Biology subjects

Hogg, K.

Publications and source records attributed to Hogg, K..

2 recordsLinked to original sources

bioRxiv2021

The Rpd3-complex regulates expression of multiple cell surface recycling factors in yeast

Intracellular trafficking pathways control residency and bioactivity of integral membrane proteins at the cell surface. Upon internalisation, surface cargo proteins can be delivered back to the plasma membrane via endosomal recycling pathways. Recycling is thought to be controlled at the metabolic and transcriptional level, but such mechanisms are not fully understood. In yeast, recycling of surface proteins can be triggered by cargo deubiquitination and a series of molecular factors have been implicated in this trafficking. In this study, we follow up on the observation that many subunits of the Rpd3 lysine deacetylase complex are required for recycling. We validate ten Rpd3-complex subunits in recycling using two distinct assays and developed tools to quantify both. Fluorescently labelled Rpd3 localises to the nucleus and complements recycling defects, which we hypothesised were mediated by modulated expression of Rpd3 target gene(s). Bioinformatics implicated 32 candidates that function downstream of Rpd3, which were over-expressed and assessed for capacity to suppress recycling defects of rpd3{Delta} cells. This effort yielded 3 hits: Sit4, Dit1 and Ldb7, which were validated with a lipid dye recycling assay. Additionally, the essential phosphatidylinositol-4-kinase Pik1 was shown to have a role in recycling. We propose recycling is governed by Rpd3 at the transcriptional level via multiple downstream target genes.

cell biology↗

bioRxiv2021

Phospholipases D1 and D2 regulate cell cycling in primary prostate cancer cells and are differentially associated with the nuclear matrix

Phospholipases D1 and D2 (PLD1/2) have been implicated in tumorigenesis. We previously detected higher expression of PLD in the nuclei of patient-derived prostate cancer (PCa) cells and prostate cancer cell lines. Here we have examined whether PLD1 or PLD2 are associated with the nuclear matrix and influence cell cycling. PLD1/PLD2 were detected by qualitative immunofluorescence in cultured PCa cells and extracted with a standardised protocol to reveal nuclear matrix-associated proteins. The effects of isoform-specific inhibition of PLD1or PLD2 on PCa cell cycle progression were analysed by flow cytometry. PLD2 mainly co-localised with the nucleolar marker fibrillarin in PCa cells. However, even after complete extraction, some PLD2 remained associated with the nuclear matrix. Inhibiting PLD2 effectively reduced PCa cell cycling into and through S phase. In contrast, PLD1 inhibition effects were weaker, and a subpopulation of cycling patient-derived PCa cells was unaffected by PLD1 inhibition. When associated with the nuclear matrix PLD2 could generate phosphatidic acid to regulate nuclear mTOR and control downstream transcriptional events. The association of PLD2 with the nucleolus also implies a role in stress regulation. The cell cycling results highlight the importance of PLD2 inhibition as a novel potential prostate cancer therapeutic mechanism by differential regulation of cell proliferation.

cancer biology↗