ALDOB K87 Lactylation Regulates Mitochondrial Fission and Metabolic Remodeling in Pulmonary Hypertension

Study Background and Research Question

Pulmonary hypertension (PH) is a fatal cardiopulmonary disorder characterized by progressive pulmonary vascular remodeling, occlusive lesions, and right ventricular failure. Despite advances in vasodilator therapies, the 5-year survival rate for patients remains below 65% (source: paper). A hallmark of PH pathogenesis is the abnormal proliferation and phenotypic switching of pulmonary artery smooth muscle cells (PASMCs), driven by complex metabolic reprogramming. While the Warburg effect—a shift from oxidative phosphorylation to aerobic glycolysis—has been observed in PH vascular cells, the molecular mechanisms linking this metabolic shift to pathological remodeling are incompletely understood. Recent research has highlighted the role of lactate not only as a metabolic byproduct but also as a substrate for protein post-translational modifications such as lactylation. However, the functional impact of non-histone protein lactylation in PH, particularly in vascular smooth muscle cell biology, has remained unclear. This study addresses the critical question: does lactylation of specific glycolytic enzymes directly regulate mitochondrial dynamics and cellular phenotype in PH?

Key Innovation from the Reference Study

The central innovation of the study by Yi et al. is the identification of lysine 87 (K87) lactylation on aldolase B (ALDOB) as a pivotal regulator of mitochondrial fission and metabolic rewiring in PH (source: paper). By integrating lactylomic profiling, molecular biology, and functional assays, the authors reveal a previously uncharacterized lactate–ALDOB–DRP1 signaling axis. This axis couples elevated glycolytic flux and lactate accumulation to increased mitochondrial fragmentation and smooth muscle cell proliferation—key drivers of PH progression. Importantly, the study demonstrates that ALDOB K87 lactylation is not merely a biomarker but actively recruits dynamin-related protein 1 (DRP1) to mitochondria through SUMO-specific peptidase 3 (SENP3)-mediated deSUMOylation of DRP1. This mechanistic insight provides new potential targets for therapeutic intervention in PH.

Methods and Experimental Design Insights

The authors employed a comprehensive lactylomic approach to profile protein lactylation in hypoxic human PASMCs and validate findings in rodent PH models. Key methodological elements include:

• Lactylome Sequencing: High-resolution mass spectrometry identified significantly elevated lactylation at ALDOB K87 under hypoxic conditions corresponding to PH models.
• Genetic and Pharmacological Modulation: The use of lactylation-mimetic and non-lactylatable ALDOB mutants, as well as pharmacological inhibitors, allowed direct assessment of K87 lactylation function.
• Functional Assays: The study assessed mitochondrial morphology, glycolytic flux, cell proliferation, and migration using imaging, metabolic, and proliferation assays.
• In Vivo Validation: Rodent models of PH were used to confirm the functional impact of ALDOB K87 lactylation on disease phenotype and vascular remodeling.

This rigorous experimental design enabled the authors to dissect the causal relationship between ALDOB lactylation, mitochondrial dynamics, and smooth muscle cell behavior.

Core Findings and Why They Matter

The main findings of the study include:

• Hypoxia-Induced ALDOB K87 Lactylation: Chronic hypoxia in PASMCs led to marked ALDOB K87 lactylation, amplifying glycolytic activity and lactate production (source: paper).
• Lactylation-Driven Mitochondrial Fission: ALDOB K87 lactylation promoted DRP1 recruitment to mitochondria via SENP3-mediated deSUMOylation, accelerating mitochondrial fragmentation and enhancing PASMC proliferation and migration.
• SIRT1 as a Delactylase: SIRT1 was identified as a delactylase for ALDOB; its downregulation in PH sustained pathological lactylation and disease progression.
• Therapeutic Modulation: Genetic or pharmacological inhibition of ALDOB lactylation reduced mitochondrial fission and attenuated PH progression in vivo, while lactylation-mimetic mutants exacerbated disease features.

These discoveries establish ALDOB K87 lactylation as a mechanistic bridge between metabolic reprogramming and mitochondrial dynamics in PH. The findings expand the current understanding of non-histone lactylation in vascular remodeling and open new avenues for targeted intervention.

Comparison with Existing Internal Articles

Several internal resources contextualize these findings:

• "PDGF-BB, Murine Recombinant Protein: Metabolic Reprogramming and Smooth Muscle Cell Proliferation in Pulmonary Hypertension Research" discusses how murine recombinant PDGF-BB acts as a potent mitogen for smooth muscle cells and can drive metabolic changes similar to those observed in PH models. While that article focuses on PDGF-BB's direct mitogenic role, the current study elucidates a distinct but complementary metabolic pathway—ALDOB K87 lactylation—that also drives aberrant PASMC proliferation.
• "PDGF-BB, Murine Recombinant Protein: Molecular Pathways and Assay Precision" details optimized protocols for smooth muscle cell proliferation assays with PDGF-BB, providing practical frameworks for studying similar mitogen-driven phenomena. This complements the current work by offering validated experimental tools to dissect the downstream effects of metabolic remodeling.
• "ALDOB K87 Lactylation Drives Mitochondrial Fission in PH" provides an accessible overview of the mechanistic axis described in the reference study, supporting the integration of lactylomic and functional data.

Together, these resources highlight the multifaceted approaches available for studying smooth muscle cell proliferation and metabolic reprogramming in vascular disease.

Limitations and Transferability

Despite its innovative contributions, the study has several limitations:

• Translational Gaps: While rodent models closely mimic human PH, species differences in lactylation dynamics and SIRT1 regulation may affect direct translational relevance.
• Cellular Specificity: The focus on PASMCs leaves open questions about the impact of ALDOB lactylation in endothelial or adventitial cells within the pulmonary vasculature.
• Therapeutic Targeting: The feasibility and specificity of pharmacologically targeting ALDOB K87 lactylation in vivo require further investigation.

Nonetheless, the integration of lactylomic profiling, functional genomics, and in vivo validation provides a robust foundation for future studies aiming to translate these findings into clinical strategies.

Protocol Parameters

• cell proliferation assay | 2–10 ng/mL PDGF-BB | smooth muscle cell proliferation | Established effective range for mitogen-driven proliferation of PASMCs and related cell types; supports assay sensitivity and reproducibility | product_spec
• cell proliferation assay | 0.1–1.0 mg/mL PDGF-BB (stock) | reagent preparation | Enables accurate dilution and stability for cell-based assays; aligns with solubility recommendations | product_spec
• hypoxic culture | 1–3% O2 | PASMC metabolic remodeling studies | Recapitulates pathophysiological oxygen levels in PH, supporting induction of glycolytic/lactylation pathways | workflow_recommendation
• mitochondrial fission assessment | live-cell imaging, DRP1 localization | metabolic and mitochondrial assays | Enables quantification of mitochondrial fragmentation and DRP1 recruitment following metabolic manipulation | workflow_recommendation

Research Support Resources

Researchers investigating smooth muscle cell proliferation, PDGFR-α and PDGFR-β signaling, and metabolic remodeling in PH can leverage validated reagents such as PDGF-BB, murine recombinant protein (SKU P1048). This non-glycosylated, E. coli-expressed growth factor supports reproducible cell proliferation assays and pathway interrogation in vascular research (source: product_spec). For detailed workflows and troubleshooting, refer to internal reviews on PDGF-BB mitogen activity and assay design (source: internal_article).