Dopaminylation of endothelial TPI1 suppresses ferroptotic angiocrine signals to promote lung regeneration over fibrosis

Medicine Respiratory System Cell Biology Biochemistry Life Sciences Immunology
dopaminylation endothelial cells TPI1 ferroptosis lung regeneration fibrosis metabolism

Dopamine Modification of TPI1 Inhibits Ferroptosis Signaling in Vascular Endothelial Cells, Promoting Lung Regeneration and Inhibiting Fibrosis

Background

The regenerative capability of the lung enables it to restore its original functional tissue after injury. However, if this regenerative process is disrupted, it often leads to maladaptive repair and fibrosis. Despite this, research on how abnormal intercellular communication compromises regenerative functions in pulmonary fibrosis remains limited. Endothelial cells (ECs), located between the systemic circulation and epithelial and mesenchymal cells, play a crucial role in metabolic support and blood flow during lung growth. Additionally, endothelial cells provide paracrine/intracrine factors, communicating with neighboring epithelial and mesenchymal cells. However, it is unclear how endothelial cells integrate systemic signals to rapidly initiate a pro-regenerative vascular secretion program to trigger lung regeneration.

Research Objective

This study reveals that dopamine, a neurotransmitter, inhibits ferroptosis by modifying the enzyme triosephosphate isomerase 1 (TPI1) in endothelial cells, thereby promoting lung regeneration instead of fibrosis. The study explores the mechanism of TPI1 dopamine modification in endothelial cells and how it functions through enhancing glucose metabolism pathways.

Source of the Paper

The study is conducted by Chunheng Mo, Hui Li, Mengli Yan, and others from several laboratories at Sichuan University and Harbin Medical University. The paper was published in the August 6, 2024, issue of the journal Cell Metabolism.

Study Details

Workflow

  1. Single-cell RNA Sequencing Analysis and Western Blot Validation: The study first used a pneumonectomy (PNX) mouse model to perform single-cell RNA sequencing (scRNA-seq) and found selective upregulation of TGM2 in lung endothelial cells. Subsequently, Western Blot confirmed the upregulation of TGM2 protein in lung endothelial cells post-PNX.
  2. Endothelial Cell-Specific TGM2 Knockout: By crossing TGM2-floxed mice with mice expressing Cre recombinase specifically, researchers constructed endothelial cell-specific TGM2 knockout mice (TGM2iDEC/iDEC) and found impaired lung function, body weight, and lung volume post-PNX. Immunostaining and flow cytometry analysis showed inhibited proliferation of endothelial cells and type 2 alveolar epithelial progenitor cells (AEC2) and increased endothelial cell death in these mice.
  3. Genomic and Proteomic Analysis: By comparing the transcriptomes of knockout and control group endothelial cells, ferroptosis-related pathways were significantly enriched in TGM2 knockout mice. The importance of TGM2-dependent dopamine modification in regulating lung regeneration was evidenced through knockout mouse experiments.
  4. Chemical Proteomics Analysis: Using synthesized clickable dopamine probes, combined with click chemistry reactions and mass spectrometry, dopamine-modified target proteins were identified in endothelial cells, revealing TPI1 as a major dopamine-modified protein.
  5. Functional Validation of TPI1 Dopamine Modification: Experiments with human umbilical vein endothelial cells (HUVECs) and knockout mice confirmed the inhibitory effect of TPI1 dopamine modification on ferroptosis.

Key Findings

  1. Impact of TGM2-Dependent Dopamine Modification on Lung Regeneration: In TGM2-deficient mice, ferroptosis in endothelial cells can be reversed by restoring the expression of ferroptosis suppressor protein 1 (FSP1), thereby enhancing lung regeneration.
  2. Mechanism of TPI1 Dopamine Modification: Experimental results showed that dopamine, through the action of TGM2 enzyme, modifies the glutamine residue (Q65) on TPI1, shifting its function from ether lipid synthesis to glucose metabolism, thus reducing lipid peroxidation and inhibiting ferroptosis.
  3. Promotion of Lung Regeneration by TPI1 Dopamine Modification: In mouse models, restoring dopamine modification of TPI1 expression in endothelial cells significantly improved lung functional recovery and reduced the expansion of fibrotic tissue.
  4. Decoding of Ferroptosis Interaction Network: Using integrated molecular dynamics simulations, the study revealed how TPI1’s Q65 dopamine modification enhances its contact with the substrate DHAP, redirecting its catalytic activity to GAP, boosting glucose metabolism and reducing lipid peroxidation.

Important Conclusions

  1. Scientific Value: This study enriches the understanding of how endothelial cells integrate systemic signals for organ regeneration by revealing the critical role of dopamine modification in lung regeneration. This finding advances the understanding of the regulatory mechanisms of vascular endothelial cells in lung function recovery.
  2. Practical Application: Repairing the dopamine modification of TPI1 can halt fibrosis progression in injured lungs, offering new possibilities for treating pulmonary fibrosis diseases. This strategy provides new targets and therapeutic approaches by enhancing glucose metabolism and inhibiting lipid peroxidation.

Study Highlights

  1. Discovery of TGM2-Dependent Dopamine Modification Pathway: This study, for the first time, revealed the key role of TGM2 in dopamine modification in lung endothelial cells and clarified how this modification promotes lung regeneration by regulating TPI1 activity.
  2. Application of Multidimensional Chemical Proteomics: Using innovative chemical proteomics strategies, TPI1 was successfully identified as a primary target for dopamine modification, demonstrating the potential of this experimental method in exploring protein modification mechanisms.
  3. Analysis of Catalytic Mechanism of Q65 Dopamine Modification: Through molecular dynamics simulations, the research team detailed how Q65 dopamine modification enhances the catalytic activity of TPI1 by altering its conformation.

Other Valuable Information

  1. Future Research Directions: The study suggests exploring the specific signaling pathways of dopamine modification in lung regeneration and its potential roles in other organs in the future.
  2. Therapeutic Potential: The study demonstrates that injection of synthesized dopamine probe Pro-DA effectively enhances dopamine modification levels of TPI1, indicating potential clinical treatment applications.

Conclusion

By revealing the pivotal role of dopamine modification in lung regeneration, this study provides new perspectives and potential therapeutic targets for understanding and treating pulmonary fibrosis. The research team’s multidimensional analysis and experimental strategy offer detailed molecular mechanisms, laying a solid foundation for future research and clinical applications.