Biology subjects

Csizmadia, T.

Publications and source records attributed to Csizmadia, T..

2 recordsLinked to original sources

bioRxiv2025

Ubiquitination of secretory granules promotes crinophagic degradation in Drosophila

Gland cells dynamically regulate their secretory granule content via balancing the rates of synthesis, maturation, secretion, and lysosomal degradation (crinophagy). The signal(s) leading to crinophagic breakdown of secretory granules are unknown. Here we show that dynamic ubiquitination of unreleased or low-grade glue-containing secretory granules marks these vesicles for crinophagy in larval salivary gland cells of Drosophila. We identify the ubiquitin ligase Cnot4 and the deubiquitinating enzyme Usp7 as mediators of glue granule ubiquitination and deubiquitination, respectively. Loss of either Cnot4 or Usp7 impairs glue granule fusion with lysosomes. Overexpression of Cnot4 induces premature crinophagy while Usp7 overexpression prevents developmental crinophagy via modulation of glue granule ubiquitination status. Our work establishes that ubiquitination of secretory granules is a key trigger of crinophagy in Drosophila, paving the way for further analysis of this barely characterized degradation route in Metazoans.

cell biology↗

bioRxiv2024

The calcium pump PMCA4b promotes epithelial cell polarization and lumen formation

Loss of epithelial cell polarity and tissue disorganization are hallmarks of carcinogenesis, in which Ca2+ signaling plays a significant role. Here we demonstrate that the plasma membrane Ca2+ pump PMCA4 (ATP2B4) is downregulated in luminal breast cancer, and this is associated with shorter relapse-free survival in patients with luminal A and B1 subtype tumors. Using the MCF-7 breast cancer cell model we show that PMCA4 silencing results in the loss of cell polarity while a forced increase in PMCA4b expression induces cell polarization and promotes lumen formation in 2D and 3D cell cultures. We identify Arf6 as a novel regulator of PMCA4b endocytic recycling essential for PMCA4 regulated lumen formation. Silencing of the single pmca gene in Drosophila melanogaster larval salivary gland destroys lumen morphology suggesting a conserved role of PMCAs in lumen morphogenesis. Our findings point to a novel role of PMCA4 in controlling epithelial cell polarity, and in the maintenance of normal glandular tissue architecture.

cell biology↗