scholarly journals A genetic screen for regulators of muscle morphogenesis in Drosophila

2021 ◽  
Author(s):  
Tiffany Ou ◽  
Gary Huang ◽  
Beth Wilson ◽  
Paul Gontarz ◽  
James B Skeath ◽  
...  
Keyword(s):  
Skeletal Muscles ◽  
Body Wall ◽  
Genetic Screen ◽  
Muscle Size ◽  
Forward Genetic Screen ◽  
Attachment Sites ◽  
Tendon Cells ◽  
Body Wall Musculature ◽  
New Alleles ◽  
Muscle Attachment Sites

Abstract The mechanisms that determine the final topology of skeletal muscles remain largely unknown. We have been developing Drosophila body wall musculature as a model to identify and characterize the pathways that control muscle size, shape, and orientation during embryogenesis (Johnson et al., 2013; Williams et al., 2015; Yang et al., 2020a; Yang et al., 2020b). Our working model argues muscle morphogenesis is regulated by (1) extracellular guidance cues that direct muscle cells toward muscle attachment sites, and (2) contact dependent interactions between muscles and tendon cells. While we have identified several pathways that regulate muscle morphogenesis, our understanding is far from complete. Here we report the results of a recent EMS-based forward genetic screen that identified a myriad of loci not previously associated with muscle morphogenesis. We recovered new alleles of known muscle morphogenesis genes, including back seat driver, kon-tiki, thisbe, and tumbleweed, arguing our screen had the depth and precision to uncover myogenic genes. We also identified new alleles of spalt-major, barren, and patched that presumably disrupt independent muscle morphogenesis pathways. Equally as important, our screen shows that at least 11 morphogenetic loci remain to be mapped and characterized. Our screen has developed exciting new tools to study muscle morphogenesis, which may provide future insights into the mechanisms that regulate skeletal muscle topology.

scholarly journals A genetic screen for regulators of muscle morphogenesis in Drosophila

2021 ◽  
Author(s):  
Aaron N Johnson ◽  
James B Skeath ◽  
Tiffany Ou ◽  
Beth Wilson ◽  
Paul Gontarz ◽  
...  
Keyword(s):  
Skeletal Muscles ◽  
Body Wall ◽  
Screening Strategy ◽  
Genetic Screen ◽  
Muscle Size ◽  
Forward Genetic Screen ◽  
Attachment Sites ◽  
Body Wall Musculature ◽  
New Alleles ◽  
Muscle Attachment Sites

The mechanisms that determine the final topology of skeletal muscles remain largely unknown. We have been developing Drosophila body wall musculature as a model to identify and characterize the pathways that control muscle size, shape, and orientation during embryogenesis (Johnson et al., 2013; Williams et al., 2015; Yang et al., 2020a; Yang et al., 2020b). Our working model argues muscle morphogenesis is regulated by (1) extracellular guidance cues that direct muscle cells toward muscle attachment sites, and (2) contact dependent interactions between muscles and tendons. While we have identified several pathways that regulate muscle morphogenesis, our understanding is far from complete. Here we report the results of a recent EMS-based forward genetic screen that identified a myriad of loci not previously associated with muscle morphogenesis. We recovered new alleles of known muscle morphogenesis genes, including bsd, kon, ths, and tum, arguing our screening strategy was effective and efficient. We also identified and sequenced new alleles of salm, barr, and ptc that presumably disrupt independent pathways directing muscle morphogenesis. Equally as important, our screen shows that at least 11 morphogenetic loci remain to be identified. This screen has developed exciting new tools to study muscle morphogenesis, which may provide future insights into the mechanisms that determine skeletal muscle topology.

scholarly journals Scx-positive tendon cells are required for correct muscle patterning

2021 ◽  
Author(s):  
Yudai Ono ◽  
Tempei Sato ◽  
Chisa Shukunami ◽  
Hiroshi Asahara ◽  
Masafumi Inui
Keyword(s):  
Skeletal Muscles ◽  
Essential Role ◽  
Cell Lineage ◽  
Attachment Site ◽  
Muscle Bundle ◽  
Muscle Attachment ◽  
Attachment Sites ◽  
Tendon Cells ◽  
Muscle Attachment Sites

SummaryThe elaborate movement of the vertebrate body is supported by the precise connection of muscle, tendon and bone. Each of the >600 distinct skeletal muscles in the human body has unique attachment sites; however, the mechanism through which muscles are reproducibly attached to designated partner tendons during embryonic development is incompletely understood. We herein show that Screlaxis-positive tendon cells have an essential role in correct muscle attachment in mouse embryos. Specific ablation of Screlaxis-positive cells resulted in dislocation of muscle attachment sites and abnormal muscle bundle morphology. Step-by-step observation of myogenic cell lineage revealed that post-fusion myofibers, but not migrating myoblasts, require tendon cells for their morphology. Furthermore, muscles could change their attachment site, even after the formation of the insertion. Our study demonstrated an essential role of tendon cells in the reproducibility and plasticity of skeletal muscle patterning, in turn revealing a novel tissue-tissue interaction in musculoskeletal morphogenesis.Graphical abstract

scholarly journals Intrinsic control of muscle attachment sites matching

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Alexandre Carayon ◽  
Laetitia Bataillé ◽  
Gaëlle Lebreton ◽  
Laurence Dubois ◽  
Aurore Pelletier ◽  
...  
Keyword(s):  
Live Imaging ◽  
Muscle Attachment ◽  
Regulatory Modules ◽  
Transcriptional Reprogramming ◽  
Attachment Sites ◽  
Tendon Cells ◽  
Evolutionarily Conserved ◽  
Selection Of ◽  
Muscle Attachment Sites

Myogenesis is an evolutionarily conserved process. Little known, however, is how the morphology of each muscle is determined, such that movements relying upon contraction of many muscles are both precise and coordinated. Each Drosophila larval muscle is a single multinucleated fibre whose morphology reflects expression of distinctive identity Transcription Factors (iTFs). By deleting transcription cis-regulatory modules of one iTF, Collier, we generated viable muscle identity mutants, allowing live imaging and locomotion assays. We show that both selection of muscle attachment sites and muscle/muscle matching is intrinsic to muscle identity and requires transcriptional reprogramming of syncytial nuclei. Live-imaging shows that the staggered muscle pattern involves attraction to tendon cells and heterotypic muscle-muscle adhesion. Unbalance leads to formation of branched muscles, and this correlates with locomotor behavior deficit. Thus, engineering Drosophila muscle identity mutants allows to investigate, in vivo, physiological and mechanical properties of abnormal muscles.

Morphology of muscle attachment sites and microarhitecture of underlying bone as the markers of physical activities of past populations

2013 ◽  
Author(s):  
Ksenija Djukic ◽  
Petar Milovanovic ◽  
Michael Hahn ◽  
Bjoern Busse ◽  
Michael Amling ◽  
...  
Keyword(s):  
Physical Activities ◽  
Muscle Attachment ◽  
Attachment Sites ◽  
Muscle Attachment Sites

scholarly journals Massively parallel in vivo CRISPR screening identifies RNF20/40 as epigenetic regulators of cardiomyocyte maturation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Nathan J. VanDusen ◽  
Julianna Y. Lee ◽  
Weiliang Gu ◽  
Catalina E. Butler ◽  
Isha Sethi ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Screen ◽  
Forward Genetics ◽  
Epigenetic Mark ◽  
Biological Processes ◽  
Dynamic Changes ◽  
Forward Genetic Screen ◽  
High Resource ◽  
Organ Systems

AbstractThe forward genetic screen is a powerful, unbiased method to gain insights into biological processes, yet this approach has infrequently been used in vivo in mammals because of high resource demands. Here, we use in vivo somatic Cas9 mutagenesis to perform an in vivo forward genetic screen in mice to identify regulators of cardiomyocyte (CM) maturation, the coordinated changes in phenotype and gene expression that occur in neonatal CMs. We discover and validate a number of transcriptional regulators of this process. Among these are RNF20 and RNF40, which form a complex that monoubiquitinates H2B on lysine 120. Mechanistic studies indicate that this epigenetic mark controls dynamic changes in gene expression required for CM maturation. These insights into CM maturation will inform efforts in cardiac regenerative medicine. More broadly, our approach will enable unbiased forward genetics across mammalian organ systems.

A novel basic helix-loop-helix protein is expressed in muscle attachment sites of the Drosophila epidermis

1994 ◽  
Vol 14 (6) ◽  
pp. 4145-4154
Author(s):  
P Armand ◽  
A C Knapp ◽  
A J Hirsch ◽  
E F Wieschaus ◽  
M D Cole
Keyword(s):  
Distinct Pattern ◽  
Bhlh Protein ◽  
Muscle Attachment ◽  
Muscle Creatine Kinase ◽  
Basic Helix Loop Helix ◽  
Helix Loop Helix ◽  
Attachment Sites ◽  
Bhlh Genes ◽  
Somatic Muscles ◽  
Muscle Attachment Sites

We have found that a novel basic helix-loop-helix (bHLH) protein is expressed almost exclusively in the epidermal attachments sites for the somatic muscles of Drosophila melanogaster. A Drosophila cDNA library was screened with radioactively labeled E12 protein, which can dimerize with many HLH proteins. One clone that emerged from this screen encoded a previously unknown protein of 360 amino acids, named delilah, that contains both basic and HLH domains, similar to a group of cellular transcription factors implicated in cell type determination. Delilah protein formed heterodimers with E12 that bind to the muscle creatine kinase promoter. In situ hybridization with the delilah cDNA localized the expression of the gene to a subset of cells in the epidermis which form a distinct pattern involving both the segmental boundaries and intrasegmental clusters. This pattern was coincident with the known sites of attachment of the somatic muscles to tendon cells in the epidermis. delilah expression persists in snail mutant embryos which lack mesoderm, indicating that expression of the gene was not induced by attachment of the underlying muscles. The similarity of this gene to other bHLH genes suggests that it plays an important role in the differentiation of epidermal cells into muscle attachment sites.

Epidermal tendon cells require Broad Complex function for correct attachment of the indirect flight muscles in Drosophila melanogaster

1999 ◽  
Vol 112 (22) ◽  
pp. 4051-4065 ◽  
Author(s):  
D.J. Sandstrom ◽  
L.L. Restifo
Keyword(s):  
Complex Function ◽  
Myotendinous Junction ◽  
Wild Type ◽  
Muscle Attachment ◽  
Attachment Sites ◽  
Tendon Cells ◽  
Flight Muscles ◽  
Broad Complex ◽  
Developing Muscle ◽  
Dorsal Epidermis

Drosophila Broad Complex, a primary response gene in the ecdysone cascade, encodes a family of zinc-finger transcription factors essential for metamorphosis. Broad Complex mutations of the rbp complementation group disrupt attachment of the dorsoventral indirect flight muscles during pupal development. We previously demonstrated that isoform BRC-Z1 mediates the muscle attachment function of rbp(+) and is expressed in both developing muscle fibers and their epidermal attachment sites. We now report two complementary studies to determine the cellular site and mode of action of rbp(+) during maturation of the myotendinous junctions of dorsoventral indirect flight muscles. First, genetic mosaics, produced using the paternal loss method, revealed that the muscle attachment phenotype is determined primarily by the genotype of the dorsal epidermis, with the muscle fiber and the ventral epidermis exerting little or no influence. When the dorsal epidermis was mutant, the vast majority of muscles detached or chose ectopic attachment sites, regardless of the muscle genotype. Conversely, wild-type dorsal epidermis could support attachment of mutant muscles. Second, ultrastructural analysis corroborated and extended these results, revealing defective and delayed differentiation of rbp mutant epidermal tendon cells in the dorsal attachment sites. Tendon cell processes, the stress-bearing links between the epidermis and muscle, were reduced in number and showed delayed appearance of microtubule bundles. In contrast, mutant muscle and ventral epidermis resembled the wild type. In conclusion, BRC-Z1 acts in the dorsal epidermis to ensure differentiation of the myotendinous junction. By analogy with the cell-cell interaction essential for embryonic muscle attachment, we propose that BRC-Z1 regulates one or more components of the epidermal response to a signal from the developing muscle.

Abstract LB247: A forward genetic screen to identify drivers of neuroendocrine prostate cancer

2021 ◽  
Author(s):  
Francisca Nunes de Almeida ◽  
Alessandro Vasciaveo ◽  
Min Zou ◽  
Matteo Di Bernardo ◽  
Andrea Califano ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
Genetic Screen ◽  
Forward Genetic Screen ◽  
Neuroendocrine Prostate Cancer

Mediolateral somitic origin of ribs and dermis determined by quail-chick chimeras

Development ◽  
2000 ◽  
Vol 127 (21) ◽  
pp. 4611-4617 ◽  
Author(s):  
I. Olivera-Martinez ◽  
M. Coltey ◽  
D. Dhouailly ◽  
O. Pourquie
Keyword(s):  
Skeletal Muscles ◽  
Body Wall ◽  
Primitive Streak ◽  
Axial Skeleton ◽  
Lateral Compartment ◽  
The Body ◽  
The Other ◽  
Lateral Part ◽  
Respective Contribution ◽  
Epaxial Muscles

Somites are transient mesodermal structures giving rise to all skeletal muscles of the body, the axial skeleton and the dermis of the back. Somites arise from successive segmentation of the presomitic mesoderm (PSM). They appear first as epithelial spheres that rapidly differentiate into a ventral mesenchyme, the sclerotome, and a dorsal epithelial dermomyotome. The sclerotome gives rise to vertebrae and ribs while the dermomyotome is the source of all skeletal muscles and the dorsal dermis. Quail-chick fate mapping and diI-labeling experiments have demonstrated that the epithelial somite can be further subdivided into a medial and a lateral moiety. These two subdomains are derived from different regions of the primitive streak and give rise to different sets of muscles. The lateral somitic cells migrate to form the musculature of the limbs and body wall, known as the hypaxial muscles, while the medial somite gives rise to the vertebrae and the associated epaxial muscles. The respective contribution of the medial and lateral somitic compartments to the other somitic derivatives, namely the dermis and the ribs has not been addressed and therefore remains unknown. We have created quail-chick chimeras of either the medial or lateral part of the PSM to examine the origin of the dorsal dermis and the ribs. We demonstrate that the whole dorsal dermis and the proximal ribs exclusively originates from the medial somitic compartment, whereas the distal ribs derive from the lateral compartment.

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