The Drivers of Diversity: Integrated genetic and hormonal cues regulate neural diversity

Stem cell-specific ecdysone signaling regulates the development and function of aDrosophilasleep homeostat

“…Briefly, we crossed 23E10-GAL4, which labels dFB neurons, to the CLIn fly (for genotype, see STAR table) and gave heat shock to the progeny at three major development time points: 0h, 48h, and 76h ALH (Figure 2E). There are two phases of neurogenesis, embryonic and larval 1,6,7,[104][105][106] . While most embryonic-born neurons die during metamorphosis [107][108][109][110][111][112] , a small population survives, undergoes metamorphosis 111,113,114 , and contributes to the adult brain [114][115][116][117] .…”

“…Proper brain function relies on generating diverse cell types at the appropriate time and place 1 . All neural (neurons and glia) cell types arise from a pool of progenitors called neural stem cells (NSCs) [1][2][3][4][5][6][7][8] . During development, NSCs divide to self-renew and generate distinct classes of neural subtypes over time.…”

“…These processes are governed by spatial and temporal programs [9][10][11][12][13] . As NSCs age, they express distinct cohorts of genes; this phenomenon is called temporal patterning, allowing individual NSCs to generate distinct progeny over time 1,[3][4][5][6][7][8] . The concept of temporal patterning was first defined in the Drosophila embryonic NSCs, which produce simple larval lineages 14 .…”

“…However, DM4 and DM6 also generate some long-field neurons, reflecting diverse classes of tangential input neurons 63,64 . In addition, each Type II NSCs generates distinct classes of neurons and glia over time 7,15,17,65,67,72 . Temporal clonal analysis has also revealed that INPs generate neurons of diverse identities after each division 7,65,72 , suggesting that Type II NSCs and INPs employ combinatorial temporal programs to diversify CX cell types 7,72 .…”

“…Interestingly, the temporal expression of EcR around ~55h after larval hatching (ALH) mediates early to late gene transition via NSC extrinsic ecdysone signaling 15 . Thus, unlike embryonic NSCs and larval optic lobe NSCs, generating complex adult lineages requires coordination of both stem cell intrinsic and extrinsic programs 7,15 . However, whether these temporally expressed genes and ecdysone play any role in the fate specification and function of the adult CX neurons is currently unknown.…”