ABSTRACT Adult stem cell function depends on continuous input from the surrounding microenvironment. However, the cues that pattern this function in high turnover tissue that undergo continuous cellular remodeling remain poorly understood. Here we demonstrate that inputs from epithelial neighbors at distinct stages of differentiation cooperatively influence cell fate in the skin epidermis. Stem cells initiate differentiation of their neighbors via the Notch ligand Jag2, linking fate decisions to the composition of the local stem cell environment. When this signal is lost, misoriented divisions and engagement with distinct ligands in the suprabasal layers can partially restore upward flux differentiating cells. Although these mechanisms help to sustain barrier function, they ultimately disrupt tissue architecture, underscoring the need for balanced fates in the stem cell compartment. Together, our findings demonstrate that distinct cellular environments reinforce early epidermal differentiation, with stem cells themselves acting as key mediators of cell fate and tissue organization.

During the first stages of embryonic development, the placenta develops under very low oxygen tension (∼1%-2% O2), so we sought to determine the regulatory role of oxygen in human trophoblast stem cells (hTSCs). We find that low oxygen promotes hTSC self-renewal but inhibits differentiation to syncytiotrophoblast (STB) and extravillous trophoblast (EVT). The transcription factor GCM1 (glial cell missing transcription factor 1) is downregulated in low oxygen, and concordantly, there is substantial reduction of GCM1-regulated genes in hypoxic conditions. Knockout of GCM1 in hTSC likewise impaired EVT and STB formation. Treatment with a phosphatidylinositol 3-kinase (PI3K) inhibitor reported to reduce GCM1 protein levels likewise counteracts spontaneous or directed differentiation. Additionally, chromatin immunoprecipitation of GCM1 showed binding near key genes upregulated upon differentiation including the contact inhibition factor CDKN1C. Loss of GCM1 resulted in downregulation of CDKN1C and corresponding loss of contact inhibition, implicating GCM1 in regulation of this critical process.

AbstractBackgroundThe interdependence of cytokines and appetite‐modifying hormones implicated in cancer anorexia‐cachexia syndrome (CACS) remains unclear. This study aimed to regroup these cytokines and hormones into distinct inflammatory (or non‐inflammatory) pathways and determine whether these pathways can classify patients with CACS phenotypes.MethodsClinical characteristics of 133 patients [61.7% male; mean age = 63.4 (SD: 13.1) years] with advanced cancer prior to oncology treatments were documented, including weight loss history. Patients completed the Functional Assessment of Anorexia‐Cachexia Therapy (FAACT) questionnaire and Timed Up and Go test and had their sex‐standardized skeletal muscle index (z‐SMI) and fat mass index (z‐FMI) derived using computed tomography scans. Their plasma levels of cytokines and appetite‐modifying hormones were also determined. Date of death was recorded. Exploratory factor analysis (EFA) was used to regroup 15 cytokines and hormone into distinct inflammatory pathways (factors). For each patient, regression factor scores (RFS), which tell how strongly the patient associates with each factor, were derived. Two‐step cluster analysis on the RFS was used to classify patients into groups. CACS phenotypes were correlated with RFS and compared between groups. Groups' survival was estimated using Kaplan–Meier analysis.ResultsPatients had low z‐SMI (mean = −3.78 cm2/m2; SD: 8.88) and z‐FMI (mean = 0.08 kg2/m2; SD: 56.25), and 62 (46.6%) had cachexia. EFA identified three factors: (F‐1) IFN‐γ, IL‐1β, Il‐4, IL‐6, IL‐10, IL‐12, TGFβ1 (positive contribution), and IL‐18 (negative); (F‐2) IL‐8, IL‐18, MCP‐1, TGFβ1, TNF‐α (positive), and ghrelin (negative); and (F‐3) TRAIL and leptin (positive), and TGFβ1 and adiponectin (negative). RFS‐1 was associated with cachexia (P = 0.002); RFS‐2, with higher CRP (P < 0.0001) and decreased physical function (P = 0.01); and RFS‐3 with better appetite (P = 0.04), lower CRP (P = 0.002), higher z‐SMI (P = 0.04) and z‐FMI (P < 0.0001), and less cachexia characteristics (all P < 0.001). Four patient groups were identified with specific RFS clusters aligning with the CACS continuum from no cachexia to pre‐cachexia, cachexia, and terminal cachexia. Compared to the other two groups, groups 1 and 2 had higher plasma levels of IL‐18 and TRAIL. Group 1 also had lower inflammatory cytokines, adiponectin, and CRP compared to the other three groups. Group 3 had inflammatory cytokine levels similar to group 2, except for TNF‐α and leptin which were lower. Group 4 had very high inflammatory cytokines, adiponectin, and CRP compared to the other 3 groups (all P < 0.0001). Groups 3 and 4 had worse cachexia characteristics (P < 0.05) and shorter survival (log rank: P = 0.0009) than the other two groups.ConclusionsThis exploratory study identified three distinct pathways of inflammation, or lack thereof, characterizing different CACS phenotypes.

Supplementary Materials and Methods, Supplementary Table, Supplementary References and Supplementary Figures S1 to S5

ZMYM2 is a transcriptional repressor whose role in development is largely unexplored. We found that Zmym2-/- mice show embryonic lethality by E10.5. Molecular characterization of Zmym2-/- embryos revealed two distinct defects. First, they fail to undergo DNA methylation and silencing of germline gene promoters, resulting in widespread upregulation of germline genes. Second, they fail to methylate and silence the evolutionarily youngest and most active LINE element subclasses in mice. Zmym2-/- embryos show ubiquitous overexpression of LINE-1 protein as well as aberrant expression of transposon-gene fusion transcripts. ZMYM2 homes to sites of PRC1.6 and TRIM28 complex binding, mediating repression of germline genes and transposons respectively. In the absence of ZMYM2, hypermethylation of histone 3 lysine 4 occurs at target sites, creating a chromatin landscape unfavourable for establishment of DNA methylation. ZMYM2-/- human embryonic stem cells also show aberrant upregulation and demethylation of young LINE elements, indicating a conserved role in repression of active transposons. ZMYM2 is thus an important new factor in DNA methylation patterning in early embryonic development.

Supplementary Materials and Methods. Table S1: List of the different oligonucleotides used for mouse genotyping. Table S2: Phenotypic evaluation of prostate-specific PTP1B-overexpressing mice. Figure S1: Ptpn1 status does not alter the transition to mPIN in PtenPE-/- mice. Figure S2: Examples of mild and moderate desmoplasia. Figure S3: HFD drives invasive prostate cancer in the AP only in absence of Ptpn1. Figure S4: Ptpn1 status does not modulate mPIN formation in PtenPE+/- mice. Figure S5: Ptpn1 status influences PtenPE-/- phenotype in a dose-dependent manner.

Epigenetic modifications on the chromatin do not occur in isolation. Chromatin-associated proteins and their modification products form a highly interconnected network, and disturbing one component may rearrange the entire system. We see this increasingly clearly in epigenetically dysregulated cancers. It is important to understand the rules governing epigenetic interactions. Here, we use the mouse embryonic stem cell (mESC) model to describe in detail the relationships within the H3K27-H3K36-DNA methylation subnetwork. In particular, we focus on the major epigenetic reorganization caused by deletion of the histone 3 lysine 36 methyltransferase NSD1, which in mESCs deposits nearly all of the intergenic H3K36me2. Although disturbing the H3K27 and DNA methylation (DNAme) components also affects this network to a certain extent, the removal of H3K36me2 has the most drastic effect on the epigenetic landscape, resulting in full intergenic spread of H3K27me3 and a substantial decrease in DNAme. By profiling DNMT3A and CHH methylation (mCHH), we show that H3K36me2 loss upon Nsd1-KO leads to a massive redistribution of DNMT3A and mCHH away from intergenic regions and toward active gene bodies, suggesting that DNAme reduction is at least in part caused by redistribution of de novo methylation. Additionally, we show that pervasive acetylation of H3K27 is regulated by the interplay of H3K36 and H3K27 methylation. Our analysis highlights the importance of H3K36me2 as a major determinant of the developmental epigenome and provides a framework for further consolidating our knowledge of epigenetic networks.

Additional file 4: Table S3. Mapping and conversion statistics for Whole Genome Bisulfite Sequencing data used in this publication.

Abstract Background DNA methylation plays an important role in regulating gene expression in mammals. The covalent DNMT1 inhibitors 5-azacytidine and decitabine are widely used in research to reduce DNA methylation levels, but they impart severe cytotoxicity which limits their demethylation capability and confounds interpretation of experiments. Recently, a non-covalent inhibitor of DNMT1 called GSK-3484862 was developed by GlaxoSmithKline. We sought to determine whether GSK-3484862 can induce demethylation more effectively than 5-azanucleosides. Murine embryonic stem cells (mESCs) are an ideal cell type in which to conduct such experiments, as they have a high degree of DNA methylation but tolerate dramatic methylation loss. Results We determined the cytotoxicity and optimal concentration of GSK-3484862 by treating wild-type (WT) or Dnmt1/3a/3b triple knockout (TKO) mESC with different concentrations of the compound, which was obtained from two commercial sources. Concentrations of 10 µM or below were readily tolerated for 14 days of culture. Known DNA methylation targets such as germline genes and GLN-family transposons were upregulated within 2 days of the start of GSK-3484862 treatment. By contrast, 5-azacytidine and decitabine induced weaker upregulation of methylated genes and extensive cell death. Whole-genome bisulfite sequencing showed that treatment with GSK-3484862 induced dramatic DNA methylation loss, with global CpG methylation levels falling from near 70% in WT mESC to less than 18% after 6 days of treatment with GSK-3484862. The treated cells showed a methylation level and pattern similar to that observed in Dnmt1-deficient mESCs. Conclusions GSK-3484862 mediates striking demethylation in mESCs with minimal non-specific toxicity.

Human embryonic stem cells (hESCs) readily differentiate to somatic or germ lineages but have impaired ability to form extra-embryonic lineages such as placenta or yolk sac. Here, we demonstrate that naive hESCs can be converted into cells that exhibit the cellular and molecular phenotypes of human trophoblast stem cells (hTSCs) derived from human placenta or blastocyst. The resulting "transdifferentiated'' hTSCs show reactivation of core placental genes, acquisition of a placenta-like methylome, and the ability to differentiate to extravillous trophoblasts and syncytiotrophoblasts. Modest differences are observed between transdifferentiated and placental hTSCs, most notably in the expression of certain imprinted loci. These results suggest that naive hESCs can differentiate to extra-embryonic lineage and demonstrate a new way of modeling human trophoblast specification and placental methylome establishment.

Protein tyrosine phosphatases are essential modulators of angiogenesis and have been identified as novel therapeutic targets in cancer and anti-angiogenesis. The roles of atypical Phosphatase of Regenerative Liver (PRL) phosphatases in this context remain poorly understood. Here, we investigate the biological function of PRL phosphatases in developmental angiogenesis in the postnatal mouse retina and in cell culture. We show that endothelial cells in the retina express PRL-2 encoded by the Ptp4a2 gene, and that inducible endothelial and global Ptp4a2 mutant mice exhibit defective retinal vascular outgrowth, arteriovenous differentiation, and sprouting angiogenesis. Mechanistically, PTP4A2 deletion limits angiogenesis by inhibiting endothelial cell migration and the VEGF-A, DLL-4/NOTCH-1 signaling pathway. This study reveals the importance of PRL-2 as a modulator of vascular development.

Abstract Specific diets can affect the risk and progression of prostate cancer (PCa). However, the interplay between diet and genetic alterations remains ill defined. Here we show that progression of PCa that is driven by Pten loss is mostly unresponsive to a high fat diet; however, in the absence of protein tyrosine phosphatase Ptpn1 (which encodes PTP1B) mice that are fed a high fat diet develop a highly invasive disease that is characterized by increased cell proliferation and Akt activation. Together with the finding that prostate-specific PTP1B overexpression does not initiate PCa by itself, we conclude that PTP1B act as an environment-dependent tumor suppressor in the context of Pten-null prostate tumors. PTP1B is a validated therapeutic target at the crossroad of metabolism (diabetes, obesity) and cancer (breast), and is currently being investigated in clinical trials. Due to PTP1B's nutrient sensing capabilities, we suggest that a careful monitoring of the balance between improving metabolic syndrome and promoting oncogenic effects under particular diets be pursued when using PTP1B-targeted therapeutics. Citation Format: David P. Labbé, Noriko Uetani, Valérie Vinette, Isabelle Aubry, Eva Migon, Jacinthe Sirois, Jody J. Haigh, Laurent Lessard, Louis R. Bégin, Lloyd C. Trotman, Marilène Paquet, Michel L. Tremblay. PTP1B deficiency potentiate prostate cancer invasiveness by sensitizing Pten-null tumors to high-fat diet. [abstract]. In: Proceedings of the AACR Special Conference: Metabolism and Cancer; Jun 7-10, 2015; Bellevue, WA. Philadelphia (PA): AACR; Mol Cancer Res 2016;14(1_Suppl):Abstract nr B39.

Abstract Diet affects the risk and progression of prostate cancer, but the interplay between diet and genetic alterations in this disease is not understood. Here we present genetic evidence in the mouse showing that prostate cancer progression driven by loss of the tumor suppressor Pten is mainly unresponsive to a high-fat diet (HFD), but that coordinate loss of the protein tyrosine phosphatase Ptpn1 (encoding PTP1B) enables a highly invasive disease. Prostate cancer in Pten−/−Ptpn1−/− mice was characterized by increased cell proliferation and Akt activation, interpreted to reflect a heightened sensitivity to IGF-1 stimulation upon HFD feeding. Prostate-specific overexpression of PTP1B was not sufficient to initiate prostate cancer, arguing that it acted as a diet-dependent modifier of prostate cancer development in Pten−/− mice. Our findings offer a preclinical rationale to investigate the anticancer effects of PTP1B inhibitors currently being studied clinically for diabetes treatment as a new modality for management of prostate cancer. Cancer Res; 76(11); 3130–5. ©2016 AACR.

Cachexia is a metabolic disorder characterised by muscle wasting, diminished response to anti-cancer treatments and poor quality of life. Our objective was to identify blood-based biomarkers of cachexia in advanced cancer patients. Hence, we characterised the plasma cytokine and blood cell mRNA profiles of patients grouped in three cohorts: patients with cachexia, pre-cachexia (no cachexia but high CRP levels: ⩾5 mg l−1) and no cachexia (no cachexia and CRP: <5 mg l−1). A total of 122 newly diagnosed cancer patients with seven cancer types were studied prior to their initial therapy. Plasma levels of 22 cytokines were quantified using the bio-plex technology. mRNAs isolated from whole blood and expression profiles were determined by the chip array technology and Ingenuity Pathway Analysis (IPA) software. In comparison with non-cachectic individuals, both pre-cachectic and cachectic patients showed an increase (⩾1.5-folds) in mRNA expression of neutrophil-derived proteases (NDPs) and significantly elevated angiotensin II (Ang II) (P=0.005 and P=0.02, respectively), TGFβ1 (P=0.042 and P<0.0001, respectively) and CRP (both P<0.0001) in the plasma. Moreover, cachectic patients displayed a significant increase in IL-6 (P=0.005), IL-8 (P=0.001) and absolute neutrophil counts (P=0.007). Ang II, TGFβ1, CRP and NDP are blood biomarkers for cancer cachexia. These findings contribute to early diagnosis and prevention of cachexia.

Cellular signaling networks operate on a tightly regulated system of protein phosphorylation and dephosphorylation. With 109 members in humans, the protein tyrosine phosphatase protein superfamily acts on many of these pathways to maintain the balance of pathway activation and deactivation within the cell. The majority of these proteins are expressed in the immune system, therefore it is no surprise that most common genetic disease associations of these are of immune origin. The phosphatase of regenerating liver (PRL) proteins represent a group of protein tyrosine phosphatases that has been implicated in a number of diseases, and largely studied in the context of cancer metastasis. However, little is known about their physiological function. One such member, PRL-2, was recently found to be involved in maintaining magnesium homeostasis within the cell, and an additional role in the proliferation of hematopoietic stem cells was uncovered. Characterization of the PRL-2 knockout mouse indicates that this phosphatase may also be further active in the more differentiated hematopoietic lineages present within the immune system given the alterations observed in the size of both the thymus and spleen, which are key lymphoid organs. Defining the physiological role of PRL-2 would not only provide a greater understanding of the processes that govern hematopoiesis but could also contribute insight into potential pathological roles of this phosphatase in the immune system.

PTP (protein-tyrosine phosphatase)-PEST is a ubiquitously expressed cellular regulator of integrin signalling. It has been shown to bind several molecules such as Shc, paxillin and Grb2, that are involved downstream of FAK (focal adhesion kinase) pathway. Through its specific association to p130cas and further dephosphorylation, PTP-PEST plays a critical role in cell-matrix interactions, which are essential during embryogenesis. We report here that ablation of the gene leads to early embryonic lethality, correlating well with the high expression of the protein during embryonic development. We observed an increased level of tyrosine phosphorylation of p130cas protein in E9.5 PTP-PEST−/− embryos, a first evidence of biochemical defect leading to abnormal growth and development. Analysis of null mutant embryos revealed that they reach gastrulation, initiate yolk sac formation, but fail to progress through normal subsequent developmental events. E9.5–10.5 PTP-PEST−/− embryos had morphological abnormalities such as defective embryo turning, improper somitogenesis and vasculogenesis, impaired liver development, accompanied by degeneration in both neuroepithelium and somatic epithelia. Moreover, in embryos surviving until E10.5, the caudal region was truncated, with severe mesenchyme deficiency and no successful liver formation. Defects in embryonic mesenchyme as well as subsequent failure of proper vascularization, liver development and somatogenesis, seemed likely to induce lethality at this stage of development, and these results confirm that PTP-PEST plays an essential function in early embryogenesis.

The active form of vitamin D, 1alpha,25-dihydroxyvitamin D [1alpha,25(OH)2D], is synthesized from its precursor 25 hydroxyvitamin D [25(OH)D] via the catalytic action of the 25(OH)D-1alpha-hydroxylase [1alpha(OH)ase] enzyme. Many roles in cell growth and differentiation have been attributed to 1,25(OH)2D, including a central role in calcium homeostasis and skeletal metabolism. To investigate the in vivo functions of 1,25(OH)2D and the molecular basis of its actions, we developed a mouse model deficient in 1alpha(OH)ase by targeted ablation of the hormone-binding and heme-binding domains of the 1alpha(OH)ase gene. After weaning, mice developed hypocalcemia, secondary hyperparathyroidism, retarded growth, and the skeletal abnormalities characteristic of rickets. These abnormalities are similar to those described in humans with the genetic disorder vitamin D dependent rickets type I [VDDR-I; also known as pseudovitamin D-deficiency rickets (PDDR)]. Altered non-collagenous matrix protein expression and reduced numbers of osteoclasts were also observed in bone. Female mutant mice were infertile and exhibited uterine hypoplasia and absent corpora lutea. Furthermore, histologically enlarged lymph nodes in the vicinity of the thyroid gland and a reduction in CD4- and CD8-positive peripheral T lymphocytes were observed. Alopecia, reported in vitamin D receptor (VDR)-deficient mice and in humans with VDDR-II, was not seen. The findings establish a critical role for the 1alpha(OH)ase enzyme in mineral and skeletal homeostasis as well as in female reproduction and also point to an important role in regulating immune function.

Ubiquinone (UQ) is a lipid found in most biological membranes and is a co-factor in many redox processes including the mitochondrial respiratory chain. UQ has been implicated in protection from oxidative stress and in the aging process. Consequently, it is used as a dietary supplement and to treat mitochondrial diseases. Mutants of the clk-1 gene of the nematode Caenorhabditis elegans are fertile and have an increased life span, although they do not produce UQ but instead accumulate a biosynthetic intermediate, demethoxyubiquinone (DMQ). DMQ appears capable to partially replace UQ for respiration in vivo and in vitro. We have produced a vertebrate model of cells and tissues devoid of UQ by generating a knockout mutation of the murine orthologue of clk-1(mclk1). We find that mclk1−/− embryonic stem cells and embryos accumulate DMQ instead of UQ. As in the nematode mutant, the activity of the mitochondrial respiratory chain of −/− embryonic stem cells is only mildly affected (65% of wild-type oxygen consumption). However, mclk1−/− embryos arrest development at midgestation, although earlier developmental stages appear normal. These findings indicate that UQ is necessary for vertebrate embryonic development but suggest that mitochondrial respiration is not the function for which UQ is essential when DMQ is present.