Biology subjects

Berry, C. W.

Publications and source records attributed to Berry, C. W..

4 recordsLinked to original sources

bioRxiv2024

Functional septate junctions between cyst cells are required for survival of transit amplifying male germ cells expressing Bag of marbles

Male germ cells from insects to mammals differentiate in a privileged microenvironment created by stage-specific junctional seals between somatic support cells that isolate meiotic and postmeiotic germ cells from bodily fluids. Here we show that action of the Drosophila germ cell differentiation factor Bag-of-marbles (Bam) is required for the somatic cyst cells associated with each cluster of transit amplifying spermatogonia to form the junctions that seal the cyst, isolating differentiating germ cells. Knockdown of septate junction (SJ) components or the transmembrane protein Side-V in somatic cyst cells resulted in elimination of most transit amplifying spermatogonia at the 8-cell stage. Germ cell death was spared in males mutant for bam, indicating that intact barriers surrounding transit amplifying progenitors are required to ensure germline survival only once differentiation has initiated. Together these results suggest that signals from spermatogonia initiating differentiation trigger their partner somatic cyst cells to form the tight junctional barrier. The close timing of onset of differentiation and the requirement for cyst cell sealing may account for the normal elimination of 20-30% of early germ cells prior to meiosis.

developmental biology↗

bioRxiv2022

Emergent dynamics of adult stem cell lineages from single nucleus and single cell RNA-Seq of Drosophila testes

Proper differentiation of sperm from germline stem cells, essential for production of the next generation, requires dramatic changes in gene expression that drive remodeling of almost all cellular components, from chromatin to organelles to cell shape itself. Here we provide a single nucleus and single cell RNA-seq resource covering all of spermatogenesis in Drosophila starting from in-depth analysis of adult testis single nucleus RNA-seq (snRNA-seq) data from the Fly Cell Atlas (FCA) study (Li et al., 2022). With over 44,000 nuclei and 6,000 cells analyzed, the data provide identification of rare cell types, mapping of intermediate steps in differentiation, and the potential to identify new factors impacting fertility or controlling differentiation of germline and supporting somatic cells. We justify assignment of key germline and somatic cell types using combinations of known markers, in situ hybridization, and analysis of extant protein traps. Comparison of single cell and single nucleus datasets proved particularly revealing of dynamic developmental transitions in germline differentiation. To complement the web-based portals for data analysis hosted by the FCA, we provide datasets compatible with commonly used software such as Seurat and Monocle. The foundation provided here will enable communities studying spermatogenesis to interrogate the datasets to identify candidate genes to test for function in vivo.

developmental biology↗

bioRxiv2022

Developmentally regulated alternate 3' end cleavage of nascent transcripts controls dynamic changes in protein expression in an adult stem cell lineage

Alternative polyadenylation (APA) generates transcript isoforms that differ in the position of the 3 cleavage site, resulting in the production of mRNA isoforms with different length 3UTRs. Although widespread, the role of APA in the biology of cells, tissues and organisms has been controversial. We identified over 500 Drosophila genes that express mRNA isoforms with a long 3UTR in proliferating spermatogonia but a short 3UTR in differentiating spermatocytes due to APA. We show that the stage-specific choice of the 3 end cleavage site can be regulated by the arrangement of a canonical polyadenylation signal (PAS) near the distal cleavage site but a variant or no recognizable PAS near the proximal cleavage site. The emergence of transcripts with shorter 3UTRs in differentiating cells correlated with changes in expression of the encoded proteins, either from off in spermatogonia to on in spermatocytes or vice versa. Polysome gradient fractionation revealed over 250 genes where the long 3UTR versus short 3UTR mRNA isoforms migrated differently, consistent with dramatic stage-specific changes in translation state. Thus, the developmentally regulated choice of an alternative site at which to make the 3end cut that terminates nascent transcripts can profoundly affect the suite of proteins expressed as cells advance through sequential steps in a differentiation lineage.

developmental biology↗

bioRxiv2018

The Dlg-module and clathrin-mediated endocytosis regulate EGFR signaling and cyst cell-germline coordination in the Drosophila testis

Tissue homeostasis and repair relies on proper communication of stem cells and their differentiating daughters with the local tissue microenvironment. In the Drosophila male germline adult stem cell lineage, germ cells proliferate and progressively differentiate enclosed in supportive somatic cyst cells, forming a small organoid, the functional unit of differentiation. Here we show that cell polarity and vesicle trafficking influence signal transduction in cyst cells, with profound effects on the germ cells they enclose. Our data suggest that both the cortical components Dlg, Scrib, Lgl and the clathrin-mediated endocytic (CME) machinery downregulate EGFR signaling. Knockdown of dlg, scrib, lgl or CME components in cyst cells resulted in germ cell death, similar to increased signal transduction via the EGFR, while lowering EGFR or downstream signaling components rescued the defects. This work provides new insights on how cell polarity and endocytosis cooperate to regulate signal transduction and sculpt developing tissues.

developmental biology↗