Sensory neuron lineage mapping and manipulation in the Drosophila olfactory system

Phing Chian Chai,Richard Benton,Steeve Cruchet,Leonore Wigger

doi:10.1038/s41467-019-08345-4

Phing Chian Chai, Richard Benton + Show 2 more

Open Access

https://doi.org/10.1038/s41467-019-08345-4

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Abstract

Nervous systems exhibit myriad cell types, but understanding how this diversity arises is hampered by the difficulty to visualize and genetically-probe specific lineages, especially at early developmental stages prior to expression of unique molecular markers. Here, we use a genetic immortalization method to analyze the development of sensory neuron lineages in the Drosophila olfactory system, from their origin to terminal differentiation. We apply this approach to define a fate map of nearly all olfactory lineages and refine the model of temporal patterns of lineage divisions. Taking advantage of a selective marker for the lineage that gives rise to Or67d pheromone-sensing neurons and a genome-wide transcription factor RNAi screen, we identify the spatial and temporal requirements for Pointed, an ETS family member, in this developmental pathway. Transcriptomic analysis of wild-type and Pointed-depleted olfactory tissue reveals a universal requirement for this factor as a switch-like determinant of fates in these sensory lineages.

Highlights

Nervous systems exhibit myriad cell types, but understanding how this diversity arises is hampered by the difficulty to visualize and genetically-probe specific lineages, especially at early developmental stages prior to expression of unique molecular markers
We first compared Green Fluorescent Protein (GFP) signals from nonimmortalized and immortalized GAL4 drivers for the antennal proneural genes, atonal and absent MD neurons and olfactory sensilla, which are expressed in sensory organ precursor (SOP) that form ac and ab/at/ai sensilla, respectively[25,26]
Late immortalization restricted labeling to fewer glomeruli, approaching the number labeled by the nonimmortalized driver, suggesting this time window reflects en expression once it has largely stabilized into the terminal adult pattern (Fig. 1d, e). These results indicate that the immortalization strategy effectively captures and preserves GAL4 driver expression during a desired developmental time window to relate early expression patterns in disc SOPs to the olfactory sensory neurons (OSNs) lineages that arise from these precursors

Summary

Introduction

Nervous systems exhibit myriad cell types, but understanding how this diversity arises is hampered by the difficulty to visualize and genetically-probe specific lineages, especially at early developmental stages prior to expression of unique molecular markers. Despite the extensive knowledge of the anatomy and function of the olfactory system[11,19,20], the developmental origins of distinct olfactory SOPs and how these relate to olfactory circuit organization are poorly understood[9,10] This is largely because of the lack of markers to trace a specific lineage from SOP birth to OSN maturation. We applied an immortalization labeling system for OSN lineages, which uses the CONVERT (or FLEXAMP) technique[21,22] and takes advantage of the large resources of Drosophila enhancer-GAL4 driver lines for genetic marking of cell subpopulations[23,24] This approach permits us to, first, generate an olfactory fate map in the antennal disc, second, visualize an entire olfactory sensory lineage and, third, characterize the role of a novel molecular determinant of OSN development

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Conclusion