Tcf1 is essential for initiation of oncogenic Notch1-driven chromatin topology in T-ALL

NOTCH1 is a well-established lineage specifier for T cells and amongst the most frequently mutated genes throughout all subclasses of T cell acute lymphoblastic leukemia (T-ALL). How oncogenic NOTCH1 signaling launches a leukemia-prone chromatin landscape during T-ALL initiation is unknown. Here we demonstrate an essential role for the high-mobility-group transcription factor Tcf1 in orchestrating chromatin accessibility and topology allowing aberrant Notch1 signaling to convey its oncogenic function. Although essential, Tcf1 is not sufficient to initiate leukemia. The formation of a leukemia-prone epigenetic landscape at the distal Notch1-regulated Myc enhancer, which is fundamental to this disease, is Tcf1-dependent and occurs within the earliest progenitor stage even before cells adopt a T lymphocyte or leukemic fate. Moreover, we discovered a unique evolutionarily conserved Tcf1-regulated enhancer element in the distal Myc-enhancer, which is important for the transition of pre-leukemic cells to full-blown disease.

Preliminary Study on Human Adipose Stem Cells Promoting Skin Wound Healing Through Notch1 Signaling Pathway

Background: Mesenchymal stem cells (MSCs) have been documented as possible candidates for wound healing treatment because their use could reinforce the regenerative capacity of many tissues. Human adipose stem cells (hADSCs) have the advantages of easy access, large quantity and easy operation. They can be fully applied in the treatment of skin wounds. In this study, we aim to explore the roles and potential mechanisms of hADSCs in cutaneous wound healing.Methods: hADSCs were obtained from human subcutaneous fat. Adipocytes and osteocytes differentiated from hADSCs were determined by staining with Oil Red O and alkaline phosphatase (ALP), respectively. We assessed the effects of hADSCs and hADSC conditional medium (CM) on wound healing in an injury model of mice. Than, we investigated the biological effects of hADSCs on human keratinocytes HaCAT cells in vitro.Results: The results showed that hADSCs could be successfully differentiated into osteogenic and lipogenic cells. hADSCs and hADSCs-CM significantly promote skin wound healing in vivo. hADSCs significantly promoted HaCAT cells proliferation and migration through activating Notch1 signaling pathway, and activated the AKT signaling pathway by Rps6kb1 kinase in HaCAT cells. In addition, we found that hADSCs-mediated activation of Rps6kb1/AKT signaling was dependent on the Notch1 signaling pathway.Conclusion: We demonstrated that hADSCs can promote skin cell-HaCAT cells proliferation and migration via Notch1 pathway, suggesting that hADSCs may provide an alternative therapeutic approach for the treatment of skin injury.

FSTL1-USP10-Notch1 Signaling Axis Protects Against Cardiac Dysfunction Through Inhibition of Myocardial Fibrosis in Diabetic Mice

The incidence of type 2 diabetes mellitus (T2DM) has been increasing globally, and T2DM patients are at an increased risk of major cardiac events such as myocardial infarction (MI). Nevertheless, the molecular mechanisms underlying MI injury in T2DM remain elusive. Ubiquitin-specific protease 10 (USP10) functions as a NICD1 (Notch1 receptor) deubiquitinase that fine-tunes the essential myocardial fibrosis regulator Notch signaling. Follistatin-like protein 1 (FSTL1) is a cardiokine with proven benefits in multiple pathological processes including cardiac fibrosis and insulin resistance. This study was designed to examine the roles of FSTL1/USP10/Notch1 signaling in MI-induced cardiac dysfunction in T2DM. High-fat-diet-treated, 8-week-old C57BL/6J mice and db/db T2DM mice were used. Intracardiac delivery of AAV9-FSTL1 was performed in T2DM mice following MI surgery with or without intraperitoneal injection of crenigacestat (LY3039478) and spautin-1. Our results demonstrated that FSTL1 improved cardiac function following MI under T2DM by reducing serum lactate dehydrogenase (LDH) and myocardial apoptosis as well as cardiac fibrosis. Further in vivo studies revealed that the protective role of FSTL1 against MI injury in T2DM was mediated by the activation of USP10/Notch1. FSTL1 protected cardiac fibroblasts (CFs) against DM-MI-induced cardiofibroblasts injury by suppressing the levels of fibrosis markers, and reducing LDH and MDA concentrations in a USP10/Notch1-dependent manner. In conclusion, FSTL1 treatment ameliorated cardiac dysfunction in MI with co-existent T2DM, possibly through inhibition of myocardial fibrosis and apoptosis by upregulating USP10/Notch1 signaling. This finding suggests the clinical relevance and therapeutic potential of FSTL1 in T2DM-associated MI and other cardiovascular diseases.

Effect of Notch1 Signaling on Cellular Proliferation and Apoptosis of Human Laryngeal Carcinoma

The pathological processes of occurrence and development of malignancies include the excessive proliferation and apoptosis resistance of neoplastic cells. The study aims to identify the effects of Notch1 signaling on the proliferation and apoptosis of laryngeal cancer cells in hypoxic microenvironment. Notch1 and Ki-67 expression in laryngeal squamous cell carcinoma (LSCC) tissue samples were detected by immunohistochemistry. The apoptotic index (AI) of LSCC was evaluated by TUNEL method. In laryngeal cancer cells, small interfering RNA (siRNA) technology was to inhibit Notch1 expression. Meanwhile, Real-time PCR detected Notch1, Hes1 and Hey1 mRNA expression, and Western blot detected Notch1 and Notch1 intracellular domain (N1ICD) protein expression. Annexin V-FITC/propidium iodide staining and Cell Counting Kit‑8 methods measured cell apoptosis and proliferation, respectively. Notch1 expression was detected in 63.55％(68/107) of LSCC samples and was significantly related to the proliferation index (PI) (P < 0.05) and AI (P < 0.05) in LSCC tissues. Furthermore, it was confirmed that hypoxia could induce proliferation and inhibit apoptosis of laryngeal carcinoma cells (P < 0.05). Meanwhile, Notch1 expression and Notch1 signaling activity could be upregulated by hypoxia (P < 0.05). In contrast, suppression of Notch1 signaling activity in hypoxic neoplastic cells could obviously decrease cell proliferation and increase cell apoptosis (both P<0.05). Our study has demonstrated that hypoxia may promote cell proliferation and inhibit cell apoptosis of laryngeal carcinoma. Notch1 signalling may exert a pivotal role in regulating the proliferation and apoptosis resistance of laryngeal cancer cells under hypoxia.

Notch1 Signaling Contributed To TLR4-Triggered NF-kB Activation In Macrophages

Background: Macrophages substantially shape the development, progression, and complications of inflammation-driven diseases. Although numerous researches support a critical role for Notch signaling in most inflammatory diseases, there is limited data on the role of Notch signaling in TLR4-induced macrophage activation and the interaction of Notch signaling with other signaling pathways(e.g., the NF-kB pathway during inflammation) in macrophages. Methods and Results: In this study, we confirmed that stimulation with TLR4 ligand LPS up-regulates Notch1 expression in RAW264.7 monocyte/macrophage-like cell line. LPS also induced the expression of Notch target genes Notch1 and Hes1 mRNA in macrophages, suggesting that TLR4 signaling enhances Notch pathway activation. The upregulation of Notch1, NICD, and Hes1 protein by LPS treatment was inhibited by the Notch1 inhibitor of DAPT. The increase of TNF-a, IL-6, and IL-1b induced by LPS was inhibited by DAPT while jagged1, the Notch1 ligand, rescued them. Furthermore, the suppression of Notch signaling by DAPT up-regulated CYLD expression but down-regulated TRAF6, IKKa/bphosphorylation, and subsequently phosphorylation and degradation of IκB-α, indicating the inhibition of TLR4-triggered NF-kB activation by DAPT. Interestingly, DAPT showed no inhibitory effect on the increase of MyD88 expression induced by LPS in our study. Conclusions: Our study shows that the stimulation of macrophages via the TLR4 signaling cascade triggers the activation of Notch1 signaling, which regulates the expression patterns of genes involved in pro-inflammatory responses through by activating NF-kB. It may be dependent on the CYLD-TRAF6-IKK pathway. The Notch1 signaling may be considered as a potential therapeutic target against infectious and inflammatory driven diseases.