Haematopoietic stem cells (HSCs) are derived early from embryonic precursors, such as haemogenic endothelial cells and pre-haematopoietic stem cells (pre-HSCs), the molecular identity of which still remains elusive. Here we use potent surface markers to capture the nascent pre-HSCs at high purity, as rigorously validated by single-cell-initiated serial transplantation. Then we apply single-cell RNA sequencing to analyse endothelial cells, CD45(-) and CD45(+) pre-HSCs in the aorta-gonad-mesonephros region, and HSCs in fetal liver. Pre-HSCs show unique features in transcriptional machinery, arterial signature, metabolism state, signalling pathway, and transcription factor network. Functionally, activation of mechanistic targets of rapamycin (mTOR) is shown to be indispensable for the emergence of HSCs but not haematopoietic progenitors. Transcriptome data-based functional analysis reveals remarkable heterogeneity in cell-cycle status of pre-HSCs. Finally, the core molecular signature of pre-HSCs is identified. Collectively, our work paves the way for dissection of complex molecular mechanisms regulating stepwise generation of HSCs in vivo, informing future efforts to engineer HSCs for clinical applications.

In the mouse embryo, the aorta-gonad-mesonephros (AGM) region is considered to be the sole location for intraembryonic emergence of hematopoietic stem cells (HSCs). Here we report that, in parallel to the AGM region, the E10.5-E11.5 mouse head harbors bona fide HSCs, as defined by long-term, high-level, multilineage reconstitution and self-renewal capacity in adult recipients, before HSCs enter the circulation. The presence of hemogenesis in the midgestation head is indicated by the appearance of intravascular cluster cells and the blood-forming capacity of a sorted endothelial cell population. In addition, lineage tracing via an inducible VE-cadherin-Cre transgene demonstrates the hemogenic capacity of head endothelium. Most importantly, a spatially restricted lineage labeling system reveals the physiological contribution of cerebrovascular endothelium to postnatal HSCs and multilineage hematopoiesis. We conclude that the mouse embryonic head is a previously unappreciated site for HSC emergence within the developing embryo.

Summary Hematopoietic stem cells (HSCs) are generated from specialized endothelial cells of the embryonic aorta. Inflammatory factors are implicated in regulating mouse HSC development, but which cells in the aorta-gonad-mesonephros (AGM) microenvironment produce these factors is unknown. In the adult, macrophages play both pro- and anti-inflammatory roles. We sought to examine whether macrophages or other hematopoietic cells found in the embryo prior to HSC generation were involved in the AGM HSC-generative microenvironment. CyTOF analysis of CD45 + AGM cells revealed predominance of two hematopoietic cell types, mannose-receptor positive macrophages and mannose-receptor negative myeloid cells. We show here that macrophage appearance in the AGM was dependent on the chemokine receptor Cx3cr1. These macrophages expressed a pro-inflammatory signature, localized to the aorta, and dynamically interacted with nascent and emerging intra-aortic hematopoietic cells (IAHCs). Importantly, upon macrophage depletion, no adult-repopulating HSCs were detected, thus implicating a role for pro-inflammatory AGM-associated macrophages in regulating the development of HSCs.

Tankyrase 1 is a poly(ADP-ribose) polymerase (PARP) which localizes to multiple subcellular sites, including telomeres and mitotic centrosomes. Poly(ADP-ribosyl)ation of the nuclear mitotic apparatus (NuMA) protein by tankyrase 1 during mitosis is essential for sister telomere resolution and mitotic spindle pole formation. In interphase cells, tankyrase 1 resides in the cytoplasm, and its role therein is not well understood. In this study, we found that herpes simplex virus (HSV) infection induced extensive modification of tankyrase 1 but not tankyrase 2. This modification was dependent on extracellular signal-regulated kinase (ERK) activity triggered by HSV infection. Following HSV-1 infection, tankyrase 1 was recruited to the nucleus. In the early phase of infection, tankyrase 1 colocalized with ICP0 and thereafter localized within the HSV replication compartment, which was blocked in cells infected with the HSV-1 ICP0-null mutant R7910. In the absence of infection, ICP0 interacted with tankyrase 1 and efficiently promoted its nuclear localization. HSV did not replicate efficiently in cells depleted of both tankyrases 1 and 2. Moreover, XAV939, an inhibitor of tankyrase PARP activity, decreased viral titers to 2 to 5% of control values. We concluded that HSV targets tankyrase 1 in an ICP0-and ERK-dependent manner to facilitate its replication. Herpes simplex virus types 1 and 2 (HSV-1 and HSV-2), members of the Herpesviridae family (17), possess large DNA genomes, share virion structures and replication mechanisms, and establish lifelong latency in host cells. The HSV genome comprises a 152-kb double-stranded DNA molecule that encodes approximately 80 gene products expressed in a temporally regulated cascade (6, 68). HSV genes are classified into three groups: immediate-early, early, and late genes. Immediate-early genes are expressed first upon infection and encode several transactivators, which in turn initiate transcription of the other early and some late genes; the latter are called leaky late or ␥1 genes (12,20,48,73). Early gene products include viral DNA replication factors that initiate viral DNA synthesis, which in turn stimulate expression of ␥1 and true late (␥2) genes, encoding mainly virion structural proteins.The immediate-early viral proteins ICP4, ICP27, ICP0, and ICP22 allow the virus to create an environment conducive to infection and counteract the intrinsic ability of cells to inhibit viral infection (29,34,55,59). ICP4 and ICP27 play essential roles in stimulating robust viral gene expression (34). The immediateearly protein ICP0 activates viral and cellular gene expression and functions as an E3 ubiquitin ligase that degrades several cellular proteins (29). ICP0 targets the promyelocytic leukemia protein (PML), a major component of nuclear foci called ND10 bodies that repress viral gene expression. ICP0 interferes with several intrinsic host defense mechanisms, including the host interferon responses (29), thereby playing a major role in establishing permissive conditions for viral infec...

SUMMARYExcessive production of reactive oxygen species (ROS) by an overactive nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system in penile tissue is an important mechanism of erectile dysfunction (ED). S-allyl cysteine (SAC), a bioactive component derived from garlic, was recently reported to exert versatile antioxidant properties. We hypothesized that SAC would be able to resolve diabetes-related ED by reducing ROS generation, and designed this study to investigate this possibility as well as to determine the related underlying mechanisms. A streptozotocin-induced diabetes rat model was established and used for comparative analysis of 4-week treatment regimens with insulin or SAC. The ratio of maximal intracavernous pressure (ICP) to mean arterial blood pressure (MAP) was measured to determine erectile function. Differential levels of ROS, NADPH oxidase subunits, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signalling pathway, and apoptosis were evaluated in cavernous tissues. Max ICP/MAP was found to be markedly decreased in untreated diabetic rats; SAC, but not insulin, treatment restored the ratio to baseline (in non-diabetic untreated controls). The corpus cavernosum of untreated diabetic rats showed increased p47 phox and p67 phox expression, ROS production and penile apoptotic index, and decreased phospho-endothelial nitric oxide synthase (phospho-eNOS, Ser1177) expression, cGMP concentration, B-cell lymphoma 2 (Bcl-2)/Bcl-2-associated X protein (Bax) ratio and smooth muscle cell number. SAC treatment normalized all the diabetes-induced effects, whereas insulin treatment partially normalized the alterations, but produced no effects on P47 phox expression, penile ROS level, apoptotic index, Bcl-2/Bax ratio and smooth muscle cell number. Collectively, these data indicate that SAC treatment can restore erectile function in diabetic rats by preventing ROS formation through modulation of NADPH oxidase subunit expression. Furthermore, the poor efficacy of conventional insulin treatment for diabetic ED may be associated with an elevated level of ROS in penile tissue.

Key Points• ATF4 positively regulates expansion of functional HSCs in mouse FL.• ATF4-Angptl3 axis in niche cells is pivotal for HSC maintenance in FL.The fetal liver (FL) serves as a predominant site for expansion of functional hematopoietic stem cells (HSCs) during mouse embryogenesis. However, the mechanisms for HSC development in FL remain poorly understood. In this study, we demonstrate that deletion of activating transcription factor 4 (ATF4) significantly impaired hematopoietic development and reduced HSC self-renewal in FL. In contrast, generation of the first HSC population in the aorta-gonad-mesonephros region was not affected. The migration activity of ATF4 2/2 HSCs was moderately reduced. Interestingly, the HSC-supporting ability of both endothelial and stromal cells in FL was significantly compromised in the absence of ATF4. Gene profiling using RNA-seq revealed downregulated expression of a panel of cytokines in ATF4 2/2 stromal cells, including angiopoietin-like protein 3 (Angptl3) and vascular endothelial growth factor A (VEGFA).Addition of Angptl3, but not VEGFA, partially rescued the repopulating defect of ATF4 2/2 HSCs in the culture. Furthermore, chromatin immunoprecipitation assay in conjunction with silencing RNA-mediated silencing and complementary DNA overexpression showed transcriptional control of Angptl3 by ATF4. To summarize, ATF4 plays a pivotal role in functional expansion and repopulating efficiency of HSCs in developing FL, and it acts through upregulating transcription of cytokines such as Angptl3 in the microenvironment. (Blood. 2015;126(21):2383-2391

Background Optimal therapeutic strategies for hepatocellular carcinoma (HCC) patients are still challenging due to the high recurrence rate after surgical resection and chemotherapy resistance. Growing evidence shows that genetic and epigenetic alterations are involved in HCC progression and resistance to therapy, however the molecular mechanisms underlying resistance to therapy have not been fully understood. Methods Expression of SIRT7 in 17 paired paraffin-embedded HCC tissues and adjacent nontumoral liver tissues was examined by immunohistochemistry and Western blot. The mRNA expression of SIRT7 in 20 paired frozen HCC tissues and adjacent nontumoral liver tissues was analyzed by quantitative RT-PCR. The biologic consequences of overexpression and knockdown of SIRT7 in HCC therapy sensitivity were studied in vitro and in vivo. Interaction between SIRT7 and p53 were studied in HCC cell lines. Results SIRT7 expression was frequently upregulated in clinical HCC samples, and its expression was highly associated with TACE-resistance and poor survival (P = 0.008.) Depletion of SIRT7 from multiple liver cancer cell lines significantly increased doxorubicin toxicity while overexpression of SIRT7 largely abolished doxorubicin induced apoptosis. At the molecular level, we observed that SIRT7 interacts with and induces deacetylation of p53 at lysines 320 and 373. Deacetylated p53 showed significantly less affinity for the NOXA promoter and its transcription. In mouse xenografts, SIRT7 suppression increased doxorubicin induced p53 activation, inhibited tumor growth and induced apoptosis. Conclusion The newly identified SIRT7-p53-NOXA axis partially illustrates the molecular mechanism of HCC resistance to therapy and represents a novel potential therapeutic target for HCC treatment. Electronic supplementary material The online version of this article (10.1186/s13046-019-1246-4) contains supplementary material, which is available to authorized users.

Comparing to human vision, conventional machine vision composed of image sensor and processor suffers from high latency and large power consumption due to physically separated image sensing and processing. Neuromorphic vision system with brain-inspired visual perception provides a promising solution to solve the challenge. Here we propose and demonstrate a prototype neuromorphic vision system by networking retinomorphic sensor with a memristive crossbar. We fabricate the retinomorphic sensor by using WSe2/h-BN/Al2O3 van der Waals heterostructures with gate-tunable photoresponses, to closely mimic the human retinal capabilities in simultaneously sensing and processing images. We then network such sensor with a large-scale Pt/Ta/HfO2/Ta one-transistor-one-memristor (1T1R) memristive crossbar, which serves as the role similar to the visual cortex in human brain. The realized neuromorphic vision system allows for fast letter recognition and object tracking, indicating the capabilities of image sensing, processing and recognition in the full analog regime. Our work suggests that such neuromorphic vision system may open up unprecedented opportunities in future visual perception applications.