Search

High-grade serous ovarian cancer (HGSOC) is responsible for the largest number of ovarian cancer deaths. The frequent therapy-resistant relapses necessitate a better understanding of mechanisms driving therapy resistance. Therefore, we mapped more than a hundred thousand cells of HGSOC patients in different phases of the disease, using single-cell RNA sequencing. Within patients, we compared chemonaive with chemotreated samples. As such, we were able to create a single-cell atlas of different HGSOC lesions and their treatment. This revealed a high intrapatient concordance between spatially distinct metastases. In addition, we found remarkable baseline differences in transcriptomics of ascitic and solid cancer cells, resulting in a different response to chemotherapy. Moreover, we discovered different robust subtypes of cancer-associated fibroblasts (CAF) in all patients. Besides inflammatory CAFs, vascular CAFs, and matrix CAFs, we identified a new CAF subtype that was characterized by high expression of STAR, TSPAN8, and ALDH1A1 and clearly enriched after chemotherapy. Together, tumor heterogeneity in both cancer and stromal cells contributes to therapy resistance in HGSOC and could form the basis of novel therapeutic strategies that differentiate between ascitic and solid disease.Implications:The newly characterized differences between ascitic and solid cancer cells before and after chemotherapy could inform novel treatment strategies for metastatic HGSOC.

Supplementary Figure from Distinct Transcriptional Programs in Ascitic and Solid Cancer Cells Induce Different Responses to Chemotherapy in High-Grade Serous Ovarian Cancer

Supplementary Table from Distinct Transcriptional Programs in Ascitic and Solid Cancer Cells Induce Different Responses to Chemotherapy in High-Grade Serous Ovarian Cancer

High-grade serous ovarian cancer (HGSOC) is responsible for the largest number of ovarian cancer deaths. The frequent therapy-resistant relapses necessitate a better understanding of mechanisms driving therapy resistance. Therefore, we mapped more than a hundred thousand cells of HGSOC patients in different phases of the disease, using single-cell RNA sequencing. Within patients, we compared chemonaive with chemotreated samples. As such, we were able to create a single-cell atlas of different HGSOC lesions and their treatment. This revealed a high intrapatient concordance between spatially distinct metastases. In addition, we found remarkable baseline differences in transcriptomics of ascitic and solid cancer cells, resulting in a different response to chemotherapy. Moreover, we discovered different robust subtypes of cancer-associated fibroblasts (CAF) in all patients. Besides inflammatory CAFs, vascular CAFs, and matrix CAFs, we identified a new CAF subtype that was characterized by high expression of STAR, TSPAN8, and ALDH1A1 and clearly enriched after chemotherapy. Together, tumor heterogeneity in both cancer and stromal cells contributes to therapy resistance in HGSOC and could form the basis of novel therapeutic strategies that differentiate between ascitic and solid disease. Implications: The newly characterized differences between ascitic and solid cancer cells before and after chemotherapy could inform novel treatment strategies for metastatic HGSOC.

The proto-oncogene MYB encodes the transcription factor c-MYB (cellular MYB, hereafter called MYB), which is often upregulated or aberrantly activated in cancer, including hematological malignancies.1,2 High Myb levels were especially found in acute myeloid leukemia (AML).2-4 Myb was identified initially as a retroviral oncogene (v-Myb) of avian myeloblastosis virus and E26.5,6 These retroviruses are able to transform immature hematopoietic cells in vitro and induce AMLs in chickens7 and mice.8 In leukemia patients, MYB is highly expressed, and in a subset of patients, this is a consequence of translocations, genomic duplications, or somatic mutations that involve the MYB gene itself.9-12 Furthermore, compelling evidence is accumulating that MYB also acts as a dependency factor for the maintenance of most myeloid, T-, and B-cell leukemias.13-15 Overexpression of viral MYB, a truncated form of MYB that lacks its negative regulatory domain, results in the spontaneous formation of T-cell lymphomas in mice.16 However, the in vivo roles of cellular MYB in tumor initiation remain largely unexplored. Here, we show, for the first time, that hematopoietic-specific overexpression of Myb is sufficient to drive B-cell neoplasms and myeloid malignancies in mice. To evaluate whether elevated MYB expression is sufficient to transform cells in vivo, we developed a conditional Myb overexpression (R26-Myb) mouse model (Figure 1A; supplemental Figure 1A,B) using an optimized pipeline for targeting the Rosa26 (R26) locus,17 which previously allowed us to model AML,17 mantle cell lymphoma,18 and immature T-cell leukemia19 in mice. Cre-mediated removal of the floxed stop cassette in mouse embryonic stem cells resulted in a 10-fold increase of Myb transcripts and a threefold upregulation of MYB protein (supplemental Figure 1C,D). R26Myb mice were crossed with Vav-iCre mice20 to enable R26-driven overexpression of Myb and a Firefly luciferase-reporter in the entire hematopoietic system (supplemental Figure 1E). Homozygous R26-Myb mice have a 10-to 15-fold increase in Myb RNA levels in the thymus and bone marrow (BM) (supplemental Figure 1F,G). Of note, we were not able to show increased MYB protein level of 10-week-old thymocytes (data not shown), probably because T-cell progenitors already express high endogenous MYB levels. We monitored an aging cohort of R26-Myb`g/`g; Vav-iCre`g/ 1 (hereafter named MybVav; n 5 21 with 9 males and 12 females) mice (Figure 1A) and found that 7 out of 21 (33%) animals spontaneously developed hematological malignancies (Figure 1B). Detailed necropsy was performed on 4 animals. MybVav mice had mild anemia and showed increased white blood cell and lymphocyte counts in peripheral blood (Figure 1C). In addition, 3 of them displayed splenomegaly (Figure 1D). Detailed flow cytometric analysis revealed that Myb overexpression resulted in the spontaneous development of both B-cell neoplasms and myeloid malignancies (Figure 1E,F). A selection of 1 MybVav tumor per mouse is represented in Figure 1E, while an overview of the immunophenotype of all MybVav tumors per mouse is shown in Figure 1F. A comparison of these MybVav tumors with their Cre-negative littermate controls can be found in supplemental Figure 2. Although cumulative genetic evidence suggests a role for Myb in T-cell

Here, we investigate the impact of hypoxia on the hepatic response of glucocorticoid receptor (GR) to dexamethasone (DEX) in mice via RNA-sequencing. Hypoxia causes three types of reprogramming of GR: (i) much weaker induction of classical GR-responsive genes by DEX in hypoxia, (ii) a number of genes is induced by DEX specifically in hypoxia, and (iii) hypoxia induces a group of genes via activation of the hypothalamic-pituitary-adrenal (HPA) axis. Transcriptional profiles are reflected by changed GR DNA-binding as measured by ChIP sequencing. The HPA axis is induced by hypothalamic HIF1α and HIF2α activation and leads to GR-dependent lipolysis and ketogenesis. Acute inflammation, induced by lipopolysaccharide, is prevented by DEX in normoxia but not during hypoxia, and this is attributed to HPA axis activation by hypoxia. We unfold new physiological pathways that have consequences for patients suffering from GC resistance.

Mantle cell lymphoma (MCL) is an aggressive B cell lymphoma with poor long-term overall survival. Currently, MCL research and development of potential cures is hampered by the lack of good in vivo models. MCL is characterized by recurrent translocations of CCND1 or CCND2, resulting in overexpression of the cell cycle regulators cyclin D1 or D2, respectively. Here, we show, for the first time, that hematopoiesis-specific activation of cyclin D2 is sufficient to drive murine MCL-like lymphoma development. Furthermore, we demonstrate that cyclin D2 overexpression can synergize with loss of p53 to form aggressive and transplantable MCL-like lymphomas. Strikingly, cyclin D2–driven lymphomas display transcriptional, immunophenotypic, and functional similarities with B1a B cells. These MCL-like lymphomas have B1a-specific B cell receptors (BCRs), show elevated BCR and NF-κB pathway activation, and display increased MALT1 protease activity. Finally, we provide preclinical evidence that inhibition of MALT1 protease activity, which is essential for the development of early life–derived B1a cells, can be an effective therapeutic strategy to treat MCL.

Regulated cell death is an integral part of life, and has broad effects on organism development and homeostasis

The protease MALT1 is a key regulator of NF-kappa B signaling and a novel therapeutic target in autoimmunity and cancer. Initial enthusiasm supported by preclinical results with MALT1 inhibitors was tempered by studies showing that germline MALT1 protease inactivation in mice results in reduced regulatory T cells and lethal multi-organ inflammation due to expansion of IFN-gamma-producing T cells. However, we show that long-term MALT1 inactivation, starting in adulthood, is not associated with severe systemic inflammation, despite reduced regulatory T cells. In contrast, IL-2-, TNF-, and IFN-gamma-producing CD4(+) T cells were strongly reduced. Limited formation of tertiary lymphoid structures was detectable in lungs and stomach, which did not affect overall health. Our data illustrate that MALT1 inhibition in prenatal or adult life has a different outcome and that long-term MALT1 inhibition in adulthood is not associated with severe side effects.

Background NANOS3 is a gene conserved throughout evolution. Despite the quite low conservation of Nanos sequences between different organisms and even between Nanos paralogs, their role in germ cell development is remarkably universal. Human Nanos3 expression is normally restricted to the gonads and the brain. However, ectopic activation of this gene has been detected in various human cancers. Until now, Nanos3 and other Nanos proteins have been studied almost exclusively in germ cell development. Methods Transgenic mice were generated by targeted insertion of a human Nanos3 cDNA into the ROSA26 locus. The transgene could be spatiotemporally induced by Cre recombinase activity removing an upstream floxed STOP cassette. A lung tumor model with ectopic Nanos3 expression was based on the lung-specific activation of the reverse tetracycline transactivator gene, in combination with a tetO-CMV promoter controlling Cre expression. When doxycycline was provided to the mice, Cre was activated leading to deletion of TP53 alleles and activation of both oncogenic KRasG12D and Nanos3. Appropriate controls were foreseen. Tumors and tumor-derived cell cultures were analyzed in various ways. Results We describe the successful generation of Nanos3LSL/− and Nanos3LSL/LSL mice in which an exogenous human NANOS3 gene can be activated in vivo upon Cre expression. These mice, in combination with different conditional and doxycycline-inducible Cre lines, allow the study of the role of ectopic Nanos3 expression in several cancer types. The Nanos3LSL mice were crossed with a non-small cell lung cancer (NSCLC) mouse model based on conditional expression of oncogenic KRas and homozygous loss of p53. This experiment demonstrated that ectopic expression of Nanos3 in the lungs has a significant negative effect on survival. Enhanced bronchiolar dysplasia was observed when Nanos3-expressing NSCLC mice were compared with control NSCLC mice. An allograft experiment, performed with cell cultures derived from primary lung tumors of control and Nanos3-expressing NSCLC mice, revealed lymph node metastasis in mice injected with Nanos3-expressing NSCLC cells. Conclusions A new mouse model was generated allowing examination of Nanos3-associated pathways and investigation of the influence of ectopic Nanos3 expression in various cancer types. This model might identify Nanos3 as an interesting target in cancer therapeutics. Electronic supplementary material The online version of this article (10.1186/s12885-019-5807-x) contains supplementary material, which is available to authorized users.

In cancer research, it remains challenging to functionally validate putative novel oncogenic drivers and to establish relevant preclinical models for evaluation of novel therapeutic strategies. Here, we describe an optimized and efficient pipeline for the generation of novel conditional overexpression mouse models in which putative oncogenes, along with an eGFP/Luciferase dual reporter, are expressed from the endogenous ROSA26 (R26) promoter. The efficiency of this approach was demonstrated by the generation and validation of novel R26 knock-in (KI) mice that allow conditional overexpression of Jarid2, Runx2, MN1 and a dominant negative allele of ETV6. As proof of concept, we confirm that MN1 overexpression in the hematopoietic lineage is sufficient to drive myeloid leukemia. In addition, we show that T-cell specific activation of MN1 in combination with loss of Pten increases tumour penetrance and stimulates the formation of Lyl1+ murine T-cell lymphoblastic leukemias or lymphomas (T-ALL/T-LBL). Finally, we demonstrate that these luciferase-positive murine AML and T-ALL/T-LBL cells are transplantable into immunocompromised mice allowing preclinical evaluation of novel anti-leukemic drugs in vivo.

Objective Full-thickness cutaneous wounds treated with split-thickness skin grafts often result in unaesthetic and hypertrophic scars. Dermal substitutes are currently used together with skin grafts in a single treatment to reconstruct the dermal layer of the skin, resulting in improved quality of scars. Adipose-derived stem cells (ASCs) have been described to enhance wound healing through structural and humoral mechanisms. In this study, we investigate the compatibility of xenogen-free isolated human ASCs seeded on human acellular dermal matrix (Glyaderm®) in a murine immunodeficient wound model. Methods Adipose tissue was obtained from abdominal liposuction, and stromal cells were isolated mechanically and cultured xenogen-free in autologous plasma-supplemented medium. Glyaderm® discs were seeded with EGFP-transduced ASCs, and implanted on 8 mm full-thickness dorsal wounds in an immunodeficient murine model, in comparison to standard Glyaderm® discs. Re-epithelialization rate, granulation thickness and vascularity were assessed by histology on days 3, 7 and 12. Statistical analysis was conducted using the Wilcoxon signed-rank test. EGFP-staining allowed for tracking of the ASCs in vivo. Hypoxic culture of the ASCs was performed to evaluate cytokine production. Results ASCs were characterized with flowcytometric analysis and differentiation assay. EGFP-tranduction resulted in 95% positive cells after sorting. Re-epithelialization in the ASC-seeded Glyaderm® side was significantly increased, resulting in complete wound healing in 12 days. Granulation thickness and vascularization were significantly increased during early wound healing. EGFP-ASCs could be retrieved by immunohistochemistry in the granulation tissue in early wound healing, and lining vascular structures in later stages. Conclusion Glyaderm® is an effective carrier to deliver ASCs in full-thickness wounds. ASC-seeded Glyaderm® significantly enhances wound healing compared to standard Glyaderm®. The results of this study encourage clinical trials for treatment of full-thickness skin defects. Furthermore, xenogen-free isolation and autologous plasma-augmented culture expansion of ASCs, combined with the existing clinical experience with Glyaderm®, aid in simplifying the necessary procedures in a GMP-laboratory setting., Highlights • ASCs obtained from human liposuction fat were isolated mechanically and cultured xenogen-free in autologous plasma-supplemented medium. • Hypoxic culture of the ASCs was performed to evaluate increased cytokine production. • Glyaderm® discs were seeded with EGFP-transduced ASCs, and implanted on full-thickness dorsal wounds in an immunodeficient murine model, in comparison to standard Glyaderm® discs. • Reëpithelialisation, granulation and vascularization in the ASC-seeded Glyaderm® side were significantly increased, resulting in complete wound healing in 12 days. • EGFP-ASCs could be retrieved by IHC in the granulation tissue in early wound healing, and lining vascular structures in later stages.

Upon intravenous injection of tumour necrosis factor (TNF) in mice, a systemic inflammatory response syndrome (SIRS) is initiated, characterized by an acute cytokine storm and induction of vascular hyperpermeability. Connexin43 hemichannels have been implicated in various pathological conditions, e.g. ischemia and inflammation, and can lead to detrimental cellular outcomes. Here, we explored whether targeting connexin43 hemichannels could alleviate TNF-induced endothelial barrier dysfunction and lethality in SIRS. Therefore, we verified whether administration of connexin43-targeting-peptides affected survival, body temperature and vascular permeability in vivo. In vitro, TNF-effects on connexin43 hemichannel function were investigated by single-channel studies and Ca2+-imaging. Blocking connexin43 hemichannels with TAT-Gap19 protected mice against TNF-induced mortality, hypothermia and vascular leakage, while enhancing connexin43 hemichannel function with TAT-CT9 provoked opposite sensitizing effects. In vitro patch-clamp studies revealed that TNF acutely activated connexin43 hemichannel opening in endothelial cells, which was promoted by CT9, and inhibited by Gap19 and intracellular Ca2+-buffering. In vivo experiments aimed at buffering intracellular Ca2+, and pharmacologically targeting Ca2+/calmodulin-dependent protein kinase-II, a known modulator of endothelial barrier integrity, demonstrated their involvement in permeability alterations. Our results demonstrate significant benefits of inhibiting connexin43 hemichannels to counteract TNF-induced SIRS-associated vascular permeability and lethality.

Rabies virus is a neurovirulent RNA virus, which causes about 59,000 human deaths each year. Treatment for rabies does not exist due to incomplete understanding of the pathogenesis. MALT1 mediates activation of several immune cell types and is involved in the proliferation and survival of cancer cells. MALT1 acts as a scaffold protein for NF-kappa B signaling and a cysteine protease that cleaves substrates, leading to the expression of immunoregulatory genes. Here, we examined the impact of genetic or pharmacological MALT1 inhibition in mice on disease development after infection with the virulent rabies virus strain CVS-11. Morbidity and mortality were significantly delayed in Malt1(-/-) compared to Malt1(-/-) mice, and this effect was associated with lower viral load, proinflammatory gene expression, and infiltration and activation of immune cells in the brain. Specific deletion of Malt1 in T cells also delayed disease development, while deletion in myeloid cells, neuronal cells, or NK cells had no effect. Disease development was also delayed in mice treated with the MALT1 protease inhibitor mepazine and in knock-in mice expressing a catalytically inactive MALT1 mutant protein, showing an important role of MALT1 proteolytic activity. The described protective effect of MALT1 inhibition against infection with a virulent rabies virus is the precise opposite of the sensitizing effect of MALT1 inhibition that we previously observed in the case of infection with an attenuated rabies virus strain. Together, these data demonstrate that the role of immunoregulatory responses in rabies pathogenicity is dependent on virus virulence and reveal the potential of MALT1 inhibition for therapeutic intervention. IMPORTANCE: Rabies virus is a neurotropic RNA virus that causes encephalitis and still poses an enormous challenge to animal and public health. Efforts to establish reliable therapeutic strategies have been unsuccessful and are hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protease that mediates the activation of several innate and adaptive immune cells in response to multiple receptors, and therapeutic MALT1 targeting is believed to be a valid approach for autoimmunity and MALT1-addicted cancers. Here, we study the impact of MALT1 deficiency on brain inflammation and disease development in response to infection of mice with the highly virulent CVS-11 rabies virus. We demonstrate that pharmacological or genetic MALT1 inhibition decreases neuroinflammation and extends the survival of CVS-11-infected mice, providing new insights in the biology of MALT1 and rabies virus infection.

MALT1 is involved in the activation of immune responses, as well as in the proliferation and survival of certain cancer cells. MALT1 acts as a scaffold protein for NF-κB signaling and a cysteine protease that cleaves substrates, further promoting the expression of immunoregulatory genes. Deregulated MALT1 activity has been associated with autoimmunity and cancer, implicating MALT1 as a new therapeutic target. Although MALT1 deficiency has been shown to protect against experimental autoimmune encephalomyelitis, nothing is known about the impact of MALT1 on virus infection in the central nervous system. Here, we studied infection with an attenuated rabies virus, Evelyn-Rotnycki-Abelseth (ERA) virus, and observed increased susceptibility with ERA virus in MALT1 −/− mice. Indeed, after intranasal infection with ERA virus, wild-type mice developed mild transient clinical signs with recovery at 35 days postinoculation (dpi). Interestingly, MALT1 −/− mice developed severe disease requiring euthanasia at around 17 dpi. A decreased induction of inflammatory gene expression and cell infiltration and activation was observed in MALT1 −/− mice at 10 dpi compared to MALT1 +/+ infected mice. At 17 dpi, however, the level of inflammatory cell activation was comparable to that observed in MALT1 +/+ mice. Moreover, MALT1 −/− mice failed to produce virus-neutralizing antibodies. Similar results were obtained with specific inactivation of MALT1 in T cells. Finally, treatment of wild-type mice with mepazine, a MALT1 protease inhibitor, also led to mortality upon ERA virus infection. These data emphasize the importance of early inflammation and activation of T cells through MALT1 for controlling the virulence of an attenuated rabies virus in the brain. IMPORTANCE Rabies virus is a neurotropic virus which can infect any mammal. Annually, 59,000 people die from rabies. Effective therapy is lacking and hampered by gaps in the understanding of virus pathogenicity. MALT1 is an intracellular protein involved in innate and adaptive immunity and is an interesting therapeutic target because MALT1-deregulated activity has been associated with autoimmunity and cancers. The role of MALT1 in viral infection is, however, largely unknown. Here, we study the impact of MALT1 on virus infection in the brain, using the attenuated ERA rabies virus in different models of MALT1-deficient mice. We reveal the importance of MALT1-mediated inflammation and T cell activation to control ERA virus, providing new insights in the biology of MALT1 and rabies virus infection.

Systemic inflammatory response syndrome (SIRS) is an inflammatory state affecting the whole body. It is associated with the presence of pro- and antiinflammatory cytokines in serum, including tumor necrosis factor (TNF). TNF has multiple effects and leads to cytokine production, leukocyte infiltration, and blood pressure reduction and coagulation, thereby contributing to tissue damage and organ failure. A sterile mouse model of sepsis, TNF-induced SIRS, was used to visualize the temporal and spatial distribution of damage in susceptible tissues during SIRS. For this, a radiopharmaceutical agent

E-cadherin-mediated cell-cell adhesion is critical for naive pluripotency of cultured mouse embryonic stem cells (mESCs). E-cadherin-depleted mESC fail to downregulate their pluripotency program and are unable to initiate lineage commitment. To further explore the roles of cell adhesion molecules during mESC differentiation, we focused on p120 catenin (p120ctn). Although one key function of p120ctn is to stabilize and regulate cadherin-mediated cell-cell adhesion, it has many additional functions, including regulation of transcription and Rho GTPase activity. Here, we investigated the role of mouse p120ctn in early embryogenesis, mESC pluripotency and early fate determination. In contrast to the E-cadherin-null phenotype, p120ctn-null mESCs remained pluripotent, but their in vitro differentiation was incomplete. In particular, they failed to form cystic embryoid bodies and showed defects in primitive endoderm formation. To pinpoint the underlying mechanism, we undertook a structure-function approach. Rescue of p120ctn-null mESCs with different p120ctn wild-type and mutant expression constructs revealed that the long N-terminal domain of p120ctn and its regulatory domain for RhoA were dispensable, whereas its armadillo domain and interaction with E-cadherin were crucial for primitive endoderm formation. We conclude that p120ctn is not only an adaptor and regulator of E-cadherin, but is also indispensable for proper lineage commitment., Author Summary Disease may be due to either excess of undesirable cells, like in cancer or autoimmune disease, or by progressive loss of vital cells. The latter, for instance, causes neurodegenerative diseases such as Alzheimer’s disease. Stem-cell based therapy holds great potential to cure devastating diseases with cell loss or dysfunctionality, because stem cells have the capacity to form any given cell type of the body. Recent advances in the field allow to obtain stem cells from virtually every patient. These stem cells could then be instructed to form the desired cells that can be reintroduced to cure the patient. Before such therapies are suited for the clinic, we first need comprehensive knowledge of the molecular mechanisms that underlie cell fate decisions. Here, we scrutinize the role of a junctional protein, called p120ctn, in both stem cells and lineage-committed cells. Importantly, this key protein has a modular structure, and each of its segments has different interaction partners and biological functions. We deleted p120ctn specifically in stem cells, and reintroduced several p120ctn mutants that lack specific protein segments. As such, we could unravel the exact molecular interaction that is required for p120ctn to drive the differentiation of stem cells towards primitive endoderm.

Unlike its family member p53, TP63 is rarely mutated in human cancer. However, ΔNp63α protein levels are often elevated in tumors of epithelial origin, such as squamous cell carcinoma and cholangiocarcinoma. To study the oncogenic properties of ΔNp63α in vivo, we generated transgenic mice overexpressing ΔNp63α from the Rosa26 locus promoter controlled by keratin 5-Cre. We found that these mice spontaneously develop epidermal cysts and ectopic ΔNp63α expression in the bile duct epithelium that leads to dilatation of the intrahepatic biliary ducts, to hepatic cyst formation and bile duct adenoma. Moreover, when subjected to models of 7,12-dimethylbenz[a]anthracene-based carcinogenesis, tumor initiation was increased in ΔNp63α transgenic mice in a gene dosage-dependent manner although ΔNp63α overexpression did not alter the sensitivity to 7,12-dimethylbenz[a]anthracene-induced cytotoxicity in vivo. However, keratinocytes isolated from ΔNp63α transgenic mice displayed increased survival and delayed cellular senescence compared with wild-type keratinocytes, marked by decreased p16Ink4a and p19Arf expression. Taken together, we show that increased ΔNp63α protein levels facilitate oncogenic transformation in the epidermis as well as in the bile duct.

Deregulation of signaling pathways that control differentiation, expansion and migration of neural crest-derived melanoblasts during normal development contributes also to melanoma progression and metastasis. Although several epithelial-to-mesenchymal (EMT) transcription factors, such as zinc finger E-box binding protein 1 (ZEB1) and ZEB2, have been implicated in neural crest cell biology, little is known about their role in melanocyte homeostasis and melanoma. Here we show that mice lacking Zeb2 in the melanocyte lineage exhibit a melanoblast migration defect and, unexpectedly, a severe melanocyte differentiation defect. Loss of Zeb2 in the melanocyte lineage results in a downregulation of the Microphthalmia-associated transcription factor (Mitf) and melanocyte differentiation markers concomitant with an upregulation of Zeb1. We identify a transcriptional signaling network in which the EMT transcription factor ZEB2 regulates MITF levels to control melanocyte differentiation. Moreover, our data are also relevant for human melanomagenesis as loss of ZEB2 expression is associated with reduced patient survival. ispartof: Cell Death and Differentiation vol:21 issue:8 pages:1250-1261 ispartof: location:England status: published

Regulated cell death is an integral part of life, and has broad effects on organism development and homeostasis1. Malfunctions within the regulated cell death process, including the clearance of dying cells, can manifest in diverse pathologies throughout various tissues including the gastrointestinal tract2. A long appreciated, yet elusively defined relationship exists between cell death and gastrointestinal pathologies with an underlying microbial component3–6, but the direct effect of dying mammalian cells on bacterial growth is unclear. Here we advance a concept that several Enterobacteriaceae, including patient-derived clinical isolates, have an efficient growth strategy to exploit soluble factors that are released from dying gut epithelial cells. Mammalian nutrients released after caspase-3/7-dependent apoptosis boosts the growth of multiple Enterobacteriaceae and is observed using primary mouse colonic tissue, mouse and human cell lines, several apoptotic triggers, and in conventional as well as germ-free mice in vivo. The mammalian cell death nutrients induce a core transcriptional response in pathogenic Salmonella, and we identify the pyruvate formate-lyase-encoding pflB gene as a key driver of bacterial colonization in three contexts: a foodborne infection model, a TNF- and A20-dependent cell death model, and a chemotherapy-induced mucositis model. These findings introduce a new layer to the complex host–pathogen interaction, in which death-induced nutrient release acts as a source of fuel for intestinal bacteria, with implications for gut inflammation and cytotoxic chemotherapy treatment. Intestinal microorganisms exploit nutrients released by apoptotic gut epithelial cells for growth.