Sphingosine kinase 1 regulates HMGB1 translocation by directly interacting with calcium/calmodulin protein kinase II-δ in sepsis-associated liver injury

Previously, we confirmed that sphingosine kinase 1 (SphK1) inhibition improves sepsis-associated liver injury. High-mobility group box 1 (HMGB1) translocation participates in the development of acute liver failure. However, little information is available on the association between SphK1 and HMGB1 translocation during sepsis-associated liver injury. In the present study, we aimed to explore the effect of SphK1 inhibition on HMGB1 translocation and the underlying mechanism during sepsis-associated liver injury. Primary Kupffer cells and hepatocytes were isolated from SD rats. The rat model of sepsis-associated liver damage was induced by intraperitoneal injection with lipopolysaccharide (LPS). We confirmed that Kupffer cells were the cells primarily secreting HMGB1 in the liver after LPS stimulation. LPS-mediated HMGB1 expression, intracellular translocation, and acetylation were dramatically decreased by SphK1 inhibition. Nuclear histone deacetyltransferase 4 (HDAC4) translocation and E1A-associated protein p300 (p300) expression regulating the acetylation of HMGB1 were also suppressed by SphK1 inhibition. HDAC4 intracellular translocation has been reported to be controlled by the phosphorylation of HDAC4. The phosphorylation of HDAC4 is modulated by CaMKII-δ. However, these changes were completely blocked by SphK1 inhibition. Additionally, by performing coimmunoprecipitation and pull-down assays, we revealed that SphK1 can directly interact with CaMKII-δ. The colocalization of SphK1 and CaMKII-δ was verified in human liver tissues with sepsis-associated liver injury. In conclusion, SphK1 inhibition diminishes HMGB1 intracellular translocation in sepsis-associated liver injury. The mechanism is associated with the direct interaction of SphK1 and CaMKII-δ.Subject terms: Hepatotoxicity, Sepsis     

A cross-talk between epithelium and endothelium mediates human alveolar–capillary injury during SARS-CoV-2 infection

COVID-19, caused by SARS-CoV-2, is an acute and rapidly developing pandemic, which leads to a global health crisis. SARS-CoV-2 primarily attacks human alveoli and causes severe lung infection and damage. To better understand the molecular basis of this disease, we sought to characterize the responses of alveolar epithelium and its adjacent microvascular endothelium to viral infection under a co-culture system. SARS-CoV-2 infection caused massive virus replication and dramatic organelles remodeling in alveolar epithelial cells, alone. While, viral infection affected endothelial cells in an indirect manner, which was mediated by infected alveolar epithelium. Proteomics analysis and TEM examinations showed viral infection caused global proteomic modulations and marked ultrastructural changes in both epithelial cells and endothelial cells under the co-culture system. In particular, viral infection elicited global protein changes and structural reorganizations across many sub-cellular compartments in epithelial cells. Among the affected organelles, mitochondrion seems to be a primary target organelle. Besides, according to EM and proteomic results, we identified Daurisoline, a potent autophagy inhibitor, could inhibit virus replication effectively in host cells. Collectively, our study revealed an unrecognized cross-talk between epithelium and endothelium, which contributed to alveolar–capillary injury during SARS-CoV-2 infection. These new findings will expand our understanding of COVID-19 and may also be helpful for targeted drug development.Subject terms: Mechanisms of disease, Viral infection     

Molecular Dynamics Simulations of PIP2 and PIP3 in Lipid Bilayers: Determination of Ring Orientation, and the Effects of Surface Roughness on a Poisson-Boltzmann Description

Molecular dynamics (MD) simulations of phosphatidylinositol (4,5)-bisphosphate (PIP₂) and phosphatidylinositol (3,4,5)-trisphosphate (PIP₃) in 1-palmitoyl 2-oleoyl phosphatidylcholine (POPC) bilayers indicate that the inositol rings are tilted ∼40° with respect to the bilayer surface, as compared with 17° for the P-N vector of POPC. Multiple minima were obtained for the ring twist (analogous to roll for an airplane). The phosphates at position 1 of PIP₂ and PIP₃ are within an Ångström of the plane formed by the phosphates of POPC; lipids in the surrounding shell are depressed by 0.5-0.8 Å, but otherwise the phosphoinositides do not substantially perturb the bilayer. Finite size artifacts for ion distributions are apparent for systems of ∼26 waters/lipid, but, based on simulations with a fourfold increase of the aqueous phase, the phosphoinositide positions and orientations do not show significant size effects. Electrostatic potentials evaluated from Poisson-Boltzmann (PB) calculations show a strong dependence of potential height and ring orientation, with the maxima on the −25 mV surfaces (17.1 ± 0.1 Å for PIP₂ and 19.4 ± 0.3 Å for PIP₃) occurring near the most populated orientations from MD. These surfaces are well above the background height of 10 Å estimated for negatively charged cell membranes, as would be expected for lipids involved in cellular signaling. PB calculations on microscopically flat bilayers yield similar maxima as the MD-based (microscopically rough) systems, but show less fine structure and do not clearly indicate the most probable regions. Electrostatic free energies of interaction with pentalysine are also similar for the rough and flat systems. These results support the utility of a rigid/flat bilayer model for PB-based studies of PIP₂ and PIP₃ as long as the orientations are judiciously chosen.     

Chicken riboflavin-binding protein. cDNA sequence and homology with milk folate-binding protein

The Rd gene is expressed in the livers and oviducts of laying hens and codes for the riboflavin-binding protein (RfBP) of egg yolk and egg white. A lambda gt11 cDNA library derived from chicken oviduct poly(A)+ RNA was screened with polyclonal rabbit antiserum to chicken RfBP. Positive clones were isolated and rescreened with a mixed oligonucleotide probe corresponding to residues 20-25 of the mature protein. The largest cDNA clone (969 base pairs) was subcloned into plasmid pIBI21, and the nucleotide sequence was determined by the dideoxynucleotide method. This clone contained the entire coding region for RfBP. The published amino acid sequence of the mature protein was confirmed. In addition, the following 17-residue signal peptide was deduced: Met-Leu-Arg-Phe-Ala-Ile-Thr-Leu-Phe-Ala-Val-Ile-Thr-Ser-Ser-Thr-Cys. Unexpectedly, the nucleotide sequence codes for 2 adjacent arginine residues at the carboxyl terminus that are not observed in the mature protein. The amino acid sequence of RfBP is homologous with bovine milk folate-binding protein. Eight of the nine pairs of cysteines involved in disulfide bonds in RfBP are conserved in folate-binding protein, as are all of the tryptophan residues. Sequence identity between homologous regions of these two vitamin-binding proteins is more than 30%.     

四川省自然保护区时空分布与影响因素

自然保护区是为保护具有代表性的生态系统和濒危动植物而划分的特定区域,在涵养水土,防风固沙、净化空气、保护生物多样性等方面发挥着重要作用。四川省有自然保护区166处,类型丰富多样,是中国自然保护地体系的重要组成部分,其保护对象涵盖珍稀动植物,保护功能涉及物种、水源和生态环境,与国家地质公园、湿地公园、森林公园等共同维系着中国西南地区,乃至青藏高原东缘的生态系统。因此,研究四川省自然保护区的空间分布格局及其影响因素具有重要的价值和意义。运用地理空间分析方法对1963-2018年间四川省自然保护区的空间分布和影响因素进行了研究。研究发现:①四川省自然保护区空间分布的总体特征以集聚为主,呈现集聚-随机-集聚的变化特征,且前期变化幅度大,后期变化幅度小,总体发展明显分为1963-1998年的单核形成与发展阶段和1998-2018年的双核阶段;②四川省自然保护区主要分布在成都平原向川西高原的过渡区域,其均衡度类型在时间上表现出由"差距悬殊"到"差距较大"的演变特征;③四川省自然保护区的重心活动范围相对较小,基本稳定在阿坝州南部。标准差椭圆的长短半轴和面积均变化强烈,总体呈现出大幅度的增长,空间分布由南-北向演变为东北-西南向;④自然保护区受到自然因素和社会因素的双重影响,高密度区域分布在地势适中、气候温和、河流众多、土壤肥沃、人口稀少的阿坝州南部与东部地区。未来,四川省生态功能建设应该立足国家公园、自然保护区和自然公园的特点、分布状况,对自然保护区分布较少的川西北、川东北和川南部分地区进行优化布局,以加强这些地区的生态功能建设。同时,探索自然保护区的发展模式,实现自然保护区与周边区域社会经济的协调发展。     

Spatial analysis of hepatocellular carcinoma and socioeconomic status in China from a Population-based Cancer Registry

Background: Little is known about geographic variations in liver cancer at high incident regions. We aimed to identify spatial variation of hepatocellular carcinoma (HCC) at a high-risk area in China and determine its association with socioeconomic status (SES). Methods: Based on 2299 liver cancer cases diagnosed in Haimen from 2003 to 2006, we calculated age–sex standardized incidence ratios (SIRs) and used two spatial scan statistics to determine the geographic variations in HCC. Bayesian hierarchical model was used to explore the association between HCC incidence and SES. Results: Age and sex SIRs for HCC varied from 0.54 to 1.97 for 24 townships. The eastern region of Haimen was identified to have a significantly increased risk of HCC. Fitting of a Bayesian hierarchical model linking per-capita fiscal revenue with SIRs of HCC indicated that the area with a lower revenue had a significantly higher incidence of HCC [β_log(revenue) = ?0.179, posterior 95% Bayesian credible interval (CI) = (?0.326, ?0.04)]. Conclusions: This study demonstrated substantial geographic variation in the incidence of HCC within a high-risk region, which was associated with SES. HCC control and intervention should focus on disadvantaged areas to reduce the HCC disparities.