Rim4 is a Thermal Sensor and Driver of Meiosis-specific Stress Granules.

Rim4 is a meiosis-specific RNA-binding protein (RBP) that sequesters mRNAs to suppress their translation. Previous work has defined the Rim4 C-terminal low-complexity domain (LCD) as sequences that form self-propagating amyloid-like aggregates. Here, we uncovered a dynamic and reversible form of Rim4 self-assembly primarily triggered by heat during meiosis, proportionally from 30°C to 42°C.

Autophagy-mediated post-transcriptional surveillance of meiotic translation in .

In , macroautophagy/autophagy plays a pivotal role and is indispensable for multiple meiotic processes. In this study, we demonstrate that Rim4, a meiosis-specific RNA-binding protein (RBP) that holds back the translation of a specific subset of meiotic transcripts until its programmed degradation by autophagy during meiotic divisions, forms a heterotrimeric complex with the yeast YWHA/14-3-3 proteins Bmh1 and Bmh2, which effectively expels mRNAs from Rim4's binding grip. We pinpoint four distinct Bmh1 and Bhm2 binding sites (BBSs) in the Rim4 structure, with two of them nestled within the RNA recognition motifs (RRMs).

Regulation of Rim4 distribution, function, and stability during meiosis by PKA, Cdc14, and 14-3-3 proteins.

Meiotic gene expression in budding yeast is tightly controlled by RNA-binding proteins (RBPs), with the meiosis-specific RBP Rim4 playing a key role in sequestering mid-late meiotic transcripts to prevent premature translation. However, the mechanisms governing assembly and disassembly of the Rim4-mRNA complex, critical for Rim4's function and stability, remain poorly understood. In this study, we unveil regulation of the Rim4 ribonucleoprotein (RNP) complex by the yeast 14-3-3 proteins Bmh1 and Bmh2.

Autophagy-mediated surveillance of Rim4-mRNA interaction safeguards programmed meiotic translation.

In yeast meiosis, autophagy is active and essential. Here, we investigate the fate of Rim4, a meiosis-specific RNA-binding protein (RBP), and its associated transcripts during meiotic autophagy. We demonstrate that Rim4 employs a nuclear localization signal (NLS) to enter the nucleus, where it loads its mRNA substrates before nuclear export.

Autophagy of an Amyloid-like Translational Repressor Regulates Meiotic Exit.

We explored the potential for autophagy to regulate budding yeast meiosis. Following pre-meiotic DNA replication, we blocked autophagy by chemical inhibition of Atg1 kinase or engineered degradation of Atg14 and observed homologous chromosome segregation followed by sister chromatid separation; cells then underwent additional rounds of spindle formation and disassembly without DNA re-replication, leading to aberrant chromosome segregation. Analysis of cell-cycle regulators revealed that autophagy inhibition prevents meiosis II-specific expression of Clb3 and leads to the aberrant persistence of Clb1 and Cdc5, two substrates of a meiotic ubiquitin ligase activated by Ama1.

Blood meal acquisition enhances arbovirus replication in mosquitoes through activation of the GABAergic system.

Mosquitoes are hematophagous insects that carry-on and transmit many human viruses. However, little information is available regarding the common mechanisms underlying the infection of mosquitoes by these viruses. In this study, we reveal that the hematophagous nature of mosquitoes contributes to arboviral infection after a blood meal, which suppresses antiviral innate immunity by activating the GABAergic pathway.

Delineating antibody recognition against Zika virus during natural infection.

Zika virus (ZIKV) is an emerging mosquito-transmitted flavivirus that shares a considerable degree of homology with dengue virus (DENV). Here, we examined longitudinal antibody response against ZIKV during natural infection in 2 convalescent individuals. By decomposing the antibody recognition into DI/DII and DIII of the E glycoprotein, we showed their development in humans followed a spatiotemporal hierarchy.

Evolutionary enhancement of Zika virus infectivity in Aedes aegypti mosquitoes.

Zika virus (ZIKV) remained obscure until the recent explosive outbreaks in French Polynesia (2013-2014) and South America (2015-2016). Phylogenetic studies have shown that ZIKV has evolved into African and Asian lineages. The Asian lineage of ZIKV was responsible for the recent epidemics in the Americas.

A Mesh-Duox pathway regulates homeostasis in the insect gut.

The metazoan gut harbours complex communities of commensal and symbiotic bacterial microorganisms. The quantity and quality of these microorganisms fluctuate dynamically in response to physiological changes. The mechanisms that hosts have developed to respond to and manage such dynamic changes and maintain homeostasis remain largely unknown.

Regulation of Antimicrobial Peptides in Aag2 Cells.

Antimicrobial peptides (AMPs) are an important group of immune effectors that play a role in combating microbial infections in invertebrates. Most of the current information on the regulation of insect AMPs in microbial infection have been gained from , and their regulation in other insects are still not completely understood. Here, we generated an AMP induction profile in response to infections with some Gram-negative, -positive bacteria, and fungi in embryonic Aag2 cells.

Progress towards understanding the pathogenesis of dengue hemorrhagic fever.

Dengue virus (DENV) is a mosquito-borne virus belonging to the Flaviviridae family. There are 4 serotypes of DENV that cause human disease through transmission by mosquito vectors. DENV infection results in a broad spectrum of clinical symptoms, ranging from mild fever to dengue hemorrhagic fever (DHF), the latter of which can progress to dengue shock syndrome (DSS) and death.

Mosquito C-type lectins maintain gut microbiome homeostasis.

The long-term evolutionary interaction between the host immune system and symbiotic bacteria determines their cooperative rather than antagonistic relationship. It is known that commensal bacteria have evolved a number of mechanisms to manipulate the mammalian host immune system and maintain homeostasis. However, the strategies employed by the microbiome to overcome host immune responses in invertebrates still remain to be understood.

Mosquito C-type lectins maintain gut microbiome homeostasis.

The long-term evolutionary interaction between the host immune system and symbiotic bacteria determines their cooperative rather than antagonistic relationship. It is known that commensal bacteria have evolved a number of mechanisms to manipulate the mammalian host immune system and maintain homeostasis. However, the strategies employed by the microbiome to overcome host immune responses in invertebrates still remain to be understood.

Core signaling pathways of survival/death in autophagy-related cancer networks.

Autophagy (macroautophagy), an evolutionarily conserved lysosomal degradation process, is implicated in a wide variety of pathological processes including cancer. Autophagy plays the Janus role in regulating several survival or death signaling pathways that may decide the fate of cancer cell. Accumulating evidence has revealed the core molecular machinery of autophagy in tumor initiation and progression; however, the intricate relationships between autophagy and cancer are still in its infancy.