The histone demethylase KDM5 controls developmental timing inDrosophilaby promoting prothoracic gland endocycles

Abstract

In Drosophila, the larval prothoracic gland integrates nutritional status with developmental signals to regulate growth and maturation through the secretion of the steroid hormone ecdysone. While the nutritional signals and cellular pathways that regulate prothoracic gland function are relatively well studied, the transcriptional regulators that orchestrate the activity of this tissue remain largely unknown. Here we show that lysine demethylase 5 (KDM5) is essential for prothoracic gland function. Indeed, restoring kdm5 expression only in the prothoracic gland in an otherwise kdm5 mutant animal is sufficient to rescue both the larval developmental delay and the pupal lethality caused by loss of KDM5. Molecularly, our studies show that KDM5 functions by promoting the endoreplication of prothoracic gland cells, a process that increases ploidy and is rate-limiting for the expression of ecdysone biosynthetic genes. This occurs through KDM5-mediated regulation of the receptor tyrosine kinase torso, which in in turn promotes polyploidization and growth through activation of the MAPK signaling pathway. Taken together, our studies provide key insights into the biological processes regulated by KDM5 and the molecular mechanisms that govern the transcriptional regulation of animal development.

The histone demethylase KDM5 is required for synaptic structure and function at theDrosophilaneuromuscular junction

“…Based on this staining, we quantified the number and size of type Ib synaptic boutons at muscle 4 of the third abdominal segment, which are predominantly responsible for muscle contraction (Newman et al, 2017), in kdm5 140 null mutants. Similar to our previous studies, we matched animals developmentally rather than chronologically due to the developmental delay of kdm5 140 larvae (Drelon et al, 2018;Drelon et al, 2019). In addition, we normalized the number of boutons to muscle size to account for any slight differences in larval size.…”

“…To determine where KDM5 function is required to mediate its effects on NMJ morphology, we restored kdm5 expression in specific cell types within kdm5 140 protein-null animals. To achieve this, we used a UAS-kdm5 transgene that drives low levels of expression (~2-fold increase over endogenous levels) and a range of Gal4 drivers (Drelon et al, 2019;Li et al, 2010;. Re-expression of kdm5 ubiquitously (Actin5c-Gal4 and da-Gal4), pan-neuronally (elav-Gal4), or in motor neurons (OK6-Gal4) significantly rescued the bouton number deficit of kdm5 140 larvae ( Figure 1D, G).…”

“…The number of male and female larvae were equal across the genotypes examined. For studies comparing wild type and kdm5 mutant larvae, animals were matched for developmental stage, not chronological age, as we previously reported (Drelon et al, 2018;Drelon et al, 2019). Wild-type wandering third instar larvae were therefore ~120 hours after egg laying (AEL) while kdm5 140 larvae were ~10 days old.…”

“…The kdm5 140 null allele, UAS-kdm5 transgene, and kdm5 JmjC* allele have been previously described (Drelon et al, 2018;Drelon et al, 2019;Navarro-Costa et al, 2016;Zamurrad et al, 2018). The UAS-shRNA transgene to knockdown kdm5 was generated as part of the TRiP project and has been well-validated by us and others (BL #35706) (Liu et al, 2014;Navarro-Costa et al, 2016).…”

“…Drosophila kdm5, also known as little imaginal discs (lid), is ubiquitously expressed and essential for developmental timing and adult survival (Drelon et al, 2018;Drelon et al, 2019;. As Drosophila KDM5 shares homology with all four mammalian KDM5 proteins, analysis of its function is expected to reveal activities relevant to KDM5A, KDM5B and KDM5C-induced ID.…”