scholarly journals Muscle Giants: Molecular Scaffolds in Sarcomerogenesis

2009 ◽  
Vol 89 (4) ◽  
pp. 1217-1267 ◽  
Author(s):  
Aikaterini Kontrogianni-Konstantopoulos ◽  
Maegen A. Ackermann ◽  
Amber L. Bowman ◽  
Solomon V. Yap ◽  
Robert J. Bloch
Keyword(s):  
Signaling Proteins ◽  
Striated Muscles ◽  
Molecular Scaffolds ◽  
Protein Ligands ◽  
Complex Process ◽  
Molecular Ruler ◽  
Specific Proteins ◽  
Contradictory Evidence ◽  
And Function ◽  
Regular Arrays

Myofibrillogenesis in striated muscles is a highly complex process that depends on the coordinated assembly and integration of a large number of contractile, cytoskeletal, and signaling proteins into regular arrays, the sarcomeres. It is also associated with the stereotypical assembly of the sarcoplasmic reticulum and the transverse tubules around each sarcomere. Three giant, muscle-specific proteins, titin (3–4 MDa), nebulin (600–800 kDa), and obscurin (∼720–900 kDa), have been proposed to play important roles in the assembly and stabilization of sarcomeres. There is a large amount of data showing that each of these molecules interacts with several to many different protein ligands, regulating their activity and localizing them to particular sites within or surrounding sarcomeres. Consistent with this, mutations in each of these proteins have been linked to skeletal and cardiac myopathies or to muscular dystrophies. The evidence that any of them plays a role as a “molecular template,” “molecular blueprint,” or “molecular ruler” is less definitive, however. Here we review the structure and function of titin, nebulin, and obscurin, with the literature supporting a role for them as scaffolding molecules and the contradictory evidence regarding their roles as molecular guides in sarcomerogenesis.

scholarly journals Drosophila chibby is required for basal body formation and ciliogenesis but not for Wg signaling

2012 ◽  
Vol 197 (2) ◽  
pp. 313-325 ◽  
Author(s):  
Camille Enjolras ◽  
Joëlle Thomas ◽  
Brigitte Chhin ◽  
Elisabeth Cortier ◽  
Jean-Luc Duteyrat ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Basal Body ◽  
Coiled Coil ◽  
Cell Types ◽  
Sensory Transduction ◽  
Basal Bodies ◽  
Neuronal Cilia ◽  
Complex Process ◽  
Specific Proteins ◽  
And Function

Centriole-to–basal body conversion, a complex process essential for ciliogenesis, involves the progressive addition of specific proteins to centrioles. CHIBBY (CBY) is a coiled-coil domain protein first described as interacting with β-catenin and involved in Wg-Int (WNT) signaling. We found that, in Drosophila melanogaster, CBY was exclusively expressed in cells that require functional basal bodies, i.e., sensory neurons and male germ cells. CBY was associated with the basal body transition zone (TZ) in these two cell types. Inactivation of cby led to defects in sensory transduction and in spermatogenesis. Loss of CBY resulted in altered ciliary trafficking into neuronal cilia, irregular deposition of proteins on spermatocyte basal bodies, and, consequently, distorted axonemal assembly. Importantly, cby1/1 flies did not show Wingless signaling defects. Hence, CBY is essential for normal basal body structure and function in Drosophila, potentially through effects on the TZ. The function of CBY in WNT signaling in vertebrates has either been acquired during vertebrate evolution or lost in Drosophila.

scholarly journals Meiosis in Polyploids and Implications for Genetic Mapping: A Review

Genes ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1517
Author(s):  
Nina Reis Soares ◽  
Marcelo Mollinari ◽  
Gleicy K. Oliveira ◽  
Guilherme S. Pereira ◽  
Maria Lucia Carneiro Vieira
Keyword(s):  
Oilseed Rape ◽  
Genetic Maps ◽  
Crop Species ◽  
Map Construction ◽  
Complex Process ◽  
New Gene ◽  
Specific Proteins ◽  
Bivalent Formation ◽  
Essential Knowledge

Plant cytogenetic studies have provided essential knowledge on chromosome behavior during meiosis, contributing to our understanding of this complex process. In this review, we describe in detail the meiotic process in auto- and allopolyploids from the onset of prophase I through pairing, recombination, and bivalent formation, highlighting recent findings on the genetic control and mode of action of specific proteins that lead to diploid-like meiosis behavior in polyploid species. During the meiosis of newly formed polyploids, related chromosomes (homologous in autopolyploids; homologous and homoeologous in allopolyploids) can combine in complex structures called multivalents. These structures occur when multiple chromosomes simultaneously pair, synapse, and recombine. We discuss the effectiveness of crossover frequency in preventing multivalent formation and favoring regular meiosis. Homoeologous recombination in particular can generate new gene (locus) combinations and phenotypes, but it may destabilize the karyotype and lead to aberrant meiotic behavior, reducing fertility. In crop species, understanding the factors that control pairing and recombination has the potential to provide plant breeders with resources to make fuller use of available chromosome variations in number and structure. We focused on wheat and oilseed rape, since there is an abundance of elucidating studies on this subject, including the molecular characterization of the Ph1 (wheat) and PrBn (oilseed rape) loci, which are known to play a crucial role in regulating meiosis. Finally, we exploited the consequences of chromosome pairing and recombination for genetic map construction in polyploids, highlighting two case studies of complex genomes: (i) modern sugarcane, which has a man-made genome harboring two subgenomes with some recombinant chromosomes; and (ii) hexaploid sweet potato, a naturally occurring polyploid. The recent inclusion of allelic dosage information has improved linkage estimation in polyploids, allowing multilocus genetic maps to be constructed.

scholarly journals Use, Purpose, and Function—Letting the Artifacts Speak

Heritage ◽  
2020 ◽  
Vol 3 (3) ◽  
pp. 587-605
Author(s):  
Jennifer A. Loughmiller-Cardinal ◽  
J. Scott Cardinal
Keyword(s):  
Functional Categories ◽  
Apparent Contradiction ◽  
Basic Premise ◽  
The Past ◽  
The People ◽  
Implicit Biases ◽  
Archaeological Materials ◽  
History Of ◽  
Contradictory Evidence ◽  
And Function

Archaeologists have likely collected, as a conservative estimate, billions of artifacts over the course of the history of fieldwork. We have classified chronologies and typologies of these, based on various formal and physical characteristics or ethno-historically known analogues, to give structure to our interpretations of the people that used them. The simple truth, nonetheless, is that we do not actually know how they were used or their intended purpose. We only make inferences—i.e., educated guesses based on the available evidence as we understand it—regarding their functions in the past and the historical behaviors they reflect. Since those inferences are so fundamental to the interpretations of archaeological materials, and the archaeological project as a whole, the way we understand materiality can significantly bias the stories we construct of the past. Recent work demonstrated seemingly contradictory evidence between attributed purpose or function versus confirmed use, however, which suggested that a basic premise of those inferences did not empirically hold to be true. In each case, the apparent contradiction was resolved by reassessing what use, purpose, and function truly mean and whether certain long-established functional categories of artifacts were in fact classifying by function. The resulting triangulation, presented here, narrows the scope on such implicit biases by addressing both empirical and conceptual aspects of artifacts. In anchoring each aspect of evaluation to an empirical body of data, we back ourselves away from our assumptions and interpretations so as to let the artifacts speak for themselves.

scholarly journals Genome Analyses and Genome-Centered Metatranscriptomics of Methanothermobacter wolfeii Strain SIV6, Isolated from a Thermophilic Production-Scale Biogas Fermenter

2019 ◽  
Vol 8 (1) ◽  
pp. 13
Author(s):  
Julia Hassa ◽  
Daniel Wibberg ◽  
Irena Maus ◽  
Alfred Pühler ◽  
Andreas Schlüter
Keyword(s):  
Microbial Community ◽  
Biogas Production ◽  
Gc Content ◽  
Production Scale ◽  
Circular Chromosome ◽  
Hydrogenotrophic Methanogenesis ◽  
Complex Process ◽  
Indigenous Microbial Community ◽  
Genome Analyses ◽  
And Function

In the thermophilic biogas-producing microbial community, the genus Methanothermobacter was previously described to be frequently abundant. The aim of this study was to establish and analyze the genome sequence of the archaeal strain Methanothermobacter wolfeii SIV6 originating from a thermophilic industrial-scale biogas fermenter and compare it to related reference genomes. The circular chromosome has a size of 1,686,891 bases, featuring a GC content of 48.89%. Comparative analyses considering three completely sequenced Methanothermobacter strains revealed a core genome of 1494 coding sequences and 16 strain specific genes for M. wolfeii SIV6, which include glycosyltransferases and CRISPR/cas associated genes. Moreover, M. wolfeii SIV6 harbors all genes for the hydrogenotrophic methanogenesis pathway and genome-centered metatranscriptomics indicates the high metabolic activity of this strain, with 25.18% of all transcripts per million (TPM) belong to the hydrogenotrophic methanogenesis pathway and 18.02% of these TPM exclusively belonging to the mcr operon. This operon encodes the different subunits of the enzyme methyl-coenzyme M reductase (EC: 2.8.4.1), which catalyzes the final and rate-limiting step during methanogenesis. Finally, fragment recruitment of metagenomic reads from the thermophilic biogas fermenter on the SIV6 genome showed that the strain is abundant (1.2%) within the indigenous microbial community. Detailed analysis of the archaeal isolate M. wolfeii SIV6 indicates its role and function within the microbial community of the thermophilic biogas fermenter, towards a better understanding of the biogas production process and a microbial-based management of this complex process.

scholarly journals Tenectin recruits integrin to stabilize bouton architecture and regulate vesicle release at the Drosophila neuromuscular junction

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Qi Wang ◽  
Tae Hee Han ◽  
Peter Nguyen ◽  
Michal Jarnik ◽  
Mihaela Serpe
Keyword(s):  
Neuromuscular Junction ◽  
Motor Neurons ◽  
Synaptic Cleft ◽  
Membrane Skeleton ◽  
Biologically Active ◽  
Striated Muscles ◽  
Local Engagement ◽  
Synaptic Junctions ◽  
Synaptic Boutons ◽  
And Function

Assembly, maintenance and function of synaptic junctions depend on extracellular matrix (ECM) proteins and their receptors. Here we report that Tenectin (Tnc), a Mucin-type protein with RGD motifs, is an ECM component required for the structural and functional integrity of synaptic specializations at the neuromuscular junction (NMJ) in Drosophila. Using genetics, biochemistry, electrophysiology, histology and electron microscopy, we show that Tnc is secreted from motor neurons and striated muscles and accumulates in the synaptic cleft. Tnc selectively recruits αPS2/βPS integrin at synaptic terminals, but only the cis Tnc/integrin complexes appear to be biologically active. These complexes have distinct pre- and postsynaptic functions, mediated at least in part through the local engagement of the spectrin-based membrane skeleton: the presynaptic complexes control neurotransmitter release, while postsynaptic complexes ensure the size and architectural integrity of synaptic boutons. Our study reveals an unprecedented role for integrin in the synaptic recruitment of spectrin-based membrane skeleton.

scholarly journals The Adapter Protein SLP-76 Mediates “Outside-In” Integrin Signaling and Function in T Cells

2009 ◽  
Vol 29 (20) ◽  
pp. 5578-5589 ◽  
Author(s):  
R. G. Baker ◽  
C. J. Hsu ◽  
D. Lee ◽  
M. S. Jordan ◽  
J. S. Maltzman ◽  
...  
Keyword(s):  
T Cells ◽  
Cell Adhesion ◽  
T Cell ◽  
Sh2 Domain ◽  
Integrin Signaling ◽  
Signaling Proteins ◽  
Adapter Protein ◽  
Tcr Signaling ◽  
Integrin Ligands ◽  
And Function

ABSTRACT The adapter protein SH2 domain-containing leukocyte protein of 76 kDa (SLP-76) is an essential mediator of signaling from the T-cell antigen receptor (TCR). We report here that SLP-76 also mediates signaling downstream of integrins in T cells and that SLP-76-deficient T cells fail to support adhesion to integrin ligands. In response to both TCR and integrin stimulation, SLP-76 relocalizes to surface microclusters that colocalize with phosphorylated signaling proteins. Disruption of SLP-76 recruitment to the protein named LAT (linker for activation of T cells) inhibits SLP-76 clustering downstream of the TCR but not downstream of integrins. Conversely, an SLP-76 mutant unable to bind ADAP (adhesion and degranulation-promoting adapter protein) forms clusters following TCR but not integrin engagement and fails to support T-cell adhesion to integrin ligands. These findings demonstrate that SLP-76 relocalizes to integrin-initiated signaling complexes by a mechanism different from that employed during TCR signaling and that SLP-76 relocalization corresponds to SLP-76-dependent integrin function in T cells.

Costameres, focal adhesions, and cardiomyocyte mechanotransduction

2005 ◽  
Vol 289 (6) ◽  
pp. H2291-H2301 ◽  
Author(s):  
Allen M. Samarel
Keyword(s):  
Growth Factor ◽  
Focal Adhesions ◽  
Growth Factor Signaling ◽  
Cellular Mechanisms ◽  
Growth And Survival ◽  
Specific Proteins ◽  
And Function ◽  
Cytoskeletal Elements ◽  
Biochemical Signals ◽  
Cellular Components

Mechanotransduction refers to the cellular mechanisms by which load-bearing cells sense physical forces, transduce the forces into biochemical signals, and generate appropriate responses leading to alterations in cellular structure and function. This process affects the beat-to-beat regulation of cardiac performance but also affects the proliferation, differentiation, growth, and survival of the cellular components that comprise the human myocardium. This review focuses on the experimental evidence indicating that the costamere and its structurally related structure the focal adhesion complex are critical cytoskeletal elements involved in cardiomyocyte mechanotransduction. Biochemical signals originating from the extracellular matrix-integrin-costameric protein complex share many common features with those signals generated by growth factor receptors. The roles of key regulatory kinases and other muscle-specific proteins involved in mechanotransduction and growth factor signaling are discussed, and issues requiring further study in this field are outlined.

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