Impact of liver-specific deletion of Dhcr24 gene on tissue gene expression

Genetic loss of the enzyme 3beta-hydroxysterol-delta24 reductase (DHCR24) results in Desmosterolosis (MIM #602398), a rare disease that presents with multiple congenital anomalies. Earlier studies to create a Dhcr24 global knockout mouse have failed as the pups died within 24 h of birth from lethal dermopathy. We generated a conditional knockout mouse model (Dhcr24flx/flx) and validated it by creating a liver-specific knockout Dhcr24flx/flx, Alb-Cre mouse using a mouse expressing cre recombinase driven by the albumin promoter. Despite increased circulatory and liver desmosterol due to loss of cholesterol synthesis in the liver, these mice demonstrated no marked changes in growth, fertility, hepatic architecture, lipoprotein secretion, etc. RNA-Seq analysis of the female mouse liver revealed no notable perturbations in pathways participating in cholesterol biosynthesis. RNA was isolated from liver, adrenal and macrophage of 1 mouse in each group. KO mouse from each sex were compared to floxed Cre negative control mouse of the same sex.编码3β-羟基类固醇Δ24还原酶（3beta-hydroxysterol-delta24 reductase, DHCR24）的基因发生遗传缺失，会引发链甾醇血症（Desmosterolosis, MIM #602398），这是一种以多发先天性畸形为表现的罕见疾病。此前构建Dhcr24全身基因敲除小鼠的研究均未成功，因幼鼠会在出生后24小时内死于致死性皮肤病变。我们成功构建了条件性基因敲除小鼠模型（Dhcr24flx/flx），并通过使用白蛋白启动子驱动Cre重组酶表达的小鼠，制备了肝脏特异性敲除小鼠Dhcr24flx/flx, Alb-Cre，以此对该模型进行验证。尽管肝脏中胆固醇合成受阻导致循环系统及肝脏内链甾醇水平升高，但此类小鼠的生长发育、生育能力、肝脏组织结构、脂蛋白分泌等均未出现显著异常。对雌性小鼠肝脏开展RNA测序（RNA-Seq）分析后发现，参与胆固醇生物合成的通路未出现明显扰动。本研究从每组1只小鼠的肝脏、肾上腺及巨噬细胞中提取总RNA，并将不同性别的基因敲除小鼠与同性别且Cre阴性的floxed对照小鼠进行对比。