Aims Adipocyte fatty acid-binding protein (A-FABP) is an adipokine implicating in various metabolic diseases. Elevated circulating levels of A-FABP correlate positively with poor prognosis in ischaemic stroke (IS) patients. No information is available concerning the role of A-FABP in the pathogenesis of IS. Experiments were designed to determine whether or not A-FABP mediates blood–brain barrier (BBB) disruption, and if so, to explore the molecular mechanisms underlying this deleterious effects. Methods and results Circulating A-FABP and its cerebral expression were increased in mice after middle cerebral artery occlusion. Genetic deletion and pharmacological inhibition of A-FABP alleviated cerebral ischaemia injury with reduced infarction volume, cerebral oedema, neurological deficits, and neuronal apoptosis; BBB disruption was attenuated and accompanied by reduced degradation of tight junction proteins and induction of matrix metalloproteinases-9 (MMP-9). In patients with acute IS, elevated circulating A-FABP levels positively correlated with those of MMP-9 and cerebral infarct volume. Mechanistically, ischaemia-induced elevation of A-FABP selectively in peripheral blood monocyte-derived macrophages and cerebral resident microglia promoted MMP-9 transactivation by potentiating JNK/c-Jun signalling, enhancing degradation of tight junction proteins and BBB leakage. The detrimental effects of A-FABP were prevented by pharmacological inhibition of MMP-9. Conclusion A-FABP is a key mediator of cerebral ischaemia injury promoting MMP-9-mediated BBB disruption. Inhibition of A-FABP is a potential strategy to improve IS outcome.

Cancer stem cells (CSCs) are characterized by self‐renewal and ‐differential potential as compared to common cancer cells and play an important role in the development and therapeutic resistance of liver hepatocellular carcinoma (LIHC). However, the specific pathogenesis of LIHC stem cells is still unclear, and the genes involved in the stemness of LIHC stem cells are currently unknown. In this study, we investigated novel biomarkers associated with LIHC and explored the expression characteristics of stem cell‐related genes in LIHC. We found that mRNA expression‐based stemness index (mRNAsi) was significantly overexpressed in liver cancer tissues. Further, mRNAsi expression in LIHC increased with the tumor pathological grade, with grade 4 tumors harboring the greatest stem cell features. Upon establishing mRNAsi scores based on mRNA expression of every gene, we found an association with poor overall survival in LIHC. Moreover, modules of interest were determined based on weighted gene co‐expression network analysis (WGCNA) inclusion criteria, and three significant modules (red, green, and brown) and 21 key genes (DCN, ECM1, HAND2, PTGIS, SFRP1, SRPX, COLEC10, GRP182, ADAMTS7, CD200, CDH11, COL8A1, FAP, LZTS1, MAP1B, NAV1, NOTCH3, OLFML2A, PRR16, TMEM119, and VCAN) were identified. Functional analysis of these 21 genes demonstrated their enrichment in pathways involved in angiogenesis, negative regulation of DNA‐binding transcription factor activity, apoptosis, and autophagy. Causal relationship with proteins indicated that the Wnt, Notch, and Hypoxia pathways are closely related to LIHC tumorigenesis. To our knowledge, this is the first report of a novel CSC biomarker, mRNAsi, to predict the prognosis of LIHC. Further, we identified 21 key genes through mRNA expression network analysis, which could be potential therapeutic targets to inhibit the stemness of cancer cells in LIHC.

The adipokine adipocyte fatty acid-binding protein (A-FABP) has been implicated in obesity-related cardio-metabolic complications. Here we show that A-FABP increases thermogenesis by promoting the conversion of T4 to T3 in brown adipocytes. We find that A-FABP levels are increased in both white (WAT) and brown (BAT) adipose tissues and the bloodstream in response to thermogenic stimuli. A-FABP knockout mice have reduced thermogenesis and whole-body energy expenditure after cold stress or after feeding a high-fat diet, which can be reversed by infusion of recombinant A-FABP. Mechanistically, A-FABP induces the expression of type-II iodothyronine deiodinase in BAT via inhibition of the nuclear receptor liver X receptor α, thereby leading to the conversion of thyroid hormone from its inactive form T4 to active T3. The thermogenic responses to T4 are abrogated in A-FABP KO mice, but enhanced by A-FABP. Thus, A-FABP acts as a physiological stimulator of BAT-mediated adaptive thermogenesis.

BACKGROUND: Exercise is an effective nonpharmacological strategy to alleviate diabetic cardiomyopathy (DCM) through poorly defined mechanisms. FGF21 (fibroblast growth factor 21), a peptide hormone with pleiotropic benefits on cardiometabolic homeostasis, has been identified as an exercise responsive factor. This study aims to investigate whether FGF21 signaling mediates the benefits of exercise on DCM, and if so, to elucidate the underlying mechanisms. METHODS: The global or hepatocyte-specific FGF21 knockout mice, cardiomyocyte-selective β-klotho (the obligatory co-receptor for FGF21) knockout mice, and their wild-type littermates were subjected to high-fat diet feeding and injection of streptozotocin to induce DCM, followed by a 6-week exercise intervention and assessment of cardiac functions. Cardiac mitochondrial structure and function were assessed by electron microscopy, enzymatic assays, and measurements of fatty acid oxidation and ATP production. Human induced pluripotent stem cell–derived cardiomyocytes were used to investigate the receptor and postreceptor signaling pathways conferring the protective effects of FGF21 against toxic lipids-induced mitochondrial dysfunction. RESULTS: Treadmill exercise markedly induced cardiac expression of β-klotho and significantly attenuated diabetes-induced cardiac dysfunction in wild-type mice, accompanied by reduced mitochondrial damage and increased activities of mitochondrial enzymes in hearts. However, such cardioprotective benefits of exercise were largely abrogated in mice with global or hepatocyte-selective ablation of FGF21, or cardiomyocyte-specific deletion of β-klotho. Mechanistically, exercise enhanced the cardiac actions of FGF21 to induce the expression of the mitochondrial deacetylase SIRT3 by AMPK-evoked phosphorylation of FOXO3, thereby reversing diabetes-induced hyperacetylation and functional impairments of a cluster of mitochondrial enzymes. FGF21 prevented toxic lipids-induced mitochondrial dysfunction and oxidative stress by induction of the AMPK/FOXO3/SIRT3 signaling axis in human induced pluripotent stem cell–derived cardiomyocytes. Adeno-associated virus-mediated restoration of cardiac SIRT3 expression was sufficient to restore the responsiveness of diabetic FGF21 knockout mice to exercise in amelioration of mitochondrial dysfunction and DCM. CONCLUSIONS: The FGF21-SIRT3 axis mediates the protective effects of exercise against DCM by preserving mitochondrial integrity and represents a potential therapeutic target for DCM. REGISTRATION: URL: https://www.clinicaltrials.gov ; Unique identifier: NCT03240978.