Escort Cells scRNA-seq

Drosophila ovarian Follicle Stem Cells (FSC) present an excellent paradigm for understanding how a community of active stem cells maintained by population asymmetry is regulated. Here we describe single-cell RNA sequencing studies of a pre-sorted population of cells that include FSCs and the neighboring cell types, Escort Cells (ECs) and Follicle Cells (FCs), which they support. Cell-type assignment relies on anterior-posterior (AP) location within the germarium. We clarify the previously determined location of FSCs and use spatially targeted lineage studies as further confirmation. The scRNA profiles among four clusters are consistent with an AP progression from anterior ECs through posterior ECs and then FSCs, to early FCs. Several genes with graded profiles from ECs to FCs are highlighted as candidate effectors of the inverse gradients of the two principal signaling pathways, Wnt and JAK-STAT, that guide FSC differentiation and division. GFP positive cells from C587-GAL4 / yw; UAS-CD8-RFP/+ ovaries were sorted via Fluorescence-activated cell sorting (FACS). The sorted cells were loaded on a Chromium Single cell Controller (10 X Genomics) using the Chromium Single-cell 3’ Library & Gel Bead kit v3 according to manufacturer’s directions.