Non-alcoholic fatty liver disease (NAFLD) has recently been considered to be under the influence of the gut microbiota, which might exert toxic effects on the human host after intestinal absorption and delivery to the liver via the portal vein. In this study, the composition of the gut microbiota in NAFLD patients and healthy subjects was determined via 16S ribosomal RNA Illumina next-generation sequencing. Among those taxa displaying greater than 0.1% average abundance in all samples, five genera, including Alistipes and Prevotella, were significantly more abundant in the gut microbiota of healthy subjects compared to NAFLD patients. Alternatively, Escherichia, Anaerobacter, Lactobacillus and Streptococcus were increased in the gut microbiota of NAFLD patients compared to healthy subjects. In addition, decreased numbers of CD4+ and CD8+ T lymphocytes and increased levels of TNF-α, IL-6 and IFN-γ were detected in the NAFLD group compared to the healthy group. Furthermore, irregularly arranged microvilli and widened tight junctions were observed in the gut mucosa of the NAFLD patients via transmission electron microscopy. We postulate that aside from dysbiosis of the gut microbiota, gut microbiota-mediated inflammation of the intestinal mucosa and the related impairment in mucosal immune function play an important role in the pathogenesis of NAFLD.
The incidence and mortality rate of cancer has been quickly increasing in the past decades. At present, cancer has become the leading cause of death worldwide. Most of the cancers cannot be effectively diagnosed at the early stage. Although there are multiple therapeutic treatments, including surgery, radiotherapy, chemotherapy, and targeted drugs, their effectiveness is still limited. The overall survival rate of malignant cancers is still low. It is necessary to further study the mechanisms for malignant cancers, and explore new biomarkers and targets that are more sensitive and effective for early diagnosis, treatment, and prognosis of cancers than traditional biomarkers and methods. Long non-coding RNAs (lncRNAs) are a class of RNA transcripts with a length greater than 200 nucleotides. Generally, lncRNAs are not capable of encoding proteins or peptides. LncRNAs exert diverse biological functions by regulating gene expressions and functions at transcriptional, translational, and post-translational levels. In the past decade, it has been demonstrated that the dysregulated lncRNA profile is widely involved in the pathogenesis of many diseases, including cancer, metabolic disorders, and cardiovascular diseases. In particular, lncRNAs have been revealed to play an important role in tumor growth and metastasis. Many lncRNAs have been shown to be potential biomarkers and targets for the diagnosis and treatment of cancers. This review aims to briefly discuss the latest findings regarding the roles and mechanisms of some important lncRNAs in the pathogenesis of certain malignant cancers, including lung, breast, liver, and colorectal cancers, as well as hematological malignancies and neuroblastoma.
FAM3A belongs to a novel cytokine-like gene family, and its physiological role remains largely unknown. In our study, we found a marked reduction of FAM3A expression in the livers of db/db and high-fat diet (HFD)-induced diabetic mice. Hepatic overexpression of FAM3A markedly attenuated hyperglycemia, insulin resistance, and fatty liver with increased Akt (pAkt) signaling and repressed gluconeogenesis and lipogenesis in the livers of those mice. In contrast, small interfering RNA (siRNA)-mediated knockdown of hepatic FAM3A resulted in hyperglycemia with reduced pAkt levels and increased gluconeogenesis and lipogenesis in the livers of C57BL/6 mice. In vitro study revealed that FAM3A was mainly localized in the mitochondria, where it increases adenosine triphosphate (ATP) production and secretion in cultured hepatocytes. FAM3A activated Akt through the p110a catalytic subunit of PI3K in an insulin-independent manner. Blockade of P2 ATP receptors or downstream phospholipase C (PLC) and IP3R and removal of medium calcium all significantly reduced FAM3A-induced increase in cytosolic free Ca 21 levels and attenuated FAM3A-mediated PI3K/Akt activation. Moreover, FAM3A-induced Akt activation was completely abolished by the inhibition of calmodulin (CaM). Conclusion: FAM3A plays crucial roles in the regulation of glucose and lipid metabolism in the liver, where it activates the PI3K-Akt signaling pathway by way of a Ca 21 /CaM-dependent mechanism. Up-regulating hepatic FAM3A expression may represent an attractive means for the treatment of insulin resistance, type 2 diabetes, and nonalcoholic fatty liver disease (NAFLD). (HEPATOLOGY 2014;59:1779-1790 T ype 2 diabetes has become one of the most prevalent and debilitating chronic diseases, with a global prevalence 6.4%, affecting about 285 million adults in the year 2010.1 Hepatic insulin resistance and fatty liver play a crucial role in the development and progression of type 2 diabetes. Liver is the key tissue regulating release of glucose into circulation during the fasting state, and hepatic insulin resistance is a decisive factor causing fasting hyperglycemia and type 2 diabetes. The liver is also one of the major organs regulating triglyceride (TG) and cholesterol (CHO) metabolism.2 Hepatic insulin resistance is mainly described as the failure of insulin to repress the expression of gluconeogenic genes through the PI3K/ Akt signaling pathway and is closely associated with the dysregulation of glucose and lipid metabolism in the liver.2 Although the underlying mechanisms remain largely unknown, increasing evidence points to
Leucine, a the branched-chain amino acids that must be supplied in daily diet, plays an important role in controlling protein synthesis and regulating cell metabolism in various cell types. In pancreatic β cells, leucine acutely stimulates insulin secretion by serving as both metabolic fuel and allosteric activator of glutamate dehydrogenase to enhance glutaminolysis. Leucine has also been shown to regulate gene transcription and protein synthesis in pancreatic islet β cells via both mTOR-dependent and -independent pathways at physiological concentrations. Long-term treatment of leucine has been shown to improve insulin secretory dysfunction of human diabetic islets via upregulation of certain key metabolic genes. In vivo, leucine administration improves glycemic control in humans and rodents with type 2 diabetes. This review aims to summarize and discuss the recent findings regarding the effects of leucine metabolism on pancreatic β cell function.
Pancreatic-derived factor (PANDER) is a pancreatic islet-specific cytokine that cosecretes with insulin and is important for b cell function. Here, we show that PANDER is constitutively expressed in hepatocytes, and its expression is significantly increased in steatotic livers of diabetic insulin-resistant db/db mice and mice fed a high-fat diet. Overexpression of PANDER in the livers of C57Bl/6 mice promoted lipogenesis, with increased Forkhead box 1 (FOXO1) expression, whereas small interfering RNA-mediated knockdown of hepatic PANDER significantly attenuated steatosis, with reduced FOXO1 expression in db/ db mice. Hepatic PANDER silencing also attenuated insulin resistance and hyperglycemia in db/db mice. In cultured hepatocytes, PANDER overexpression induced lipid deposition, increased FOXO1 expression, and suppressed insulin-stimulated Akt activation and FOXO1 inactivation. Moreover, FOXO1 overexpression increased PANDER expression in cultured hepatocytes and mouse livers. Conclusion: PANDER promotes lipogenesis and compromises insulin signaling in the liver by increasing FOXO1 activity. PANDER may represent a potential therapeutic target for the treatment of fatty liver and insulin resistance. (HEPATOLOGY 2011;53:1906-1916
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