sperm development and intercellular cytoplasm sharing through ring canals do not require an intact fusome.

Animal germ cells communicate directly with each other during gametogenesis through intercellular bridges, often called ring canals (RCs), that form as a consequence of incomplete cytokinesis during cell division. Developing germ cells in have an additional specialized organelle connecting the cells called the fusome. Ring canals and the fusome are required for fertility in females, but little is known about their roles during spermatogenesis.

HtsRC-Mediated Accumulation of F-Actin Regulates Ring Canal Size During Oogenesis.

Ring canals in the female germline of are supported by a robust filamentous actin (F-actin) cytoskeleton, setting them apart from ring canals in other species and tissues. Previous work has identified components required for the expansion of the ring canal actin cytoskeleton, but has not identified the proteins responsible for F-actin recruitment or accumulation. Using a combination of CRISPR-Cas9 mediated mutagenesis and UAS-Gal4 overexpression, we show that HtsRC-a component specific to female germline ring canals-is both necessary and sufficient to drive F-actin accumulation.

Proximity labeling reveals novel interactomes in live tissue.

Gametogenesis is dependent on intercellular communication facilitated by stable intercellular bridges connecting developing germ cells. During oogenesis, intercellular bridges (referred to as ring canals; RCs) have a dynamic actin cytoskeleton that drives their expansion to a diameter of 10 μm. Although multiple proteins have been identified as components of RCs, we lack a basic understanding of how RC proteins interact together to form and regulate the RC cytoskeleton.

Targeted substrate degradation by Kelch controls the actin cytoskeleton during ring canal expansion.

During oogenesis, specialized actin-based structures called ring canals form and expand to accommodate growth of the oocyte. Previous work demonstrated that Kelch and Cullin 3 function together in a Cullin 3-RING ubiquitin ligase complex (CRL3) to organize the ring canal cytoskeleton, presumably by targeting a substrate for proteolysis. Here, we use tandem affinity purification followed by mass spectrometry to identify HtsRC as the CRL3 ring canal substrate.

Actin Cytoskeletal Organization in Drosophila Germline Ring Canals Depends on Kelch Function in a Cullin-RING E3 Ligase.

The Drosophila Kelch protein is required to organize the ovarian ring canal cytoskeleton. Kelch binds and cross-links F-actin in vitro, and it also functions with Cullin 3 (Cul3) as a component of a ubiquitin E3 ligase. How these two activities contribute to cytoskeletal remodeling in vivo is not known.

Mapping the putative G protein-coupled receptor (GPCR) docking site on GPCR kinase 2: insights from intact cell phosphorylation and recruitment assays.

G protein-coupled receptor kinases (GRKs) phosphorylate agonist-occupied receptors initiating the processes of desensitization and β-arrestin-dependent signaling. Interaction of GRKs with activated receptors serves to stimulate their kinase activity. The extreme N-terminal helix (αN), the kinase small lobe, and the active site tether (AST) of the AGC kinase domain have previously been implicated in mediating the allosteric activation.