Dichotomous role of pancreatic HUWE1/MULE/ARF-BP1 in modulating beta cell apoptosis in mice under physiological and genotoxic conditions

Aims/hypothesis

Diabetes mellitus represents a significant burden on the health of the global population. Both type 1 and type 2 diabetes share a common feature of a reduction in functional beta cell mass. A newly discovered ubiquitination molecule HECT, UBA and WWE domain containing 1, E3 ubiquitin protein ligase (HUWE1 [also known as MULE or ARF-BP1]) is a critical regulator of p53-dependent apoptosis. However, its role in islet homeostasis is not entirely clear.

Methods

We generated mice with pancreas-specific deletion of Huwe1 using a Cre-loxP recombination system driven by the Pdx1 promoter (Pdx1cre ⁺ Huwe1 ^fl/fl) to assess the in vivo role of HUWE1 in the pancreas.

Results

Targeted deletion of Huwe1 in the pancreas preferentially activated p53-mediated beta cell apoptosis, leading to reduced beta cell mass and diminished insulin exocytosis. These defects were aggravated by ageing, with progressive further decline in insulin secretion and glucose homeostasis in older mice. Intriguingly, Huwe1 deletion provided protection against genotoxicity, such that Pdx1cre ⁺ Huwe1 ^fl/fl mice were resistant to multiple-low-dose-streptozotocin-induced beta cell apoptosis and diabetes.

Conclusion/interpretation

HUWE1 expression in the pancreas is essential in determining beta cell mass. Furthermore, HUWE1 demonstrated divergent roles in regulating beta cell apoptosis depending on physiological or genotoxic conditions.     

Cyclodextrin Reduces Intravenous Toxicity of a Model Compound

Solubilization of new chemical entities for toxicity assessment must use excipients that do not negatively impact drug pharmacokinetics and toxicology. In this study, we investigated the tolerability of a model freebase compound, GDC-0152, solubilized by pH adjustment with succinic acid and complexation with hydroxypropyl-β-cyclodextrin (HP-β-CD) to enable intravenous use. Solubility, critical micelle concentration, and association constant with HP-β-CD were determined. Blood compatibility and potential for hemolysis were assessed in vitro. Local tolerability was assessed after intravenous and subcutaneous injections in rats. A pharmacokinetic study was conducted in rats after intravenous bolus administration.GDC-0152 exhibited pH-dependent solubility that was influenced by self-association. The presence of succinic acid increased solubility in a concentration-dependent manner. HP-β-CD alone also increased solubility, but the extent of solubility enhancement was significantly lower than succinic acid alone. Inclusion of HP-β-CD in the solution of GDC-0152 improved blood compatibility, reduced hemolytic potential by ～20-fold in vitro, and increased the maximum tolerated dose to 80 mg/kg.     

国家药品标准物质保障供应综合数据平台建设

目的：进一步提高国家药品标准物质供应保障的能力和水平,更好支撑药品监管需求和服务行业发展。方法：将信息化管理和分析方法与现有的标准物质管理技术要求相结合,研究建立数字化、可视化的数据共享系统。结果：建成的国家药品标准物质保障供应综合数据平台,可显示各品种的研制生产阶段和效率。结论：该平台试运行一年来已成为指导研制、生产和管理的有力抓手,为对接国际标准ISO 17034奠定了重要基础。     

塑料薄膜氧气透过量测定能力验证研究

目的：组织实施塑料薄膜氧气透过量测定能力验证项目,评价检验机构对氧气透过量的检测能力。方法：制备单一水平样品,采用单因素方差分析对样品均匀性进行检验。对能力验证结果进行统计分析,以z比分数评价实验室检测能力。结果：样品均匀性符合要求,满足能力验证计划要求。38家实验室参加塑料薄膜氧气透过量能力验证项目,满意数为34家,满意率为89.5%。结论：多数实验室检测结果满意,部分实验室检测能力有待提高。     

磷酸左奥硝唑酯二钠细菌内毒素检测方法验证

目的：建立磷酸左奥硝唑酯二钠细菌内毒素的常规检测方法。方法：按《中华人民共和国药典》2015年版通则1143细菌内毒素检查法进行。结果：在验证条件下,样品原液稀释至6.25 mg·mL^-1时,对细菌内毒素检查法无干扰作用。结论：建立的方法用于检查磷酸左奥硝唑酯二钠的细菌内毒素可行。     

多法测量塑料薄膜水蒸气透过量的一致性研究

目的：评价杯式法、电解法和红外法3种方法测量塑料薄膜水蒸气透过量的数据一致性。方法：采用厚度均匀的塑料薄膜,经杯式法、电解法和红外法3种方法测量其水蒸气透过量,等效检验评价测定结果的一致性。结果：杯式法、电解法和红外法测量塑料薄膜的水蒸气透过量分别为7.03、7.02和6.99 g/（m²·day）。结论：3种方法的测量结果等效。这为多种方法测量塑料薄膜水蒸气透过量的实验室数据对比提供了一定的数据基础。     

Polymorphism analysis of Glutathione S-transferase A1 in patients with hematological diseases and its effect on GST enzyme activity

Glutathione S-transferases (GSTs) are important drug-metabolizing enzymes that catalyze the binding of glutathione (GSH) to electrophilic substances. GST has genetic polymorphism, and the enzyme activity of GST affects the metabolism of certain drugs in vivo. In the present day, we investigated the GST enzyme activity and GSTA1 gene polymorphism in 170 patients with hematological diseases and explored their relationship. The GSTA1 gene polymorphism of the patient was analyzed by PCR- restriction fragment length polymorphism (PCR-RFLP) technique, and the base sequences of the four mutation sites (-631, -567, -69, and -52) in the promoter region were determined by DNA-Sequencer. The patient's GST enzyme activity was calculated by measuring the rate at which it catalyzed the reaction between 1-chloro-2,4-dinitrobenzene (CDNB) and GSH. The average GST enzyme activities of males and females were 5.20±0.13 and 5.17±0.12 nmol/min/mL, respectively, and the difference was not significant (P = 0.91). The frequencies of genotypes GSTA1*A*A (wild genotype), GSTA1*A*B (heterozygous genotype), and GSTA1*B*B (homozygous mutant genotype) were 75.3%, 22.9%, and 1.8%, respectively. Alleles GSTA1*A and *B were distributed at 86.8% and 13.2%, respectively. The genotype frequency distribution between males and females was no significant difference by Pearson’s chi-square test (P = 0.743). The average GST activity of the heterozygous mutant genotype (4.83±0.76 nmol/min/mL) was lower than the wild genotype (5.34±1.26 nmol/min/mL, P = 0.018), and higher than that of the homozygous mutant genotype (3.32±0.07 nmol/min/mL, P = 0.022). These findings might help us improve the individualized treatment of patients with hematological diseases in the future and promote the development of precision medicine for blood diseases.