LGR4基因调控小鼠肺组织糖皮质激素受体表达及肺发育

LGR4 regulates glucocorticoid receptor expression and lung development

目的:探讨LGR4基因缺失引起新生小鼠死亡的原因及其可能的机制。方法:观察LGR4基因敲除(KO)小鼠出生后48h内的表现,记录其死亡时间,并对不同基因型小鼠进行生存分析取LGR4 KO纯合的新生小鼠及不同胚胎期小鼠的肺脏进行病理切片和HE染色,观察其组织形态学改变,并将结果与基因型为野生型(WT)、杂合型的小鼠比较采用ELISA法检测LGR4 KO纯合小鼠、WT小鼠血清中皮质酮水平,并用蛋白印迹(Western blot)半定量检测小鼠胎肺中糖皮质激素受体(GR)的蛋白水平。结果:LGR4 KO纯合小鼠出生后出现不同程度的呼吸因难、紫绀等表观.52.2%的LGR4 KO纯合小鼠在出生后28h内死亡,组织学检查发现,LGR4 KO纯合小鼠的肺脏在胚胎晚期和新生期存在明显的结构异常,包括肺泡减少、肺间隔增厚、细胞密度增加。此外,LGR4缺失还引起小鼠胚胎晚期肺中GR水平明显下调,但其对小鼠肾上腺的皮质酮分泌功能并无显著影响。结论:LGR4缺失可引起小鼠肺胚胎晚期发育障碍和新生小鼠肺结构异常,导致小鼠出生后早期死亡,而GR水平的下调可能是其重要机制。

Objective To investigate the cause of death of neonatal mice with LGR4 gene absent and its possible mechanism. Methods The appearance of LGR4 gene knockout （KO） mice was observed for 48 hours after birth, the time of death was recorded, and a survival analysis of mice with different genotypes was performed. Lungs from newborn mice and fetal mice in different embryonic stages were examined pathologically with HE stain and their histomorphological changes studied. Serum corticosterone level was determined by ELISA and glucocorticoid receptor （GR） protein level in lungs was assessed semi-quantitatively by Western blot. Results LGR4 knockout mice displayed various degree of respiratory distress and cyanosis and 52.2% died within 28 hours after birth. Histological examination revealed obvious abnormality in lung architecture of LGR4 knockout mice during late embryonic stage and at birth, including reduced alveolar space, thickened interalveolar septa and dense cellularity. The knockout of LGR4 also leaded to marked reduction of expression of GR in the lung while had little influence on corticosterone secretion of adrenal gland. Conclusions Absence of LGR4 impairs the lung development during late embryonic stage and leads to early death of mice after birth. Reduced expression of GR may be implicated in the above-mentioned lung abnormalities.