FAM3A mediates PPARγ's protection in liver ischemia-reperfusion injury by activating Akt survival pathway and repressing inflammation and oxidative stress

Crystal structure combined with metabolomics and biochemical studies indicates that FAM3A participates in fatty acid beta-oxidation upon binding of acyl-L-carnitine

As the first member of the family with sequence similarity 3 (FAM3), FAM3A promotes synthesis of ATP in mitochondria of hepatic cells and cells from other organs. Dysregulations of FAM3A are involved in the development of diabetes and nonalcoholic fatty liver disease (NAFLD). So far, the molecule mechanism under the physiological and pathological functions of FAM3A is largely unexplored. Here, we determined the crystal structure of FAM3A at high resolution of 1.38Å, complexed with an unknown-source compound which was characterized through metabolomics and confirmed as methacholine by thermal shift assay and surface plasmon resonance (SPR). Exploration for natural ligands of FAM3A was conducted through the same molecular interaction assays. The observed binding of acyl-L-carnitine molecules indicated FAM3A participating in fatty acid beta-oxidation. Knockdown and rescue assays coupled with fatty acid oxidation determination confirmed the role of FAM3A in beta-oxidation. This investigation reveals the molecular mechanism for the biological function of FAM3A and would provide basis for identifying drug target for treatment of diabetes and NAFLD.

Hydrogen Regulates Ulcerative Colitis by Affecting the Intestinal Redox Environment

The redox balance in the intestine plays an important role in maintaining intestinal homeostasis, and it is closely related to the intestinal mucosal barrier, intestinal inflammation, and the gut microbiota. Current research on the treatment of ulcerative colitis has focused on immune disorders, excessive inflammation, and oxidative stress. However, an imbalance in intestinal redox reaction plays a particularly critical role. Hydrogen is produced by some anaerobic bacteria via hydrogenases in the intestine. Increasing evidence suggests that hydrogen, as an inert gas, is crucial for immunity, inflammation, and oxidative stress and plays a protective role in ulcerative colitis. Hydrogen maintains the redox state balance in the intestine in ulcerative colitis and reduces damage to intestinal epithelial cells by exerting its selective antioxidant ability. Hydrogen also regulates the intestinal flora, reduces the harmful effects of bacteria on the intestinal epithelial barrier, promotes the restoration of normal anaerobic bacteria in the intestines, and ultimately improves the integrity of the intestinal epithelial barrier. The present review focuses on the therapeutic mechanisms of hydrogen-targeting ulcerative colitis.

Unveiling the Crucial Roles of O2•- and ATP in Hepatic Ischemia-Reperfusion Injury Using Dual-Color/Reversible Fluorescence Imaging

Hepatic ischemia-reperfusion injury (HIRI) is mainly responsible for morbidity or death due to graft rejection after liver transplantation. During HIRI, superoxide anion (O2•-) and adenosine-5'-triphosphate (ATP) have been identified as pivotal biomarkers associated with oxidative stress and energy metabolism, respectively. However, how the temporal and spatial fluctuations of O2•- and ATP coordinate changes in HIRI and particularly how they synergistically regulate each other in the pathological mechanism of HIRI remains unclear. Herein, we rationally designed and successfully synthesized a dual-color and dual-reversible molecular fluorescent probe (UDP) for dynamic and simultaneous visualization of O2•- and ATP in real-time, and uncovered their interrelationship and synergy in HIRI. UDP featured excellent sensitivity, selectivity, and reversibility in response to O2•- and ATP, which rendered UDP suitable for detecting O2•- and ATP and generating independent responses in the blue and red fluorescence channels without spectral crosstalk. Notably, in situ imaging with UDP revealed for the first time synchronous O2•- bursts and ATP depletion in hepatocytes and mouse livers during the process of HIRI. Surprisingly, a slight increase in ATP was observed during reperfusion. More importantly, intracellular O2•-─succinate dehydrogenase (SDH)─mitochondrial (Mito) reduced nicotinamide adenine dinucleotide (NADH)─Mito ATP─intracellular ATP cascade signaling pathway in the HIRI process was unveiled which illustrated the correlation between O2•- and ATP for the first time. This research confirms the potential of UDP for the dynamic monitoring of HIRI and provides a clear illustration of HIRI pathogenesis.

FAM3A mediates the phenotypic switch of human aortic smooth muscle cells stimulated with oxidised low-density lipoprotein by influencing the PI3K-AKT pathway

Family with sequence similarity 3 member A (FAM3A) is a multifunctional protein that is related to the pathological process of various disorders. FAM3A is reportedly able to affect the phenotypic change of vascular smooth muscle cells under a hypertensive state. Whether FAM3A mediates the phenotypic switch of vascular smooth muscle cells under an atherosclerotic state remains unaddressed. This work investigated the roles and mechanisms of FAM3A in mediating the phenotypic switch of human aortic smooth muscle cells (HASMCs) stimulated with oxidised low-density lipoprotein (ox-LDL) in vitro. FAM3A expression was elevated in HASMCs following ox-LDL treatment. FAM3A silencing led to a suppressive effect on ox-LDL-provoked proliferation, migration and inflammation of HASMCs, whereas FAM3A overexpression had an opposite effect. Ox-LDL elicited a change in HASMCs from a contractile phenotype to a synthetic phenotype, which was inhibited by FAM3A silencing or enhanced by FAM3A overexpression. Further investigation elucidated that FAM3A silencing repressed and FAM3A overexpression promoted ox-LDL-induced activation of the PI3K-AKT pathway in HASMCs. Reactivation of AKT reversed the suppressive effect of FAM3A silencing on the ox-LDL-induced phenotypic switch of HASMCs. Restraining AKT blocked the promoting effect of FAM3A overexpression on the ox-LDL-induced phenotypic switch of HASMCs. In summary, this work elucidates that FAM3A mediates the ox-LDL-induced phenotypic switch of HASMCs by influencing the PI3K-AKT pathway, indicating a potential role for FAM3A in atherosclerosis.

Effect of the Non-steroidal Anti-inflammatory Drug Diclofenac on Ischemia-Reperfusion Injury in Rat Liver: A Nitric Oxide-Dependent Mechanism

Ischemia/reperfusion injury (IRI) is an inevitable complication of liver surgery and transplantation. The purpose of this study was to examine the beneficial effects of diclofenac on hepatic IRI and the mechanism behind it. Wistar rats' livers were subjected to warm ischemia for 60 min followed by 24 h of reperfusion. Diclofenac was administered intravenously 15 min before ischemia at 10, 20, and 40 mg/kg body weight. To determine the mechanism of diclofenac protection, the NOS inhibitor L-Nitro-arginine methyl ester (L-NAME) was administered intravenously 10 min after diclofenac injection (40 mg/kg). Liver injury was evaluated by aminotransferases (ALT and AST) activities and histopathological analysis. Oxidative stress parameters (SOD, GPX, MPO, GSH, MDA, and PSH) were also determined. Then, eNOS gene transcription and p-eNOS and iNOS protein expressions were evaluated. The transcription factors PPAR-γ and NF-κB in addition to the regulatory protein IκBα were also investigated. Finally, the gene expression levels of inflammatory (COX-2, IL-6, IL-1β, IL-18, TNF-α, HMGB-1, and TLR-4) and apoptosis (Bcl-2 and Bax) markers were measured. Diclofenac, at the optimal dose of 40 mg/kg, decreased liver injury and maintained histological integrity. It also reduced oxidative stress, inflammation, and apoptosis. Its mechanism of action essentially depended on eNOS activation rather than COX-2 inhibition, since pre-treatment with L-NAME abolished all the protective effects of diclofenac. To our knowledge, this is the first study demonstrating that diclofenac protects rat liver against warm IRI through the induction of NO-dependent pathway. Diclofenac reduced oxidative balance, attenuated the activation of the subsequent pro-inflammatory response and decreased cellular and tissue damage. Therefore, diclofenac could be a promising molecule for the prevention of liver IRI.

FAM3A maintains metabolic homeostasis by interacting with F1-ATP synthase to regulate the activity and assembly of ATP synthase

Reduced mitochondrial ATP synthase (ATPS) capacity plays crucial roles in the pathogenesis of metabolic disorders. However, there is currently no effective strategy for synchronously stimulating the expressions of ATPS key subunits to restore its assembly. This study determined the roles of mitochondrial protein FAM3A in regulating the activity and assembly of ATPS in hepatocytes. FAM3A is localized in mitochondrial matrix, where it interacts with F1-ATPS to initially activate ATP synthesis and release, and released ATP further activates P2 receptor-Akt-CREB pathway to induce FOXD3 expression. FOXD3 synchronously stimulates the transcriptions of ATPS key subunits and assembly genes to increase its assembly and capacity, augmenting ATP synthesis and inhibiting ROS production. FAM3A, FOXD3 and ATPS expressions were reduced in livers of diabetic mice and NAFLD patients. FOXD3 expression, ATPS capacity and ATP content were reduced in various tissues of FAM3A-deficient mice with dysregulated glucose and lipid metabolism. Hepatic FOXD3 activation increased ATPS assembly to ameliorate dysregulated glucose and lipid metabolism in obese mice. Hepatic FOXD3 inhibition or knockout reduced ATPS capacity to aggravate HFD-induced hyperglycemia and steatosis. In conclusion, FAM3A is an active ATPS component, and regulates its activity and assembly by activating FOXD3. Activating FAM3A-FOXD3 axis represents a viable strategy for restoring ATPS assembly to treat metabolic disorders.

Imipramine activates FAM3A-FOXA2-CPT2 pathway to ameliorate hepatic steatosis

Mitochondrial FAM3A has been revealed to be a viable target for treating diabetes and nonalcoholic fatty liver disease (NAFLD). However, its distinct mechanism in ameliorating hepatic steatosis remained unrevealed. High-throughput RNA sequencing revealed that carnitine palmityl transferase 2 (CPT2), one of the key enzymes for lipid oxidation, is the downstream molecule of FAM3A signaling pathway in hepatocytes. Intensive study demonstrated that FAM3A-induced ATP release activated P2 receptor to promote the translocation of calmodulin (CaM) from cytoplasm into nucleus, where it functioned as a co-activator of forkhead box protein A2 (FOXA2) to promote the transcription of CPT2, increasing free fatty acid oxidation and reducing lipid deposition in hepatocytes. Furthermore, antidepressant imipramine activated FAM3A-ATP-P2 receptor-CaM-FOXA2-CPT2 pathway to reduce lipid deposition in hepatocytes. In FAM3A-deficient hepatocytes, imipramine failed to activate CaM-FOXA2-CPT2 axis to increase lipid oxidation. Imipramine administration significantly ameliorated hepatic steatosis, hyperglycemia and obesity of obese mice mainly by activating FAM3A-ATP-CaM-FOXA2-CPT2 pathway in liver and thermogenesis in brown adipose tissue (BAT). In FAM3A-deficient mice fed on high-fat-diet, imipramine treatment failed to correct the dysregulated lipid and glucose metabolism, and activate thermogenesis in BAT. In conclusion, imipramine activates FAM3A-ATP-CaM-FOXA2-CPT2 pathway to ameliorate steatosis. For depressive patients complicated with metabolic disorders, imipramine may be recommended in priority as antidepressive drug.

Resveratrol promotes liver cell survival in mice liver-induced ischemia-reperfusion through unfolded protein response: a possible approach in liver transplantation

Background

Ischemia-reperfusion (I/R) of the liver is a multifactorial condition that happens during transplantation and surgery. The deleterious effects of I/R result from the acute production of reactive oxygen species (ROS), which can trigger immediate tissue damage and induce a series of destructive cellular responses, including apoptosis organ failure and inflammation. The production of ROS in the I/R process can damage the antioxidant system and cause liver damage. Resveratrol has been shown to have antioxidant properties in several investigations. Here, we address the therapeutic effect of resveratrol on I/R-induced liver injury by focusing on unfolded protein response (UPR) signaling pathway.

Methods

Five minutes before reperfusion, resveratrol was injected into the tail vein of mice. They were ischemic for 1 h and then re-perfused for 3 h before being slaughtered (I/R). The activity of liver enzymes and the expression levels of genes involved in the unfolded protein response pathway were used to measure the hepatic damage.

Results

Our results revealed that the low dose of resveratrol (0.02 and 0.2 mg/kg) post-ischemic treatment significantly reduced the ALT and AST levels. In addition, compared with the control group, the expression of UPR pathway genes GRP78, PERK, IRE1α, CHOP, and XBP1 was significantly reduced in the resveratrol group. In the mice that received lower doses of resveratrol (0.02 and 0.2 mg/kg), the histopathological changes induced by I/R were significantly improved; however, the highest dose (2 mg/kg) of resveratrol could not significantly protect and solve the I/R damage.

Conclusion

The findings of this study suggest that hepatic ischemia occurs after liver transplantation and that receiving low-dose resveratrol treatment before reperfusion may promote graft survival through inhibition of UPR arms, especially PERK and IRE1α.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40360-022-00611-4.

ATP Secretion and Metabolism in Regulating Pancreatic Beta Cell Functions and Hepatic Glycolipid Metabolism

Diabetes (DM), especially type 2 diabetes (T2DM) has become one of the major diseases severely threatening public health worldwide. Islet beta cell dysfunctions and peripheral insulin resistance including liver and muscle metabolic disorder play decisive roles in the pathogenesis of T2DM. Particularly, increased hepatic gluconeogenesis due to insulin deficiency or resistance is the central event in the development of fasting hyperglycemia. To maintain or restore the functions of islet beta cells and suppress hepatic gluconeogenesis is crucial for delaying or even stopping the progression of T2DM and diabetic complications. As the key energy outcome of mitochondrial oxidative phosphorylation, adenosine triphosphate (ATP) plays vital roles in the process of almost all the biological activities including metabolic regulation. Cellular adenosine triphosphate participates intracellular energy transfer in all forms of life. Recently, it had also been revealed that ATP can be released by islet beta cells and hepatocytes, and the released ATP and its degraded products including ADP, AMP and adenosine act as important signaling molecules to regulate islet beta cell functions and hepatic glycolipid metabolism via the activation of P2 receptors (ATP receptors). In this review, the latest findings regarding the roles and mechanisms of intracellular and extracellular ATP in regulating islet functions and hepatic glycolipid metabolism would be briefly summarized and discussed.

Novel Targets and Therapeutic Strategies to Protect Against Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI), a fascinating topic that has drawn a lot of interest in the last few years, is a major complication caused by a variety of clinical situations, such as liver transplantation, severe trauma, vascular surgery, and hemorrhagic shock. The IRI process involves a series of complex events, including mitochondrial deenergization, metabolic acidosis, adenosine-5'-triphosphate depletion, Kupffer cell activation, calcium overload, oxidative stress, and the upregulation of pro-inflammatory cytokine signal transduction. A number of protective strategies have been reported to ameliorate IRI, including pharmacological therapy, ischemic pre-conditioning, ischemic post-conditioning, and machine reperfusion. However, most of these strategies are only at the stage of animal model research at present, and the potential mechanisms and exact therapeutic targets have yet to be clarified. IRI remains a main cause of postoperative liver dysfunction, often leading to postoperative morbidity or even mortality. Very recently, it was reported that the activation of peroxisome proliferator-activated receptor γ (PPARγ), a member of a superfamily of nuclear transcription factors activated by agonists, can attenuate IRI in the liver, and FAM3A has been confirmed to mediate the protective effect of PPARγ in hepatic IRI. In addition, non-coding RNAs, like LncRNAs and miRNAs, have also been reported to play a pivotal role in the liver IRI process. In this review, we presented an overview of the latest advances of treatment strategies and proposed potential mechanisms behind liver IRI. We also highlighted the role of several important molecules (PPARγ, FAM3A, and non-coding RNAs) in protecting against hepatic IRI. Only after achieving a comprehensive understanding of potential mechanisms and targets behind IRI can we effectively ameliorate IRI in the liver and achieve better therapeutic effects.

Intracellular ATP Signaling Contributes to FAM3A-Induced PDX1 Upregulation in Pancreatic Beta Cells

FAM3A is a recently identified mitochondrial protein that stimulates pancreatic-duodenal homeobox 1 (PDX1) and insulin expressions by promoting ATP release in islet β cells. In this study, the role of intracellular ATP in FAM3A-induced PDX1 expression in pancreatic β cells was further examined. Acute FAM3A inhibition using siRNA transfection in mouse pancreatic islets significantly reduced PDX1 expression, impaired insulin secretion, and caused glucose intolerance in normal mice. In vitro , FAM3A overexpression elevated both intracellular and extracellular ATP contents and promoted PDX1 expression and insulin secretion. FAM3A-induced increase in cellular calcium (Ca ²⁺ ) levels, PDX1 expression, and insulin secretion, while these were significantly repressed by inhibitors of P2 receptors or the L-type Ca ²⁺ channels. FAM3A-induced PDX1 expression was abolished by a calmodulin inhibitor. Likewise, FAM3A-induced β-cell proliferation was also inhibited by a P2 receptor inhibitor and an L-type Ca ²⁺ channels inhibitor. Both intracellular and extracellular ATP contributed to FAM3A-induced PDX1 expression, insulin secretion, and proliferation of pancreatic β cells.

Xenoextracellular matrix-rosiglitazone complex-mediated immune evasion promotes xenogenic bioengineered root regeneration by altering M1/M2 macrophage polarization

Xenogenic extracellular matrix (xECM)-based organ transplantation will be a promising approach to address the problem of donor shortage for allotransplantation, which has achieved great success in organ regeneration. However, current approaches to utilize xECM-based organ have limited capacity to yield the host a biofriendly microenvironment for long-term immunity homeostasis, compromising the application of these xenografts for repairing and replacing damaged tissues. As the key innate immune cells, macrophages directly determine the prognosis of xenografts in long term. However, it has not been fully elucidated that how to modulate their biological behavior for microenvironment homeostasis in tissue reconstruction. In this study, we report a robust strategy to impart an immunosuppressive surface to naturally sponge-like porous xECM scaffolds by loading rosiglitazone (RSG) to activate peroxisome proliferators receptors-γ (PPAR-γ). The resultant xECM-RSG complex, enabling RSG to be delivered sequentially and continuously to cells without obvious systemic side effects, is recognized as "self" to escape immune monitoring in local immunoregulation by downregulating the expression of proinflammatory NOS2+ M1 macrophages and oxygen species (ROS) through suppressing NF-κB expression, greatly facilitating the regeneration of enthesis anchoring between the transplanted xenograft and host in both heterotopic and orthotopic models. The newly formed bio-root is morphologically and biomechanically equivalent to native tooth root with a significant expression of odontogenic differentiation-related critical proteins. Therefore, the PPAR-γ-NF-κB axis activated by the xECM-RSG complex enables the xenografts to converse towards M2 macrophages with a modest immunosuppressive capacity for facilitating in xECM-based tissue or organ regeneration.

PPARγ in Ischemia-Reperfusion Injury: Overview of the Biology and Therapy

Ischemia-reperfusion injury (IRI) is a complex pathophysiological process that is often characterized as a blood circulation disorder caused due to various factors (such as traumatic shock, surgery, organ transplantation, burn, and thrombus). Severe metabolic dysregulation and tissue structure destruction are observed upon restoration of blood flow to the ischemic tissue. Theoretically, IRI can occur in various tissues and organs, including the kidney, liver, myocardium, and brain, among others. The advances made in research regarding restoring tissue perfusion in ischemic areas have been inadequate with regard to decreasing the mortality and infarct size associated with IRI. Hence, the clinical treatment of patients with severe IRI remains a thorny issue. Peroxisome proliferator-activated receptor γ (PPARγ) is a member of a superfamily of nuclear transcription factors activated by agonists and is a promising therapeutic target for ameliorating IRI. Therefore, this review focuses on the role of PPARγ in IRI. The protective effects of PPARγ, such as attenuating oxidative stress, inhibiting inflammatory responses, and antagonizing apoptosis, are described, envisaging certain therapeutic perspectives.

Protective effects of Lizhong decoction on ulcerative colitis in mice by suppressing inflammation and ameliorating gut barrier

ETHNOPHARMACOLOGICAL RELEVANCE

Lizhong Decoction (LZD) is a classical prescription firstly recorded in "Shanghan Lun". It has been used to clinically treat ulcerative colitis (UC) for thousands of years. However, its mechanism is not clear up to now.

AIM OF THE STUDY

The goal of this study was to assess the amelioration of LZD on dextran sodium sulfate (DSS)-induced colitis in mice and further clarify its mechanism.

MATERIALS AND METHODS

The ulcerative colitis model induced by DSS was successfully established and applied to evaluate the intervention effect after oral administration of LZD. Furthermore, the expression of key targets in inflammatory signaling pathways and intestinal tight junction proteins were investigated by enzyme-linked immunosorbent assay (ELISA) and quantitative real time polymerase chain reaction (qPCR) analysis.

RESULTS

The results showed that all doses of LZD could notably improve DSS-induced colon lesions, reduce histological scores, prolong colon length and increase body weight. Colonic inflammation in UC mice was significantly alleviated by inhibiting the activities of myeloperoxidase (MPO) and superoxide dismutase (SOD), reducing the yield of nitric oxide (NO) and inflammatory cytokines such as interferon-γ (IFN-γ), tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6), and along with promoting the production of anti-inflammatory cytokines such as interleukin-4 (IL-4) and interleukin-10 (IL-10) after LZD treatment. Furthermore, LZD remarkably down-regulated the level of toll-like receptor 4 (TLR4) and nuclear factor-κB (NF-κB) mRNA and up-regulated the expression of tight junction proteins (zonula occluden-1, occludin and claudin-1) in UC mice.

CONCLUSION

In summary, this study indicated that LZD could notably improve UC symptoms by suppressing inflammation and ameliorating gut barrier, which provided scientific basis for its clinical application in the future.

Analysis of miRNAs and their target genes associated with mucosal damage caused by transport stress in the mallard duck intestine

Bowel health is an important factor for duck rearing that has been linked to feed uptake and growth and death rates. Because the regulatory networks associated with acute stress-mediated injury in the duck gastrointestinal tract have not clearly elucidated, we aimed to explore potential miRNA-mRNA pairs and their regulatory roles in oxidative stress injury caused by transport stress. Here, 1-day-old mallard ducklings from the same breeder flock were collected and transported for 8 h, whereas the control group was not being transported. Various parameters reflecting oxidative stress and the tissue appearance of the intestine were assessed. The data showed that the plasma T-AOC and SOD concentrations were decreased in the transported ducklings. The intestine of the transported ducklings also displayed significant damage. High-throughput sequencing of the intestine revealed 44 differentially expressed miRNAs and 75 differentially expressed genes, which constituted 344 miRNA-mRNA pairs. KEGG pathway analysis revealed that the metabolic, FoxO signaling, influenza A and TGF-β signaling pathways were mainly involved in the mechanism underlying the induction of intestinal damage induced by simulated transport stress in ducks. A miRNA-mRNA pair, miR-217-5p/CHRDL1, was selected to validate the miRNA-mRNA negative relationship, and the results showed that miR-217-5p could influence CHRDL1 expression. This study provides new useful information for future research on the regulatory network associated with mucosal damage in the duck intestine.

Repurposing Doxepin to Ameliorate Steatosis and Hyperglycemia by Activating FAM3A Signaling Pathway

Mitochondrial protein FAM3A suppresses hepatic gluconeogenesis and lipogenesis. This study aimed to screen drug(s) that activates FAM3A expression and evaluate its effect(s) on hyperglycemia and steatosis. Drug-repurposing methodology predicted that antidepressive drug doxepin was among the drugs that potentially activated FAM3A expression. Doxepin was further validated to stimulate the translocation of transcription factor HNF4α from the cytoplasm into the nucleus, where it promoted FAM3A transcription to enhance ATP synthesis, suppress gluconeogenesis, and reduce lipid deposition in hepatocytes. HNF4α antagonism or FAM3A deficiency blunted doxepin-induced suppression on gluconeogenesis and lipid deposition in hepatocytes. Doxepin administration attenuated hyperglycemia, steatosis, and obesity in obese diabetic mice with upregulated FAM3A expression in liver and brown adipose tissues (BAT). Notably, doxepin failed to correct dysregulated glucose and lipid metabolism in FAM3A-deficient mice fed on high-fat diet. Doxepin's effects on ATP production, Akt activation, gluconeogenesis, and lipogenesis repression were also blunted in FAM3A-deficient mouse livers. In conclusion, FAM3A is a therapeutic target for diabetes and steatosis. Antidepressive drug doxepin activates FAM3A signaling pathways in liver and BAT to improve hyperglycemia and steatosis of obese diabetic mice. Doxepin might be preferentially recommended as an antidepressive drug in potential treatment of patients with diabetes complicated with depression.

FAM3A plays crucial roles in controlling PDX1 and insulin expressions in pancreatic beta cells

So far, the mechanism that links mitochondrial dysfunction to PDX1 inhibition in the pathogenesis of pancreatic β cell dysfunction under diabetic condition remains largely unclear. This study determined the role of mitochondrial protein FAM3A in regulating PDX1 expression in pancreatic β cells using gain- and loss-of function methods in vitro and in vivo. Within pancreas, FAM3A is highly expressed in β, α, δ, and pp cells of islets. Islet FAM3A expression was correlated with insulin expression under physiological and diabetic conditions. Mice with specific knockout of FAM3A in islet β cells exhibited markedly blunted insulin secretion and glucose intolerance. FAM3A-deficient islets showed significant decrease in PDX1 expression, and insulin expression and secretion. FAM3A overexpression upregulated PDX1 and insulin expressions, and augmented insulin secretion in cultured islets and β cells. Mechanistically, FAM3A enhanced ATP production to elevate cellular Ca²⁺ level and promote insulin secretion. Furthermore, FAM3A-induced ATP release activated CaM to function as a co-activator of FOXA2, stimulating PDX1 gene transcription. In conclusion, FAM3A plays crucial roles in controlling PDX1 and insulin expressions in pancreatic β cells. Inhibition of FAM3A will trigger mitochondrial dysfunction to repress PDX1 and insulin expressions.

FOXO1 inhibition prevents renal ischemia-reperfusion injury via cAMP-response element binding protein/PPAR-γ coactivator-1α-mediated mitochondrial biogenesis

BACKGROUND AND PURPOSE

Growing evidence indicates targeting mitochondrial dynamics and biogenesis could accelerate recovery from renal ischemia-reperfusion (I/R) injury, but the underlying mechanisms remain elusive. Transcription factor forkhead box O1 (FOXO1) is a key regulator of mitochondrial homeostasis and plays a pathological role in the progression of renal disease.

EXPERIMENTAL APPROACH

A mouse model of renal I/R injury and a hypoxia/reoxygenation (H/R) injury model for human renal tubular epithelial cells were used.

KEY RESULTS

I/R injury up-regulated renal expression of FOXO1 and treatment with FOXO1-selective inhibitor AS1842856 prior to I/R injury decreased serum urea nitrogen, serum creatinine and the tubular damage score after injury. Post-I/R injury AS1842856 treatment could also ameliorate renal function and improve the survival rate of mice following injury. AS1842856 administration reduced mitochondrial-mediated apoptosis, suppressed the overproduction of mitochondrial ROS and accelerated recovery of ATP both in vivo and in vitro. Additionally, FOXO1 inhibition improved mitochondrial biogenesis and suppressed mitophagy. Expression of PPAR-γ coactivator 1α (PGC-1α), a master regulator of mitochondrial biogenesis, was down-regulated in both I/R and H/R injury, which could be abrogated by FOXO1 inhibition. Experiments using integrated bioinformatics analysis and coimmunoprecipitation established that FOXO1 inhibited PGC-1α transcription by competing with cAMP-response element binding protein (CREB) for its binding to transcriptional coactivators CREBBP/EP300 (CBP/P300).

CONCLUSION AND IMPLICATIONS

These findings suggested that FOXO1 was critical to maintain mitochondrial function in renal tubular epithelial cells and FOXO1 may serve as a therapeutic target for pharmacological intervention in renal I/R injury.

FAM3A protects chondrocytes against interleukin-1β-induced apoptosis through regulating PI3K/Akt/mTOR pathway

Chondrocyte death due to apoptosis is central for osteoarthritis (OA) pathogenesis. The family with sequence similarity 3A (FAM3A) is a mitochondrial protein that plays an important role for cellular adaptation to stress and cell survival. Yet, whether FAM3A is associated with chondrocyte apoptosis and OA pathogenesis remains uncharacterized. In this study, we found that FAM3A expression was downregulated in cartilage tissue from an experimental OA mouse model. Besides, FAM3A expression was also reduced in chondrocytes treated with interleukin-1β (IL-1β), an inflammatory cytokine that promotes cartilage degradation. Moreover, we discovered that FAM3A attenuated chondrocyte apoptosis induced by IL-1β treatment in vitro, suggesting a protective effect of FAM3A against chondrocyte apoptosis. Moreover, mechanistically, FAM3A activated PI3K/Akt/mTOR pathway in IL-1β-treated chondrocytes, and blockade of PI3K/Akt/mTOR pathway with specific inhibitors, wortmannin and LY294002, diminished FAM3A effect on IL-1β-induced chondrocyte apoptosis, hence demonstrating that FAM3A attenuates IL-1β-induced chondrocyte apoptosis through activating the pro-survival PI3K/Akt/mTOR pathway. In conclusion, our study may identify FAM3A as a potential regulator of chondrocyte apoptosis involved in OA pathogenesis.

3-Dehydroandrographolide protects against lipopolysaccharide-induced inflammation through the cholinergic anti-inflammatory pathway

Acute lung injury (ALI) is a deadly disease without effective chemotherapy, so far. Traditional Chinese medicine andrographis herba is frequently used in the treatment of respiratory diseases. In searching for natural anti-ALI components from andrographis herba, the activities of 3-dehydroandrographolide (3-DA), a new natural andrographolide product from andrographis herba were evaluated. In this study, murine macrophage RAW 264.7 cells and BALB/c mice were treated with LPS (lipopolysaccharide, 100 ng/ml in vitro; 3 mg/kg, intratracheal) to establish inflammation models. 3-DA attenuated the release of pro-inflammatory cytokines IL-6 and TNF-α, inhibited the degradation and phosphorylation of IκBα, and suppressed the nuclear translocation of NF-κB p65 as well as the phosphorylation of Akt at Ser473 in LPS-stimulated RAW 264.7 macrophage cells. Furthermore, 3-DA increased α7nAchR expression level and bound with α7nAchR. More importantly, the anti-inflammatory effects of 3-DA were counteracted in the presence of α7nAchR siRNA or methyllycaconitine (MLA, a α7nAchR specific inhibitor), suggesting that α7nAchR is a potential target in the anti-inflammatory effects of 3-DA. Besides, 3-DA significantly inhibited inflammation in LPS-induced ALI mice, which was associated with the decrease of lung water content and inflammatory cytokines, the inhibition of neutrophil and macrophage infiltration, and activation of the NF-κB/Akt signaling pathway. Moreover, these protective effects were attenuated by the treatment of MLA. Taken together, 3-DA alleviates LPS-induced inflammation via the cholinergic anti-inflammatory pathway in vitro and in vivo. These findings provide a rationale for the role of the cholinergic anti-inflammatory pathway in inflammation and the promising clinical application of 3-DA to treat ALI.

Endothelial microvesicles in hypoxic hypoxia diseases

Hypoxic hypoxia, including abnormally low partial pressure of inhaled oxygen, external respiratory dysfunction-induced respiratory hypoxia and venous blood flow into the arterial blood, is characterized by decreased arterial oxygen partial pressure, resulting in tissue oxygen deficiency. The specific characteristics include reduced arterial oxygen partial pressure and oxygen content. Hypoxic hypoxia diseases (HHDs) have attracted increased attention due to their high morbidity and mortality and mounting evidence showing that hypoxia-induced oxidative stress, coagulation, inflammation and angiogenesis play extremely important roles in the physiological and pathological processes of HHDs-related vascular endothelial injury. Interestingly, endothelial microvesicles (EMVs), which can be induced by hypoxia, hypoxia-induced oxidative stress, coagulation and inflammation in HHDs, have emerged as key mediators of intercellular communication and cellular functions. EMVs shed from activated or apoptotic endothelial cells (ECs) reflect the degree of ECs damage, and elevated EMVs levels are present in several HHDs, including obstructive sleep apnoea syndrome and chronic obstructive pulmonary disease. Furthermore, EMVs have procoagulant, proinflammatory and angiogenic functions that affect the pathological processes of HHDs. This review summarizes the emerging roles of EMVs in the diagnosis, staging, treatment and clinical prognosis of HHDs.

Exercise induced improvements in insulin sensitivity are concurrent with reduced NFE2/miR-432-5p and increased FAM3A

AIMS

Little is known regarding whether the NFE2/miR-423-5p and FAM3A-ATP-Akt pathway in liver mediates exercise allured alleviation of insulin resistance connected with diet-induced obesity. This research inquired the influence of exercise on liver insulin sensitivity and whole body insulin resistance in high-fat diet fed rats.

MATERIALS AND METHODS

Forty male Sprague-Dawley rats at seven-week-old were assigned to four groups at random: standard diet as normal control group (NC, n = 10), high-fat diet group (HFD, n = 10), high-fat diet with chronic exercise intervention group (HFD-CE, n = 10) and high-fat diet with acute exercise intervention group (HFD-AE, n = 10).

KEY FINDINGS

Compared with rats fed with a standard diet, eight-week high-fat diet feeding lead to elevated body weight, visceral fat content and serum FFAs, and decreased insulin sensitivity index. Moreover, high-fat diet enhanced NFE2 protein expression and miR-423-5p level, decreased FAM3A mRNA and protein expression, ATP level and Akt phosphorylation in liver. In contrast, physical exercise, both chronic and acute exercise alleviated whole body insulin resistance, reduced hepatic NFE2 and miR-423-5p expression, and serum FFAs level, meanwhile enhanced FAM3A mRNA and protein expression, ATP level and Akt phosphorylation in liver. The current findings indicated that exercise in diet-induced obesity, both chronic and acute, induce a momentous regulation in NFE2/miR-423-5p and FAM3A-ATP-Akt pathway in liver, and improve hepatic insulin sensitivity and whole body insulin resistance.

SIGNIFICANCE

All these results supply crucial evidence in our comprehending of the molecular mechanism that connected exercise to an alleviation of insulin resistance.

Novel Targets for Treating Ischemia-Reperfusion Injury in the Liver

Liver ischemia-reperfusion injury (IRI) is a major complication of hemorrhagic shock, liver transplantation, and other liver surgeries. It is one of the leading causes for post-surgery hepatic dysfunction, always leading to morbidity and mortality. Several strategies, such as low-temperature reperfusion and ischemic preconditioning, are useful for ameliorating liver IRI in animal models. However, these methods are difficult to perform in clinical surgeries. It has been reported that the activation of peroxisome proliferator activated receptor gamma (PPARγ) protects the liver against IRI, but with unidentified direct target gene(s) and unclear mechanism(s). Recently, FAM3A, a direct target gene of PPARγ, had been shown to mediate PPARγ’s protective effects in liver IRI. Moreover, noncoding RNAs, including LncRNAs and miRNAs, had also been reported to play important roles in the process of hepatic IRI. This review briefly discussed the roles and mechanisms of several classes of important molecules, including PPARγ, FAM3A, miRNAs, and LncRNAs, in liver IRI. In particular, oral administration of PPARγ agonists before liver surgery or liver transplantation to activate hepatic FAM3A pathways holds great promise for attenuating human liver IRI.

FAM3 gene family: A promising therapeutical target for NAFLD and type 2 diabetes

Non-alcoholic fatty liver disease (NAFLD) and diabetes are severe public health issues worldwide. The Family with sequence similarity 3 (FAM3) gene family consists of four members designated as FAM3A, FAM3B, FAM3C and FAM3D, respectively. Recently, there had been increasing evidence that FAM3A, FAM3B and FAM3C are important regulators of glucose and lipid metabolism. FAM3A expression is reduced in the livers of diabetic rodents and NAFLD patients. Hepatic FAM3A restoration activates ATP-P2 receptor-Akt and AMPK pathways to attenuate steatosis and hyperglycemia in obese diabetic mice. FAM3C expression is also reduced in the liver under diabetic condition. FAM3C is a new hepatokine that activates HSF1-CaM-Akt pathway and represses mTOR-SREBP1-FAS pathway to suppress hepatic gluconeogenesis and lipogenesis. In contrast, hepatic expression of FAM3B, also called PANDER, is increased under obese state. FAM3B promotes hepatic lipogenesis and gluconeogenesis by repressing Akt and AMPK activities, and activating lipogenic pathway. Under obese state, the imbalance among hepatic FAM3A, FAM3B and FAM3C signaling networks plays important roles in the pathogenesis of NAFLD and type 2 diabetes. This review briefly discussed the latest research progress on the roles and mechanisms of FAM3A, FAM3B and FAM3C in the regulation of hepatic glucose and lipid metabolism.

Protective role of puerarin on LPS/D-Gal induced acute liver injury via restoring autophagy

Acute liver injury is a destructive liver disorder resulting from overwhelming liver inflammation, oxidative stress and hepatocyte death. Puerarin is a natural flavonoid compound isolated from the traditional Chinese herb radix puerariae. This study investigated the protective effects of puerarin against lipopolysaccharide (LPS)/D-galactosamine (D-Gal)-induced liver injury and the potential mechanisms in mice. Mice were given an intraperitoneal administration of puerarin 200 mg/kg 2 h prior to LPS (50 μg/kg)/D-Gal (400 mg/kg) injection and were sacrificed 6 h post LPS/D-Gal treatment. The results showed that administration of puerarin substantially alleviated LPS/D-Gal-induced acute liver injury in mice by increased survival rates, improved liver histopathology, reduced plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels, alleviated production of pro-inflammatory cytokines, and suppressed hepatocyte apoptosis. Moreover, puerarin pretreatment activated autophagy by increased the ratio of LC3B-II/I and the protein levels of Beclin-1, decreased the levels of p62 protein expression. Taken together, these findings demonstrated that puerarin could prevent the LPS/D-Gal-induced liver injury in mice, and its mechanisms might be associated with the increments of autophagy and suppression of apoptosis.

Effects of initiating time and dosage of Panax notoginseng on mucosal microvascular injury in experimental colitis

AIM

To investigate the effects of Panax notoginseng (PN) on microvascular injury in colitis, its mechanisms, initial administration time and dosage.

METHODS

Dextran sodium sulfate (DSS)- or iodoacetamide (IA)-induced rat colitis models were used to evaluate and investigate the effects of ethanol extract of PN on microvascular injuries and their related mechanisms. PN administration was initiated at 3 and 7 d after the model was established at doses of 0.5, 1.0 and 2.0 g/kg for 7 d. The severity of colitis was evaluated by disease activity index (DAI). The pathological lesions were observed under a microscope. Microvessel density (MVD) was evaluated by immunohistochemistry. Vascular permeability was evaluated using the Evans blue method. The serum concentrations of cytokines, including vascular endothelial growth factor (VEGF)A121, VEGFA165, interleukin (IL)-4, IL-6, IL-10 and tumor necrosis factor (TNF)-α, were detected by enzyme-linked immunosorbent assay. Myeloperoxidase (MPO) and superoxide dismutase (SOD) were measured to evaluate the level of oxidative stress. Expression of hypoxia-inducible factor (HIF)-1α protein was detected by western blotting.

RESULTS

Obvious colonic inflammation and injuries of mucosa and microvessels were observed in DSS- and IA-induced colitis groups. DAI scores, serum concentrations of VEGFA121, VEGFA165, VEGFA165/VEGFA121, IL-6 and TNF-α, and concentrations of MPO and HIF-1α in the colon were significantly higher while serum concentrations of IL-4 and IL-10 and MVD in colon were significantly lower in the colitis model groups than in the normal control group. PN promoted repair of injuries of colonic mucosa and microvessels, attenuated inflammation, and decreased DAI scores in rats with colitis. PN also decreased the serum concentrations of VEGFA121, VEGFA165, VEGFA165/VEGFA121, IL-6 and TNF-α, and concentrations of MPO and HIF-1α in the colon, and increased the serum concentrations of IL-4 and IL-10 as well as the concentration of SOD in the colon. The efficacy of PN was dosage dependent. In addition, DAI scores in the group administered PN on day 3 were significantly lower than in the group administered PN on day 7.

CONCLUSION

PN repairs vascular injury in experimental colitis via attenuating inflammation and oxidative stress in the colonic mucosa. Efficacy is related to initial administration time and dose.

FAM3C activates HSF1 to suppress hepatic gluconeogenesis and attenuate hyperglycemia of type 1 diabetic mice

FAM3C, a member of FAM3 gene family, has been shown to improve insulin resistance and hyperglycemia in obese mice. This study further determined whether FAM3C functions as a hepatokine to suppress hepatic gluconeogenesis of type 1 diabetic mice. In STZ-induced type 1 diabetic mouse liver, the FAM3C-HSF1-CaM signaling axis was repressed. Hepatic FAM3C overexpression activated HSF1-CaM-Akt pathway to repress gluconeogenic gene expression and ameliorate hyperglycemia of type 1 diabetic mice. Moreover, hepatic HSF1 overexpression also activated CaM-Akt pathway to repress gluconeogenic gene expression and improve hyperglycemia of type 1 diabetic mice. Hepatic FAM3C and HSF1 overexpression had little effect on serum insulin levels in type 1 diabetic mice. In cultured hepatocytes, conditioned medium of Ad-FAM3C-infected cells induced Akt phosphorylation. Moreover, Akt activation and gluconeogenesis repression induced by FAM3C overexpression were reversed by the treatment with anti-FAM3C antibodies. Treatment with recombinant FAM3C protein induced Akt activation in a HSF1- and CaM-dependent manner in cultured hepatocytes. Furthermore, recombinant FAM3C protein repressed gluconeogenic gene expression and gluconeogenesis by inactivating FOXO1 in a HSF1-dependent manner in cultured hepatocytes. In conclusion, FAM3C is a new hepatokine that suppresses hepatic gluconeogenic gene expression and gluconeogenesis independent of insulin by activating HSF1-CaM-Akt pathway.