Biology subjects

Balsinde, J.

Publications and source records attributed to Balsinde, J..

3 recordsLinked to original sources

bioRxiv2026

Defensive lipid droplets are PUFA reservoirs driving bacterial clearance and inflammation

Lipid droplets (LDs) rapidly form in infected cells to participate in the defence against microbes. Here, we investigate the involvement of LD lipids in these immune responses. Comparative shotgun and targeted lipidomics demonstrate that in vivo host LDs accumulate polyunsaturated fatty acids (PUFAs). PUFAs arrive at cells from the bloodstream to be further metabolised into complex PUFAs accrued by LD-triglycerides and -phospholipids. Host lipid metabolism is transcriptionally controlled by rapid, transient, and intricate immune programs initiated by pathogen-associated molecular patterns and relayed by cytokines such as interferons (type I and II), interleukins (IL-1{beta}), and tumour necrosis factor. When this lipid and signalling environment is reproduced in cultured macrophages, newly formed LDs accumulate defensive proteins, coordinate the synthesis of complex PUFAs, and become PUFA reservoirs and suppliers. Among LD-PUFAs, the {omega}-6 arachidonic acid is the most actively metabolised during the initial phases of innate immunity. Released from LDs by adipose triglyceride lipase, arachidonic acid is used by macrophages for prostaglandin synthesis, bacterial phagocytosis, and elimination of microbes. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=163 HEIGHT=200 SRC="FIGDIR/small/711356v2_ufig1.gif" ALT="Figure 1"> View larger version (107K): org.highwire.dtl.DTLVardef@14d65eorg.highwire.dtl.DTLVardef@5ecc1org.highwire.dtl.DTLVardef@fa99e5org.highwire.dtl.DTLVardef@8d9632_HPS_FORMAT_FIGEXP M_FIG C_FIG

cell biology↗

bioRxiv2021

Intracellular pools of DAG-activated TRPC3 channels are essential for TLR4 activation

Toll-like receptor 4, the receptor for bacterial lipopolysaccharide (LPS), drives inflammatory responses that protect against pathogens and boost the adaptive immunity. LPS responses are known to depend on calcium fluxes, but the molecular mechanisms involved are poorly understood. Here we present evidence that the transient receptor potential canonical channel 3 (TRPC3) is activated intracellularly during macrophage exposure to LPS and is essential for Ca2+ release from internal stores. In this way TRPC3 participates in cytosolic Ca2+ elevations, TLR4 endocytosis, activation of inflammatory transcription factors and cytokine upregulation. We also report that TRPC3 is activated by diacylglycerol (DAG) generated by the phosphatidic acid phosphatase lipin-1. In accord with this, lipin-1-deficient cells show reduced Ca2+ responses to LPS challenge. A cameleon indicator directed to the endoplasmic reticulum shows that this is the organelle from which TRPC3 mediates the Ca2+ release. Finally, pharmacological inhibition of TRPC3 reduces systemic inflammation induced by LPS in mice. Collectively, our study unveils a central component of LPS-triggered Ca2+ signaling that involves intracellular sensing of lipin-1-derived DAG by TRPC3.

immunology↗

bioRxiv2018

ECM deposition is driven by caveolin1-dependent regulation of exosomal biogenesis and cargo sorting

The composition and physical properties of the extracellular matrix (ECM) critically influence tumour cell behaviour, and ECM deposition and remodelling by stromal fibroblast populations is therefore pivotal for tumour progression. The molecular mechanisms by which stromal and tumour cell populations regulate ECM layering are poorly understood. Tumour-stroma interaction is critically dependent on cell-cell communication mediated by exosomes, small vesicles secreted by most cell types and generated within multivesicular bodies (MVBs). Here, we show that caveolin-1 (Cav1), an essential regulator of stromal remodelling and tumour cell fate, plays a central role in modulating both exosome biogenesis and exosomal protein cargo sorting through cholesterol-dependent mechanisms. Quantitative proteomics profiling revealed that a major share of Cav1-dependent exosomal cargoes are compsed of ECM proteins, one of the most important components being tenascin-C (TnC). Comparative functional assays demonstrated that Cav1 is required for fibroblast-derived exosomes to depose ECM and promote tumour cell invasiveness. Exosomes purified from Cav1WT cells, but not those from Cav1-null cells, were able to nucleate distant stromal niches in different organs in vivo. These findings suggest a key role for Cav1 as a cholesterol rheostat in MVBs, and seems to determine ECM deposition by eliciting ECM component sorting into specific exosome pools. These results, together with previous work, support a model in which Cav1 is a central regulatory hub for tumour-stroma interactions through a novel exosome-dependent ECM deposition mechanism.

cell biology↗