ProLLM: Protein Chain-of-Thoughts Enhanced LLM for Protein-Protein Interaction Prediction

The prediction of protein-protein interactions (PPIs) is crucial for understanding biological functions and diseases. Previous machine learning approaches to PPI prediction mainly focus on direct physical interactions, ignoring the broader context of nonphysical connections through intermediate proteins, thus limiting their effectiveness. The emergence of Large Language Models (LLMs) provides a new opportunity for addressing this complex biological challenge. By transforming structured data into natural language prompts, we can map the relationships between proteins into texts. This approach allows LLMs to identify indirect connections between proteins, tracing the path from upstream to downstream. Therefore, we propose a novel framework ProLLM that employs an LLM tailored for PPI for the first time. Specifically, we propose Protein Chain of Thought (ProCoT), which replicates the biological mechanism of signaling pathways as natural language prompts. ProCoT considers a signaling pathway as a protein reasoning process, which starts from upstream proteins and passes through several intermediate proteins to transmit biological signals to downstream proteins. Thus, we can use ProCoT to predict the interaction between upstream proteins and downstream proteins. The training of ProLLM employs the ProCoT format, which enhances the model’s understanding of complex biological problems. In addition to ProCoT, this paper also contributes to the exploration of embedding replacement of protein sites in natural language prompts, and instruction fine-tuning in protein knowledge datasets. We demonstrate the efficacy of ProLLM through rigorous validation against benchmark datasets, showing significant improvement over existing methods in terms of prediction accuracy and generalizability. Our results highlight the potential of LLMs to transform the field of PPI, serving as a robust potential tool for various categories of biological and medical research. The code is available at: https://github.com/MingyuJ666/ProLLM.

Paper

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Reviewer YsHM5/10 · confidence 4/52024-04-21

Summary

The paper introduces ProLLM, a new framework employing a LLM specifically tailored for predicting Protein-Protein Interactions (PPIs), crucial in understanding biological functions and diseases. It leverages a unique approach called Protein Chain-of-Thought (ProCoT), which simulates signaling pathways in natural language prompts to predict interactions, focusing on both physical and non-physical connections between proteins. ProLLM outperforms traditional graph-based methods and existing LLM approaches by incorporating protein-specific embeddings and instruction fine-tuning.

Rating

5

Confidence

4

Ethics flag

1

Reasons to accept

1. The paper introduces an innovative approach to solving PPI task, which improves prediction accuracy and meanwhile enhances the interpretability. 2. The authors provide a comprehensive survey in the Related Work section, detailing previous studies and advancements. 3. The overall presentation of the paper is of high quality. The text is well-crafted and fluid. The figures are clear and effective.

Reasons to reject

1. My primary concern lies with the practice in this paper behind flattening highly structured protein data into sequential language. The authors mention that "we directly integrate the protein vectors generated from ProtTrans into our model to replace the original word embedding in the protein name’s place", which describes their method of encoding protein data for the LLM. However, the paper lacks essential details and descriptions of how this protein encoder aligns with the backbone LLM. The specifics of how alignment training is conducted are also not clear. 2. The experimental analysis appears to be the weakest aspect of the paper. The analysis conducted is neither thorough nor solid. The authors do not delve deeply into exploring how their proposed ProCoT actually functions, nor do they examine scenarios where it might fail. There is a need for well-designed experiments to validate the mechanisms described in section 3.1.3, which would significantly strengthen the conclusions and its robustness.

Questions to authors

See above

Reviewer bZnW6/10 · confidence 4/52024-05-08

Summary

- The paper presents a sophisticated approach that leverages large language models (LLMs) to predict protein-protein interactions (PPIs) by representing the complex signaling pathways in a natural language format. The use of the Protein Chain of Thought (ProCoT) to simulate signaling pathways as a reasoning chain is a unique method that effectively blends computational biology with advanced NLP techniques. - The paper is well-structured, methodologically sound, and systematically presented. The inclusion of detailed figures, such as the ProLLM framework and examples of ProCoT, enhances the clarity and understandability of the proposed method. - The concept of using LLMs, specifically the adapted Flan-T5 model infused with protein-specific embeddings, for modeling PPIs through natural language is novel and innovative. The introduction of ProCoT as a means to contextualize protein interactions within signaling pathways demonstrates original thinking. - The significance of this work is high, as it proposes a new avenue for PPI prediction which is crucial for understanding biological functions and the mechanism of diseases. The results show a significant improvement over existing methods, which could influence future research in computational biology and drug development.

Rating

6

Confidence

4

Ethics flag

1

Reasons to accept

- Innovative Conceptual Framework: The paper introduces an innovative method of simulating protein signaling pathways using natural language processing models. By transforming protein interactions into a chain of reasoning with the ProCoT format, the paper leverages the power of LLMs, such as Flan-T5, in a novel biological context. This approach is pioneering as it merges two distinct fields: computational biology and language modeling. This methodology could lead to more intuitive and explainable models for protein interaction, which are crucial for understanding complex biological processes and drug discovery. - Impressive Performance: The model demonstrates superior performance metrics, particularly in terms of prediction accuracy and generalizability across multiple datasets, as indicated by the micro-F1 scores provided. The performance improvements are robust, with ProLLM outperforming existing graph-based and LLM-based methods significantly. The high performance indicates that ProLLM can be a more effective tool in the predictive analysis of PPIs, which could transform how researchers approach the prediction of biological interactions. - Potential for Broad Impact: The model's ability to accurately predict interactions can directly contribute to better understanding of diseases and the development of therapeutic strategies, especially in complex diseases like cancer where protein interactions play a crucial role. Beyond immediate research applications, the methodology could be adapted for other types of molecular or genetic interactions, broadening its impact. - Well-Documented and Reproducible Research: The authors provide access to source code and detailed documentation, which facilitates replication and further investigation by other researchers. This openness not only enhances the scientific integrity of the research but also encourages further innovations and improvements by the broader scientific community.

Reasons to reject

- Scope of Evaluation and Applicability: While the paper presents strong performance on benchmark datasets, these datasets often have well-defined and controlled conditions that may not adequately represent the messy, heterogeneous data encountered in real-world biological research. This raises concerns about the model's robustness and effectiveness outside of academic test conditions. The focus on specific datasets might have tailored the model excessively to those conditions. There is insufficient evidence on how well the model adapts to datasets with different characteristics or to PPI predictions in less-studied organisms, which limits the understanding of its broader applicability. - Practical Implications for Broader Adoption: The computational demands for training and running such large-scale models, especially when fine-tuning with extensive protein datasets, might be prohibitive for many research institutions, particularly those with limited IT infrastructure. The dynamic nature of both biological research (with continually updating data and new protein interactions being discovered) and machine learning models (requiring regular updates to maintain performance) poses significant challenges in maintaining the relevance and accuracy of the model over time. - Potential Overfitting and Model Bias: The use of a highly complex model architecture, such as a large language model tailored with specific protein data, increases the risk of overfitting. This concern is exacerbated if the model has been overly optimized for high performance on the benchmark datasets without sufficient regularization or cross-validation strategies. The adaptation of language models to biological data involves assumptions and simplifications that may introduce biases, particularly in how protein interactions are represented and predicted. These biases could affect the predictive accuracy when the model is applied to new or different types of protein data, leading to erroneous conclusions or missed interactions.

Questions to authors

- Can you elaborate on how ProLLM handles the variability and potential noise in real-world biological datasets? - How does ProLLM ensure that the model does not overfit to the training data, given the complexity of the model and the specificity of the datasets used? - Given the innovative use of language models in predicting PPIs, what are the limitations of this approach in terms of computational resources and scalability?

Reviewer F5aN8/10 · confidence 4/52024-05-13

Summary

This manuscript introduces an approach for predicting protein-protein interactions, especially those due to indirect interactions, such as those found in a pathway. The approach uses an LLM that has been upgraded with protein vectors, fine-tuned for protein tasks, and - most importantly - set up using chain-of-thought to reason through the process step by step.

Rating

8

Confidence

4

Ethics flag

1

Reasons to accept

Protein-protein interaction prediction is a critical task for understanding biological systems, with applications across all of biology and medicine. This manuscript is well-written, with a discussion of related work that appears to be comprehensive, and with a very comprehensive evaluation and results that clearly support the methods proposed. Moreover, as stated by the manuscript, this may be the first work to explore protein-protein interaction as a natural language inference problem.

Reasons to reject

The only concerns I have are quite minor: 1. It would be helpful to explain a bit better why indirect protein-protein interactions are so important and difficult. 2. The manuscript refers to the approach as converting the PPI prediction into a natural language processing problem. While quite possibly true, natural language processing is a very large field. I believe that the task here would be more specifically termed natural language inference or, possibly, natural language understanding. 3. Section 3.1.2 references the principles of "co-expression" and "co-localization" but these are not defined. And a couple of edits: 1. I think "learn the law of signal pathways" (page 2) would be more accurate as "learn the mechanism of signal pathways." 2. In section 4.2 "Procot" should probably by "ProCoT"

Questions to authors

Given the strong performance, the ProTrans embeddings clearly work well with the other embeddings used. However different training processes typically do not produce embeddings that align in this way. How was this accomplished?

Reviewer rKT97/10 · confidence 3/52024-05-23

Summary

The authors introduce a novel framework, ProLLM that uses LLMs to investigate PPIs. For this, they devise ProCoT that transforms the gene signaling pathways and protein functions into NL prompts. They discuss how to train and fine tune ProCoT. Experiments and ablation studies are provided that demonstrate the robustness of ProLLM. The paper is well written, and previous literature and gaps in the field are thoroughly discussed.

Rating

7

Confidence

3

Ethics flag

1

Reasons to accept

The proposed method seems to be effective; the work shows the importance of using an LLM for PPI for the first time.

Reasons to reject

None

Questions to authors

* Related to Definition 2 and thereafter: How can prompts handle the diverse and various nature of feedback/feedforward loops amongst the genes/proteins? For example, many of these connections are triggered by environmental cues. While it is impossible to know all/what the environmental contexts are, how are the authors making sure that, at least, the canonical pathway directions are captured sans context? * Section 3.1.2. Expand DFS in the main text (and then refer to it in the appendix)

Reviewer F5aN2024-05-31

Thank you for the response. These all make sense and I assume there will be (very minor) updates to the manuscript. My (positive) recommendation remains unchanged.

Authorsrebuttal2024-06-01

Thank you very much for your support and feedback. We will add the new clarification in the revised version.

Authorsrebuttal2024-06-06

A Friendly Reminder

Dear Reviewer YsHM, Thanks again for your valuable comments and precious time. As the author-reviewer discussion period draws to a close, we genuinely hope you could have a look at the new results and clarifications and kindly let us know if they have addressed your concerns. We would appreciate the opportunity to engage further if needed. Best, Authors of Paper 51

Authorsrebuttal2024-06-06

A Friendly Reminder

Dear Reviewer bZnW, Thanks again for your valuable comments and precious time. As the author-reviewer discussion period draws to a close, we genuinely hope you could have a look at the new results and clarifications and kindly let us know if they have addressed your concerns. We would appreciate the opportunity to engage further if needed. Best, Authors of Paper 51

Program Chairsdecision2024-07-10

Decision

Accept

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