Biology subjects

Carreras-Sureda, A.

Publications and source records attributed to Carreras-Sureda, A..

3 recordsLinked to original sources

bioRxiv2026

PefA, an ALG-2-like Ca2+ sensor, regulates ESCRT and autophagy responses to mycobacterial vacuole damage

Calcium influx is a universal early signal triggering membrane repair pathways, yet how Ca2+ sensors coordinate the balance between ESCRT-mediated sealing and autophagy-based responses at damaged endolysosomes and pathogen-containing vacuoles remains unclear. Here we use the Dictyostelium discoideum-Mycobacterium marinum infection model, a surrogate to study intracellular pathogenesis of Mycobacterium tuberculosis, combined with genetic, imaging, and proteomic analyses to identify the penta-EF-hand protein PefA, an ALG-2-like Ca2+ sensor, as a Ca2+-responsive regulator that orchestrates recruitment of the E3 ubiquitin ligase TrafE, ESCRT components, and the autophagy machinery to damaged membranes. PefA is transcriptionally upregulated and accumulates at the mycobacterial vacuole, promoting timely repair that preserves vacuolar integrity and supports bacterial replication. Loss of PefA impairs ESCRT and autophagy engagement, leading to premature bacterial escape into the cytosol and altered infection outcomes. These findings uncover a conserved Ca2+-dependent mechanism linking membrane damage sensing to coordinated repair pathways and shapes host-pathogen interactions, with direct relevance to tuberculosis pathogenesis and host resilience to infection. TeaserThe PefA calcium sensor times membrane repair and autophagy to control vacuole integrity during mycobacterial infection.

microbiology↗

bioRxiv2022

The lipid transfer proteins Nir2 and Nir3 sustain phosphoinositide signaling and actin dynamics during phagocytosis

Changes in membrane phosphoinositides and local Ca2+ elevations at sites of particle capture coordinate the dynamic remodeling of the actin cytoskeleton during phagocytosis. Here, we show that the phosphatidylinositol (PI) transfer proteins PITPNM1 (Nir2) and PITPNM2 (Nir3) maintain PI(4,5)P2 homeostasis at phagocytic cups, thereby promoting actin contractility and the sealing of phagosomes. Nir3 and to a lesser extent Nir2 accumulated in ER cisternae juxtaposed to phagocytic cups when expressed in phagocytic mouse fibroblasts. CRISPR-Cas9 editing of Nir2 and Nir3 genes decreased plasma membrane PI(4,5)P2 levels, store-operated Ca2+ entry (SOCE), and receptor-mediated phagocytosis, stalling particle capture at cup stage. Re-expression of either Nir2 or Nir3 restored phagocytosis, but not SOCE, proportionally to the PM PI(4,5)P2 levels. Phagosomes forming in Nir2/3-edited cells had decreased overall PI(4,5)P2 levels but normal periphagosomal Ca2+ signals. Nir2/3 editing reduced the density of contractile actin rings at sites of particle capture, causing repetitive low-intensity contractile events indicative of abortive phagosome closure. We conclude that Nir-mediated lipid transfer maintains phosphoinositide homeostasis at phagocytic cups, thereby sustaining the signals that initiate the remodeling of the actin cytoskeleton during phagocytosis. Summary statementChanges in membrane phosphoinositides coordinate actin remodeling during phagocytosis, but whether lipid transport proteins contribute to this process is not known. Here, we show that the phosphatidylinositol transfer proteins Nir2 and Nir3 are recruited to phagocytic cups and drive the formation of contractile actin rings during particle engulfment. Using gene editing and re-expression, we show that Nir2 and Nir3 maintain PI(4,5)P2 signaling competence at phagocytic cups and promote the actin-dependent sealing of phagocytic vacuoles. These observations establish that lipid transport proteins maintain the phosphoinositide signals that drive the remodeling of the actin cytoskeleton during phagocytosis.

cell biology↗

bioRxiv2021

S-acylation targets ORAI1 channels to lipid rafts for efficient Ca2+ signaling by T cell receptors at the immune synapse

Efficient immune responses require Ca2+ fluxes across ORAI1 channels during engagement of T cell receptors (TCR) at the immune synapse (IS) between T cells and antigen presenting cells. Here, we show that ZDHHC20-mediated S-acylation of the ORAI1 channel at residue Cys143 is required for TCR assembly and signaling at the IS. Cys143 mutations reduced ORAI1 currents and store-operated Ca2+ entry in HEK-293 cells and nearly abrogated long-lasting Ca2+ elevations, NFATC1 translocation, and IL-2 secretion evoked by TCR engagement in Jurkat T cells. The acylation-deficient channel had reduced mobility in lipids, accumulated in cholesterol-poor domains, formed tiny clusters, failed to reach the IS and unexpectedly also prevented TCR recruitment to the IS. Our results establish S-acylation as a critical regulator of ORAI1 channel assembly and function at the IS and reveal that local Ca2+ fluxes are required for TCR recruitment to the synapse.

biochemistry↗