Ensemble framework to infer large-scale causal gene regulatory networks from transcriptomic data

现在已经确定，复杂的生物表型不是由单个基因控制的，而是由相互作用的基因和基因产物的网络控制的。因此，破译基因调控网络（GRN）的结构对于进一步理解人类细胞中的基本过程至关重要。然而，在细胞内领域的分子相互作用的映射仍然是从高通量生物数据产生生物学知识的管道中的瓶颈。 生物信息学和高性能计算的最新进展使得从转录组数据集合中推断无向大规模调控网络成为可能。然而，很少有网络推理方法可以推断预测基因相互作用的方向性（因果关系），尽管这是更好地解释GRNs的关键。推断大规模GRNs时的另一个挑战在于定量评估其有效性。流行的，但薄弱，验证程序包括（i）表明，正在研究的算法在模拟数据集上表现良好，对于这些数据集，真实的底层网络是已知的;（ii）使用不完整的“金标准”数据集，如已知的转录因子及其靶点，这很难概括可以从转录组数据推断出的相互作用;以及（iii）使用低通量实验室实验来验证一些预测的相互作用，这些相互作用仅代表推断的GRN的非常小且可能有偏差的部分。 我们的研究计划从几个角度解决这些问题。首先，我们将基于我们最近在网络生物学领域的贡献，开发新的机器学习方法，从而能够推断大规模因果GRNs。这些方法将是新颖的，在他们的网络和因果关系推理的集成方法的实施，并从生物医学文献中提取的先验知识的整合。其次，我们将扩展我们最近发布的验证框架，以定量评估和比较我们的新方法与最先进的网络推理技术。第三，我们将开发一个计算平台，使生物学家能够利用我们的计算工具，充分映射他们的基因或感兴趣的途径到大GRNs。 为了实现这些目标，我将依靠我与著名的计算机科学家，生物信息学家和生物学家的密切合作，这不仅将确保我的方法应用于真实的和新的数据，而且这些方法的发展正在不断评估，以影响更大的生物和医学研究的研究人员社区。

It is now established that complex biological phenotypes are not governed by single genes but instead by networks of interacting genes and gene products. As a consequence, deciphering the structure of the gene regulatory network (GRN) is crucial to further our understanding of fundamental processes in human cells. However, the mapping of molecular interactions in the intracellular realm remains the bottleneck in the pipeline to produce biological knowledge from high-throughput biological data. Recent advances in bioinformatics and high-performance computing made it possible to infer undirected large-scale regulatory networks from collections of transcriptomic data. However very few network inference methods can infer the directionality (causality) of predicted gene interactions, despite this being key in the process of better interpreting GRNs. Another challenge when inferring large-scale GRNs consists in quantitatively assessing their validity. Popular, however weak, validation procedures include (i) showing that the algorithm under study performs well on simulated datasets for which the true underlying network is known by construction; (ii) using incomplete ‘gold standard’ datasets, such as known transcription factors and their targets, which poorly recapitulate the interactions that can be inferred from transcriptomic data; and (iii) using low-throughput laboratory experiments to validate a few predicted interactions, which represent only a very small and potentially biased part of the inferred GRN. Our research program addresses these issues from several angles. First we will build on our recent contributions in the field of network biology to develop new machine learning methods enabling inference of large-scale causal GRNs. These methods will be novel in their implementation of an ensemble approach for network and causality inference, and their integration of priors extracted from the biomedical literature. Second we will extend our recently published validation framework to quantitatively assess and compare our new methods with state-of-the-art network inference techniques. Third we will develop a computational platform to allow biologists to leverage our computational tools to adequately map their genes or pathways of interest into large GRNs. To achieve these objectives, I will rely on my close collaborations with renowned computer scientists, bioinformaticians, and biologists, This will not only ensure that my methods are applied to real and new data, but also that the development of these methods are being continuously evaluated in order to impact the larger community of researchers involved in biological and medical studies.