Pvr regulates cyst stem cell division in the Drosophila testis niche, and has functions distinct from Egfr

Expression of ABC transporters in the Drosophila testis stem cell niche: Comparison of two approaches

The ABC transporter gene family encodes proteins that form transmembrane channels and hydrolyze ATP to pump various substrates into and out of cells. Adult stem cell populations in numerous mammalian tissues express members of this gene family in order to efflux toxins or vital dyes, thereby conferring the "side population" trait, and cancer stem cells exhibit multidrug resistance upon expression of members of this gene family. In this study we investigated the expression of ABC transporters in a leading model organism stem cell niche, the Drosophila testis. We screened enhancer and gene trap lines with insertions near ABC transporter genes and identified six transporters with tissue-specific expression in the testis (ABCB7, MRP, rdog, CG3164, CG31121, and CG9663). Contrary to our expectation, we did not observe mostly stem cell-restricted expression patterns for these genes. We also report the expression patterns of ABC transporter genes in the testis from the published Fly Cell Atlas consortium single-cell sequencing of the testis (Li et al., 2022). Comparison of the expression levels and patterns of the six positive genes from the enhancer/gene trap screen with the FCA data showed only weak correlation between the two gene expression approaches. While there are reasons that the techniques might show different results, our work highlights the need for caution in over-reliance on single techniques to investigate gene expression.

L(1)10Bb serves as a conservative determinant for soma-germline communications via cellular non-autonomous effects within the testicular stem cell niche

The testicular stem cell niche is the central regulator of spermatogenesis in Drosophila melanogaster. However, the underlying regulatory mechanisms are unclear. This study demonstrated the crucial role of lethal (1) 10Bb [l(1)10Bb] in regulating the testicular stem cell niche. Dysfunction of l(1)10Bb in early-stage cyst cells led to male fertility disorders and compromised cyst stem cell maintenance. Moreover, the dysfunction of l(1)10Bb in early-stage cyst cells exerted non-autonomous effects on germline stem cell differentiation, independently of hub signals. Notably, our study highlights the rescue of testicular defects through ectopic expression of L(1)10Bb and the human homologous protein BUD31 homolog (BUD31). In addition, l(1)10Bb dysfunction in early-stage cyst cells downregulated the expression of spliceosome subunits in the Sm and the precursor RNA processing complexes. Collectively, our findings established l(1)10Bb as a pivotal factor in the modulation of Drosophila soma-germline communications within the testicular stem cell niche.

A new experimental evidence-weighted signaling pathway resource in FlyBase

Research in model organisms is central to the characterization of signaling pathways in multicellular organisms. Here, we present the comprehensive and systematic curation of 17 Drosophila signaling pathways using the Gene Ontology framework to establish a dynamic resource that has been incorporated into FlyBase, providing visualization and data integration tools to aid research projects. By restricting to experimental evidence reported in the research literature and quantifying the amount of such evidence for each gene in a pathway, we captured the landscape of empirical knowledge of signaling pathways in Drosophila.

A new experimental evidence-weighted signaling pathway resource in FlyBase

Research in model organisms is central to the characterization of signaling pathways in multicellular organisms. Here, we present the systematic curation of 17 Drosophila signaling pathways using the Gene Ontology framework to establish a comprehensive and dynamic resource that has been incorporated into FlyBase, providing visualization and data integration tools to aid research projects. By restricting to experimental evidence reported in the research literature and quantifying the amount of such evidence for each gene in a pathway, we captured the landscape of empirical knowledge of signaling pathways in Drosophila .

Summary statement

Comprehensive curation of Drosophila signaling pathways and new visual displays of the pathways provides a new FlyBase resource for researchers, and new insights into signaling pathway architecture.