RESUMEN
The meiotic TopoVI B subunit (MTopVIB) plays an essential role in double-strand break formation in mouse (Mus musculus), Arabidopsis (Arabidopsis thaliana), and rice (Oryza sativa), and recent work reveals that rice MTopVIB also plays an unexpected role in meiotic bipolar spindle assembly, highlighting multiple functions of MTopVIB during rice meiosis. In this work, we characterized the meiotic TopVIB in maize (Zea mays; ZmMTOPVIB). The ZmmtopVIB mutant plants exhibited normal vegetative growth but male and female sterility. Meiotic double-strand break formation was abolished in mutant meiocytes. Despite normal assembly of axial elements, mutants showed severely affected synapsis and disrupted homologous pairing. Importantly, we showed that bipolar spindle assembly was also affected in ZmmtopVIB, resulting in triad and polyad formation. Overall, our results demonstrate that ZmMTOPVIB plays critical roles in double-strand break formation and homologous recombination. In addition, our results suggest that the function of MTOPVIB in bipolar spindle assembly is likely conserved across different monocots.
Asunto(s)
Roturas del ADN de Doble Cadena , Meiosis/genética , Meiosis/fisiología , Complejo Sinaptonémico/genética , Complejo Sinaptonémico/fisiología , Zea mays/genética , Zea mays/fisiología , Productos Agrícolas/genética , Productos Agrícolas/fisiología , Regulación de la Expresión Génica de las Plantas , Genes de PlantasRESUMEN
Plakin proteins form connections that link the cell membrane to the intermediate filament cytoskeleton. Their interactions are mediated by a highly conserved linker domain through an unresolved mechanism. Here analysis of the human periplakin linker domain structure reveals a bi-lobed module transected by an electropositive groove. Key basic residues within the periplakin groove are vital for co-localization with vimentin in human cells and compromise direct binding which also requires acidic residues D176 and E187 in vimentin. We propose a model whereby basic periplakin linker domain residues recognize acidic vimentin side chains and form a complementary binding groove. The model is shared amongst diverse linker domains and can be used to investigate the effects of pathogenic mutations in the desmoplakin linker associated with arrhythmogenic right ventricular cardiomyopathy. Linker modules either act solely or collaborate with adjacent plakin repeat domains to create strong and adaptable tethering within epithelia and cardiac muscle.
Asunto(s)
Plaquinas/química , Plaquinas/metabolismo , Vimentina/química , Vimentina/metabolismo , Secuencia de Aminoácidos , Aminoácidos Acídicos/química , Aminoácidos Acídicos/genética , Aminoácidos Acídicos/metabolismo , Ácido Aspártico/metabolismo , Ácido Glutámico/metabolismo , Células HeLa , Humanos , Filamentos Intermedios/química , Filamentos Intermedios/metabolismo , Modelos Moleculares , Mutación Missense , Plaquinas/genética , Unión Proteica/genética , Dominios y Motivos de Interacción de Proteínas/genética , Estructura Cuaternaria de Proteína , Vimentina/genéticaRESUMEN
In collective cell migration, directional protrusions orient cells in response to external cues, which requires coordinated polarity among the migrating cohort. However, the molecular mechanism has not been well defined. Drosophila border cells (BCs) migrate collectively and invade via the confined space between nurse cells, offering an in vivo model to examine how group polarity is organized. Here, we show that the front/back polarity of BCs requires Rap1, hyperactivation of which disrupts cluster polarity and induces misoriented protrusions and loss of asymmetry in the actin network. Conversely, hypoactive Rap1 causes fewer protrusions and cluster spinning during migration. A forward genetic screen revealed that downregulation of the Hippo (Hpo) pathway core components hpo or mats enhances the Rap1V12-induced migration defect and misdirected protrusions. Mechanistically, association of Rap1V12 with the kinase domain of Hpo suppresses its activity, which releases Hpo signaling-mediated suppression of F-actin elongation, promoting cellular protrusions in collective cell migration.
Asunto(s)
Movimiento Celular , Polaridad Celular , Extensiones de la Superficie Celular/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/citología , Drosophila melanogaster/metabolismo , Péptidos y Proteínas de Señalización Intracelular/metabolismo , Proteínas Serina-Treonina Quinasas/metabolismo , Transducción de Señal , Proteínas de Unión a Telómeros/metabolismo , Actomiosina/metabolismo , Animales , Epistasis Genética , Modelos Biológicos , Complejo ShelterinaRESUMEN
Current intraocular pressure (IOP) measurement using air puff could be erroneous without applying proper corrections. Although noncontact tonometry is not considered to be accurate, it is still popularly used by eye clinics. It is thus necessary to extract the correct information from their results. This study proposes a practical approach to correctly measure IOP in vivo. By embedding a new model-based correction to the Corvis® ST, we can extract the corneal Young's modulus from the patient data. This Young's modulus can be used to correct the IOP readings. The tests were applied to 536 right eyes of 536 healthy subjects (228 male and 308 female) between March of 2012 and April of 2016. The tests were applied to patients at the Department of Ophthalmology, National Taiwan University Hospital and the Hung-Chuo Eye Clinics. The statistical analysis showed that the value for the Young's modulus was independent of all the other parameters collected from the Corvis ST, including the corneal thickness and the intraocular pressure. Therefore, it is important to independently measure the Young's modulus instead of depending on the correlation with the other parameters. This study adds the methodology of measuring corneal stiffness in vivo for ophthalmologists' reference in diagnosis.
