Specification of neuronal subtypes by different levels of Hunchback

Abstract

During the development of the central nervous system, neural progenitors generate an enormous number of distinct types of neuron and glial cells by asymmetric division. Intrinsic genetic programs define the combinations of transcription factors that determine the fate of each cell, but the precise mechanisms by which all these factors are integrated at the level of individual cells are poorly understood. Here, we analyzed the specification of the neurons in the ventral nerve cord of Drosophila that express Crustacean cardioactive peptide (CCAP). There are two types of CCAP neurons: interneurons and efferent neurons. We found that both are specified during the Hunchback temporal window of neuroblast 3-5, but are not sibling cells. Further, this temporal window generates two ganglion mother cells that give rise to four neurons, which can be identified by the expression of empty spiracles. We show that the expression of Hunchback in the neuroblast increases over time and provide evidence that the absolute levels of Hunchback expression specify the two different CCAP neuronal fates.

Steroid hormone induction of temporal gene expression in Drosophila brain neuroblasts generates neuronal and glial diversity

“…Drosophila embryonic neuroblasts change gene expression rapidly, often producing just one progeny in each temporal transcription factor window (Baumgardt et al, 2009; Isshiki et al, 2001; Moris-Sanz et al, 2014; Novotny et al, 2002; Pearson and Doe, 2003; Tran and Doe, 2008). In contrast, larval neuroblasts divide ~50 times over their 120 hr lineage (Truman and Bate, 1988; Yu and Lee, 2007).…”

Steroid hormone induction of temporal gene expression in Drosophila brain neuroblasts generates neuronal and glial diversity

“…Drosophila embryonic neuroblasts change gene expression rapidly, often producing just one progeny in each temporal transcription factor window (Baumgardt et al, 2009; Isshiki et al, 2001; Moris-Sanz et al, 2014; Novotny et al, 2002; Pearson and Doe, 2003; Tran and Doe, 2008). In contrast, larval neuroblasts divide ~50 times over their 120h lineage (Truman and Bate, 1988; Yu and Lee, 2007).…”

Drosophila embryonic type II neuroblasts: origin, temporal patterning, and contribution to the adult central complex

“…First, dorsoventral, anterior-posterior, and Hox spatial patterning cues generate unique neuroblast identities (Chu-LaGraff and Doe, 1993;Prokop and Technau, 1994;Skeath et al, 1995;McDonald et al, 1998;Weiss et al, 1998;Skeath and Thor, 2003;Marin et al, 2012;Estacio-Gómez and Díaz-Benjumea, 2014;Moris-Sanz et al, 2015). Second, the temporal transcription factors Hunchback (Hb), Krüppel, Nubbin/Pdm2 (referred to here as Pdm), Castor (Cas) and Grainy head (Grh) specify unique GMC identities within each neuroblast lineage (Brody and Odenwald, 2000;Berger et al, 2001;Isshiki et al, 2001;Novotny et al, 2002;Cenci and Gould, 2005;Kanai et al, 2005;Grosskortenhaus et al, 2006;Mettler et al, 2006;Urban and Mettler, 2006;Maurange et al, 2008;Tran and Doe, 2008;Tsuji et al, 2008;Ulvklo et al, 2012;Herrero et al, 2014;Moris-Sanz et al, 2014).…”