The Genetic Network of Forkhead Gene Family in Development of Brown Planthoppers

We identified 18 distinct Fox genes in the genome of the brown planthopper, Nilaparvata lugens, and further found a novel insect-specific subfamily that we temporarily named FoxT. A total of 16 genes were highly expressed in the eggs, while NlFoxL2 and NlFoxT are female- and male-specific genes, respectively. Large scale RNAi and RNA-seq analyses were used to reveal the functions and potential targets of NlFoxs. In the eggs, NlFoxA, NlFoxN1 and NlFoxN2 are indispensable to early embryogenesis by regulating different target genes; NlFoxG and NlFoxQ co-regulate NlSix3 for brain development; and NlFoxC, NlFoxJ1 and NlFoxP have complementary effects on late embryogenesis. Moreover, NlFoxA, NlFoxNl and NlFoxQ have pleiotropism. NlFoxA and NlFoxQ regulate the expression of NlCHS1 and cuticular proteins, respectively, thereby participating in the formation of cuticles. NlFoxN1, which regulates the expression of NlKrt9 is involved in the formation of intermediate filament frameworks. Our previous studies have revealed that NlFoxL2 and NlFoxO play important roles in chorion formation and wing polyphenism. Altogether, N. lugens Fox genes exhibit functional diversity in embryonic development and organogenesis. This comprehensive study combines genomics, transcriptomics and phenomics, thereby constructing a complex genetic network that spans the entire life cycle of the brown planthopper.

In control of biology: of mice, men and Foxes

Forkhead proteins comprise a highly conserved family of transcription factors, named after the original forkhead gene in Drosophila. To date, over 100 forkhead genes have been identified in a large variety of species, all sharing the evolutionary conserved ‘forkhead’ DNA-binding domain, and the cloning and characterization of forkhead genes have continued in recent years. Forkhead transcription factors regulate the expression of countless genes downstream of important signalling pathways in most, if not all, tissues and cell types. Recent work has provided novel insights into the mechanisms that contribute to their functional diversity, including functional protein domains and interactions of forkheads with other transcription factors. Studies using loss- and gain-of-function models have elucidated the role of forkhead factors in developmental biology and cellular functions such as metabolism, cell division and cell survival. The importance of forkhead transcription factors is underlined by the developmental defects observed in mutant model organisms, and multiple human disorders and cancers which can be attributed to mutations within members of the forkhead gene family. This review provides a comprehensive overview of current knowledge on forkhead transcription factors, from structural organization and regulatory mechanisms to cellular and developmental functions in mice and humans. Finally, we will discuss how novel insights gained from involvement of ‘Foxes’ in the mechanisms underlying human pathology may create new opportunities for treatment strategies.