Maternal serum-derived exosomal lactoferrin as a marker in detecting and predicting ventricular septal defect in fetuses

Among different types of congenital heart diseases, ventricular septal defect is the most frequently diagnosed type and is frequently missed in early prenatal screening programs. Herein, we explored the role of maternal serum-derived exosomes in detecting and predicting ventricular septal defect in fetuses in the early stage of pregnancy. A total of 104 pregnant women consisting of 52 ventricular septal defect cases and 52 healthy controls were recruited. TMT/iTRAQ proteomic analysis uncovered 15 maternal serum exosomal proteins, which showed differential expression between ventricular septal defect and control groups. Among these, four down-regulated proteins, lactoferrin, SBSN, DCD, and MBD3, were validated by Western blot. The protein lactoferrin was additionally verified by ELISA which was able to distinguish ventricular septal defects from controls with area under the ROC curve (AUC) 0.804 (p < 0.001). Our findings reveal that lactoferrin in maternal serum-derived exosomes may be a potential biomarker for non-invasive prenatal diagnosis of fetal ventricular septal defects.     

Mechanical unfolding of a β-barrel membrane protein by single-molecule force spectroscopy

正Dear Editor.Transmembrane proteins withβ-barrel topology are mainly found in the outer membranes (OMs) of Gram-negative bacteria,mitochondria and chloroplasts (Wimley,2003).These proteins usually contain even numbers ofβ-strands,ranging from 8-36.To achieve an overall cylindrical topology,the polypeptide chain of aβ-barrel OMP must fold to form a series of anti-parallelβ-strands with eachβ-strand hydrogen-bonding to its neighboring strands (Otzen and Andersen,2013).The folding and insertion of aβ-barrel OMP in vivo requires an evolutionarily conserved multiprotein complex termedβ-barrel assembly machinery(BAM) complex (Noinaj et al.,2015).The structures of the     

MiR-323a regulates ErbB3/EGFR and blocks gefitinib resistance acquisition in colorectal cancer

The rapid onset of resistance to epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) limits its clinical utility in colorectal cancer (CRC) patients, and pan-erb-b2 receptor tyrosine kinase (ErbB) treatment strategy may be the alternative solution. The aim of this study was to develop a possible microRNA multi-ErbB treatment strategy to overcome EGFR-TKI resistance. We detect the receptor tyrosine kinase activity in gefitinib-resistant colorectal cancer cells, ErbB3/EGFR is significantly activated and provides a potential multi-ErbB treatment target. MiR-323a-3p, a tumor suppressor, could target both ErbB3 and EGFR directly. Apoptosis is the miR-323a-3p inducing main biological process by functional enrichment analysis, and The EGFR and ErbB signaling are the miR-323a-3p inducing main pathway by KEGG analysis. MiR-323a-3p promotes CRC cells apoptosis by targeting ErbB3-phosphoinositide 3‐kinases (PI3K)/PKB protein kinase (Akt)/glycogen synthase kinase 3 beta (GSK3β)/EGFR-extracellular regulated MAP kinase (Erk1/2) signaling directly. And miR-323a-3p, as a multi-ErbBs inhibitor, increase gefitinib sensitivity of the primary cell culture from combination miR-323a-3p and gefitinib treated subcutaneous tumors. MiR-323a-3p reverses ErbB3/EGFR signaling activation in gefitinib-resistant CRC cell lines and blocks acquired gefitinib resistance.Subject terms: Colorectal cancer, Cancer therapeutic resistance     

EGFR/MET promotes hepatocellular carcinoma metastasis by stabilizing tumor cells and resisting to RTKs inhibitors in circulating tumor microemboli

The receptor tyrosine kinases (RTKs) family is well-recognized as vital targets for the treatment of hepatocarcinoma cancer (HCC) clinically, whereas the survival benefit of target therapy sorafenib is not satisfactory for liver cancer patients due to metastasis. EGFR and MET are two molecules of the RTK family that were related to the survival time of liver cancer patients and resistance to targeted therapy in clinical reports. However, the mechanism and clinical therapeutic value of EGFR/MET in HCC metastasis are still not completely clarified. The study confirmed that EGFR/MET was highly expressed in HCC cells and tissues and the phosphorylation was stable after metastasis. The expression of EGFR/MET was up-regulated in circulating tumor microemboli (CTM) to accelerate IL-8 production and resistance to the lethal effect of leukocytes. Meanwhile, highly expressed EGFR/MET effectively regulated the Ras/MAPK pathway and stabilized suspended HCC cells by facilitating proliferation and inhibiting apoptosis. Moreover, EGFR/MET promoted phosphorylation of hetero-RTKs, which was dependent on high-energy phosphoric acid compounds rather than their direct interactions. In conclusion, highly expressed EGFR/MET could be used in CTM identification and suitable for preventing metastasis of HCC in clinical practice.Subject terms: Liver cancer, Metastasis     

Peroxisome-generated succinate induces lipid accumulation and oxidative stress in the kidneys of diabetic mice

Diabetes normally causes lipid accumulation and oxidative stress in the kidneys, which plays a critical role in the onset of diabetic nephropathy; however, the mechanism by which dysregulated fatty acid metabolism increases lipid and reactive oxygen species (ROS) formation in the diabetic kidney is not clear. As succinate is remarkably increased in the diabetic kidney, and accumulation of succinate suppresses mitochondrial fatty acid oxidation and increases ROS formation, we hypothesized that succinate might play a role in inducing lipid and ROS accumulation in the diabetic kidney. Here we demonstrate a novel mechanism by which diabetes induces lipid and ROS accumulation in the kidney of diabetic animals. We show that enhanced oxidation of dicarboxylic acids by peroxisomes leads to lipid and ROS accumulation in the kidney of diabetic mice via the metabolite succinate. Furthermore, specific suppression of peroxisomal β-oxidation improved diabetes-induced nephropathy by reducing succinate generation and attenuating lipid and ROS accumulation in the kidneys of the diabetic mice. We suggest that peroxisome-generated succinate acts as a pathological molecule inducing lipid and ROS accumulation in kidney, and that specifically targeting peroxisomal β-oxidation might be an effective strategy in treating diabetic nephropathy and related metabolic disorders.     

同域分布的黑麂和小麂的时空生态位分化

生态位分化是解释物种共存的重要理论。Schonenr认为空间维度对生态位差异形成的影响程度最高,营养维度次之,时间维度则最后被启动。为验证这一假说,我们于2018年12月至2019年11月,在浙江清凉峰国家级自然保护区龙塘山区域采用公里网格法布设52台红外相机,对同域分布且食性相似的黑麂和小麂种群进行监测,计算平均拍摄率,分析不同季节黑麂和小麂对不同植被类型、海拔、坡位、水源距离的选择差异,并运用核密度估计法分析二者日活动节律及重叠程度。结果显示,(1)黑麂和小麂对空间生态位的选择出现分化：黑麂偏好针阔混交林,主要栖息于1 301～1 500 m的高海拔地区,回避下坡位和谷地,在距离水源较近的区域内活动频繁;小麂则偏好落叶阔叶林,主要栖息于901～1 100 m的中海拔地区,偏好中坡位,回避谷地,对水源距离没有明显的选择倾向。(2)黑麂和小麂均为晨昏性活动的昼行性动物,二者全年日活动节律重叠程度较高(Δ4=0.86),仅冬季较低(Δ1=0.65)。上述结果支持Schonenr的假说：首先,空间维度对物种生态位分化的影响大于时间维度,龙塘山区域黑麂和小麂主要通过选择不同的栖息地来增加空间...     

Amino acid starvation‐induced LDLR trafficking accelerates lipoprotein endocytosis and LDL clearance

Mammalian cells utilize Akt‐dependent signaling to deploy intracellular Glut4 toward cell surface to facilitate glucose uptake. Low‐density lipoprotein receptor (LDLR) is the cargo receptor mediating endocytosis of apolipoprotein B‐containing lipoproteins. However, signaling‐controlled regulation of intracellular LDLR trafficking remains elusive. Here, we describe a unique amino acid stress response, which directs the deployment of intracellular LDLRs, causing enhanced LDL endocytosis, likely via Ca²⁺ and calcium/calmodulin‐dependent protein kinase II‐mediated signalings. This response is independent of induction of autophagy. Amino acid stress‐induced increase in LDL uptake in vitro is comparable to that by pravastatin. In vivo, acute AAS challenge for up to 72 h enhanced the rate of hepatic LDL uptake without changing the total expression level of LDLR. Reducing dietary amino acids by 50% for 2 to 4 weeks ameliorated high fat diet‐induced hypercholesterolemia in heterozygous LDLR‐deficient mice, with reductions in both LDL and VLDL fractions. We suggest that identification of signaling‐controlled regulation of intracellular LDLR trafficking has advanced our understanding of the LDLR biology, and may benefit future development of additional therapeutic strategies for treating hypercholesterolemia.     

Camptothecin effectively treats obesity in mice through GDF15 induction

Elevated circulating levels of growth differentiation factor 15 (GDF15) have been shown to reduce food intake and lower body weight through activation of hindbrain receptor glial-derived neurotrophic factor (GDNF) receptor alpha-like (GFRAL) in rodents and nonhuman primates, thus endogenous induction of this peptide holds promise for obesity treatment. Here, through in silico drug-screening methods, we found that small molecule Camptothecin (CPT), a previously identified drug with potential antitumor activity, is a GDF15 inducer. Oral CPT administration increases circulating GDF15 levels in diet-induced obese (DIO) mice and genetic ob/ob mice, with elevated Gdf15 expression predominantly in the liver through activation of integrated stress response. In line with GDF15’s anorectic effect, CPT suppresses food intake, thereby reducing body weight, blood glucose, and hepatic fat content in obese mice. Conversely, CPT loses these beneficial effects when Gdf15 is inhibited by a neutralizing antibody or AAV8-mediated liver-specific knockdown. Similarly, CPT failed to reduce food intake and body weight in GDF15’s specific receptor GFRAL-deficient mice despite high levels of GDF15. Together, these results indicate that CPT is a promising anti-obesity agent through activation of GDF15-GFRAL pathway.

Elevated circulating levels of growth differentiation factor 15 (GDF15) have been shown to reduce food intake and lower body weight in rodents and nonhuman primates. This study reveals that the small molecule Camptothecin induces endogenous GDF15, suppressing food intake and reducing body weight in obese mice, suggesting a promising candidate for anti-obesity treatment.