Development of an animal model to test HDAC6 as a drug target to reduce and/or prevent fetal growth restriction

项目总结 胎儿生长中断会对人类健康造成严重后果，包括胎儿和 新生儿发病率和死亡率，以及潜在的终身健康问题。胎儿生长受限(FGR) 在所有人类怀孕中发生的比例高达10%。不幸的是，缺乏对FGR的治疗。分子 促进胎儿生长的机制代表了治疗和/或预防FGR的潜在治疗策略。我们 已经确定了丝裂原活化蛋白激酶4(MAP3K4)的一个以前未知的角色 通过诱导胰岛素样生长因子的表达和活性促进胎儿和胎盘生长 1受体(IGF1R)和胰岛素受体(IR)。在2022年发表的最新研究中，我们发现灭活 MAP3K4激活域的突变导致FGR。MAP3K4激酶失活(KI) 小鼠在断奶前表现出很高的致死率，存活的成鼠的生长持续减少。表达式和 在培养的KI滋养层细胞和KI胎盘中，IGF1R和IR的激活均降低。机制(S)由 哪些MAP3K4控制这些受体代表了治疗FGR的新方法。MAP3K4抑制 组蛋白脱乙酰基酶6(HDAC6)的表达和活性。KI滋养层细胞高表达HDAC6 减少HDAC6可恢复IGF1R和IR的表达和活性。基于这些发现， 我们推测，HDAC6在Ki胎盘中也可能是过度活跃的，抑制HDAC6可能会挽救和 防止FGR。高选择性和耐受性良好的HDAC6抑制剂的可用性提供了独特的 开发治疗FGR的治疗方法的机会。然而，目前仍不清楚是否将HDAC6作为目标 怀孕会促进胎儿和胎盘的生长。我们的初步数据显示，HDAC6在 怀孕提高了发育期间KI胚胎的存活率。然而，这次救援可能在一定程度上是应该的。 以达到HDAC6抑制剂的靶向作用。为了验证我们的预测，即删除HDAC6将阻止KI中的FGR 小鼠，我们建议通过将HDAC6基因敲除的小鼠与MAP3K4Ki小鼠交配来从基因上删除HDAC6 老鼠。将评估缺乏HDAC6的MAP3K4Ki小鼠的存活和生长。此外，胎儿和胎盘 将测量大小，并对胎盘IGF1R、IR和Akt的表达和活性进行量化。这些 新的结果将与HDAC6升高时观察到的生长限制和致命性进行比较。 我们预测，从MAP3K4Ki个体中缺失HDAC6将促进胎儿生长并提高存活率， 提示HDAC6抑制剂有可能成为治疗FGR的新工具。

PROJECT SUMMARY Disruption of fetal growth results in severe consequences to human health, including increased fetal and neonatal morbidity and mortality, as well as potential lifelong health problems. Fetal growth restriction (FGR) occurs in up to 10% of all human pregnancies. Unfortunately, treatments for FGR are lacking. Molecular mechanisms promoting fetal growth represent potential therapeutic strategies to treat and/or prevent FGR. We have identified a previously unknown role for the mitogen activated protein kinase kinase kinase 4 (MAP3K4) in promoting fetal and placental growth by inducing the expression and activity of the insulin-like growth factor 1 receptor (IGF1R) and insulin receptor (IR). In recent work published in 2022, we discovered that inactivation of MAP3K4 kinase activity by a mutation in the kinase domain results in FGR. MAP3K4 Kinase-Inactive (KI) mice display high lethality prior to weaning and persistent growth reduction of surviving adults. Expression and activation of the IGF1R and IR are reduced in both cultured KI trophoblasts and KI placentas. Mechanism(s) by which MAP3K4 controls these receptors represent novel approaches to treat FGR. MAP3K4 inhibits the expression and activity of histone deacetylase 6 (HDAC6). KI trophoblasts have elevated HDAC6 expression and activity, and reduction of HDAC6 restores IGF1R and IR expression and activity. Based on these findings, we hypothesize that HDAC6 may also be hyperactive in KI placentas, and HDAC6 inhibition may rescue and prevent FGR. The availability of highly selective and well-tolerated HDAC6 inhibitors provides a unique opportunity for developing a therapy to treat FGR. However, it remains unknown if targeting HDAC6 during pregnancy will improve fetal and placental growth. Our preliminary data show that inhibition of HDAC6 during pregnancy increased the survival of KI embryos during development. However, this rescue may be due in part to off target effects of HDAC6 inhibitors. To test our prediction that deletion of HDAC6 will prevent FGR in KI mice, we propose to genetically delete HDAC6 from MAP3K4 KI mice by mating them with HDAC6 knockout mice. Survival and growth of MAP3K4 KI mice lacking HDAC6 will be assessed. In addition, fetal and placental size will be measured, and placental expression and activity of the IGF1R, IR, and Akt will be quantified. These new results will be compared to growth restriction and lethality observed in the presence of elevated HDAC6. We predict that deletion of HDAC6 from MAP3K4 KI individuals will improve fetal growth and increase survival, indicating that HDAC6 inhibitors may represent a new therapeutic tool to treat FGR.