DNA damage-induced activation of CUL4B targets HUWE1 for proteasomal degradation

The E3 ubiquitin ligase HUWE1/Mule/ARF-BP1 plays an important role in integrating/coordinating diverse cellular processes such as DNA damage repair and apoptosis. A previous study has shown that HUWE1 is required for the early step of DNA damage-induced apoptosis, by targeting MCL-1 for proteasomal degradation. However, HUWE1 is subsequently inactivated, promoting cell survival and the subsequent DNA damage repair process. The mechanism underlying its regulation during this process remains largely undefined. Here, we show that the Cullin4B-RING E3 ligase (CRL4B) is required for proteasomal degradation of HUWE1 in response to DNA damage. CUL4B is activated in a NEDD8-dependent manner, and ubiquitinates HUWE1 in vitro and in vivo. The depletion of CUL4B stabilizes HUWE1, which in turn accelerates the degradation of MCL-1, leading to increased induction of apoptosis. Accordingly, cells deficient in CUL4B showed increased sensitivity to DNA damage reagents. More importantly, upon CUL4B depletion, these phenotypes can be rescued through simultaneous depletion of HUWE1, consistent with the role of CUL4B in regulating HUWE1. Collectively, these results identify CRL4B as an essential E3 ligase in targeting the proteasomal degradation of HUWE1 in response to DNA damage, and provide a potential strategy for cancer therapy by targeting HUWE1 and the CUL4B E3 ligase.     

Prevalence of Gestational Diabetes Mellitus and Its Risk Factors in Chinese Pregnant Women: A Prospective Population-Based Study in Tianjin,China

Objective

We compared the increases in the prevalence of gestational diabetes mellitus (GDM) based on the 1999 World Health Organization (WHO) criteria and its risk factors in Tianjin, China, over a 12-year period. We also examined the changes in the prevalence using the criteria of International Association of Diabetes and Pregnancy Study Group (IADPSG).

Methods

In 2010-2012, 18589 women who registered within 12 weeks of gestation underwent a glucose challenge test (GCT) at 24-28 gestational weeks. Amongst them, 2953 women with 1-hour plasma glucose ≥7.8 mmol/L underwent a 75-gram 2-hour oral glucose tolerance test (OGTT) and 781 women had a positive GCT but absented from the standard OGTT. An adjusted prevalence of GDM was calculated for the whole cohort of women by including an estimate of the proportion of women with positive GCTs who did not have OGTTs but would have been expected to have GDM. Logistic regression was used to obtain odds ratios and 95% confidence intervals using the IADPSG criteria. The prevalence of GDM risk factors was compared to the 1999 survey.

Results

The adjusted prevalence of GDM by the 1999 WHO criteria was 8.1%, a 3.5-fold increase as in 1999. Using the IADPSG criteria increased the adjusted prevalence further to 9.3%. Advanced age, higher pre-pregnancy body mass index, Han-nationality, higher systolic blood pressure (BP), a family history of diabetes, weight gain during pregnancy and habitual smoking were risk factors for GDM. Compared to the 1999 survey, the prevalence of overweight plus obesity had increased by 1.8 folds, age≥30 years by 2.3 folds, systolic BP by 2.3 mmHg over the 12-year period.

Conclusions

Increasing prevalence of overweight/obesity and older age at pregnancy were accompanied by increasing prevalence of GDM, further increased by change in diagnostic criteria.     

Morphology and morphogenesis of a new marine cyrtophorid ciliate, Hartmannula sinica nov. spec. (Protozoa, Ciliophora, Cyrtophorida) from China

The living morphology, infraciliature and morphogenesis of a new marine cyrtophorid ciliate, Hartmannula sinica nov. spec., collected from Qingdao, north China, have been investigated. The new species is characterized by: size in vivo 90–130×40–50 μm, body long elliptical in outline, cilium-free field covered with a conspicuous alveolar layer; 24–31 ventral kineties, the rightmost 6–9 of which extend apically; 20–24 nematodesmal rods; about 15 sparsely distributed contractile vacuoles; a yellowish pigment spot is always present near the anterior tip of the cell. Morphogenetic events exhibit a pattern, which is homologous with that of related cyrtophorids. The main features are as follows: (1) preoral and circumoral kineties of opisthe develop from the oral primordium that forms in mid-body from sections of 3 postoral kineties, while parental preoral and circumoral kineties are retained; (2) parental cytostome and nematodesmal rods are resorbed in middle divisional stages and then replaced by newly formed structures; (3) the heteromerous macronucleus unifies in the late divisional stage.     

In vitro induction of tetraploid in pomegranate (Punica granatum)

Tetraploid plants were obtained in pomegranate (Punica granatum L. var. `Nana') by colchicine treatment of shoots propagated in vitro. Shoots cultured on MS medium supplemented with 10 mg l^–1 colchicine, 1.0 mg l^–1 BA and 0.1 mg l^–1 NAA for 30 days produced tetraploids at a high frequency of 20%. No tetraploids were detected by treating the shoots in 5000 mg l^–1 colchicine for 114 h. Shoots treated by 5000 mg l^–1 colchicine for 96 h produced three morphological mutants with narrow leaves, which were later confirmed as mixoploids that separated into diploids and tetraploids after further subculture. In vitro tetraploid plants had shorter roots, wider and shorter leaves than the diploid ones. Tetraploid pomegranate plants grew and flowered normally in pots, but possessed flowers with increased diameter and decreased length compared to diploids. The number of pollen grains per anther was higher in tetraploids, but the viability of pollen decreased significantly.     

重组肾上腺髓质素表达载体的构建及在哺乳动物细胞中的表达

为探索通过体内表达肾上腺髓质素（adrenomedullin,AM）治疗高血压和慢性心衰的可能性,本实验构建了重组AM真核表达载体,并在无内源笥AM表达的K562细胞株上进行了体外表达实验。实验中采用RT－PCR技术扩增AM cDNA片段,并将扩增的cDNA片段插入pcDNA3.1真核表达质粒,构建成含AM cDNA的重组质料pcDNA3.1AM。用脂质体介导将该质粒转染培养的人白血病细腻K562株,在转染的细胞中,用RT－PCR检测证实有AM mRNA存在;用班点免疫分析方法检测转染细胞的培养液上清,证实有AM多肽存在,表明本实验中构建的重组pcDNA3.1AM载体能够在哺乳类细胞中表达AM。     

中药凌霄花的药理学考察

实验结果表明,凌霄花对离体猪冠状动脉条具有抑制收缩的作用;对大鼠血栓形成有抑制作用;能加快红细胞电泳,增加红细胞电泳率,使血液红细胞处于分散状态;对离体孕子宫能显著增强收缩活性,增加收缩频率及增强收缩强度。以上结果可初步说明,凌霄花行血去瘀的作用及其“孕妇慎用”的合理性。凌霄花的３种混淆品（白泡桐花,毛泡桐花,兰考泡桐花）的药理作用与凌霄花不同,故不能作凌霄花使用。