A diet-induced type 2 diabetes model in Drosophila

We showed in this present study that HSD feeding could induce type 2 diabetes-like phenotype in fruit flies, resembling the key disease features including hyperglycemia, glucosuria, increased hunger and thirsty, unexplained weight loss, and reduced female fecundity. We also showed that HSD-fed flies shared similar molecular mechanisms underlying type 2 diabetes patients, including both insulin deficiency and insulin resistance. Last but not least, disrupting insulin signaling in fruit flies could mimic the effect of HSD feeding to induce type 2 diabetes-like phenotype, further confirming that these phenotypes were a result of compromised insulin signaling upon HSD feeding. Taken together, we demonstrated that this diet-induced type 2 diabetes model in fruit flies rightly and comprehensively recapitulated the physiological, metabolic, behavioral, and molecular features of human type 2 diabetes, offering a valid and accessible model to study the underlying mechanism of this disease and to validate potential diagnostics and therapeutic tools. Given the highly conserved regulatory framework of physiology and metabolism between flies and human, our work has paved a way to generate novel insights into type 2 diabetes, a common, severe, and yet poorly understood disease in human. Total RNA from fly brains or fat body was extracted from 5-day-old female flies using the RNeasy Mini kit (Qiagen, Germany), subjected to poly(A) mRNA isolation, cDNA synthesization, library preparation (NEBNext Ultra RNA Library Prep Kit, NEB), and sequencing (Illumina Hiseq X Ten). Sequence data were subsequently mapped to Drosophila genome and uniquely mapped reads were collected for further analysis. Gene expression was calculated by the RPKM (Reads Per Kilobase of exon per Million reads mapped). The genes with p-value less 0.05 and fold change more than 1 were considered as the differentially expressed gene.本研究证实，高糖饮食（High-Sugar Diet，HSD）喂养可在果蝇（fruit flies）中诱导出2型糖尿病样表型，该表型具备人类2型糖尿病的关键疾病特征，包括高血糖、糖尿、多食多饮、不明原因体重减轻以及雌性生育力下降。本研究同时发现，高糖饮食喂养的果蝇与2型糖尿病患者共享相似的分子发病机制，涵盖胰岛素缺乏与胰岛素抵抗两种类型。尤为重要的是，在果蝇中阻断胰岛素信号通路可模拟高糖饮食喂养的效应，诱导产生2型糖尿病样表型，进一步证实上述表型是高糖饮食喂养后胰岛素信号通路受损的直接结果。综上，本研究表明，这种果蝇饮食诱导2型糖尿病模型能够准确且全面地复现人类2型糖尿病的生理、代谢、行为与分子特征，可为该疾病的发病机制研究以及潜在诊断与治疗工具的验证提供一个可靠且易获取的实验模型。鉴于果蝇与人类在生理与代谢调控通路方面具有高度保守性，本研究为深入理解人类2型糖尿病（一种常见、严重却尚未被充分认知的疾病）提供了全新的研究视角。本研究从5日龄雌性果蝇的脑组织或脂肪体中提取总RNA，所用试剂为RNeasy Mini试剂盒（Qiagen，德国），随后依次进行poly(A) mRNA富集、cDNA合成、文库构建（NEBNext Ultra RNA文库制备试剂盒，NEB）以及测序（Illumina Hiseq X Ten）。测序所得序列数据随后比对至果蝇基因组（Drosophila genome），收集唯一比对reads用于后续分析。基因表达量通过RPKM（Reads Per Kilobase of exon per Million reads mapped）进行计算。将fold change大于1且p值小于0.05的基因认定为差异表达基因。