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1.
Mol Biol Cell ; 31(17): 1846-1856, 2020 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-32520628

RESUMO

Microtubules of the mitotic spindle direct cytokinesis in metazoans but this has not been documented in fungi. We report evidence that microtubule nucleators at the spindle pole body help coordinate cytokinetic furrow formation in fission yeast. The temperature-sensitive cps1-191 strain (Liu et al., 1999) with a D277N substitution in ß-glucan synthase 1 (Cps1/Bgs1) was reported to arrest with an unconstricted contractile ring. We discovered that contractile rings in cps1-191 cells constrict slowly and that an mto2S338N mutation is required with the bgs1D277Nmutation to reproduce the cps1-191 phenotype. Complexes of Mto2 and Mto1 with γ-tubulin regulate microtubule assembly. Deletion of Mto1 along with the bgs1D277N mutation also gives the cps1-191 phenotype, which is not observed in mto2S338N or mto1Δ cells expressing bgs1+. Both mto2S338N and mto1Δ cells nucleate fewer astral microtubules than normal and have higher levels of Rho1-GTP at the division site than wild-type cells. We report multiple conditions that sensitize mto1Δ and mto2S338N cells to furrow ingression phenotypes.


Assuntos
Proteínas de Transporte/metabolismo , Proteínas Associadas aos Microtúbulos/metabolismo , Microtúbulos/metabolismo , Proteínas de Schizosaccharomyces pombe/metabolismo , Proteínas de Transporte/fisiologia , Citocinese/fisiologia , Proteínas Associadas aos Microtúbulos/genética , Proteínas Associadas aos Microtúbulos/fisiologia , Centro Organizador dos Microtúbulos , Microtúbulos/fisiologia , Fenótipo , Schizosaccharomyces/genética , Schizosaccharomyces/metabolismo , Proteínas de Schizosaccharomyces pombe/genética , Proteínas de Schizosaccharomyces pombe/fisiologia , Fuso Acromático , Tubulina (Proteína)/genética
2.
J Cell Biol ; 219(4)2020 04 06.
Artigo em Inglês | MEDLINE | ID: mdl-32328638

RESUMO

Fragile-X mental retardation autosomal homologue-1 (FXR1) is a muscle-enriched RNA-binding protein. FXR1 depletion is perinatally lethal in mice, Xenopus, and zebrafish; however, the mechanisms driving these phenotypes remain unclear. The FXR1 gene undergoes alternative splicing, producing multiple protein isoforms and mis-splicing has been implicated in disease. Furthermore, mutations that cause frameshifts in muscle-specific isoforms result in congenital multi-minicore myopathy. We observed that FXR1 alternative splicing is pronounced in the serine- and arginine-rich intrinsically disordered domain; these domains are known to promote biomolecular condensation. Here, we show that tissue-specific splicing of fxr1 is required for Xenopus development and alters the disordered domain of FXR1. FXR1 isoforms vary in the formation of RNA-dependent biomolecular condensates in cells and in vitro. This work shows that regulation of tissue-specific splicing can influence FXR1 condensates in muscle development and how mis-splicing promotes disease.


Assuntos
Processamento Alternativo/genética , Células Musculares/metabolismo , Proteínas de Ligação a RNA/genética , Proteínas de Xenopus/genética , Adulto , Idoso , Animais , Células Cultivadas , Feminino , Humanos , Lactente , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos , Pessoa de Meia-Idade , Desenvolvimento Muscular , Músculos/metabolismo , Proteínas de Ligação a RNA/metabolismo , Xenopus , Proteínas de Xenopus/metabolismo , Adulto Jovem
3.
Mol Biol Cell ; 27(13): 2000-7, 2016 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-27193301

RESUMO

Nuclei in syncytia found in fungi, muscles, and tumors can behave independently despite cytoplasmic translation and the homogenizing potential of diffusion. We use a dynactin mutant strain of the multinucleate fungus Ashbya gossypii with highly clustered nuclei to assess the relative contributions of nucleus and cytoplasm to nuclear autonomy. Remarkably, clustered nuclei maintain cell cycle and transcriptional autonomy; therefore some sources of nuclear independence function even with minimal cytosol insulating nuclei. In both nuclear clusters and among evenly spaced nuclei, a nucleus' transcriptional activity dictates local cytoplasmic contents, as assessed by the localization of several cyclin mRNAs. Thus nuclear activity is a central determinant of the local cytoplasm in syncytia. Of note, we found that the number of nuclei per unit cytoplasm was identical in the mutant to that in wild-type cells, despite clustered nuclei. This work demonstrates that nuclei maintain autonomy at a submicrometer scale and simultaneously maintain a normal nucleocytoplasmic ratio across a syncytium up to the centimeter scale.


Assuntos
Núcleo Celular/metabolismo , Células Gigantes/metabolismo , Ciclo Celular/fisiologia , Núcleo Celular/fisiologia , Divisão do Núcleo Celular/fisiologia , Ciclinas/metabolismo , Citoplasma/metabolismo , Citoplasma/patologia , Proteínas Fúngicas/metabolismo , Fungos/metabolismo , Células Gigantes/fisiologia , Mitose , Saccharomycetales/metabolismo , Ativação Transcricional
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