Transcription profiling of prosaposin deficient mice show molecular alterations precede neuronal deficits

Prosaposin encodes, in tandem, four small acidic activator proteins (saposins) with specificities for glycosphingolipids hydrolases in lysosomes. To explore the molecular mechanism(s) of disease progression, temporal transcriptome microarray analyses of cerebrum and cerebellum tissues were conducted using mRNA from three prosaposin deficiency mouse models: PS-NA (hypomorphic prosaposin deficiency), PS-/- (prosaposin null) and 4L/PS-NA (a V394L/V394L glucocerebrosidase mutation and PS-NA) mice. Our results indicate that regionally specific gene expression abnormalities preceded the histological and behavioral changes and CEBPD is a candidate regulator of brain disease in prosaposin deficiency. The alterations of gene expression are detected at birth and are more profound in cerebellum than cerebrum. Experiment Overall Design: In order to increase the temporal resolution of expression profile in brain, the disease progression in those models were inverstigated in two regions of brains (cerebellum and cerebrum) at three or four time points according to the genotypes. PS-/-: new born (0d), 10 days (10d), 20 days (20d), 25 days (25d); PS-NA: new born, 4 weeks (4w), 12 weeks (12w), 18 weeks (18w); 4L/PS-NA: 4 weeks (4w), 12 weeks (12w), 18 weeks (18w). The data from those models were analyzed relative to the corresponding wild type at same time point (0d, 10d, 20d, 4w, 12w, 18w).鞘脂激活蛋白原（Prosaposin）可串联编码四种酸性小分子量激活蛋白（鞘脂激活蛋白，saposins），这类蛋白对溶酶体中的糖鞘脂水解酶具有特异性激活活性。为探究疾病进展的分子机制，研究人员针对大脑与小脑组织开展了时序转录组微阵列分析，实验材料取自三种Prosaposin缺陷型小鼠模型：PS-NA（低功能型Prosaposin缺陷模型）、PS-/-（Prosaposin完全敲除模型）以及4L/PS-NA（携带V394L/V394L葡糖脑苷脂酶突变且搭载PS-NA背景的模型）小鼠。本研究结果显示，区域特异性基因表达异常早于组织学与行为学改变出现，且CEBPD（CCAAT增强子结合蛋白δ）可作为Prosaposin缺陷相关脑部疾病的候选调控因子。基因表达改变在新生小鼠体内即可被检测到，且小脑内的改变较大脑更为显著。实验整体设计：为提升脑部基因表达谱的时序分辨率，研究人员依据基因型，针对上述模型的疾病进展，分别在大脑两个区域（小脑与大脑）设置3或4个采样时间点开展研究。PS-/-模型：新生（0日龄，0d）、10日龄（10d）、20日龄（20d）、25日龄（25d）；PS-NA模型：新生、4周龄（4w）、12周龄（12w）、18周龄（18w）；4L/PS-NA模型：4周龄（4w）、12周龄（12w）、18周龄（18w）。所有模型的实验数据均与对应时间点的野生型样本进行对比分析，对照时间点包括0d、10d、20d、4w、12w及18w。