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

项目摘要 胎儿生长的中断导致对人类健康的严重后果，包括胎儿生长和发育的增加。 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） 发生在10%的人类妊娠中。FGR的治疗方法缺乏。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（MAP 3 K4）以前未知的作用， 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（IGF 1 R）和胰岛素受体（IR）。在2022年发表的最新研究中，我们发现， MAP 3 K4激酶活性的突变导致FGR。MAP 3 K4激酶失活（KI） 小鼠在断奶前表现出高致死率，存活的成年小鼠的生长持续下降。表达及 IGF 1 R和IR的活化在培养的KI滋养层细胞和KI胎盘中均降低。机制 其中MAP 3 K4控制这些受体代表了治疗FGR的新方法。MAP 3 K4抑制了 组蛋白去乙酰化酶6（HDAC 6）的表达和活性。KI滋养细胞具有升高的HDAC 6表达 HDAC 6的减少恢复了IGF 1 R和IR的表达和活性。根据这些发现， 我们假设HDAC 6在KI胎盘中也可能是过度活跃的，HDAC 6抑制可以挽救和 预防FGR。高选择性和耐受性良好的HDAC 6抑制剂的可用性提供了独特的 这是开发治疗FGR的疗法的机会。然而，目前尚不清楚是否针对HDAC 6， 怀孕会促进胎儿和胎盘的生长。我们的初步数据表明，HDAC 6的抑制， 怀孕增加了KI胚胎在发育过程中的存活率。然而，这一救助可能部分是由于 HDAC 6抑制剂的脱靶效应。为了验证我们的预测，即删除HDAC 6将防止KI中的FGR， 小鼠，我们建议通过将它们与HDAC 6敲除小鼠交配，从MAP 3 K4 KI小鼠中遗传删除HDAC 6 小鼠将评估缺乏HDAC 6的MAP 3 K4 KI小鼠的存活和生长。此外，胎儿和胎盘 测量胎盘大小，并定量胎盘表达和IGF 1 R、IR和Akt的活性。这些 将新的结果与在HDAC 6升高的情况下观察到的生长限制和致死率进行比较。 我们预测从MAP 3 K4 KI个体中缺失HDAC 6将改善胎儿生长并增加存活率， 表明HDAC 6抑制剂可能代表治疗FGR的新治疗工具。

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.