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At least 19 recordsLinked to original sources
PubMed2025

Balancing LncRNA H19 and miR-675 Bioconversion as a Key Regulator of Embryonic Myogenesis Under Maternal Obesity.

BACKGROUND: Maternal obesity (MO) impairs fetal skeletal muscle development, but the underlying mechanisms remain poorly defined. The regulatory roles of lncRNA H19 and its first exon derived microRNA675 (miR675) in prenatal muscle development remain to be examined. H19/Igf2 are in the same imprinting cluster with H19 expressed from the maternal allele while Igf2 expresses paternally. H19 contains a G-rich loop, and KH-type splicing regulatory protein (KHSRP) mediates the biogenesis of pre-miRNAs containing G-rich loops, which depends on its phosphorylation by AKT, a key mediator of IGF2 signalling. This study aims to depict the elusive function of these regulators that are affected by MO during embryonic myogenesis. METHODS: Single-cell transcriptomic sequencing and GeoMx spatial RNA sequencing were performed to identify the differentially expressed genes between embryos from MO and control (CT) mice. Both E11.5 and E13.5 embryos were collected and analysed to validate the sequencing data. The roles of H19 and miR657 in myogenesis were further analysed in P19 embryonic cells via CRISPR/dCas9-mediated H19 activation and inhibition. The epigenetic changes of H19 were analysed by methylated DNA immunoprecipitation, and allele-targeted analysis of H19 was performed by crossing C57BL/6J and CAST/EiJ mice. RESULTS: Transcriptomic analysis showed that MO embryos contained less differentiated myocytes (1.34%) than CT embryos (2.86%). Myogenesis-related GO biological processes were down-regulated in the MO embryonic myotome region. MO embryos showed lower expression of myogenic transcription factors such as Myf5, Myod1, Myog, Mef2c and Myh3 (p&#x2009;<&#x2009;0.05). MO altered epigenetic modifications of the H19 genomic cluster, showing a decreased methylation level in H19 imprinting control region (p&#x2009;<&#x2009;0.05) and a diallelic expression pattern of H19, which elevated its expression in MO embryos. Overexpression of H19 inhibited myogenesis in P19 cells, but miR675 promoted myogenesis, suggesting the critical regulatory roles of bioconversion of H19 to miR675. A KHSRP mediates the biogenesis of miR675, a process that relies on its phosphorylation by IGF2/AKT signalling. Knocking-down of KHSRP and inhibition of AKT abolished miR675 biogenesis. MO suppressed IGF2/AKT signalling and blocked KHSRP-dependent miR675 biogenesis in embryos. CONCLUSIONS: We found differential effects of H19 and miR675 on embryonic myogenesis. MO up-regulates H19 but blocks its miR675 bioconversion via suppressing IGF2/AKT/KHSRP signalling axis. Myogenesis in MO embryos was impeded due to the highly accumulated H19 and blocked miR675 biogenesis.

RNA, Long Noncoding↗
PubMed1978

Myogenesis in primary cell cultures from Drosophila melanogaster: protein synthesis and actin heterogeneity during development.

Muscle cell cultures from Drosophila melanogaster were obtained by plating dissociated gastrula stage embryo cells on protamine-treated culture dishes. They myogenic cells in these cultures fuse to form multinucleated pulsating cells by 15 hr after plating. An analysis of protein synthesis during myogenesis in these cultures, as measured by the incorporation of 35S-methionine and analyzed by two-dimensional polyacrylamide gel electrophoresis, showed profound changes in the pattern of protein synthesis. This analysis enabled us to identify three distinct classes of proteins. Class A proteins, the most abundant, are synthesized continuously throughout myogenesis, class B proteins are those proteins whose synthesis is initiated during myogenesis and continued throughout development; class C proteins are those synthesized at specific times during development. In addition, three forms of actin have been identified in these cultures. Actin I, which shows increased synthesis concomitant with the myogenic development in these cultures, is apparently a muscle-specific form of actin. Actin II, the predominant "cytoplasmic" form of actin in the nonmuscle Schneider cell line 2, is also the major form in the gastrula cultures before differentiation begins. Synthesis of this actin continues in the myogenic cultures. Actin III is a rapidly turning over form of actin which does not accumulate in either the Schneider cells or the myogenic cultures.

Actins↗
PubMed1977

An electron microscopic study of early developmental stages, myogenesis, oogenesis and cnidogenesis in the anthomedusa, Podocoryne carnea M. Sars.

This descriptive electron microscopic study of the blastogenetic medusa development of Podocoryne carnea focuses on the earliest stages of primordium formation, myogenesis, oogenesis and cnidogenesis. The events which take place at the cellular level prior to the formation of stage 1 (Frey, '68), which are characterized by ecto- and entodermal accumulations of undifferentiated I-cells and the beginning of transdifferentiation of epithelial cells, have been subdivided into four distinct stages (U1-U4). The genealogy of cells participating in medusa differentiation indicates that some cell types of the medusa are derived by transdifferentiation from the polyp's epithelial cells, while others originate by differentiation from I-cells. The myogenesis of the subumbrellar muscle cells resembles vertebrate myocardiac differentiation in many respects.

Animals↗
PubMed1978

Alterations in iodinated cell surface proteins during myogenesis.

Lactoperoxidase catalysed iodination was used to label surface proteins of chick embryo muscle cells during myogenesis. Both quantitative and qualitative changes were observed between 125I-labelled surface proteins of pre-fusion, mid-fusion, and post-fusion cells. Significantly, two bands at 245,000 molecular weight were present at pre-fusion but were observed as a single band at mid- and post-fusion. Radioactivity in this band increased selectively at post-fusion with a concomitant increase in lower molecular weight labelled proteins.

Animals↗
PubMed1977

Alteration in cell surface LETS protein during myogenesis.

Cell surface alterations during myogenesis have been investigated in Yaffe's myogenic cell line L8, using indirect immunofluorescence with an antibody against the large external transformation-sensitive (LETS) protein. The immunofluorescent technique reveals a susbstantial alteration in the distribution of this surface antigen. With the prefused myoblasts, LETS protein is dispersed all over the cell surface; following myoblast fusion, this pattern is markedly changed. All of the fibril-like surface LETS protein disappears, and in some myotubes, discrete clusters of LETS protein become conspicuous. By use of radioimmunological assay, the total LETS protein is quantitatively reduced upon myoblast fusion.

Antigens↗
PubMed1978

Beta-adrenergic receptors and myogenesis.

The rat myogenic cell line, L8, contains a beta-adrenergic catecholamine-sensitive adenylate cyclase. Prior to cell fusion, and continuing thereafter, beta-adrenergic sites, as determined by the stereospecific binding of (125I)-hydroxybenqylpindolol, I1(125I)IHYP] increases from 470 to 2000 sites/cell. There is also an increase in adenylate cyclase (2-5 fold) and endogenous cAMP (5-30 fold) following stimulation by catecholamine. The dissociation constant (KD) of (125I)IHYP for unfused and fused cell-homogenates, as determined by estimation with Scatchard analysis, by direct determination at receptor concentrations well below the KD, or by association (4.6 X 10(8) M-1 min-1); and dissociation (0.028 min-1) kinetics; ranged from about 40 to 70 pM. The acquisition of beta-receptors prior to fusion in L8 cells may implicate this system in the regulation of myogenesis.

Adenylyl Cyclases↗
PubMed1975

The role of cyclic AMP in myogenesis.

The effect of exogenously administered cyclic AMP derivatives and of endogenously elevated cyclic AMP levels on the spontaneous fusion of skeletal muscle myoblasts has been investigated. Contrary to earlier reports, cAMP does not appear to have a direct inhibitory effect on the fusion of an established line (L8) of rat myoblasts. Similarly, cAMP did not block the fusion of primary chick myoblasts. However, fusion of the rat myoblasts was prevented when the cAMP induced inhibition of growth prevented the cells from reaching the "critical" cell density necessary for fusion.

Bucladesine↗
PubMed1975

Utilization of yolk platelets and lipid bodies during the myogenesis of Xenopus laevis (Daudin).

The premyoblast and differentiating mononuclear myoblasts of the metameric striated muscles of Xenopus laevis were analysed for vitellolysis and lipid body utilization. In the course of myoblast differentiation the stainability of platelets stained with safranin and fast green shows essential variations. The platelets appear to lose their affinity for safranin and subsequently begin to stain with fast green. The yolk platelets were found to contain basic proteins, non-histone proteins, and phospholipids. The lipid bodies appear in the myoblast cytoplasm at the onset of vitellolysis and they disappear after yolk reserves have been utilized. After the deutoplasmatic material has been used the myoblast nuclei begin to divide and this leads to the formation of polykaryocytes.

Animals↗
PubMed1976

Expression of differentiative traits in the absence of cell fusion during myogenesis in culture.

Fusion of myoblasts is inhibited in cultures at low Ca++ concentration (0.44 mM); yet creatine phosphokinase and myokinase activities as well as myosin synthesis and the appearance of post-mitotic myoblasts do not significantly differ from those of control cultures (grown at 1.04 mM Ca++) which undergo cell fusion. When Ca++ concentration is increased to the control value after the second day of culture, fusion occurs very rapidly and it is not inhibited by actinomycin D or cycloheximide. Treatment with 0.06 mM bromodeoxyuridine strongly inhibits creatine phosphokinase activity and myotubes formation. The study of the kinetics of reversal of cell fusion and of creatine phosphokinase activity after removal of the analog, shows that this process is slower than the decrease of the relative content of bromodeoxyuridine incorporated into DNA. The result obtained support the following conclusions: a) the expression of the differentiative characters examined does not require cell fusion; b) the process of myotube formation seems to imply two subsequent stages consisting first of a slow maturative process, which is followed by the actual fusion of cell membranes; the former is Ca++ independent, the latter is Ca++ dependent and does not require RNA or protein synthesis.

Adenylate Kinase↗
PubMed1979

Manipulation of myogenesis in vitro: reversible inhibition by DMSO.

A system has been developed for the detailed analysis of the transition from proliferative myoblast to differentiated muscle cell. Dimethylsulfoxide (DMSO) prevents the terminal differentiation of L8 myoblasts in vitro, and its effect is reversible. DMSO (2%) inhibits the fusion of myoblasts to form multinucleate myotubes, the normal increases in activity of creatine phosphokinase (CPK) and acetylcholinesterase, and the synthesis of alpha-actin and acetylcholine receptor protein. Upon removal of DMSO from the medium, a lag precedes the onset of differentiation. The potential to inhibit muscle differentiation reversibly is not specific to DMSO, but is shared by a number of compounds, including dimethylformamide, hexamethylbisacetamide and butyric acid, all potent inducers of gene expression in Friend erythroleukemia cells. L8 cells routinely cease DNA synthesis and initiate fusion and muscle protein synthesis once they are confluent. In the presence of DMSO, however, nearly all cells continue DNA synthesis, even several days after reaching confluence. Protein synthetic patterns of DMSO-inhibited cells are almost indistinguishable from those of untreated myoblasts and distinct from differentiated myotubes. It appears that cells exposed to DMSO are locked indefinitely in a proliferative myoblast stage of development and are unable to enter the Go phase of the cell cycle necessary for initiation of differentiation. DMSO coordinately inhibits all the differentiative parameters measured. In contrast, cytochalasin B uncouples normally linked differentiative events so that fusion is inhibited while muscle-specific protein synthesis proceeds. DMSO has similar effects on both cytochalasin B-treated and fusing control cultures, suggesting that its primary effect is exerted not at the level of fusion but earlier in the differentiative time-table. Once fusion and the synthesis of muscle-specific proteins are well under way, the addition of DMSO is ineffective and differentiation continues in its presence. The potential to manipulate muscle gene expression in vitro makes this system particularly useful for the detailed analysis of the processes involved in the transition to the differentiated state and for determining the linkage of developmental events.

Actins↗