic backgrounds and thus for developing precision medicine. Here, we generate sensorimotor organoids containing physiologically functional neuromuscular junctions (NMJs) within a cultured organoid system and apply the model to different subgroups of amyotrophic lateral sclerosis (ALS). Using a range of molecular, genomic, and physiological techniques, we identify and characterize motor neurons and skeletal muscle, along with sensory neurons, astrocytes, microglia, and vasculature. Organoid cultures derived from ALS subject iPSC lines and isogenic lines edited to harbor familial ALS mutations all show impairment at the level of the NMJ, as detected by both contraction and immunocytochemical measurements. The physiological resolution of the human NMJ synapse, combined with the generation of major cellular cohorts exerting autonomous and non-cell autonomous effects in motor and sensory diseases, may prove valuable for more comprehensive disease modeling.

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A distinct cardiopharyngeal mesoderm genetic hierarchy establishes antero-posterior patterning of esophagus striated muscle

10.1101/600841 ◽

2019 ◽

Author(s):

Glenda Comai ◽

Églantine Heude ◽

Sebastien Mella ◽

Sylvain Paisant ◽

Francesca Pala ◽

...

Keyword(s):

Skeletal Muscle ◽

Smooth Muscle ◽

Striated Muscle ◽

Striated Muscles ◽

Loss Of Function ◽

Pharmacological Studies ◽

Posterior Migration ◽

Functional Relevance ◽

Genetic Signatures ◽

Genetic Hierarchy

SUMMARYIn most vertebrates, the upper digestive tract is composed of muscularised jaws linked to the esophagus that permit food uptake and swallowing. Masticatory and esophagus striated muscles (ESM) share a common cardiopharyngeal mesoderm (CPM) origin, however ESM are unusual among striated muscles as they are established in the absence of a primary skeletal muscle scaffold. Using mouse chimeras, we show that the transcription factors Tbx1 and Isl1 are required cell-autonomously for myogenic specification of ESM progenitors. Further, genetic loss-of-function and pharmacological studies point to Met/HGF signalling for antero-posterior migration of esophagus muscle progenitors, where HGF ligand is expressed in adjacent smooth muscle cells. These observations highlight the functional relevance of a smooth and striated muscle progenitor dialogue for ESM patterning. Our findings establish a Tbx1-Isl1-Met genetic hierarchy that uniquely regulate esophagus myogenesis and identify distinct genetic signatures that can be used as a framework to interpret pathologies arising within CPM derivatives.

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Synaptic dysfunction in neurodegenerative and neurodevelopmental diseases: an overview of induced pluripotent stem-cell-based disease models

Open Biology ◽

10.1098/rsob.180138 ◽

2018 ◽

Vol 8 (9) ◽

pp. 180138 ◽

Cited By ~ 33

Author(s):

Era Taoufik ◽

Georgia Kouroupi ◽

Ourania Zygogianni ◽

Rebecca Matsas

Keyword(s):

Stem Cell ◽

Neurodegenerative Diseases ◽

Pluripotent Stem Cell ◽

Clinical Symptoms ◽

Induced Pluripotent Stem Cell ◽

Autism Spectrum ◽

Synaptic Dysfunction ◽

Disease Models ◽

Cellular Mechanisms ◽

Induced Pluripotent

Synaptic dysfunction in CNS disorders is the outcome of perturbations in physiological synapse structure and function, and can be either the cause or the consequence in specific pathologies. Accumulating data in the field of neuropsychiatric disorders, including autism spectrum disorders, schizophrenia and bipolar disorder, point to a neurodevelopmental origin of these pathologies. Due to a relatively early onset of behavioural and cognitive symptoms, it is generally acknowledged that mental illness initiates at the synapse level. On the other hand, synaptic dysfunction has been considered as an endpoint incident in neurodegenerative diseases, such as Alzheimer's, Parkinson's and Huntington's, mainly due to the considerably later onset of clinical symptoms and progressive appearance of cognitive deficits. This dichotomy has recently been challenged, particularly since the discovery of cell reprogramming technologies and the generation of induced pluripotent stem cells from patient somatic cells. The creation of ‘disease-in-a-dish’ models for multiple CNS pathologies has revealed unexpected commonalities in the molecular and cellular mechanisms operating in both developmental and degenerative conditions, most of which meet at the synapse level. In this review we discuss synaptic dysfunction in prototype neurodevelopmental and neurodegenerative diseases, emphasizing overlapping features of synaptopathy that have been suggested by studies using induced pluripotent stem-cell-based systems. These valuable disease models have highlighted a potential neurodevelopmental component in classical neurodegenerative diseases that is worth pursuing and investigating further. Moving from demonstration of correlation to understanding mechanistic causality forms the basis for developing novel therapeutics.

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Mitochondrial Biogenesis in Striated Muscle

Canadian Journal of Applied Physiology ◽

10.1139/h94-002 ◽

1994 ◽

Vol 19 (1) ◽

pp. 12-48 ◽

Cited By ~ 27

Author(s):

David A. Hood ◽

Atila Balaban ◽

Michael K. Connor ◽

Elaine E. Craig ◽

Mary L. Nishio ◽

...

Keyword(s):

Skeletal Muscle ◽

Mitochondrial Biogenesis ◽

Protein Import ◽

Striated Muscle ◽

Cellular Systems ◽

Future Research ◽

Striated Muscles ◽

Muscle Gene Expression ◽

Key Words Heart ◽

Muscle Gene

Mitochondrial biogenesis (synthesis) has been observed to occur in skeletal muscle in response to chronic use. It also occurs in cardiac muscle during growth and hypertrophy, and it may be impaired during the aging process. This review summarizes the literature on the processes of mitochondrial biogenesis at the biochemical and molecular levels, with particular reference to striated muscles. Mitochondrial biogenesis involves the expression of nuclear and mitochondrial genes and the coordination of these two genomes, the synthesis of proteins and phospholipids and their import into the organelle, and the incorporation of these lipids and proteins into their appropriate locations within the matrix, inner or outer membranes. The emphasis is on the regulation of these events, with information derived in part from other cellular systems. Although descriptions of mitochondrial content changes in heart and skeletal muscle during altered physiological states are plentiful, much work is needed at the molecular level to investigate the regulatory processes involved. A knowledge of biochemical and molecular biology techniques is essential for continued progress in the field. This is a promising area, and potential new avenues for future research are suggested. Key words: heart, skeletal muscle, gene expression, heme metabolism, protein import

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Beta 1D integrin displaces the beta 1A isoform in striated muscles: localization at junctional structures and signaling potential in nonmuscle cells.

The Journal of Cell Biology ◽

10.1083/jcb.132.1.211 ◽

1996 ◽

Vol 132 (1) ◽

pp. 211-226 ◽

Cited By ~ 146

Author(s):

A M Belkin ◽

N I Zhidkova ◽

F Balzac ◽

F Altruda ◽

D Tomatis ◽

...

Keyword(s):

Skeletal Muscle ◽

Amino Acids ◽

Map Kinases ◽

Neuromuscular Junctions ◽

Critical Role ◽

Functional Characterization ◽

Focal Adhesions ◽

Integrin Subunit ◽

Striated Muscles ◽

Adult Skeletal Muscle

The cytoplasmic domains of integrins provide attachment of these extracellular matrix receptors to the cytoskeleton and play a critical role in integrin-mediated signal transduction. In this report we describe the identification, expression, localization, and initial functional characterization of a novel form of beta 1 integrin, termed beta 1D. This isoform contains a unique alternatively spliced cytoplasmic domain of 50 amino acids, with the last 24 amino acids encoded by an additional exon. Of these 24 amino acids, 11 are conserved when compared to the beta 1A isoform, but 13 are unique (Zhidkova, N. I., A. M. Belkin, and R. Mayne. 1995. Biochem. Biophys. Res. Commun. 214:279-285; van der Flier, A., I. Kuikman, C. Baudoin, R, van der Neuf, and A. Sonnenberg. 1995. FEBS Lett. 369:340-344). Using an anti-peptide antibody against the beta 1D integrin subunit, we demonstrated that the beta 1D isoform is synthesized only in skeletal and cardiac muscles, while very low amounts of beta 1A were detected by immunoblot in striated muscles. Whereas beta 1A could not be detected in adult skeletal muscle fibers and cardiomyocytes by immunofluorescence, beta 1D was localized to the sarcolemma of both cell types. In skeletal muscle, beta 1D was concentrated in costameres, myotendinous, and neuromuscular junctions. In cardiac muscle this beta 1 isoform was found in costamers and intercalated discs. beta 1D was associated with alpha 7A and alpha 7B in adult skeletal muscle. In cardiomyocytes of adult heart, alpha 7B was the major partner for the beta 1D isoform. beta 1D could not be detected in proliferating C2C12 myoblasts, but it appeared immediately after myoblast fusion and its amount continued to rise during myotube growth and maturation. In contrast, expression of the beta 1A isoform was downregulated during myodifferentiation in culture and it was completely displaced by beta 1D in mature differentiated myotubes. We also analyzed some functional properties of the beta 1D integrin subunit. Expression of human beta 1D in CHO cells led to its localization at focal adhesions. Clustering of this integrin isoform on the cell surface stimulated tyrosine phosphorylation of pp125FAK (focal adhesion kinase) and caused transient activation of mitogen-activated protein (MAP) kinases. These data indicate that beta 1D and beta 1A integrin isoforms are functionally similar with regard to integrin-mediated signaling.

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