Biology subjects

Petrilli, V.

Publications and source records attributed to Petrilli, V..

4 recordsLinked to original sources

bioRxiv2025

Transient volume stabilization reveals the key role a PM permeability in pyroptotic cell swelling.

Pyroptosis, an inflammatory form of cell death, is characterized by massive cell swelling and plasma membrane rupture. Although swelling was recently shown to occur in two steps, the molecular and biophysical mechanisms driving this process remained unclear. Using fast quantitative microscopy, we reveal that between the two swelling phases, cell volume transiently stabilizes despite sustained plasma membrane permeability to ions and small molecules. From a biophysical perspective, the existence of such a plateau is puzzling, as ion pumps should not be able to regulate cell volume under these conditions. To address this, we developed a physical model based on an ion pump and leak framework that incorporates the dynamics of non-selective pore formation. Experimentally, we demonstrate that the plateau phase is controlled by the dynamics of the GSDMD pore enlargement, which is modulated by Ninj1 activation, possibly through intracellular calcium. Ninj1-mediated lesions are also required for the second swelling phase. We further show that fully opened GSDMD pores display an effective hydrodynamic radius slightly above 1.9 nm, providing an insitu upper bound for pore size. Together, our findings demonstrate that pyroptotic volume dysregulation emerges from the successive and interdependent actions of GSDMD and Ninj1, each imparting distinct permeability regimes associated with increased water filtration and decreased ion selectivity due to pore opening. These insights bridge molecular and biophysical perspectives on lytic cell death and may inform the broader understanding of membrane rupture in inflammatory and pathological contexts. Significance StatementAmong programmed modes of lytic cell death, pyroptosis mediated by gasdermin D (GSDMD) and ninjurin-1 (Ninj1) involves dramatic changes in cell shape and large volume fluctuations, fundamentally altering the cells physical properties. By combining optogenetics, quantitative microscopy, and modeling, we show that a progressive increase in plasma membrane pore size drives cell swelling and membrane lysis through successive and interdependent actions of GSDMD and Ninj1, each imparting distinct permeability regimes associated with increased water filtration and decreased ion selectivity. A deeper understanding of these dynamic cell modifications will shed light on the molecular and biophysical mechanisms driving different forms of cell death.

biophysics↗

bioRxiv2025

Oncogenic Stress is a Novel Immunogenic Signal Driven by the Unfolded Protein Response and Detected by Neutrophils

Breast cancer (BC) is the leading cause of cancer-related death in women. However, early detection of BC remains a major clinical challenge and represents a significant obstacle to effective prevention. To improve early clinical management, a deeper understanding of the preneoplastic immune microenvironment of BC is crucial. Among innate immune populations, neutrophils have emerged as important modulators of tumor development, but their role during the initiation of BC remains poorly understood. By integrating depletion experiments with transcriptomic profiling of sorted preneoplatic epithelial cells and neutrophils in spontaneous breast cancer mouse models, we observed that neutrophils contribute to tumor surveillance of preneoplastic stage with the activation of the unfolded protein response (UPR) in the preneoplastic epithelial compartment. To decipher the early anti-tumoral role of neutrophil, we developed an in vitro co-culture model of human mammary epithelial cells undergoing oncogenic stress with activation of the UPR (eHMEC), with human primary neutrophils. eHMEC display an immunoactive secretome as well as immunogenic membrane ligands, and neutrophils are the only immune cell population detecting eHMEC immunogenic signals leading to their recruitment, activation, production of reactive oxygen species and degranulation. Altogether, our work identifies for the first-time neutrophils as the earliest immune cell involved in immunosurveillance of preneoplastic BC epithelial cells, paving the way for potential therapeutic approaches targeting neutrophils to intercept early steps of BC tumorigenesis.

immunology↗

bioRxiv2024

Ninjurin-1 mediated plasma membrane rupture is a two-step process requiring cell swelling

Ninjurin-1 (NINJ1) executes cell lysis by polymerizing into filaments, yet how these form membrane lesions is unknown. Integrating cell-based assays with molecular dynamics simulations, we demonstrate that NINJ1-driven membrane rupture starts with the lateral association of NINJ1 dimers into double filaments. Subsequently, swelling of necrotic cells increases plasma membrane tension, leading to separation of the filament interface and NINJ1 lesion opening. Inhibiting cell swelling prevents this increase in tension, blocking NINJ1-mediated plasma membrane rupture without disrupting NINJ1 oligomerization, implicating membrane tension as key for opening NINJ1 lesions. The NINJ1 homolog NINJ2 oligomerizes but fails to form membrane lesions during cell death due to the greater stability of its dimer. Finally, using atomic force microscopy of NINJ1-containing proteoliposomes, we show that NINJ1 forms large pores by stabilizing membrane edges. In summary, our findings support a model whereby membrane tension drives a zipper-like opening of NINJ1 double filaments, initiating necrotic cell lysis.

immunology↗

bioRxiv2023

An optogenetic approach to control and monitor inflammasome activation.

Inflammasomes are multiprotein platforms which control caspase-1 activation, leading to the processing of proinflammatory cytokines into mature and active cytokines IL-1{beta} and IL-18, and to pyroptosis through the cleavage of gasdermin-D (GSDMD). Inflammasomes assemble upon activation of specific cytosolic pattern recognition receptors (PRRs) by damage-associated molecular patterns (DAMPs) or pathogen-associated molecular patterns (PAMPs). They converge to the nucleation of apoptosis-associated speck-like containing a caspase activation and recruitment domain (ASC) to form hetero-oligomers with caspase-1. Studying inflammasome encoding activities remains challenging because PAMPs and DAMPs are sensed by a large diversity of cytosolic and membranous PRRs. To bypass the different signals required to activate the inflammasome, we designed an optogenetic approach to temporally and quantitatively manipulate ASC assembly (i.e. in a PAMP- or DAMP-independent manner). We reveal that controlling light-sensitive oligomerization of ASC is sufficient to recapitulate the classical features of inflammasomes within minutes, and enabled us to decipher the complexity of volume regulation and pore opening during pyroptosis. Overall, this approach offers interesting perspective to decipher PRR signaling pathways in the field of innate immunity.

immunology↗