Mosquito-borne arboviruses are responsible for recent dengue, chikungunya, and Zika pandemics. The yellow-fever mosquito, Aedes aegypti, plays an important role in the transmission of all three viruses. We developed a miRNA-based approach that results in a dual resistance phenotype in mosquitoes to dengue serotype 3 (DENV-3) and chikungunya (CHIKV) viruses. The target viruses are from two distinct arboviral families and the antiviral mechanism is designed to function through the endogenous miRNA pathway in infected mosquitoes. Challenge experiments showed reductions in viral transmission efficiency of transgenic mosquitoes. Several components of mosquito fitness were examined, and transgenic mosquitoes with the PUb promoter showed minor fitness costs at all developing stages. Further development of these strains with gene editing tools could make them candidates for releases in population replacement strategies for sustainable control of multiple arbovirus diseases.

Summary The insect sex determination and the intimately linked dosage compensation pathways represent a challenging evolutionary puzzle that has been solved only in Drosophila melanogaster . Analyses of orthologs of the Drosophila genes identified in non-drosophilid taxa 1 , 2 revealed that evolution of sex determination pathways is consistent with a bottom-up mode, 3 where only the terminal genes within the pathway are well conserved. doublesex ( dsx ), occupying a bottom-most position and encoding sex-specific proteins orchestrating downstream sexual differentiation processes, is an ancient sex-determining gene present in all studied species. 2 , 4 , 5 With the exception of lepidopterans, its female-specific splicing is known to be regulated by transformer ( tra ) and its co-factor transformer-2 ( tra2 ). 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 , 20 Here we show that in the African malaria mosquito Anopheles gambiae , a gene, which likely arose in the Anopheles lineage and which we call femaleless ( fle ), controls sex determination in females by regulating splicing of dsx and fruitless ( fru ; another terminal gene within a branch of the sex determination pathway). Moreover, fle represents a novel molecular link between the sex determination and dosage compensation pathways. It is necessary to suppress activation of dosage compensation in females, as demonstrated by the significant upregulation of the female X chromosome genes and a correlated female-specific lethality, but no negative effect on males, in response to fle knockdown. This unexpected property, combined with a high level of conservation in sequence and function in anopheline mosquitoes, makes fle an excellent target for genetic control of all major vectors of human malaria.

Parkin and PINK1 play an important role in mitochondrial quality control, whose malfunction may also be involved in the pathogenesis of amyotrophic lateral sclerosis (ALS). Excessive TDP-43 accumulation is a pathological hallmark of ALS and is associated with Parkin protein reduction in spinal cord neurons from sporadic ALS patients. In this study, we reveal that Parkin and PINK1 are differentially misregulated in TDP-43 proteinopathy at RNA and protein levels. Using knock-in flies, mouse primary neurons, and TDP-43Q331K transgenic mice, we further unveil that TDP-43 downregulates Parkin mRNA, which involves an unidentified, intron-independent mechanism and requires the RNA-binding and the protein–protein interaction functions of TDP-43. Unlike Parkin, TDP-43 does not regulate PINK1 at an RNA level. Instead, excess of TDP-43 causes cytosolic accumulation of cleaved PINK1 due to impaired proteasomal activity, leading to compromised mitochondrial functions. Consistent with the alterations at the molecular and cellular levels, we show that transgenic upregulation of Parkin but downregulation of PINK1 suppresses TDP-43-induced degenerative phenotypes in a Drosophila model of ALS. Together, these findings highlight the challenge associated with the heterogeneity and complexity of ALS pathogenesis, while pointing to Parkin–PINK1 as a common pathway that may be differentially misregulated in TDP-43 proteinopathy.

The mitochondrion is a highly dynamic organelle that is critical for energy production and numerous metabolic processes. Drosophila Chchd2, a homolog of the human disease-related genes CHCHD2 and CHCHD10, encodes a mitochondrial protein. In this study, we found that loss of Chchd2 in flies resulted in progressive degeneration of photoreceptor cells and reduced muscle integrity. In the flight muscles of adult Chchd2 mutants, some mitochondria exhibited curling cristae and a reduced number of cristae compared to those of controls. Overexpression of Chchd2 carrying human disease-related point mutations failed to fully rescue the mitochondrial defects in Chchd2 mutants. In fat body cells, loss of Chchd2 resulted in fragmented mitochondria that could be partially rescued by Marf overexpression and enhanced by Opa1 RNAi. The expression level of Opa1 was reduced in Chchd2 mutants and increased when Chchd2 was overexpressed. The chaperonelike protein P32 co-immunoprecipitated with Chchd2 and YME1L, a protease known to processes human OPA1. Moreover, the interaction between P32 and YME1L enhanced YME1L activity and promoted Opa1 degradation. Finally, Chchd2 stabilized Opa1 by competing with P32 for YME1L binding. We propose a model whereby Chchd2 regulates mitochondrial morphology and tissue homeostasis by fine-tuning the levels of OPA1.

Summary Physiological trade-offs between mosquito immune response and reproductive capability can arise due to insufficient resource availability. C-type lectin family members may be involved in these processes. We established a GCTL-3 −/− mutant Aedes aegypti using CRISPR/Cas9 to investigate the role of GCTL-3 in balancing the costs associated with immune responses to arboviral infection and reproduction. GCTL-3 −/− mutants showed significantly reduced DENV-2 infection rate and gut commensal microbiota populations, as well as upregulated JAK/STAT, IMD, Toll, and AMPs immunological pathways. Mutants also had significantly shorter lifespans than controls and laid fewer eggs due to defective germ line development. dsRNA knock-down of Attacin and Gambicin , two targets of the AMPs pathway, partially rescued this reduction in reproductive capabilities. Upregulation of immune response following GCTL-3 knock-out therefore comes at a cost to reproductive fitness. Knock-out of other lectins may further improve our knowledge of the molecular and genetic mechanisms underlying reproduction-immunity trade-offs in mosquitoes.