Dendritic diversification through transcription factor-mediated suppression of alternative morphologies

Abstract

Neurons display a striking degree of functional and morphological diversity, and the developmental mechanisms that underlie diversification are of significant interest for understanding neural circuit assembly and function. We find that the morphology of Drosophila sensory neurons is diversified through a series of suppressive transcriptional interactions involving the POU domain transcription factors Pdm1 (Nubbin) and Pdm2, the homeodomain transcription factor Cut, and the transcriptional regulators Scalloped and Vestigial. Pdm1 and Pdm2 are expressed in a subset of proprioceptive sensory neurons and function to inhibit dendrite growth and branching. A subset of touch receptors show a capacity to express Pdm1/2, but Cut represses this expression and promotes more complex dendritic arbors. Levels of Cut expression are diversified in distinct sensory neurons by selective expression of Scalloped and Vestigial. Different levels of Cut impact dendritic complexity and, consistent with this, we show that Scalloped and Vestigial suppress terminal dendritic branching. This transcriptional hierarchy therefore acts to suppress alternative morphologies to diversify three distinct types of somatosensory neurons.

Characterization of proprioceptive system dynamics in behavingDrosophilalarvae using high-speed volumetric microscopy

“…Here, we applied multi-spectral, high-speed, volumetric Swept Confocally Aligned Planar Excitation (SCAPE) microscopy [9,10] to characterize the dynamics of neuronal activity in crawling Drosophila larvae. We focused on the Drosophila multidendritic (md) neurons, which are located just within the larval body wall and innervate connective tissues [11,12], the epidermis [13,14] and internal nerves [15]. A subset of six md neurons ( Fig.…”

“…A subset of six md neurons ( Fig. 1a) extend axons to more dorsal neuropil regions important for motor control, suggesting that they are proprioceptors that provide feedback on body position [15][16][17][18]. This feedback is thought to be particularly important during crawling, which involves periodic strides driven by segmental muscle contractions progressing from posterior to anterior along the body [19].…”

Persistent Epigenetic Reprogramming of Sweet Taste by Diet

“…However, we discovered that PRC2.1 did not directly bind to neuronal genes in these cells and that, instead, it targeted transcription factors involved in sensory neuron development, synaptic function, and axon targeting. Specifically, on a high sugar diet Pcl binding was increased at the cad , GATAe , nub/pdm , Ptx1 loci and decreased at the Scro locus, with corresponding changes in the mRNA levels of these genes ( Interestingly, several of the transcription factors we identified -Ptx1 , Scro , and nub/pdm -have been shown to control the proper branching, synaptic connectivity, and function of sensory neurons (Corty et al, 2016;Iyer et al, 2013;Neumann and Cohen, 1998;Parrish et al, 2006Parrish et al, , 2007Vorbrüggen et al, 1997;Zaffran et al, 2000) , while others ( cad , nub/pdm ) play a role in neuroblast development (Doe, 2017;Kohwi and Doe, 2013) ; PRC2 also functions as a competence factor in neural proliferation, differentiation and sensory neurons (Bahrampour et al, 2019;Doe, 2017;Parrish et al, 2007) . Importantly, we found that the 4 activators that are repressed by Pcl in the high sugar condition are enriched in the Gr5a+ cells on a control diet, while Scro is depleted.…”

Regulatory logic driving stable levels of defective proventriculus expression during terminal photoreceptor specification in flies

“…Regulatory mechanisms must ensure that expression levels remain within a narrow range for days and even years while providing robustness against acute perturbations caused by activity and environment. In some cases, the transcription factors that dictate cell type-specific expression levels have been identified (Corty et al, 2016), but how these regulatory inputs are interpreted by DNA elements has not been characterized. Furthermore, it is unclear how transcription factor feedback and cis-regulatory redundancy contribute to ensuring proper expression levels in neurons.…”