Biology subjects

Mulero, V.

Publications and source records attributed to Mulero, V..

14 recordsLinked to original sources

bioRxiv2025

Teleost-specific ictacalcins exhibit similar structural organization, cation-dependent activation and transcriptional regulation as human S100 proteins

S100 proteins are highly versatile calcium-binding proteins from vertebrates. Following extracellular release, they become instrumental in immune and antimicrobial defenses, initiating the inflammatory response through receptor signaling and providing direct control of bacterial invaders via nutritional immunity. While mammalian S100s have been extensively studied, very little is known about the more recently discovered S100 proteins from teleost fish, including those with no strict orthologs in mammals. Comparable functioning between both clades would allow to expand their study into the highly popular zebrafish model, particularly suited for live imaging and mechanistic exploration of immune and inflammatory processes. To fill the gap of knowledge on teleost S100s, we here provide a detailed structural and biochemical characterization of S100i1 and S100i2 from Danio rerio, two teleost-specific S100s absent in mammals. We demonstrate that they nevertheless share conserved tertiary and quaternary organization with mammalian S100s. In addition, they exhibit comparable calcium binding properties and undergo a similar calcium-dependent activation mechanism. Furthermore, they display analogous expression pattern, being enriched in tissues highly exposed to the environment like gills and skin, the latter constituting an important reservoir of S100 proteins in mammals. Finally, our results show, for the very first time, that s100i2/i2 gene expression is differentially modulated in sterile disease conditions associated with sustained inflammation or high hypoxic state. Altogether, these findings underline the strong parallelism existing between mammalian and teleost-specific S100 proteins despite their divergent evolution, opening up new avenues to explore their biology in the zebrafish model.

immunology↗

bioRxiv2025

Inhibition of NLRP1 Inflammasome Activation by Tyrosine Kinase Inhibitors Restores Erythropoiesis in Diamond-Blackfan Anemia Syndrome

Diamond-Blackfan Anemia Syndrome (DBAS) is characterized by impaired erythropoiesis due to dysfunctional ribosome biogenesis and aberrant cellular signaling. Here, we investigate how ribosomal stress-induced activation of the NLRP1 inflammasome modulates erythroid differentiation in DBAS. We demonstrate that FDA/EMA-approved tyrosine kinase inhibitors (TKIs) effectively mitigate defective erythropoiesis in Diamond-Blackfan anemia syndrome (DBAS) by inhibiting NLRP1 inflammasome activation. Specifically, nilotinib enhances erythroid differentiation in K562 cells through suppression of the ZAK/P38/NLRP1/CASP1 axis, leading to increased GATA1 protein levels and upregulation of key erythroid genes involved in iron acquisition, hemoglobin synthesis, and erythrocyte structure. These effects were validated in human CD34+ hematopoietic stem and progenitor cells (HSPCs) and zebrafish models, where nilotinib, along with other TKIs (imatinib, dasatinib, and bosutinib), promoted erythropoiesis at the expense of myelopoiesis and reduced caspase-1 activity. Importantly, in RPS19-deficient zebrafish and human models and HSPCs from patients with DBAS, nilotinib, imatinib and dasatinib rescued defective erythroid differentiation and restored hemoglobin levels. These findings highlight the potential of TKIs to address the erythroid defects observed in ribosomopathies like DBAS. Given the limited treatment options available for DBAS and other congenital anemias, our study provides compelling evidence for repurposing TKIs as a novel therapeutic strategy to alleviate pathological NLRP1 activation and improve erythropoiesis. This work opens new avenues for managing ribosome-related disorders and advancing personalized medicine approaches for hematopoietic diseases.

immunology↗

bioRxiv2025

Macrophage Inflammasome Activation Drives Anti-inflammatory Responses via Neutrophil-Derived ASC Speck Transfer and Gasdermin-Dependent Caspase-1 Inhibition

Inflammasomes are critical components of the innate immune system, traditionally associated with pro-inflammatory responses. While the inflammasome in macrophages has been extensively studied and linked to pyroptosis and cytokine release, the neutrophil inflammasome remains poorly understood. Neutrophil inflammasome activation drives unique outcomes such as NETosis and robust IL-1{beta} production without inducing pyroptosis. In contrast, macrophage inflammasome activation promotes pyroptosis and the release of cytokines like IL-1 and IL-18. Here, using zebrafish models of Salmonella enterica serovar Typhimurium infection and COVID-19-associated cytokine storm syndrome (CSS), we reveal opposing roles of neutrophil and macrophage inflammasomes: neutrophil inflammasomes are pro-inflammatory, whereas macrophage inflammasomes mediate anti-inflammatory responses. We show that Gasdermin E- and Ninjurin-1-mediated cell death in neutrophils releases ASC specks, which are taken up by macrophages. This transfer negatively regulates caspase-1 activity via the C-terminal domain of Gasdermin E, promoting the resolution of inflammation. To our knowledge, this is the first study to reveal the anti-inflammatory role of the macrophage inflammasome, document the in vivo transfer of ASC specks between neutrophils and macrophages, and uncover the negative feedback regulation of the inflammasome by the C-terminal domain of Gsdme. These results offer novel insights into potential therapeutic approaches for hyperinflammatory diseases like bacterial infections and COVID-19-associated CSS.

immunology↗

bioRxiv2023

Peds1 deficiency in zebrafish results in myeloid cell apoptosis and exacerbated inflammation

Plasmalogens are glycerophospholipids with a vinyl ether bond that confers unique properties. Recent identification of the gene encoding PEDS1, the desaturase generating the vinyl ether bond, enables evaluation of the role of plasmalogens in health and disease. Here, we report that Peds1-deficient zebrafish larvae display delayed development, increased basal inflammation, normal hematopoietic stem and progenitor cell emergence, and cell-autonomous myeloid cell apoptosis. In a sterile acute inflammation model, Peds1-deficient larvae exhibited impaired inflammation resolution and tissue regeneration, increased interleukin-1{beta} and NF-{kappa}B activities, and elevated ROS levels at the wound site. Abnormal immune cell recruitment, neutrophil persistence, and fewer but predominantly pro-inflammatory macrophages was observed. Chronic skin inflammation worsened in Peds1-deficient larvae but was mitigated by exogenous plasmalogen, which also alleviated hyper-susceptibility to bacterial infection, as did pharmacological inhibition of caspase-3 and colony-stimulating factor 3-induced myelopoiesis. Overall, our results highlight an important role for plasmalogens in myeloid cell biology and inflammation. KeypointsO_LIPlasmalogens are crucial for cell autonomous survival, recruitment and activation of neutrophils and macrophages. C_LIO_LIPlasmalogen production aids inflammation resolution, while supplementation reduces inflammation and boosts bacterial clearance. C_LI

immunology↗

bioRxiv2022

Pro-tumor and prothrombotic activities of hepsin in colorectal cancer cells and suppression by venetoclax

Hepsin is a type II transmembrane serine protease whose expression has been linked to greater tumorigenicity and worse prognosis in different tumors such as prostate and gastric cancer. Recently, our group described hepsin expression in the primary biopsy as a potential biomarker of thrombosis and metastasis in localized colorectal cancer patients. Here we explored the role of hepsin in this tumor. Hepsin overexpression increased Caco-2 cell migration and invasion, higher phosphorylation of Erk1/2 and STAT3 and led to more thrombin generation in plasma. Indeed, our study revealed higher plasma levels of hepsin in metastatic colorectal cancer patients, which was associated with a greater tendency toward thrombosis. By virtual screening of a FDA-approved drug library, we identified venetoclax as a potent hepsin inhibitor, reducing the metastatic and prothrombotic phenotype of Caco-2 cells, but not of other colorectal cancer cells without hepsin expression. Interestingly, pre-treating Caco-2 cells overexpressing hepsin with venetoclax reduced its in vivo invasiveness. Taken together, our results demonstrate that elevated hepsin levels correlate with a more aggressive and prothrombotic tumor phenotype. Likewise, they evidence an antitumor role for venetoclax as a hepsin inhibitor. This lays the groundwork for molecular targeted therapy for colorectal cancer.

cancer biology↗

bioRxiv2022

A zebrafish model of COVID-19-associated cytokine storm syndrome reveals that the Spike protein signals via TLR2

Understanding the mechanism of virulence of SARS-CoV-2 and host innate immune responses are essential to develop novel therapies. One of the most studied defense mechanisms against invading pathogens, including viruses, are Toll-like receptors (TLRs). Among them, TLR3, TLR7, TLR8 and TLR9 detect different forms of viral nucleic acids in endosomal compartments, whereas TLR2 and TLR4 recognize viral structural and nonstructural proteins outside the cell. Although many different TLRs have been shown to be involved in SARS-CoV-2 infection and detection of different structural proteins, most studies have been performed in vitro and the results obtained are rather contradictory. In this study, we report using the unique advantages of the zebrafish model for in vivo imaging and gene editing that the S1 domain of the Spike protein from the Wuhan strain (S1WT) induced hyperinflammation in zebrafish larvae via a Tlr2/Myd88 signaling pathway and independently of interleukin-1{beta} production. In addition, S1WT also triggered emergency myelopoiesis, but in this case through a Tlr2/Myd88-independent signaling pathway. These results shed light on the mechanisms involved in the COVID-19-associated cytokine storm syndrome.

immunology↗

bioRxiv2022

Combination therapy targeting inflammasome and fibrogenesis alleviates inflammation and fibrosis in a zebrafish model of silicosis

Silicosis is a long-term lung disease caused by the inhalation of large amounts of crystalline silica dust. As there is no effective treatment available, patients are provided with supportive care, and some may be considered for lung transplantation. There is therefore an evident need for a better understanding of the diseases biology and for identifying new therapeutic targets and therapies. In this context, our group has developed a larval zebrafish model of silicosis by injecting silica crystals into the hindbrain ventricle, a cavity into which immune cells can be recruited and that mimics the alveolar environment of the human lung. The injection of silica crystals into this cavity led to the initiation of local and systemic immune responses driven through both TLR- and inflammasome-dependent signaling pathways, followed by fibrosis, as happens in human patients. The combination of the inflammasome inhibitor VX-765 and the antifibrotic agent pirfenidone was found to be the best therapy to alleviate both inflammation and fibrosis. The zebrafish model of silicosis developed here is a unique tool that will shed light onto the molecular mechanisms involved in the progression of this devastating disease and for identifying novel drugs that improve the quality of life of silicosis patients.

immunology↗

bioRxiv2021

A zebrafish model of COVID-19-associated cytokine storm syndrome reveals differential proinflammatory activities of Spike proteins of SARS-CoV-2 variants of concern.

The sudden and unexpected appearance of the COVID-19 pandemic turned the whole world upside down in a very short time. One of the main challenges faced has been to understand COVID-19 patient heterogeneity, as a minority develop life-threatening hyperinflammation, the so-called cytokine storm syndrome (CSS). Using the unique advantages of the zebrafish model we report here the proinflammatory role of Spike (S) proteins from different SARS-CoV-2 variants of concern after injection into the hindbrain ventricle, a cavity filled with cerebrospinal fluid to which immune cells can be easily recruited and that mimics the alveolar environment of the human lung. We found that wild type/Wuhan variant S1 (S1WT) protein promoted neutrophil and macrophage recruitment, local and systemic hyperinflammation, emergency myelopoiesis, and hemorrhages. In addition, S1{gamma} protein was more proinflammatory and S1{delta} was less proinflammatory than S1WT and, strikingly, S1{beta} promoted delayed and long-lasting inflammation. Pharmacological inhibition of the canonical inflammasome robustly alleviated S1 protein-induced inflammation and emergency myelopoiesis. In contrast, genetic inhibition of angiotensin-converting enzyme 2 strengthened the proinflammatory activity of S1, and the administration of angiopoietin (1-7) fully rescued S1-induced hyperinflammation and hemorrhages. These results shed light into the mechanisms orchestrating the COVID-19-associated CSS and the host immune response to different SARS-CoV-2 S protein variants. HighlightsO_LIS proteins of SARS-CoV-2 promote hyperinflammation, neutrophilia, monocytosis and hemorrhages in zebrafish. C_LIO_LIS protein effects in zebrafish are mediated via the canonical inflammasome and the Ace2/Angiopoietin (1-7) axis. C_LIO_LIDelta S1 is less proinflammatory than wild type S1 and fails to induce emergency myelopoiesis in zebrafish. C_LIO_LINaive and primed human white blood cells are unable to respond to S proteins. C_LI

immunology↗

bioRxiv2021

Telomerase and Alternative Lengthening of Telomeres coexist in the regenerating zebrafish caudal fins

Telomeres are essential for chromosome protection and genomic stability, and telomerase function is critical to organ homeostasis. Zebrafish has become a useful vertebrate model for understanding the cellular and molecular mechanisms of regeneration. The regeneration capacity of the caudal fin of wild-type zebrafish is not affected by repetitive amputation, but the behavior of telomeres during this process has not yet been studied. In this study, the regeneration process was characterized in a telomerase deficient zebrafish model. Moreover, the regenerative capacity after repetitive amputations and at different ages was studied. Regenerative efficiency decreases with aging in all genotypes and surprisingly, telomere length is maintained even in telomerase deficient genotypes. Our results suggest that telomere length can be maintained by the regenerating cells through the recombination-mediated Alternative Lengthening of Telomeres (ALT) pathway, which is likely to support high rates of cell proliferation during the tailfin regeneration process. As far as we know, this is the first animal model to study ALT mechanism in regeneration, which opens a wealth of possibilities to study new treatments of ALT dependent processes.

genetics↗

bioRxiv2021

NAMPT-derived NAD+ fuels PARP1 to promote skin inflammation through parthanatos

Several studies have revealed a correlation between chronic inflammation and NAD+ metabolism but the precise mechanism involved is unknown. Here we report that the genetic and pharmacological inhibition of nicotinamide phosphoribosyltransferase (Nampt), the rate-limiting enzyme in the salvage pathway of NAD+ biosynthesis, reduced oxidative stress, inflammation, and keratinocyte DNA damage, hyperproliferation and cell death in zebrafish models of chronic skin inflammation, while all these effects were reversed by NAD+ supplementation. Similarly, genetic and pharmacological inhibition of poly ADP-ribose (PAR) polymerase 1 (Parp1), overexpression of PAR glycohydrolase, inhibition of apoptosis-inducing factor 1, inhibition of NADPH oxidases and reactive oxygen species (ROS) scavenging, all phenocopied the effects of Nampt inhibition. Pharmacological inhibition of NADPH oxidases/NAMPT/PARP/AIFM1 axis decreased expression of pathology-associated genes in human organotypic 3D skin models of psoriasis. Consistently, an aberrant induction of both NAMPT amounts and PARP activity was observed in lesional skin from psoriasis patients. In conclusion, hyperactivation of PARP1 in response to ROS-induced DNA damage, fueled by NAMPT-derived NAD+, mediates skin inflammation through parthanatos cell death. HighlightsO_LINAMPT inhibition alleviates inflammation in zebrafish and human epidermis organoid models of psoriasis. C_LIO_LINADPH oxidase-derived ROS mediates keratinocyte DNA damage and Parp1 overactivation. C_LIO_LIInhibition of parthanatos cell death phenocopies the effects of NAMPT inhibition in zebrafish and human psoriasis models. C_LIO_LINAMPT and PAR metabolism is altered in psoriasis patients. C_LI

immunology↗

bioRxiv2020

TERT-mediated induction of MIR500A contributes to tumor invasiveness by targeting Hedgehog pathway

The classical activity of telomerase (TERT) is to maintain telomere homeostasis, ensuring chromosome stability and cellular proliferation. However, increasing evidences of telomere-independent human TERT functions have been lastly obtained. We report here that TERT directly binds to the TCF binding elements (TBE) located upstream the oncomiR MIR500A inducing its expression and promoting cancer invasiveness. This function is independent of telomerase activity, since catalytic inactive TERT also induces MIR500A expression and telomerase inhibitors directed against TERT, but not to its RNA component TERC, inhibit telomerase-induced MIR500A expression and cancer invasiveness. Mechanistically, telomerase-induced MIR500A down-regulates key genes of the Hedgehog signaling pathway, namely patched 1 (PTCH1), Gli family zinc finger 3 (GLI3) and cullin 3 (CUL3), increasing tumor invasiveness. Our results show a crucial role of the TERT/MIR500A/Hedgehog axis is tumor aggressiveness, pointing out to the relevance of inhibiting the extracurricular functions of telomerase to fight cancer.

cancer biology↗

bioRxiv2019

UFMylation of MRE11 is essential for telomere length and hematopoietic stem cell survival

Genetic studies using knockout mouse models provide strong evidence for the essential role of the ubiquitin-like protein UFM1 for hematopoiesis, especially erythroid development, yet its biological roles in this process are largely unknown. Here we have identified a UFL1-dependent UFMylation of the MRE11 nuclease on the K281 and K282 residues. We show that Hela cells lacking the specific UFM1 E3 ligase display severe telomere shortening. We further demonstrate either by deleting UFM1 or by mutating MRE11 UFMylation sites that preventing MRE11 UFMylation impacts its interaction with the telomere protein TRF2. However, the MRE11 function in double-strand-break repair remains intact. We validate these results in vivo by showing that Zebrafish knockouts for the genes ufl1 and ufm1 have shorter telomeres in hematopoietic cells. Here we present UFMylation has a new mechanisms of regulation for telomere length maintenance with a role in hematopoiesis. Key pointsModification of MRE11 by UFM1 regulates telomere maintenance and cell death in HSCs Scientific categoryUFMylation, telomere maintenance, hematopoietic stem cell survival.

molecular biology↗

bioRxiv2019

SPINT1 regulates the aggressiveness of skin cutaneous melanoma and its crosstalk with tumor immune microenvironment

Skin cutaneous melanoma (SKCM) is the deadliest form of skin cancer and while incidence rates are declining for most cancers, they have been steadily rising for SKCM worldwide. Serine protease inhibitor, kunitz-type, 1 (SPINT1) is a type II transmembrane serine protease inhibitor that has been shown to be involved in the development of several types of cancer. We report here a high prevalence of SPINT1 genetic alterations in SKCM patients and their association with altered tumor immune microenvironment and poor patient survival. We used the unique advantages of the zebrafish to model the impact of SPINT1 deficiency in early transformation, progression and metastatic invasion of SKCM. Our results reveal that Spint1a deficiency facilitates oncogenic transformation, regulates the tumor/immune microenvironment crosstalk, accelerates the onset of SKCM and promotes metastatic invasion. Notably, Spint1a deficiency is required at both cell autonomous and nonautonomous levels to enhance invasiveness of SKCM. These results suggest the relevance of clinical intervention on this signaling pathway for precision SKCM medicine.\n\nSummary statementA zebrafish model shows that Spint1a deficiency facilitates oncogenic transformation, regulates the tumor/immune microenvironment crosstalk, accelerates the onset of SKCM, and promotes metastatic invasion in cell autonomous and non-autonomous manners.

cancer biology↗

bioRxiv2018

Olfactory sensory neurons mediate ultra-rapid antiviral immune responses in teleosts in a TrkA-dependent manner

The nervous system is known to regulate host immune responses. However, the ability of neurons to detect danger and initiate immune responses at barrier tissues is unclear. Vertebrate olfactory sensory neurons (OSNs) are located in direct contact with the external environment and therefore directly exposed to pathogens. Here, we report that nasal delivery of rhadboviruses induced apoptosis in crypt OSNs in rainbow trout olfactory organ (OO) via the interaction of the OSN TrkA receptor with viral glycoprotein. This signal resulted in pro-inflammatory responses in the OO and dampened inflammation in the olfactory bulb (OB). CD8+ cells infiltrated the OO within minutes of nasal viral delivery and this response was abrogated when TrkA was blocked. Infiltrating CD8+ cells originated from the microvasculature surrounding the OB and not the periphery. Ablation of crypt neurons in zebrafish resulted in increased susceptibility to rhabdoviral challenge. Our results, therefore, indicate a novel function for OSNs as a first layer of pathogen detection in vertebrates.

immunology↗