femaleless Controls Sex Determination and Dosage Compensation Pathways in Females of Anopheles Mosquitoes

• Published in: Current biology 2021-03, Vol.31 (5), p.1084-1091.e4
• Main Authors: Krzywinska, Elzbieta, Ferretti, Luca, Li, Jianwei, Li, Jian-Chiuan, Chen, Chun-Hong, Krzywinski, Jaroslaw
• Format: Article
• Language: English
• Subjects: Animals; Anopheles - genetics; Anopheles gambiae; DNA-Binding Proteins - genetics; Dosage Compensation, Genetic; Drosophila melanogaster - genetics; Drosophila melanogaster - metabolism; Drosophila Proteins - genetics; Drosophila Proteins - metabolism; Female; female-specific lethality; genetic vector control; Malaria; malaria vectors; Male; Mosquito Vectors; Nerve Tissue Proteins - genetics; sex determination pathway evolution; Sex Determination Processes - genetics; Transcription Factors - metabolism; transgenesis
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2020.12.014

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 taxa1,2 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).6–20 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. •fle is a new sex determination pathway element conserved in Anopheles mosquitoes•fle may have originated in the Anopheles lineage and is highly conserved in Anopheles•fle suppresses activation of dosage compensation in females•Depletion of fle transcripts is lethal or otherwise deleterious to females Krzywinska et al. identify a new element of the sex determination pathway in Anopheles. femaleless (fle), in addition to controlling splicing of dsx and fru, is essential for suppression of dosage compensation and viability of females. Female-deleterious effects upon fle knockdown make fle a promising target for control of malaria mosquitoes.