Transgenerational Effects of Smoking-Induced Changes to Sperm DNA Methylation

 描述（由申请人提供）：据估计，直接或通过二手烟暴露于烟草烟雾影响了世界三分之一以上的人口，根据世界卫生组织的数据，烟草每年导致近600万人死亡。除了巨大的健康后果外，最近和新出现的数据表明，烟草烟雾暴露可能会产生跨代后果。例如，怀孕前吸烟的男性的孩子患儿童白血病的风险增加。这表明吸烟会导致配子中的遗传和/或表观遗传变化，从而对后代健康产生负面影响。从初步研究中我们知道，与非吸烟者相比，全球精子DNA甲基化水平显着降低，多项研究表明，烟草烟雾暴露会改变体细胞组织中的甲基化模式。在这项研究中，我们建议充分表征烟草烟雾暴露对小鼠精子DNA甲基化模式的影响。我们将进行育种实验，以跟踪观察到的两代后代的变化。此外，由于烟草烟雾诱导的甲基化变化被假定为通过氧化应激途径发生，我们将使用一种小鼠模型，其中主要的抗氧化反应途径（Nrf 2）已被破坏，以确定这种基因破坏是否放大了由于烟草烟雾暴露而发生的表观遗传变化以及该效应的跨代后果。最后，我们将使用甲基化微阵列来评估烟草烟雾暴露对150名吸烟男性和150名非吸烟男性精子甲基化组的影响。这些实验是了解烟草烟雾暴露的潜在长期跨代影响的关键一步，并将深入了解吸烟诱导的甲基化扰动的机制。目标3中提出的人类研究将有助于深入了解动物研究与人类父系介导的跨代遗传的相关性。

 DESCRIPTION (provided by applicant): It is estimated that exposure to tobacco smoke, either directly, or through second hand smoke affects more than one third of the world's population, and according to the World Health Organization, tobacco kills almost 6 million people annually. In addition to its enormous health consequences, recent and emerging data indicate that tobacco smoke exposure may have transgenerational consequences. For example, children of men who smoked prior to conception have increased risk of developing childhood leukemia. This indicates that smoking can cause heritable genetic and/or epigenetic changes in the gametes that can negatively impact offspring health. From pilot studies we know that global sperm DNA methylation levels are significantly reduced compared with non-smokers, and multiple studies have demonstrated that tobaccos smoke exposure changes methylation patterns in somatic tissues. For this study we propose to fully characterize the effect of tobacco smoke exposure on sperm DNA methylation patterns in the mouse. We will perform breeding experiments to follow the observed changes in offspring across two generations. In addition, as tobacco smoke induced methylation changes are postulated to occur in through oxidative stress pathways, we will use a mouse model in which a major antioxidant response pathway (Nrf2) has been disrupted to determine whether this gene disruption amplifies the epigenetic changes that occur due to tobacco smoke exposure as well as the transgenerational consequences of that effect. Lastly, we will use a methylation microarray to assess the effects of tobacco smoke exposure on the sperm methylome in 150 men who smoke compared with 150 non- smokers. These experiments are a critical step in understanding the potential long term, transgenerational effects of tobacco smoke exposure and will lend insight into the mechanisms for exposure-induced methylation perturbations. The human studies proposed in Aim 3 will lend insight into the relevance of animal studies for paternally mediated, transgenerational inheritance in humans.