Project description:Despite the well-known role of MET in liver regeneration following partial-hepatectomy (PHx), its role in the clinically-relevant acetaminophen (APAP)-induced liver injury (AILI) model remains unexplored. AILI markedly differs from PHx because it is associated with massive liver necrosis. This study aims to delineate the role of MET specifically in AILI. Hepatocyte-specific MET-KO mice were given a toxic-dose of APAP and assessed for hepatotoxicity/regeneration parameters. MET deletion strikingly exacerbated initial hepatotoxicity and impaired subsequent proliferative response, culminating in significant mortality. Mechanistically, MET deletion enhanced JNK-activation and its mitochondrial translocation, resulting in excessive mitochondrial oxidative-damage, releasing cell-death inducer AIF into cytosol. Excess JNK-activation was attributed to reduced inhibitory activity of AKT on JNK in the absence of MET-signaling. Pharmacological activation of AKT reduced JNK-activation and hepatotoxicity in MET-KO mice. RNA-sequencing/immunoblotting not only showed repression of proliferative/survival signaling, but also activation of cell death/senescence pathways along with impaired unfolded-protein-response in MET-KO mice. Analysis of published single-nucleus RNA-sequencing data showed proliferation in livers from APAP-induced ALF patients was associated with strong activation of HGF/MET signaling in hepatocytes, with spatial-transcriptomics showing striking induction of HGF surrounding the necrotic-zones. Interestingly, 35% of the genes altered in human-ALF were regulated by MET in the mouse AILI-model. In conclusion, our study demonstrates that MET is crucial for restraining hepatotoxicity following APAP overdose via inhibiting mitochondrial cell-death signaling pathway.
Project description:Purpose: This study investigated the protective effect and further elucidated the mechanisms of action of O. elatus on acetaminophen (APAP)-induced liver injury (AILI). Methods: O. elatus chlorogenic-enriched fraction (OEB) was administrated orally daily for seven consecutive days, followed by a single intraperitoneal injection of an overdose of APAP after the final OEB administration. Results: OEB decreased alanine aminotransferase, aspartate aminotransferase, total cholesterol, total triglycerides contents, regulated superoxide dismutase, catalase, glutathione, malondialdehyde levels, and affected the metabolism of APAP. Furthermore, OEB treatment regulated lipid metabolism, activated the peroxisome proliferator-activated receptors signaling pathway in mice with AILI, affected immune cells, and decreased neutrophil infiltration. Conclusions: This study indicated that OEB is a potential drug candidate for the prevention of APAP-induced hepatotoxicity and elucidated a potential protective mechanism by OEB.
Project description:RNAseq of liver homogenate 24h after APAP (300mg/kg) exposure followed by either MSC or HDF at 90 min. MSCs, not HDFs, ameliorate APAP-induced liver injury.
Project description:The relative quantification of sex-specific proteomic responses led to the detection of potential biomarkers for hepatotoxicity and as well as the identification of the underlying molecular perturbation needed to unravel the impact of APAP-induced liver injury on physiological system.
Project description:Background The axon guidance cue Slit2 recently has been found to regulate calcium homeostasis and molecular signaling in various stress events in different organs. However, whether Slit2 plays a role in cardiac ischemia-reperfusion (IR) injury has not been reported. Here, we aimed to investigate the role of Slit2 and the underlying mechanisms in cardiac IR injury. Methods Langendorff-perfused isolated hearts from Slit2-overexpressing (Slit2-Tg) mice and their background strain C57BL/6J mice were subjected to 20 min of global ischemia followed by 40 min of reperfusion. Left ventricular function of isolated hearts was monitored. Infarct size of post-IR hearts was determined by staining with 2,3,5-triphenyltetrazolium chloride (TTC) and histological changes of cardiac tissues and cells were determined with hematoxylin-eosin (HE) staining and transmission electron microscopy. Transcriptomic analysis was used to predict the biological processes and signaling pathways affected by Slit2 overexpression in the post-IR myocardium. Pro-Q staining and Western blotting was used to assess the phosphorylation levels of cardiac myofilaments and expression levels of myofilament-associated protein kinase and phosphatases. Results Slit2 overexpression increased post-IR left ventricular developed pressure (LVDP) by 35% and reduced infarct size by 53%, along with decreased myofibrillar disruption, mitochondrial swelling, and mitochondrial cristae dissolution. Slit2 overexpression significantly changed post-IR gene expression profiles. Functional products of these genes include regulation of cation transmembrane transport, cation homeostasis, collagen fibril organization, and regulation of heart rate. And post-IR myocardial KEGG pathways upregulated by Slit2 overexpression include ECM-receptor interaction, PI3K-Akt signaling pathway, and adrenergic signaling. Slit2 overexpression impacted myofilament phosphorylation together with myofilament-associated protein kinase C (PKC) isoforms and protein phosphatases (PPs). IR in C57BL/6J hearts upregulated phosphorylation of cardiac troponin-I (cTnI), which was suppressed by Slit2 overexpression. Myofilament‐associated PKCε, PKCδ, and PP2A were significantly increased post‐IR in C57BL/6J hearts, but in Slit2‐Tg hearts, myofilament‐associated PKCε and PP2A were increased and PKCδ was suppressed. Conclusions Our results demonstrate that Slit2 overexpression protects cardiac function and reduces IR injury, which is associated with Slit2‐induced gene profile shifts. The suppression of MyBP‐C and troponin‐I phosphorylation, and myofilament‐associated PKCδ levels induced by Slit2 overexpression could contribute to the cardioprotection of Slit2 in post-IR myocardium.
Project description:Acetaminophen (APAP) is a commonly used analgesic responsible for more than half of acute liver failure cases. Identification of previously unknown genetic risk factors would provide mechanistic insights and novel therapeutic targets for APAP-induced liver injury. This study used a genome-wide CRISPR-Cas9 screen to evaluate genes that are protective against, or cause susceptibility to, APAP-induced liver injury. HuH7 human hepatocellular carcinoma cells containing CRISPR-Cas9 gene knockouts were treated with 15mM APAP for 30 minutes to 4 days. A gene expression profile was developed based on the 1) top screening hits, 2) overlap of expression data from APAP overdose studies, and 3) predicted affected biological pathways. We further demonstrated the implementation of intermediate time points for the identification of early and late response genes. This study illustrated the power of a genome-wide CRISPR-Cas9 screen to systematically identify novel genes involved in APAP-induced hepatotoxicity and to provide potential targets to develop novel therapeutic modalities.
Project description:Sympathetic tone has long been known as a central signaling axis inhibiting osteogenesis. However, the mechanism of this nerve to bone influence remains elusive, especially regarding the specific cellular targets of sympathetic activity. Recently, a bona fide tissue-resident stem cell giving rise to skeletal cell types, skeletal stem cells (SSCs), have been identified. To explore if and how nerves impact SSCs, we utilized mice with conditional deletion of SLIT2, a classic axonal repellent, finding that neural (Slit2syn1 mice) and sympathetic (Slit2th mice) but not bone stem/progenitor (Slit2prx1 mice) or sensory (Slit2adv mice) deletion of Slit2, led to osteopenia due to impaired bone formation associated with an increase in sympathetic innervation and a decrease in the numbers of SSCs. Consistent with this, pharmacological or surgical sympathectomy caused expansion of the SSC pool. More directly, wild type (WT) SSCs transplanted orthotopically into the bones of Slit2th mice with increased sympathetic innervation displayed impaired osteogenic capability, demonstrating that sympathetic nerves functionally contribute to the SSC niche. In line with these findings, the increased sympathetic innervation in Slit2th mice disrupted bone regeneration and bone fracture healing by reducing SSC expansion. Transcriptomic profiling in sympathetic neurons identified Follistatin-like 1 (FSTL1) as a SLIT2-regulated soluble factor that suppressed SSC self-renewal and osteogenic capacity. Accordingly, ablation of Fstl1 in sympathetic neurons enhanced SSC-driven osteogenesis and attenuated the bone loss seen in Slit2th mice in vivo. Altogether, our study both newly establishes SLIT2 as a regulator of skeletal sympathetic innervation and establishes sympathetic nerves as a key component of the SSC niche, providing new therapeutic opportunities to augment SSC function to treat skeletal disorders.