Biology subjects

de Bruin, A.

Publications and source records attributed to de Bruin, A..

15 recordsLinked to original sources

bioRxiv2026

MASH-in-a-dish reveals fatty acid-driven itaconate crosstalk between Kupffer cells and hepatocytes

Metabolic dysfunction-associated steatohepatitis (MASH) is characterized by lipid-driven sterile inflammation and fibrosis that leads to liver failure and liver cancer. Metabolites are increasingly recognized as signaling molecules and regulate disease progression through cell-cell crosstalk. To overcome the challenges of studying metabolite crosstalk between different cell types in MASH livers, we developed a novel in vitro MASH model, "MASH-in-a-dish", a Transwell co-culture system of mouse hepatocyte-derived organoids (HepOrgs), Kupffer cells (KCs), and hepatic stellate cells (HSCs) in a chemically defined liver co-culture medium. MASH-in-a-dish models key clinical features of clinical MASH, including steatosis, hepatocyte ballooning, inflammation and fibrosis. MASH-in-a-dish allowed for rapid and specific separation of co-cultured HepOrgs, KCs and HSCs, enabling cell type-specific metabolomics and stable-isotope fluxomics analysis. Using MASH-in-a-dish, we identified 19 MASH-associated, cell interaction-responsive metabolites and demonstrated that fatty acids, via the carnitine shuttle, drive KC itaconate production, which aggravated oxidative stress, steatosis, and cell damage in lipid-stressed HepOrgs. Inhibiting itaconate production by KC-specific Acod1 knockout in the MASH-in-a-dish system mitigated hepatocyte damage. Our results show that MASH-in-a-dish is a powerful in vitro platform to study cell-cell interactions in MASH pathogenesis and identify itaconate crosstalk between Kupffer cells and hepatocytes as a novel pathogenic mechanism and a potential therapeutic target in MASH.

biochemistry↗

bioRxiv2025

Non-cell-autonomous mechanisms of tumor initiation and relapse by chromosomal instability

Chromosomal instability (CIN) is a hallmark of cancer, and a primary cause of genetic heterogeneity in tumors. Depending on the degree of CIN and the affected tissue, CIN can promote or suppress tumor formation, and high CIN induction has been proposed as a therapeutic strategy. How CIN achieves these effects is unclear. Here we use a conditional mouse model of graded CIN in combination with longitudinal monitoring of DMBA/TPA-initiated skin tumors to show that low CIN increases the frequency of skin tumor initiation, while higher CIN accelerates onset and growth rates. Strikingly, gene recombination analysis of the tumors reveals that upon high CIN induction the fast-growing tumors originate from rare low CIN cells, suggesting a strong non-cell-autonomous effect of high CIN. Gene expression analysis and immunohistochemistry show that high CIN causes epidermal hyperplasia, immune evasion and a regenerative response that stimulates low CIN tumor growth beyond what is achieved by induction of low CIN alone. Such cell-extrinsic effects may be a common mechanism of tumor formation by CIN, as we observe it also in CIN-induced tumors of the intestine, breast and mesentery. When high CIN is induced in established skin tumors, mimicking CIN-based therapy, tumors regress but relapse quickly. Relapsed tumors, too, arose from rare low CIN cells. Our findings have implications for our understanding of the contributions of CIN to cancer initiation and progression and give caution to the rationale for CIN therapies. Significance statementChromosomal instability (CIN) is a source of genetic diversity in cancer. Different degrees of CIN can be highly oncogenic or tumor suppressive, the latter being a rationale for CIN-based therapies. Using a mouse model for precise control of CIN levels, we show that low CIN promotes tumor initiation, while moderate CIN accelerates both initiation and tumor growth. Surprisingly, moderate CIN acts through its effects on the surrounding tissue rather than directly within tumor cells, by triggering a regenerative response accompanied by immune evasion. When very high CIN is induced in existing tumors, tumors initially regress but rapidly relapse. These findings inform on the contributions of CIN to cancer initiation and progression and give caution to the rationale for CIN therapies.

cancer biology↗

bioRxiv2022

Adrenal cortex size, homeostasis and tumorigenesis is regulated by gonadal hormones via androgen receptor/β-catenin signalling crosstalk.

Female bias is highly prevalent among adrenal cortex hyperplasia and neoplasia, but the reasons behind this phenomenon are poorly understood. In this article, we show that overexpression of the secreted WNT agonist R-spondin-1 leads to ectopic activation of WNT/{beta}-catenin signalling and causes sex-specific adrenocortical hyperplasia in mice. While female adrenals show ectopic proliferation, male adrenals display excessive immune system activation and cortical thinning. Using a combination of genetic manipulations and hormonal treatment, we show that gonadal androgens suppress ectopic proliferation in the adrenal cortex and determine the selective activation of WNT-related genes Axin2 and Wnt4. Notably, genetic removal of androgen receptor (AR) from adrenocortical cells restores the mitogenic effect of WNT/{beta}-catenin signalling. This is the first demonstration that AR activity in the adrenal cortex determines susceptibility to canonical WNT signalling-induced hyperplasia. TeaserActivation of R-spondin signaling in the adrenal cortex leads to a sexually dimorphic phenotype causing tumors in females and immune cell recruitment in males

cancer biology↗

bioRxiv2022

T cell cholesterol efflux suppresses apoptosis and senescence and increases atherosclerosis in middle aged mice

Atherosclerosis is a chronic inflammatory disease driven by hypercholesterolemia. During aging, T-cells accumulate cholesterol, which could lead to a pro-inflammatory phenotype. However, the role of cholesterol efflux pathways mediated by ATP-binding cassette A1 and G1 (ABCA1/ABCG1) in T-cell-dependent age-related inflammation and atherosclerosis remains poorly understood. In this study, we generated mice with T-cell-specific Abca1/Abcg1-deficiency on the low-density-lipoprotein-receptor deficient (Ldlr-/-) background. T-cell Abca1/Abcg1-deficiency decreased blood, lymph node, and splenic T-cells, and increased T-cell activation and apoptosis. T-cell Abca1/Abcg1-deficiency induced a premature T-cell aging phenotype in middle-aged (12-13 months) Ldlr-/- mice, reflected by upregulation of senescence markers. Despite T-cell senescence and enhanced T-cell activation, T-cell Abca1/Abcg1-deficiency decreased atherosclerosis and aortic inflammation in middle-aged Ldlr-/- mice, accompanied by decreased T-cells in atherosclerotic plaques. We attribute these effects to T-cell apoptosis downstream of T-cell activation. Collectively, T-cell cholesterol efflux pathways are critical for maintaining T-cell numbers, suppress senescence, and induce atherosclerosis in middle-aged Ldlr-/- mice.

immunology↗

bioRxiv2021

Cancer tolerance to chromosomal instability is driven by Stat1 inactivation in vivo

Chromosomal instability is a hallmark of cancer, but also an instigator of aneuploidy-induced stress, reducing cellular fitness. To better understand how cells with CIN adjust to aneuploidy and adopt a malignant fate in vivo, we performed a genome-wide mutagenesis screen in mice. We find that specifically aneuploid tumors inactivate Stat1 signaling in combination with increased Myc activity. By contrast, loss of p53 is common, but not enriched in CIN tumors. Validation in another tissue type confirmed that CIN promotes immune cell infiltration, which is alleviated by Stat1 loss combined with Myc activation, but not with p53 inactivation, or Myc activation alone. Importantly, we find that this mechanism is preserved in human aneuploid cancers. We conclude that aneuploid cancers inactivate Stat1 signaling to circumvent immune surveillance.

cancer biology↗

bioRxiv2021

Oncogenic RAS sensitizes cells to drug-induced replication stress via transcriptional silencing of P53

Cancer cells often experience high basal levels of DNA replication stress (RS), for example due to hyperactivation of oncoproteins like MYC or RAS. Therefore, cancer cells are considered to be sensitive to drugs that exacerbate the level of RS or block the intra S-phase checkpoint. Consequently, RS-inducing drugs including ATR and CHK1 inhibitors are used or evaluated as anti-cancer therapies. However, drug resistance and lack of biomarkers predicting therapeutic efficacy limit efficient use. This raises the question what determines sensitivity of individual cancer cells to RS. Here, we report that oncogenic RAS does not only enhance the sensitivity to ATR/CHK1 inhibitors by directly causing RS. Instead, we observed that HRASG12V dampens the activation of the P53-dependent transcriptional response to drug-induced RS, which in turn confers sensitivity to RS. We demonstrate that inducible expression of HRASG12V sensitized retina pigment epithelial (RPE-hTERT) as well as osteosarcoma (U2OS) cells to ATR and CHK1 inhibitors. Using RNA-sequencing of FACS-sorted cells we discovered that P53 signaling is the sole transcriptional response to RS. However, oncogenic RAS attenuates the transcription of P53 and its target genes. Accordingly, live cell imaging showed that HRASG12V exacerbates RS in S/G2-phase, which could be rescued by stabilization of P53. Thus, our results demonstrate that transcriptional control of P53 is a prime determinant in the response to ATR/CHK1 inhibitors and show that hyperactivation of the MAPK pathway impedes this response. Our findings suggest that the level of oncogenic MAPK signaling could predict sensitivity to intra-S-phase inhibition in cancers with intact P53.

cancer biology↗

bioRxiv2021

Deletion of Serf2 shifts amyloid conformation in an Aβ amyloid mouse model

In age-related neurodegenerative disease, like Alzheimers and Parkinsons disease, disease-specific proteins become aggregation-prone and form amyloid-like deposits. Depletion of SERF proteins ameliorates this toxic process in worm- and human cell models for disease. Whether SERF modifies amyloid pathology in mammalian brain, however, has remained unknown. Here, we generated SERF2 brain-specific knockout mice which, unlike full body knockout mice, were viable, and showed no major behavioral and cognitive abnormalities. We combined these knockout mice with the APPPS1 mouse model for human amyloid beta aggregation. Using structure-specific amyloid dyes, previously used to distinguish amyloid polymorphisms in human brain, we show that knockout of SERF2 alters the structure of amyloid fibrils and deposits. Moreover, scanning transmission electron microscopy revealed thicker, shorter and more densely packed amyloid in absence of SERF2. Altogether, our data reveal pleiotropic functions of SERF in development and aging and support a function as a modifier of amyloid aggregation in mammalian brain. Our results indicate that single cellular factors like SERF can determine the structural outcome of amyloid aggregation, offering possibilities for polymorphism-based disease interventions.

molecular biology↗

bioRxiv2020

Acute systemic loss of Mad2 leads to intestinal atrophy in adult mice

Chromosomal instability (CIN) is a hallmark of cancer, leading to aneuploid cells. To study the role that CIN plays in tumor evolution, several mouse models have been engineered over the last two decades. These studies have unequivocally shown that systemic high-grade CIN is embryonic lethal. We and others have previously shown that embryonic lethality can be circumvented by provoking CIN in a tissue-specific fashion. In this study, we provoke systemic high-grade CIN in adult mice as an alternative to circumvent embryonic lethality. For this, we disrupt the spindle assembly checkpoint (SAC) by alleviating Mad2 or truncating Mps1, both essential genes for SAC functioning, with or without p53 inactivation. We find that disruption of the SAC leads to rapid villous atrophy, atypia and apoptosis of intestinal epithelia, substantial weight loss, and death within 10 days after the start of the CIN insult. Despite this severe intestinal phenotype, most other tissues are unaffected, except for minor abnormalities in spleen, presumably due to the low proliferation rate in these tissues. We conclude that high-grade CIN in vivo in adult mice is most toxic to intestinal epithelia, presumably due to the high cell turnover in this tissue.

cancer biology↗

bioRxiv2020

PIDDosome-induced p53-activation for ploidy restriction facilitates hepatocarcinogenesis

Polyploidization frequently precedes tumorigenesis but also occurs during normal development in several tissues. Hepatocyte ploidy is controlled by the PIDDosome during development and regeneration. The PIDDosome multi-protein complex is activated by supernumerary centrosomes to induce p53 and restrict proliferation of polyploid cells, otherwise prone for chromosomal instability. PIDDosome-deficiency in the liver results in drastically increased polyploidy. To investigate PIDDosome-induced p53-activation in the pathogenesis of liver cancer, we chemically induced hepatocellular carcinoma (HCC) in mice. Strikingly, PIDDosome-deficiency reduced tumor number and burden, despite the inability to activate p53 in polyploid cells. Liver tumors arise primarily from cells with low ploidy, indicating an intrinsic pro-tumorigenic effect of PIDDosome-mediated ploidy restriction. These data suggest that hyperpolyploidization caused by PIDDosome-deficiency protects from HCC. Moreover, high tumor cell density, as a surrogate marker of low ploidy, predicts of survival of HCC patients receiving liver transplantation. Together, we show that the PIDDosome is a potential therapeutic target to manipulate hepatocyte polyploidization for HCC prevention and tumor cell density serves as a novel prognostic marker for recurrence free survival in HCC patients.

cancer biology↗

bioRxiv2020

Spontaneous liver disease in wild-type C57BL/6JOlaHsd mice fed semisynthetic diet

Mouse models are frequently used to study mechanisms of human diseases. Recently, we observed a spontaneous bimodal variation in liver weight in C57BL/6JOlaHsd mice fed a semisynthetic diet. We now characterized the spontaneous variation in liver weight and its relationship with parameters of hepatic lipid and bile acid (BA) metabolism. In male C57BL/6JOlaHsd mice fed AIN-93G from birth to postnatal day (PN)70, we measured plasma BA, lipids, Very low-density lipoprotein (VLDL)-triglyceride (TG) secretion, and hepatic mRNA expression patterns. Mice were sacrificed at PN21, PN42, PN63 and PN70. Liver weight distribution was bimodal at PN70. Mice could be subdivided into two nonoverlapping groups based on liver weight: 0.6 SD 0.1 g (approximately one-third of mice, small liver; SL), and 1.0 SD 0.1 g (normal liver; NL; p<0.05). Liver histology showed a higher steatosis grade, inflammation score, more mitotic figures and more fibrosis in the SL versus the NL group. Plasma BA concentration was 14-fold higher in SL (p<0.001). VLDL-TG secretion rate was lower in SL mice, both absolutely (-66%, p<0.001) and upon correction for liver weight (-44%, p<0.001). Mice that would later have the SL-phenotype showed lower food efficiency ratios during PN21-28, suggesting the cause of the SL phenotype is present at weaning (PN21). Our data show that approximately one-third of C57BL/6JOlaHsd mice fed semisynthetic diet develop spontaneous liver disease with aberrant histology and parameters of hepatic lipid, bile acid and lipoprotein metabolism. Study designs involving this mouse strain on semisynthetic diets need to take the SL phenotype into account. Plasma lipids may serve as markers for the identification of the SL phenotype.

pathology↗

bioRxiv2020

Excessive E2F transcription in single cancer cells precludes transient cell cycle exit after DNA damage.

E2F transcription factors control the expression of cell cycle genes. Cancers often demonstrate enhanced E2F target gene expression, which can be explained by increased percentages of replicating cells. However, we now demonstrate in human cancer biopsies that individual neoplastic cells display abnormally high levels of E2F-dependent transcription. To mimic this situation, we deleted the atypical E2F repressors (E2F7/8) in untransformed cells. Individual cells with elevated E2F-activity during S/G2-phase failed to exit the cell cycle after DNA damage and underwent mitosis. In contrast, wild type cells completed S-phase and then exit the cell cycle by activating the APC/CCdh1 via repression of the E2F-target Emi1. Strikingly, many arrested wildtype cells could eventually inactivate APC/CCdh1 to execute a second round of DNA replication and mitosis, thereby becoming tetraploid. Cells with elevated E2F-transcription fail to exit the cell cycle after DNA damage which potentially causes genomic instability, promotes malignant progression and reduces drug sensitivity.

cancer biology↗

bioRxiv2019

Sox8 and Sox9 act redundantly for ovarian-to-testicular fate reprogramming in the absence of Rspo1 in mouse sex reversal

In mammals, testicular differentiation is initiated by transcription factors SRY and SOX9 in XY gonads, and ovarian differentiation involves R-spondin1 (RSPO1) mediated activation of WNT/{beta}-catenin signaling in XX gonads. Accordingly, the absence of RSPO1/Rspo1 in XX humans and mice leads to testicular differentiation and female-to-male sex reversal in a manner that does not require Sry or Sox9 in mice. Here we show that an alternate testis-differentiating factor exists and that this factor is Sox8. Specifically, genetic ablation of Sox8 and Sox9 prevents ovarian-to-testicular reprogramming observed in XX Rspo1 loss-of-function mice. Consequently, Rspo1 Sox8 Sox9 triple mutant gonads developed as atrophied ovaries. Thus, SOX8 alone can compensate for the loss of SOX9 for Sertoli cell differentiation during female-to-male sex reversal.

developmental biology↗

bioRxiv2019

OTULIN prevents liver inflammation and hepatocellular carcinoma by inhibiting FADD- and RIPK1 kinase-mediated hepatocyte apoptosis

Inflammatory signaling pathways are tightly regulated to avoid chronic inflammation and the development of inflammatory pathologies. OTULIN is a deubiquitinating enzyme that specifically cleaves linear ubiquitin chains generated by the linear ubiquitin chain assembly complex (LUBAC), and OTULIN deficiency causes OTULIN-related autoinflammatory syndrome (ORAS) in humans. OTULIN was shown to negatively control NF-{kappa}B signaling in response to various stimuli, but also to protect cells from tumor necrosis factor (TNF)-induced apoptosis. To investigate the importance of OTULIN in liver homeostasis and pathology, we developed a novel mouse line specifically lacking OTULIN in liver parenchymal cells. These mice spontaneously develop a severe liver disease, characterized by liver inflammation, hepatocyte apoptosis and compensatory hepatocyte proliferation, leading to steatohepatitis, fibrosis and hepatocellular carcinoma (HCC). Genetic ablation of Fas-associated death domain (FADD) completely rescues the severe liver pathology, and knock-in expression of kinase inactive receptor-interacting protein kinase 1 (RIPK1) significantly protects from developing liver disease, demonstrating that death receptor-mediated apoptosis of OTULIN-deficient hepatocytes triggers disease pathogenesis in this model. Finally, we demonstrate that type I interferons contribute to disease pathogenesis in hepatocyte-specific OTULIN deficient mice. Together, our study reveals the critical importance of OTULIN in protecting hepatocytes from death, and thereby avoid development of chronic liver inflammation and HCC in mice.

cancer biology↗

bioRxiv2019

Differences in word learning: bilingualism or linguistic experience?

Bilinguals may be better than monolinguals at word learning due to their increased experience with language learning. In addition, bilinguals that have languages that are orthotactically different could be more used to dissimilar orthotactic patterns. The current study examines how bilinguals with languages that are orthotactically similar and dissimilar and monolinguals learn novel words that violate or respect the orthotactic legality of the languages they know and how this learning may be affected by the similarity between the bilinguals two languages. In Experiment 1, three groups of children were tested: monolinguals, Spanish-Basque bilinguals (dissimilar orthotactic languages), and Spanish-Catalan bilinguals (similar orthotactic languages). After an initial word learning phase, they were tested in a recall task and a recognition task. Results showed that Spanish-Basque bilingual children performed differently than the other two groups. While Spanish monolinguals and Spanish-Catalan bilinguals recognized illegal words worse than legal words, Spanish-Basque bilinguals showed equal performance in learning illegal and legal patterns. A replication study conducted with two new groups of Spanish-Basque children (one group with high Basque proficiency and one group with a lower proficiency) indicated that the effects were not driven by the proficiency in the second language since a similar performance on legal and illegal patterns was observed in both groups. In Experiment 2, two groups of adults, monolinguals and Spanish-Basque bilinguals, were tested with the same task used in Experiment 1. The effect seen in children seems to be absent in adults. Spanish-Basque bilingual adults showed better overall learning performance than monolinguals, irrespective of the illegality of the items. Differences between groups could be due to the effect of having acquired literacy and linguistic competence.

neuroscience↗

bioRxiv2018

Reduced expression of C/EBPβ-LIP extends health- and lifespan in mice

Ageing is associated with physical decline and the development of age-related diseases such as metabolic disorders and cancer. Few conditions are known that attenuate the adverse effects of ageing, including calorie restriction (CR) and reduced signalling through the mechanistic target of rapamycin complex 1 (mTORC1) pathway. Synthesis of the metabolic transcription factor C/EBP {beta} -LIP is stimulated by mTORC1, which critically depends on a short upstream open reading frame (uORF) in the C/EBP {beta}-mRNA. Here we describe that reduced C/EBP {beta} -LIP expression due to genetic ablation of the uORF delays the development of age-associated phenotypes in mice. Moreover, female C/EBP {beta}{Delta}uORF mice display an extended lifespan. Since LIP levels increase upon aging in wt mice, our data reveal an important role for C/EBP{beta} in the aging process and suggest that restriction of LIP expression sustains health and fitness. Thus, therapeutic strategies targeting C/EBP {beta} -LIP may offer new possibilities to treat age-related diseases and to prolong healthspan.

cell biology↗