Biology subjects

Sanz, A.

Publications and source records attributed to Sanz, A..

12 recordsLinked to original sources

bioRxiv2026

Defining a Biofabrication Window for Visible-Light Photocrosslinkable Protein Bioinks in Extrusion Bioprinting

Extrusion bioprinting requires simultaneous control of material processability, rapid post-deposition stabilization, geometric fidelity, and cell compatibility. Here, we defined an experimental biofabrication window for three visible-light photocrosslinkable protein formulations based on silk fibroin (SF), gelatin methacryloyl (GelMA), and collagen methacryloyl (ColMA) using a extrusion-bioprinting workflow and ruthenium/sodium persulfate (Ru/SPS) photochemistry. Material-specific photocrosslinking conditions were first established under 430-nm irradiation and subsequently evaluated by ATR-FTIR spectroscopy, unconfined compression, short-term ARPE-19 cytocompatibility, and printing assays. Stable bulk hydrogels were obtained using 1-Ru/SPS, 45 mW, and 5 min for SF; 2.5- Ru/SPS, 45 mW, and 7 min for GelMA; and 2.5- Ru/SPS, 45 mW, and 6 min for ColMA. The selected formulations formed compliant hydrogels with initial compressive moduli of 0.60, 0.52, and 2.55 kPa for SF, GelMA, and ColMA, respectively, without significant differences among groups. Short-term XTT assays identified the unreacted Ru/SPS-containing precursor as a major biological constraint, whereas photoinitiator-free SF and GelMA maintained metabolic activity close to the culture-medium reference. GelMA and SF generated interconnected lattices with printability indices of 0.893 and 0.963, respectively. Detailed SF analysis showed high positional accuracy (96.9%) despite substantial post-deposition spreading, demonstrating that positioning accuracy and dimensional fidelity are distinct properties. Cell-laden printing was achieved with both SF and GelMA, and independent extrusion testing showed no statistically significant reduction in short-term ARPE-19 viability after SF bioprinting. Following the complete printing and photocrosslinking workflow, both formulations contained predominantly viable cells, but only SF retained the printed grid-associated cellular architecture under the tested conditions. These findings support the concept that biofabrication performance is an operational property arising from the intersection of photocrosslinking, cytocompatibility, extrusion compatibility, geometric fidelity, and post-fabrication structural stability.

bioengineering↗

bioRxiv2026

Pathogenic PTCD1 variants cause mitochondrial protein aggregation and cardiomyopathy

Disorders of mitochondrial oxidative phosphorylation affecting multiple respiratory chain complexes are among the most common causes of mitochondrial disease in humans. However, impaired energy metabolism alone does not fully account for tissue-specific vulnerability and disease progression, suggesting that additional molecular mechanisms contribute to disease pathology. We previously identified PTCD1 variants in a child with infantile cardiomyopathy associated with a combined respiratory chain deficiency. Here, we establish the pathogenicity of three PTCD1 (NM_015545.4) variants in which p.(Arg113Trp) and p.(Gly184Arg) segregate in cis whereas p.(Arg130*) is present in trans, demonstrating that disrupted mitochondrial proteostasis contributes to tissue damage in PTCD1 deficiency. PTCD1 patient cardiac tissue characterisation revealed impaired mitoribosome biogenesis, alongside increased aggregation of selective mitochondrial matrix proteins. Cell models expressing individual and combined PTCD1 missense variants, coupled with proteomics, recapitulated the protein aggregation, with the cis p.(Arg113Trp);p.(Gly184Arg) combination showing the most severe effect. Protein aggregation was accompanied by altered OPA1 processing and mitochondrial network remodelling. Our findings establish accumulating proteotoxic stress arising from impaired mitoribosome assembly as a pathogenic mechanism in post-mitotic tissues, driving PTCD1 cardiomyopathy.

cell biology↗

bioRxiv2026

A conserved mechanism for regulation of mtDNA copy number in eukaryotes

Mitochondrial mass and mitochondrial DNA (mtDNA) copy number are coupled to metabolic demand at the cellular, tissue and organismal level, however, the molecular basis for homeostatic regulation of mtDNA is not understood. Here we show that mitochondria and mtDNA copy number are regulated by compartmentalisation of iron-sulfur (Fe-S) clusters, glutathione and cysteine, a mechanism we exemplify in model systems ranging from plants to human cells. Using genome-wide CRISPR screens we discovered that the mitochondrial ABC-family transporter, ABCB7, is a negative regulator of mtDNA copy number. Partial silencing of ABCB7 in human cells increased mtDNA 2-3 fold, enhancing mitochondrial mass and function. ABCB7 silencing compelled co-incident mitochondrial accumulation and cytosolic depletion of Fe-S clusters, simultaneously engaging the cellular iron starvation response and stabilising the mitochondrial glutathione transporter, SLC25A39. Transport of glutathione from the cytosol into mitochondria was co-incident with mitochondrial cysteine accumulation and cytosolic cysteine depletion, which was necessary and sufficient to increase mtDNA copy number in an integrated stress response-dependent fashion, with induction of PGC1{beta} and ERR. Silencing or partial loss of function mutations in the ABCB7 homologs of D.melanogaster, S.cerevisiae and A. thaliana elicited similar increases of mtDNA within these organisms. These data reveal a fundamental metabolic logic coupling compartmentalisation of redox co-factors to organellar genome content; a conserved axis across eukaryotes that pre-dates several elements of the mtDNA replication machinery.

cell biology↗

bioRxiv2026

Human NLRP1 and NLRP3 interact driving inflammation in inflammosomopathies and inflammatory diseases

Inflammasomes are multiprotein complexes that form and activate after exposure to pathogenic microbes and host danger signals that trigger an inflammatory response. Although NLRP1 and NLRP3 inflammasomes share structural similarities and can be activated by similar stimuli, no evidence of heterotypic inflammasome assemblies has been reported. Here, we identify a unique interaction between NLRP1 and NLRP3 in human cells, forming a hybrid inflammasome, to drive inflammation. NLRP1 is essential for this hydrid inflammasome activation and NLRP3-mediated Caspase-1 activation and release of IL-1{beta} and IL-18. The presence of the heterocomplex inflammasome was confirmed in blood samples from patients after kidney transplantation and is associated with inflammatory responses driven by NLRP3 and MEFV mutations that cause inflammasomopathies. Our findings reveal an unexpected level of intricacy in inflammasome composition, pinpointing hybrid targets that may pave the way for innovative pharmacological treatments for inflammatory disorders. Significance StatementPrevious findings showed interactions between NLRP3 and NLRC4 or NLRP3 and NLRP11 showing that would be possible the interaction of the inflammasomes as supercomplexes and not working alone. Now, we show a new inflammasome heterocomplex inflammasome between NLRP1 and NLRP3 which is associated to the inflammatory profile in autoimmune diseases patietns and transplanted patients. These findings could open a new research topic for the design of dual inflammasomes inhibitors.

immunology↗

bioRxiv2023

Developmental mitochondrial Complex I activity determines lifespan

Aberrant mitochondrial function has been associated with an increasingly large number of human disease states. Observations from in vivo models where mitochondrial function is altered suggest that adaptations to mitochondrial dysfunction may underpin disease pathology. We hypothesized that the severity of these maladaptations could be shaped by the plasticity of the system when mitochondrial dysfunction manifests. To investigate this, we have used inducible fly models of mitochondrial complex I (CI) dysfunction to reduce mitochondrial function at two stages of the fly lifecycle, from early development and adult eclosion. Here, we show that in early life (developmental) mitochondrial dysfunction results in severe reductions in survival and stress resistance in adulthood, while flies where mitochondrial function is perturbed from adulthood, are long-lived and stress resistant despite having up to an 75% reduction in CI activity. After excluding developmental defects as a cause, we went on to molecularly characterize these two populations of mitochondrially compromised flies, short- and long-lived. We find that our short-lived flies have unique transcriptomic and metabolomic responses which overlap significantly in discreet models of CI dysfunction. Our data demonstrate that early mitochondrial dysfunction via CI depletion elicits an adaptive response which severely reduces survival, while CI depletion from adulthood is not sufficient to reduce survival and stress resistance.

molecular biology↗

bioRxiv2023

The Role of Respiratory Complex IV in Lifespan Length and Quality

The contribution of mitochondria to lifespan determination remains controversial, as impaired mitochondrial function can paradoxically both shorten and extend longevity. During ageing, mitochondria accumulate defects that disrupt electron transport and elevate the production of reactive oxygen species (ROS) per unit of ATP. Here, we developed Drosophila melanogaster models carrying mitochondria that phenocopy aged organelles--termed "aged-like" mitochondria--to dissect the developmental versus adult contributions of mitochondrial dysfunction to lifespan regulation. Inducing aged-like mitochondria during development caused profound metabolic maladaptation and markedly reduced adult lifespan, without signs of accelerated ageing. In contrast, restricting their expression to adulthood resulted in only a modest reduction in lifespan, accompanied by an increased mortality rate, indicative of accelerated ageing. Enhancing mitochondrial function exclusively during development by expressing the alternative oxidase (AOX) mitigated these metabolic defects and significantly extended adult survival. Likewise, developmental overexpression of Rheb, an activator of Target of Rapamycin (TOR) signalling, improved adult survival without restoring mitochondrial respiration. Finally, we show that mitochondrial respiratory capacity cannot be reinstated in adults with "aged-like" mitochondria, as oxidative phosphorylation (OXPHOS) protein levels are largely established during development and remain stable throughout adult life. We propose that Drosophila permanently tunes adult metabolism according to developmental cues to optimise reproductive fitness, at the expense of long-term survival.

molecular biology↗

bioRxiv2023

NLRP1 inflammasome modulates senescence and senescence-associated secretory phenotype

Senescence is a cellular aging-related process triggered by different stresses and characterized by the secretion of various inflammatory factors referred to as the senescence-associated secretory phenotype (SASP). Here, we present evidence that the inflammasome sensor, NLRP1, is a key mediator of senescence induced by irradiation both in vitro and in vivo. The NLRP1 inflammasome promotes senescence by regulating the expression of p16, p21, p53, and SASP in Gasdermin D (GSDMD)-dependent manner as these responses are reduced in conditions of NLRP1 insufficiency or GSDMD inhibition. Mechanistically, the NLRP1 inflammasome is activated downstream of the cytosolic DNA sensor cGMP-AMP (cGAMP) synthase (cGAS) in response to genomic damage. These findings provide a rationale for inhibiting the NLRP1 inflammasome-GSDMD axis to treat senescence-driven disorders.

immunology↗

bioRxiv2021

ROS signalling requires uninterrupted electron flow and is lost during ageing in flies

Mitochondrial Reactive Oxygen Species (mtROS) are cellular messengers essential for cellular homeostasis. In response to stress, reverse electron transport (RET) by respiratory complex I generates high levels of mtROS. Suppression of ROS produced via RET (ROS-RET) reduces survival under stress, while activation of ROS-RET extends lifespan in basal conditions. Here, we demonstrate that ROS-RET signalling requires increased electron entry and uninterrupted electron flow through the electron transport chain (ETC). We found that ROS-RET is abolished in old fruit flies where electron flux is reduced. Instead, mitochondria in aged flies produce consistently high levels of mtROS. Finally, we demonstrate that in young flies reduction of electron exit from the ETC, but not electron entry, phenocopies mtROS generation observed in old individuals. Our results define the mechanism by which ROS signalling is lost during ageing. HighlightsO_LIROS-RET signalling requires an uninterrupted flow of electrons through the ETC. C_LIO_LIROS-RET signalling fails during ageing, with mitochondria producing persistently high levels of ROS. C_LIO_LIInterruption of ROS-RET signalling compromises stress adaptation in old flies. C_LIO_LIReducing electron exit suppresses ROS-RET signalling and phenocopies ROS production observed in old mitochondria. C_LI

physiology↗

bioRxiv2021

L-arginine ameliorates defective autophagy in GM2 gangliosidoses by mTOR modulation

Tay-Sachs and Sandhoff diseases (GM2 gangliosidosis) are autosomal recessive disorders of lysosomal function that cause fatal and progressive neurodegeneration in infants and young children. Impaired hydrolysis catalysed by {beta}-hexosaminidase A (HexA) leads to the accumulation of its specific substrate, GM2 ganglioside, in neuronal lysosomes. Despite the development of a florid storage phenotype, the role of autophagy and its regulation by the mammalian target of rapamycin (mTOR) has yet to be explored in the neuropathogenesis. Accordingly, we investigated the effects on autophagy and lysosomal integrity using skin fibroblasts obtained from patients with Tay-Sachs and Sandhoff diseases. Pathological autophagosomes, with enhanced expression of the p62/SQSTM1 protein, suggested impaired autophagic flux, an abnormality confirmed by electron microscopy and biochemical studies revealing the accelerated release of mature cathepsins and HexA into the cytosol, indicating increased lysosomal permeability. GM2 fibroblasts showed inappropriately diminished mTOR signalling with reduced basal mTOR activity. Accordingly, provision of a positive nutrient signal by L-arginine supplementation partially restored mTOR activity and ameliorated the cytopathological abnormalities - and immediately suggests an avenue for therapeutic exploration in this cruel disease. We also contend that the expression of autophagy/lysosome/mTOR-associated molecules may prove useful peripheral biomarkers for facile monitoring of systemic treatment of GM2 gangliosidosis and neurodegenerative disorders that affect the lysosomal function and disrupt autophagy

cell biology↗

bioRxiv2020

Inhibition of the NLRP3 inflammasome prevents ovarian aging

Inflammation is a hallmark of many processes during aging and reproductive physiology, negatively affecting female fertility. The goal of this study was to evaluate the role of the NLRP3 inflammasome in ovarian aging and female fertility. Age-dependent increased expression of NLRP3 in the ovary was observed in female WT mice during reproductive aging. High expression of NLRP3, caspase 1 and IL-1{beta} was also observed in granulosa cells from patients with primary ovarian insufficiency. Ablation of the NLRP3 inflammasome improved the survival and pregnancy rates in mice, increased hormonal levels of AMH, a biochemical marker of ovarian reserve, and autophagy rates in ovarian tissue. Deficiency of the NLRP3 inflammasome also reduced serum FSH and estradiol levels. Consistent with these results, pharmacological inhibition of NLRP3 using a direct NLRP3 inhibitor, MCC950, improved fertility in female mice to levels comparable to those of Nlrp3-/- mice. These results suggest that the NLRP3 inflammasome is implicated in the age-dependent loss of female fertility and position this inflammasome as a potential new therapeutic target for the treatment of infertility.

immunology↗

bioRxiv2020

Calcitriol increases frataxin levels and restores altered markers in cell models of Friedreich Ataxia

Friedreich Ataxia (FA) is a neurodegenerative disease caused by the deficiency of frataxin, a mitochondrial protein. In primary cultures of dorsal root ganglia neurons, we showed that frataxin depletion resulted in decreased levels of the mitochondrial calcium exchanger NCLX, neurite degeneration and apoptotic cell death. Here we describe that frataxin-deficient dorsal root ganglia neurons display low levels of ferredoxin 1, a mitochondrial Fe/S cluster-containing protein that interacts with frataxin and, interestingly, is essential for the synthesis of calcitriol, the active form of vitamin D. We provide data that calcitriol supplementation, used at nanomolar concentrations, is able to reverse the molecular and cellular markers altered in DRG neurons. Calcitriol is able to recover both ferredoxin 1 and NCLX levels and restores mitochondrial membrane potential. Accordingly, apoptotic markers and neurite degeneration are reduced resulting in cell survival recovery with calcitriol supplementation. All these beneficial effects would be explained by the finding that calcitriol is able to increase the mature frataxin levels in both, frataxin-deficient DRG neurons and cardiomyocytes; remarkably, this increase also occurs in lymphoblastoid cell lines derived from FA patients. In conclusion, these results provide molecular bases to consider calcitriol for an easy and affordable therapeutic approach for FA patients.

biochemistry↗

bioRxiv2020

Autophagy promotes cell and organismal survival by maintaining NAD(H) pools

Autophagy is an essential catabolic process that promotes clearance of surplus or damaged intracellular components1. As a recycling process, autophagy is also important for the maintenance of cellular metabolites during periods of starvation2. Loss of autophagy is sufficient to cause cell death in animal models and is likely to contribute to tissue degeneration in a number of human diseases including neurodegenerative and lysosomal storage disorders3-7. However, it remains unclear which of the many cellular functions of autophagy primarily underlies its role in cell survival. Here we have identified a critical role of autophagy in the maintenance of nicotinamide adenine dinucleotide (NAD+/NADH) levels. In respiring cells, loss of autophagy caused NAD(H) depletion resulting in mitochondrial membrane depolarisation and cell death. We also found that maintenance of NAD(H) is an evolutionary conserved function of autophagy from yeast to human cells. Importantly, cell death and reduced viability of autophagy-deficient animal models can be partially reversed by supplementation with an NAD(H) precursor. Our study provides a mechanistic link between autophagy and NAD(H) metabolism and suggests that boosting NAD(H) levels may be an effective intervention strategy to prevent cell death and tissue degeneration in human diseases associated with autophagy dysfunction.

cell biology↗