Jian Tang

Biographie

Jian Tang est professeur agrégé au département de sciences de la décision de HEC. Il est aussi professeur associé au département informatique et recherche opérationnelle (DIRO) de l'Université de Montréal et un membre académique principal à Mila – Institut québécois d’intelligence artificielle. Il est titulaire d'une chaire de recherche en IA Canada-CIFAR et le fondateur de BioGeometry, une entreprise en démarrage spécialisée dans l'IA générative pour la découverte d'anticorps. Ses principaux domaines de recherche sont les modèles génératifs profonds, l'apprentissage automatique des graphes et leurs applications à la découverte de médicaments. Il est un leader international dans le domaine de l'apprentissage automatique des graphes, et son travail représentatif sur l'apprentissage de la représentation des nœuds, LINE, a été largement reconnu et cité plus de 5 000 fois. Il a également réalisé de nombreux travaux pionniers sur l'IA pour la découverte de médicaments, notamment le premier cadre d'apprentissage automatique à source ouverte pour la découverte de médicaments, TorchDrug et TorchProtein.

Étudiants actuels

Huiyu Cai

Doctorat - UdeM

huiyu.cai@mila.quebec

Zewen Chi

Stagiaire de recherche - Beijing Institute of Technology

Doctorat - UdeM

Stagiaire de recherche - HEC

Michael Galkin

Collaborateur·rice de recherche

Farzaneh Heidari

Doctorat - UdeM

Superviseur⋅e principal⋅e :

Guillaume Rabusseau

Jerry Lu

Doctorat - UdeM

Stephen Lu

Stagiaire de recherche - McGill

stephen.lu@mila.quebec

Meng Qu

Doctorat - UdeM

Chence Shi

Doctorat - UdeM

Walter Virany

Collaborateur·rice de recherche

Chuanru Wang

Maîtrise recherche - UdeM

Sophie Xhonneux

Doctorat - UdeM

Superviseur⋅e principal⋅e :

Gauthier Gidel

lpxhonneux@gmail.com

Minghao Xu

Collaborateur·rice de recherche

Xinyu Yuan

Doctorat - UdeM

zhaocheng.zhu@umontreal.ca

Zhihao Zhan

Doctorat - UdeM

Doctorat - UdeM

Jianan Zhao

Doctorat - UdeM

Doctorat - UdeM

Publications

Pre-training Protein Structure Encoder via Siamese Diffusion Trajectory Prediction

Zuobai Zhang

Minghao Xu

Aurelie Lozano

Vijil Chenthamarakshan

Payel Das

Due to the determining role of protein structures on diverse protein functions, pre-training representations of proteins on massive unlabele… (voir plus)d protein structures has attracted rising research interests. Among recent efforts on this direction, mutual information (MI) maximization based methods have gained the superiority on various downstream benchmark tasks. The core of these methods is to design correlated views that share common information about a protein. Previous view designs focus on capturing structural motif co-occurrence on the same protein structure, while they cannot capture detailed atom/residue interactions. To address this limitation, we propose the Siamese Diffusion Trajectory Prediction (SiamDiff) method. SiamDiff builds a view as the trajectory that gradually approaches protein native structure from scratch, which facilitates the modeling of atom/residue interactions underlying the protein structural dynamics. Specifically, we employ the multimodal diffusion process as a faithful simulation of the structure-sequence co-diffusion trajectory, where rich patterns of protein structural changes are embedded. On such basis, we design a principled theoretical framework to maximize the MI between correlated multimodal diffusion trajectories. We study the effectiveness of SiamDiff on both residue-level and atom-level structures. On the EC and ATOM3D benchmarks, we extensively compare our method with previous protein structure pre-training approaches. The experimental results verify the consistently superior or competitive performance of SiamDiff on all benchmark tasks compared to existing baselines. The source code will be made public upon acceptance.

2023-02-01

ICLR.cc/2023/Conference (rejected)

Protein Representation Learning by Geometric Structure Pretraining

Zuobai Zhang

Minghao Xu

Arian Rokkum Jamasb

Vijil Chenthamarakshan

Aurelie Lozano

Payel Das

Learning effective protein representations is critical in a variety of tasks in biology such as predicting protein function or structure. Ex… (voir plus)isting approaches usually pretrain protein language models on a large number of unlabeled amino acid sequences and then finetune the models with some labeled data in downstream tasks. Despite the effectiveness of sequence-based approaches, the power of pretraining on known protein structures, which are available in smaller numbers only, has not been explored for protein property prediction, though protein structures are known to be determinants of protein function. In this paper, we propose to pretrain protein representations according to their 3D structures. We first present a simple yet effective encoder to learn the geometric features of a protein. We pretrain the protein graph encoder by leveraging multiview contrastive learning and different self-prediction tasks. Experimental results on both function prediction and fold classification tasks show that our proposed pretraining methods outperform or are on par with the state-of-the-art sequence-based methods, while using much less pretraining data. Our implementation is available at https://github.com/DeepGraphLearning/GearNet.

2023-02-01

ICLR.cc/2023/Conference (poster)

Protein Sequence and Structure Co-Design with Equivariant Translation

Chence Shi

Chuanrui Wang

Jiarui Lu

Bozitao Zhong

Proteins are macromolecules that perform essential functions in all living organisms. Designing novel proteins with specific structures and … (voir plus)desired functions has been a long-standing challenge in the field of bioengineering. Existing approaches generate both protein sequence and structure using either autoregressive models or diffusion models, both of which suffer from high inference costs. In this paper, we propose a new approach capable of protein sequence and structure co-design, which iteratively translates both protein sequence and structure into the desired state from random initialization, based on context features given a priori. Our model consists of a trigonometry-aware encoder that reasons geometrical constraints and interactions from context features, and a roto-translation equivariant decoder that translates protein sequence and structure interdependently. Notably, all protein amino acids are updated in one shot in each translation step, which significantly accelerates the inference process. Experimental results across multiple tasks show that our model outperforms previous state-of-the-art baselines by a large margin, and is able to design proteins of high fidelity as regards both sequence and structure, with running time orders of magnitude less than sampling-based methods.

2023-02-01

ICLR.cc/2023/Conference (poster)

FusionRetro: Molecule Representation Fusion via Reaction Graph for Retrosynthetic Planning

Songtao Liu

Zhengkai Tu

Minkai Xu

Zuobai Zhang

Peilin Zhao

Rex Ying

Lu Lin

Dinghao Wu

Retrosynthetic planning is a fundamental problem in drug discovery and organic chemistry, which aims to ﬁnd a complete multi-step syntheti… (voir plus)c route from a set of starting materials to the target molecule, determining crucial process ﬂow in chemical production. Existing approaches combine single-step retrosynthesis models and search algorithms to ﬁnd synthetic routes. However, these approaches generally consider the two pieces in a decoupled manner, taking only the product as the input to predict the reactants per planning step and largely ignoring the important context information from other intermediates along the synthetic route. In this work, we perform a series of experiments to identify the limitations of this decoupled view and propose a novel retrosynthesis framework that also exploits context information for retrosynthetic planning. We view synthetic routes as reaction graphs, and propose to incorporate the context by three principled steps: encode molecules into embeddings, aggregate information over routes, and readout to predict reactants. The whole framework can be efﬁciently optimized in an end-to-end fashion. Comprehensive experiments show that by fusing in context information over routes, our model sig-niﬁcantly improves the performance of retrosyn-thetic planning over baselines that are not context-aware, especially for long synthetic routes.

2023-01-01

(publié)

www.semanticscholar.org

FusionRetro: Molecule Representation Fusion via In-Context Learning for Retrosynthetic Planning

Songtao Liu

Zhengkai Tu

Minkai Xu

Zuobai Zhang

Lu Lin

Rex Ying

Zhitao Ying

Peilin Zhao

Dinghao Wu

2023-01-01

ICML (publié)

A Group Symmetric Stochastic Differential Equation Model for Molecule Multi-modal Pretraining

Shengchao Liu

weitao Du

Zhi-Ming Ma

Hongyu Guo

Molecule pretraining has quickly become the go-to schema to boost the performance of AI-based drug discovery. Naturally, molecules can be re… (voir plus)presented as 2D topological graphs or 3D geometric point clouds. Although most existing pertaining methods focus on merely the single modality, recent research has shown that maximizing the mutual information (MI) between such two modalities enhances the molecule representation ability. Meanwhile, existing molecule multi-modal pretraining approaches approximate MI based on the representation space encoded from the topology and geometry, thus resulting in the loss of critical structural information of molecules. To address this issue, we propose MoleculeSDE. MoleculeSDE leverages group symmetric (e.g., SE(3)-equivariant and reflection-antisymmetric) stochastic differential equation models to generate the 3D geometries from 2D topologies, and vice versa, directly in the input space. It not only obtains tighter MI bound but also enables prosperous downstream tasks than the previous work. By comparing with 17 pretraining baselines, we empirically verify that MoleculeSDE can learn an expressive representation with state-of-the-art performance on 26 out of 32 downstream tasks.

2023-01-01

ICML (publié)

Physics-Inspired Protein Encoder Pre-Training via Siamese Sequence-Structure Diffusion Trajectory Prediction

Zuobai Zhang

Minghao Xu

Aurelie Lozano

Vijil Chenthamarakshan

Payel Das

Pre-training methods on proteins are recently gaining interest, leveraging either protein sequences or structures, while modeling their join… (voir plus)t energy landscape is largely unexplored. In this work, inspired by the success of denoising diffusion models, we propose the DiffPreT approach to pre-train a protein encoder by sequence-structure multimodal diffusion modeling. DiffPreT guides the encoder to recover the native protein sequences and structures from the perturbed ones along the multimodal diffusion trajectory, which acquires the joint distribution of sequences and structures. Considering the essential protein conformational variations, we enhance DiffPreT by a physics-inspired method called Siamese Diffusion Trajectory Prediction ( SiamDiff ) to capture the correlation between different conformers of a protein. SiamDiff attains this goal by maximizing the mutual information between representations of diffusion trajectories of structurally-correlated conformers. We study the effectiveness of DiffPreT and SiamDiff on both atom-and residue-level structure-based protein understanding tasks. Experimental results show that the performance of DiffPreT is consistently competitive on all tasks, and SiamDiff achieves new state-of-the-art performance, considering the mean ranks on all tasks. The source code will be released upon acceptance.

2023-01-01

arXiv.org (prépublication)

GraphCG: Unsupervised Discovery of Steerable Factors in Graphs

Shengchao Liu

Chengpeng Wang

Weili Nie

Hanchen Wang

Jiarui Lu

Bolei Zhou

Deep generative models have been extensively explored recently, especially for the graph data such as molecular graphs and point clouds. Yet… (voir plus), much less investigation has been carried out on understanding the learned latent space of deep graph generative models. Such understandings can open up a unified perspective and provide guidelines for essential tasks like controllable generation. In this paper, we first examine the representation space of the recent deep generative model trained for graph data, observing that the learned representation space is not perfectly disentangled. Based on this observation, we then propose an unsupervised method called GraphCG, which is model-agnostic and task-agnostic for discovering steerable factors in graph data. Specifically, GraphCG learns the semantic-rich directions via maximizing the corresponding mutual information, where the edited graph along the same direction will possess certain steerable factors. We conduct experiments on two types of graph data, molecular graphs and point clouds. Both the quantitative and qualitative results show the effectiveness of GraphCG for discovering steerable factors. The code will be public in the near future.

2022-11-22

NeurIPS.cc/2022/Workshop/GLFrontiers (publié)

Flaky Performances when Pretraining on Relational Databases

Shengchao Liu

David Vazquez

Pierre-Andre Noel

2022-11-09

ArXiv (prépublication)

Implications of Topological Imbalance for Representation Learning on Biomedical Knowledge Graphs

Stephen Bonner

Ufuk Kirik

Ola Engkvist

Ian P Barrett

Adoption of recently developed methods from machine learning has given rise to creation of drug-discovery knowledge graphs (KGs) that utiliz… (voir plus)e the interconnected nature of the domain. Graph-based modelling of the data, combined with KG embedding (KGE) methods, are promising as they provide a more intuitive representation and are suitable for inference tasks such as predicting missing links. One common application is to produce ranked lists of genes for a given disease, where the rank is based on the perceived likelihood of association between the gene and the disease. It is thus critical that these predictions are not only pertinent but also biologically meaningful. However, KGs can be biased either directly due to the underlying data sources that are integrated or due to modelling choices in the construction of the graph, one consequence of which is that certain entities can get topologically overrepresented. We demonstrate the effect of these inherent structural imbalances, resulting in densely connected entities being highly ranked no matter the context. We provide support for this observation across different datasets, models as well as predictive tasks. Further, we present various graph perturbation experiments which yield more support to the observation that KGE models can be more influenced by the frequency of entities rather than any biological information encoded within the relations. Our results highlight the importance of data modelling choices, and emphasizes the need for practitioners to be mindful of these issues when interpreting model outputs and during KG composition.

2022-07-26

Briefings in Bioinformatics (publié)

Subgraph Retrieval Enhanced Model for Multi-hop Knowledge Base Question Answering

Jing Zhang

Xiaokang Zhang

Jifan Yu

Jie Tang

Cuiping Li

Hong Chen

2022-05-01

Proceedings of the 60th Annual Meeting of the Association for Computational Linguistics (Volume 1: Long Papers) (publié)

Subgraph Retrieval Enhanced Model for Multi-hop Knowledge Base Question Answering

Jing Zhang

Xiaokang Zhang

Jifan Yu

Jie Tang

Cuiping Li

Hong Chen

Recent works on knowledge base question answering (KBQA) retrieve subgraphs for easier reasoning. The desired subgraph is crucial as a small… (voir plus) one may exclude the answer but a large one might introduce more noises. However, the existing retrieval is either heuristic or interwoven with the reasoning, causing reasoning on the partial subgraphs, which increases the reasoning bias when the intermediate supervision is missing. This paper proposes a trainable subgraph retriever (SR) decoupled from the subsequent reasoning process, which enables a plug-and-play framework to enhance any subgraph-oriented KBQA model. Extensive experiments demonstrate SR achieves significantly better retrieval and QA performance than existing retrieval methods. Via weakly supervised pre-training as well as the end-to-end fine-tuning, SR achieves new state-of-the-art performance when combined with NSM (He et al., 2021), a subgraph-oriented reasoner, for embedding-based KBQA methods. Codes and datasets are available online (https://github.com/RUCKBReasoning/SubgraphRetrievalKBQA)

2022-02-27

ArXiv (preprint)