A circular intronic RNA ciPVT1 delays endothelial cell senescence by regulating the miR‐24‐3p/CDK4/pRb axis

Circular RNAs (circRNAs) have been established to be involved in numerous processes in the human genome, but their function in vascular aging remains largely unknown. In this study, we aimed to characterize and analyze the function of a circular intronic RNA, ciPVT1, in endothelial cell senescence. We observed significant downregulation of ciPVT1 in senescent endothelial cells. In proliferating endothelial cells, ciPVT1 knockdown induced a premature senescence‐like phenotype, inhibited proliferation, and led to an impairment in angiogenesis. An in vivo angiogenic plug assay revealed that ciPVT1 silencing significantly inhibited endothelial tube formation and decreased hemoglobin content. Conversely, overexpression of ciPVT1 in old endothelial cells delayed senescence, promoted proliferation, and increased angiogenic activity. Mechanistic studies revealed that ciPVT1 can sponge miR‐24‐3p to upregulate the expression of CDK4, resulting in enhanced Rb phosphorylation. Moreover, enforced expression of ciPVT1 reversed the senescence induction effect of miR‐24‐3p in endothelial cells. In summary, the present study reveals a pivotal role for ciPVT1 in regulating endothelial cell senescence and may have important implications in the search of strategies to counteract the development of age‐associated vascular pathologies.     

LPS/Bcl3/YAP1 signaling promotes Sox9+HNF4α+ hepatocyte-mediated liver regeneration after hepatectomy

Recent reports have demonstrated that Sox9⁺HNF4α⁺ hepatocytes are involved in liver regeneration after chronic liver injury; however, little is known about the origin of Sox9⁺HNF4α⁺ hepatocytes and the regulatory mechanism. Employing a combination of chimeric lineage tracing, immunofluorescence, and immunohistochemistry, we demonstrate that Sox9⁺HNF4α⁺ hepatocytes, generated by transition from mature hepatocytes, play an important role in the initial phase after partial hepatectomy (PHx). Additionally, knocking down the expression of Sox9 suppresses hepatocyte proliferation and blocks the recovery of lost hepatic tissue. In vitro and in vivo assays demonstrated that Bcl3, activated by LPS, promotes hepatocyte conversion and liver regeneration. Mechanistically, Bcl3 forms a complex with and deubiquitinates YAP1 and further induces YAP1 to translocate into the nucleus, resulting in Sox9 upregulation and mature hepatocyte conversion. We demonstrate that Bcl3 promotes Sox9⁺HNF4α⁺ hepatocytes to participate in liver regeneration, and might therefore be a potential target for enhancing regeneration after liver injury.Subject terms: Ubiquitylation, Transdifferentiation, NF-kappaB, Regeneration, Stem-cell research     

SLC25A38 as a novel biomarker for metastasis and clinical outcome in uveal melanoma

Risk of metastasis is increased by the presence of chromosome 3 monosomy in uveal melanoma (UM). This study aimed to identify more accurate biomarker for risk of metastasis in UM. A total of 80 patients with UM from TCGA were assigned to two groups based on the metastatic status, and bioinformatic analyses were performed to search for critical genes for risk of metastasis. SLC25A38, located on chromosome 3, was the dominant downregulated gene in metastatic UM patients. Low expression of SLC25A38 was an independent predictive and prognostic factor in UM. The predictive potential of SLC25A38 expression was superior to that of pervious reported biomarkers in both TCGA cohort and {"type":"entrez-geo","attrs":{"text":"GSE22138","term_id":"22138"}}GSE22138 cohort. Subsequently, its role in promoting metastasis was explored in vitro and in vivo. Knock-out of SLC25A38 could enhance the migration ability of UM cells, and promote distant metastasis in mice models. Through the inhibition of CBP/HIF-mediated pathway followed by the suppression of pro-angiogenic factors, SLC25A38 was situated upstream of metastasis-related pathways, especially angiogenesis. Low expression of SLC25A38 promotes angiogenesis and metastasis, and identifies increased metastatic risk and worse survival in UM patients. This finding may further improve the accuracy of prognostic prediction for UM.Subject terms: Eye cancer, Prognostic markers     

CRL4-DCAF8L1 Regulates BRCA1 and BARD1 Protein Stability

BRCA1 is frequently down-regulated in breast cancer, the underlying mechanism is unclear. Here we identified DCAF8L1, an X-linked gene product, as a DDB1-Cullin associated Factor (DCAF) for CUL4 E3 ligases to target BRCA1 and BARD1 for proteasomal degradation. Forced expression of DCAF8L1 caused reduction of BRCA1 and BARD1, and impaired DNA damage repair function, conferring increased sensitivity to irradiation and DNA damaging agents, as well as Olaparib, a PARPi anticancer drug; while depletion of DCAF8L1 restored BRCA1 and suppressed the growth of its xenograft tumors. Furthermore, the expression of DCAF8L1 was induced in human H9 ES cells during transition from primed to naïve state when Xi chromosome was reactivated. Aberrant expression of DCAF8L1 was observed in human breast fibroadenoma and breast cancer. These findings suggest that CRL4^DCAF8L1 is an important E3 ligase that may participate in the development of breast cancer, probably through regulating the stability of BRCA1 and BARD1 tumor suppressor, linking BRCA1 and X chromosome inactivation to breast carcinogenesis.     

Extracellular Matrix Lumican Promotes Bacterial Phagocytosis,and Lum?/? Mice Show Increased Pseudomonas aeruginosa Lung Infection Severity

Phagocytosis is central to bacterial clearance, but the exact mechanism is incompletely understood. Here, we show a novel and critical role for lumican, the connective tissue extracellular matrix small leucine-rich repeat proteoglycan, in CD14-mediated bacterial phagocytosis. In Psuedomonas aeruginosa lung infections, lumican-deficient (Lum^−/−) mice failed to clear the bacterium from lungs, tissues, and showed a dramatic increase in mortality. In vitro, phagocytosis of nonopsonized Gram-negative Escherichia coli and P. aeruginosa was inhibited in Lum^−/− peritoneal macrophages (MΦs). Lumican co-localized with CD14, CD18, and bacteria on Lum^+/+ MΦ surfaces. Using two different P. aeruginosa strains that require host CD14 (808) or CD18/CR3 (P1) for phagocytosis, we showed that lumican has a larger role in CD14-mediated phagocytosis. Recombinant lumican (rLum) restored phagocytosis in Lum^−/− MΦs. Surface plasmon resonance showed specific binding of rLum to CD14 (K_A = 2.15 × 10⁶ m⁻¹), whereas rLumY20A, and not rLumY21A, where a tyrosine in each was replaced with an alanine, showed 60-fold decreased binding. The rLumY20A variant also failed to restore phagocytosis in Lum^−/− MΦs, indicating Tyr-20 to be functionally important. Thus, in addition to a structural role in connective tissues, lumican has a major protective role in Gram-negative bacterial infections, a novel function for small leucine-rich repeat proteoglycans.     

Molecular phylogeny of 48 species of damselfishes (Perciformes: Pomacentridae) using 12S mtDNA sequences

Phylogenetic relastionships within the family pomacentridae teleostei: Perciformes) were inferred by analyzing a portion of the 12S mitochondrial ribosomal DNA gene. Thirty-four pomacentrid species were sequenced for this study and the resulting data were combined with previously published pomacentrid sequence data to form a combined matrix of 53 pomacentrids representing 48 different species in 18 genera. Four outgroup species were also drawn from published data; these taxa were taken from the other three putative families of the suborder Labroidei, as well as a single representative of the family Moronidae. The data set contained 1053 data columns after alignment according to ribosomal secondary structure and the removal of all ambiguously aligned positions. The resulting strict consensus tree topology generally agreed with the previous molecular hypothesis, and recovers a monophyletic Pomacentridae and subfamily Amphiprioninae. The two other subfamilies included, Chrominae and Pomacentrinae, were found to be polyphyletic. A monophyletic group consisting of the Amphiprioninae, Pomacentrus, Acanthochromis, Amblyglyphidodon, Neoglyphidodon, Chrysiptera, Neopomacentrus, and Teixeirichthys was found. This group was recovered as the sister group to a clade consisting of a paraphyletic Chromis and a monophyletic Dascyllus. A sister-group relationship between the genus Pomacentrus and the subfamily Amphiprioninae was observed.     

High Resolution Human Leukocyte Antigen Class I Allele Frequencies and HIV-1 Infection Associations in Chinese Han and Uyghur Cohorts

Background

Host immunogenetic factors such as HLA class I polymorphism are important to HIV-1 infection risk and AIDS progression. Previous studies using high-resolution HLA class I profile data of Chinese populations appeared insufficient to provide information for HIV-1 vaccine development and clinical trial design. Here we reported HLA class I association with HIV-1 susceptibility in a Chinese Han and a Chinese Uyghur cohort.

Methodology/Principal Findings

Our cohort included 327 Han and 161 Uyghur ethnic individuals. Each cohort included HIV-1 seropositive and HIV-1 seronegative subjects. Four-digit HLA class I typing was performed by sequencing-based typing and high-resolution PCR-sequence specific primer. We compared the HLA class I allele and inferred haplotype frequencies between HIV-1 seropositive and seronegative groups. A neighbor-joining tree between our cohorts and other populations was constructed based on allele frequencies of HLA-A and HLA-B loci. We identified 58 HLA-A, 75 HLA-B, and 32 HLA-Cw distinct alleles from our cohort and no novel alleles. The frequency of HLA-B*5201 and A*0301 was significantly higher in the Han HIV-1 negative group. The frequency of HLA-B*5101 was significantly higher in the Uyghur HIV-1 negative group. We observed statistically significant increases in expectation-maximization (EM) algorithm predicted haplotype frequencies of HLA-A*0201-B*5101 in the Uyghur HIV-1 negative group, and of Cw*0304-B*4001 in the Han HIV-1 negative group. The B62s supertype frequency was found to be significantly higher in the Han HIV-1 negative group than in the Han HIV-1 positive group.

Conclusions

At the four-digit level, several HLA class I alleles and haplotypes were associated with lower HIV-1 susceptibility. Homogeneity of HLA class I and Bw4/Bw6 heterozygosity were not associated with HIV-1 susceptibility in our cohort. These observations contribute to the Chinese HLA database and could prove useful in the development of HIV-1 vaccine candidates.     

重组大肠杆菌热稳定性过氧化氢酶的纯化及性质研究

将产热稳定性过氧化氢酶的重组大肠杆菌培养后菌体破碎得到的粗酶液经热处理、硫酸铵分级沉淀、DEAE\|Sephadex A\|50离子交换层析、HiPrep16/10 Phenyl疏水作用层析、Superdex200 HR 10/30凝胶层析提纯后得到电泳纯的酶,比酶活达到15629U/mg。此酶的最适温度为70℃,最适pH70,在60℃保温60min酶活力基本不变,在pH3～8的范围内比较稳定。此酶的Km和Vmax分别为775mmol/L和278mmol\5min\+\{-1\}·mg-1。1mmol/L的Zn2+、Ba2+、Mn2+可使该酶完全失活,KCN、NaN\-3、Na\-2S\-2O\-4、巯基乙醇对酶活力有抑制作用,50mmol/L的EDTA不影响酶活性。     

蝎毒耐热蛋白对大鼠急性分离海马神经元兴奋性的影响

应用全细胞膜片钳记录技术在电流钳模式下观察经持续高温等特殊处理后分离纯化的30～50 kDa蝎毒耐热蛋白(scorpion venom heat resistant protein,SVHRP)(国家发明专利,专利号ZL01 106166.92)对急性分离大鼠海马神经元兴奋性的影响.结果发现SVHRP可致海马神经元兴奋性降低.神经元经1×10-2 μg/mL SVHRP处理后动作电位发放模式改变,发放频率减少.在52个受检细胞中,有45个细胞产生位相放电(占86.54%);7个细胞产生重复放电(占13.46%).在产生位相放电的45个细胞中,有8个细胞在SVHRP处理后仍可以诱发出位相放电(占17.78%);37个细胞在SVHRP处理后无法诱导出位相放电(占82.22%),SVHRP处理后动作电位的产生与处理前相比,有显著差异(P＜0.01,n=45);在产生重复放电的7个细胞中,在1×10-2μg/mL SVHRP作用后均不能再次诱发出重复放电,而是产生一个动作电位或不再产生动作电位,药物处理前产生的动作电位个数为14.57±1.00,SVHRP处理后产生动作电位的个数为0.57±0.20,二者之间有显著性差异(P＜0.01,n=7).1×10-4 μg/mLSVHRP处理后,诱发动作电位产生的基强度由(75.10±8.99)pA增加到(119.85±12.73)pA(P＜0.01,n=8);阈电位由(-41.17±2.15)mV升至(-32.40±1.48)mV(P＜0.01,n=8);动作电位峰值由(68.49±2.33)mV下降至(54.71±0.81)mV(P＜0.01,n=8).由于神经元超兴奋性被认为是癫痫发作的基本机制之一,因此上述结果表明SVHRP有可能通过降低海马神经元兴奋性发挥其抗癫痫作用,这为蝎毒药物的进一步开发提供理论依据.