Rathinasabapathy Anandharajan, Copeland Courtney, Crabtree Amber, Carrier Erica J, Moore Christy, Shay Sheila, Gladson Santhi, Austin Eric D, Kenworthy Anne K, Loyd James E, Hemnes Anna R, West James D
Allergy, Pulmonary and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, TN, United States.
Pulmonary and Critical Care Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA, United States.
Front Med (Lausanne). 2020 Sep 11;7:540. doi: 10.3389/fmed.2020.00540. eCollection 2020.
In 2012, mutations in Cav1 were found to be the driving mutation in several cases of heritable pulmonary arterial hypertension (PAH). These mutations replaced the last 21 amino acids of Cav1 with a novel 22-amino-acid sequence. Because previously only Cav1 knockouts had been studied in the context of PAH, examining the effects of this novel mutation holds promise for new understanding of the role of Cav1 in disease etiology. The new 22 amino acids created by the human mutation were knocked into the native mouse Cav1 locus. The mice underwent hemodynamic, energy balance, and inflammatory measurements, both at baseline and after being stressed with either a metabolic or an inflammatory challenge [low-dose lipopolysaccharide (LPS)]. To metabolically challenge the mice, they were injected with streptozotocin (STZ) and fed a high-fat diet for 12 weeks. Very little mutant protein was found (roughly 2% of wild-type by mass spectrometry), probably because of degradation after failure to traffic from the endoplasmic reticulum. The homozygous mutants developed a mild, low-penetrance PAH similar to that described previously in knockouts, and neither baseline nor metabolic nor inflammatory stress resulted in pressures above normal in heterozygous animals. The homozygous mutants had increased lean mass and worsened oral glucose tolerance, as previously described in knockouts. Novel findings include the preservation of Cav2 and accessory proteins in the liver and the kidney, while they are lost with homozygous Cav1 mutation in the lungs. We also found that the homozygous mutants had a significantly lower tolerance to voluntary spontaneous exercise than the wild-type mice, with the heterozygous mice at an intermediate level. The mutants also had higher circulating monocytes, with both heterozygous and homozygous animals having higher pulmonary MCP1 and MCP5 proteins. The heterozygous animals also lost weight at an LPS challenge level at which the wild-type mice continued to gain weight. The Cav1 mutation identified in human patients in 2012 is molecularly similar to a knockout of Cav1. It results in not only metabolic deficiencies and mild pulmonary hypertension, as expected, but also an inflammatory phenotype and reduced spontaneous exercise.
2012年，人们发现Cav1基因突变是几例遗传性肺动脉高压（PAH）的驱动性突变。这些突变用一个新的22个氨基酸的序列取代了Cav1的最后21个氨基酸。由于之前仅在PAH背景下研究过Cav1基因敲除，因此研究这种新突变的影响有望让人对Cav1在疾病病因学中的作用有新的认识。人类突变产生的新的22个氨基酸被敲入天然小鼠Cav1基因座。对这些小鼠进行了血流动力学、能量平衡和炎症指标的测量，测量在基线时以及在受到代谢或炎症刺激[低剂量脂多糖（LPS）]后进行。为了对小鼠进行代谢刺激，给它们注射链脲佐菌素（STZ）并喂食高脂饮食12周。发现突变蛋白极少（通过质谱分析约为野生型的2%），这可能是因为未能从内质网转运后发生了降解。纯合突变体出现了轻度、低外显率的PAH，类似于之前在基因敲除小鼠中描述的情况，杂合动物无论是在基线时、代谢应激时还是炎症应激时，血压均未高于正常水平。纯合突变体的瘦体重增加，口服葡萄糖耐量恶化，这与之前在基因敲除小鼠中的描述一致。新发现包括肝脏和肾脏中Cav2及辅助蛋白得以保留，而在肺部纯合Cav1突变时这些蛋白会缺失。我们还发现，纯合突变体对自愿自发运动的耐受性明显低于野生型小鼠，杂合小鼠则处于中间水平。突变体的循环单核细胞也更多，杂合和纯合动物的肺部MCP1和MCP5蛋白水平均更高。在LPS刺激水平下，野生型小鼠体重持续增加，而杂合动物体重却下降。2012年在人类患者中鉴定出的Cav1突变在分子水平上类似于Cav1基因敲除。它不仅导致了预期的代谢缺陷和轻度肺动脉高压，还导致了炎症表型和自发运动减少。
