Biology subjects

Browder, K. C.

Publications and source records attributed to Browder, K. C..

3 recordsLinked to original sources

bioRxiv2023

Targeting the Hippo pathway in cancers via ubiquitination dependent TEAD degradation

The Hippo pathway is among the most frequently altered key signaling pathways in cancer. TEAD1-4 are essential transcription factors and key downstream effectors in the Hippo pathway in human cells. Here, we identified RNF146 as a ubiquitin ligase (E3) of TEADs, which negatively regulates their stability in cells through proteasome-mediated degradation. We show that RNF146-mediated TEAD ubiquitination is dependent on the TEAD PARylation state. We further validated the genetic interaction between RNF146 and the Hippo pathway in cancer cell lines and the model organism Drosophila melanogaster. Despite the RNF146 and proteasome-mediated degradation mechanisms, TEADs are stable proteins with a long half-life in cells. We demonstrate that degradation of TEADs can be greatly enhanced pharmacologically with heterobifunctional chemical inducers of protein degradation (CIDEs). These TEAD-CIDEs can effectively suppress activation of YAP/TAZ target genes in a dose-dependent manner and exhibit significant anti-proliferative effects in YAP/TAZ-dependent tumor cells, thus phenocopying the effect of genetic ablation of TEAD protein. Collectively, this study demonstrates that the ubiquitin-proteasome system plays an important role in regulating TEAD functions and provides a proof-of-concept demonstration that pharmacologically induced TEAD ubiquitination could be leveraged to target YAP/TAZ-driven cancers.

cancer biology↗

bioRxiv2023

Nicotinic acetylcholine receptor signaling maintains epithelial barrier integrity

Disruption of epithelial barriers is a common disease manifestation in chronic degenerative diseases of the airways, lung and intestine. Extensive human genetic studies have identified risk loci in such diseases, including in chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases (IBD). The genes associated with these loci have not fully been determined, and functional characterization of such genes requires extensive studies in model organisms. Here, we report the results of a screen in Drosophila melanogaster that allowed for rapid identification, validation and prioritization of COPD risk genes that were selected based on risk loci identified in human genome-wide association studies (GWAS) studies. Using intestinal barrier dysfunction in flies as a readout, our results validate the impact of candidate gene perturbations on epithelial barrier function in 56% of the cases, resulting in a prioritized target gene list. We further report the functional characterization in flies of one family of these genes, encoding for nicotinic acetylcholine receptor subunits (nAchR). We find that nAchR signaling in enterocytes of the fly gut promotes epithelial barrier function and epithelial homeostasis by regulating the production of the peritrophic matrix. Our findings identify COPD associated genes critical for epithelial barrier maintenance, and provide insight into the role of epithelial nAchR signaling for homeostasis.

genetics↗

bioRxiv2020

The Drosophila EGFR ligand mSpitz is delivered to cytoplasmic capes at sites of non-canonical RNA export on the nuclear envelope via the endosomal system

Nuclear-cytoplasmic communication is not limited to nuclear pores, with both proteins and RNA using alternative routes between these compartments. We previously characterized cytoplasmic capes (large invaginations of the nuclear envelope in Drosophila), which are enriched for the membrane-bound EGF receptor ligand mSpitz, endosome-related organelles and ubiquitylated proteins. Closely associated with capes are groups of perinuclear vesicles resembling those seen at sites of RNP export via a budding mechanism. Here, we demonstrate that mSpitz delivery to capes requires passage through the endosomal system. We also show that capes are closely associated with sites of non-canonical RNP export as well as the dFrizzled2 receptor C terminal fragment, a core component of this export pathway. Video microscopy of glands in intact larvae indicates that cytoplasmic capes are stable structures that persist for at least 90 minutes without conspicuous growth. We further show that capes appear with the growth of the salivary gland rather than its developmental stage. Finally, we show that the large F-actin binding protein {beta}H-spectrin, which modulates endosomal trafficking, as well as its partner -spectrin are required for cape formation. Cytoplasmic capes therefore represent a subspecialization of the nuclear envelope where endosomal trafficking and RNP export are closely associated. SynopsisWe further characterize large invaginations of the nuclear envelope called cytoplasmic capes in Drosophila. The EGF receptor ligand mSpitz is concentrated in capes and we show that it traffics to this compartment via endosomes. The presence of RNP and the dFrizzled2 receptor C-terminal fragment also indicates that non-canonical RNA export is concentrated at capes. In vivo imaging shows that capes persist for at least 90 minutes. Finally, the large F-actin crosslinker /{beta}{square}-spectrin is shown to be required for cape formation. Abstract Figure O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=200 SRC="FIGDIR/small/203000v1_ufig1.gif" ALT="Figure 1"> View larger version (42K): org.highwire.dtl.DTLVardef@55435borg.highwire.dtl.DTLVardef@1b92320org.highwire.dtl.DTLVardef@1b13af8org.highwire.dtl.DTLVardef@96ab1e_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗