ALDOB K87 Lactylation Regulates Mitochondrial Fission in Pulmonary Hypertension

Study Background and Research Question

Pulmonary hypertension (PH) is a progressive, life-threatening vascular disorder marked by abnormal proliferation and migration of pulmonary artery smooth muscle cells (PASMCs), ultimately resulting in vascular remodeling and right heart failure. Despite advances in vasodilator-based therapies, long-term survival remains poor, with a five-year survival rate below 65%. A growing body of evidence indicates that metabolic reprogramming—specifically, a shift from oxidative phosphorylation to glycolysis (the Warburg effect)—is central to PASMC pathobiology in PH. However, the molecular links between metabolic remodeling, mitochondrial dynamics, and smooth muscle cell proliferation have remained elusive.

Key Innovation from the Reference Study

The recent study by Yi et al. (2026) uncovers a previously unappreciated role for lysine lactylation of aldolase B (ALDOB) at residue K87 in regulating mitochondrial fission and metabolic rewiring in PH. By integrating lactylomic profiling with in vitro and in vivo models, the authors reveal that hypoxia-induced lactate accumulation drives ALDOB K87 lactylation, which in turn orchestrates a signaling cascade involving dynamin-related protein 1 (DRP1) recruitment to mitochondria. This mechanistic axis connects lactate metabolism with pathological mitochondrial fragmentation and PASMC proliferation, offering a new molecular framework for understanding and potentially intervening in PH progression.

Methods and Experimental Design Insights

The study employed a comprehensive multi-tiered approach to dissect the role of ALDOB K87 lactylation in PH:

• Lactylome Sequencing: Hypoxic human PASMCs were profiled to identify global changes in protein lactylation. ALDOB K87 emerged as a significantly upregulated lactylation site.
• Rodent PH Models: Findings from cell-based assays were validated using rodent models of PH, ensuring translational relevance.
• Functional Manipulation: Genetic and pharmacological tools were used to modulate ALDOB lactylation (including lactylation-mimetic and lactylation-deficient mutants), allowing causal inference regarding its impact on mitochondrial structure and cell proliferation.
• Protein Interaction and Localization Studies: The recruitment of DRP1 to mitochondria was tracked, and the role of sentrin/SUMO-specific peptidase 3 (SENP3) in mediating DRP1 deSUMOylation was interrogated.
• Delactylase Investigation: Sirtuin 1 (SIRT1) was identified and validated as a delactylase for ALDOB, with expression modulation experiments confirming its regulatory significance in PH context.

This layered design allowed the authors to move from global post-translational modification mapping through mechanistic dissection to disease modeling, bridging molecular, cellular, and organismal insights.

Core Findings and Why They Matter

The central findings of Yi et al. (2026) can be summarized as follows:

• ALDOB K87 Lactylation is Hypoxia-Induced and Self-Reinforcing: Under hypoxic conditions typical of PH, increased glycolytic flux leads to lactate buildup, which in turn amplifies ALDOB K87 lactylation. This forms a positive feedback loop, further driving glycolytic activity and lactate production.
• Lactylated ALDOB Recruits DRP1 via SENP3-Mediated DeSUMOylation: Post-translationally modified ALDOB recruits DRP1 to mitochondria, facilitated by SENP3-dependent DRP1 deSUMOylation. This promotes mitochondrial fission—a process shown to be central to the hyperproliferative PASMC phenotype in PH.
• Loss of SIRT1 Sustains Pathological Lactylation: SIRT1, downregulated in PH, acts as a delactylase, normally restraining ALDOB K87 lactylation. Its reduced activity in PH perpetuates the pathogenic signaling axis.
• Genetic or Pharmacological Suppression Ameliorates Disease: Targeted suppression of ALDOB lactylation in vivo attenuates mitochondrial fission, PASMC proliferation, and PH progression. Conversely, expression of a lactylation-mimetic ALDOB mutant exacerbates disease features.

These findings establish a lactate–ALDOB–DRP1 axis as a critical driver of mitochondrial and metabolic remodeling in PH, linking metabolic and structural determinants of PASMC pathology. The study thus points toward new intervention points—distinct from traditional vasodilator strategies—focused on metabolic and post-translational modification pathways.

Comparison with Existing Internal Articles

Several recent internal reviews have contextualized the importance of metabolic and mitochondrial dynamics in vascular research:

• "ALDOB K87 Lactylation Orchestrates Mitochondrial Fission in PH" and related articles similarly highlight the centrality of the lactate–ALDOB–DRP1 axis in PH pathogenesis, reinforcing the mechanistic links described by Yi et al. (2026). These reviews provide additional commentary on the interplay between metabolic flux and mitochondrial behavior in PASMCs.
• "Optimizing Cell Proliferation Assays with Murine Recombinant PDGF-BB" bridges metabolic remodeling research with assay development, including protocols for stimulating smooth muscle cell proliferation—a readout directly relevant to the pathogenic processes described in the reference study.
• For practical workflow translation, the guide "Applied Workflows with Murine Recombinant PDGF-BB in Vascular Research" details optimized approaches for controlling smooth muscle and connective tissue cell proliferation, which may be adapted for studies investigating the effects of metabolic and mitochondrial interventions.

Together, these internal resources complement the mechanistic advances of Yi et al. (2026) by providing actionable protocols and broader context for vascular remodeling assays.

Limitations and Transferability

While the study by Yi et al. (2026) provides compelling evidence for the lactate–ALDOB–DRP1 axis in PH, several limitations should be considered:

• Species and Model Specificity: Although both human cell-based and rodent models were used, further validation in primary human PH tissues and diverse animal models will be critical to generalizing the findings.
• Complexity of In Vivo Microenvironments: The in vitro PASMC proliferation and mitochondrial fission assays, while informative, may not fully recapitulate the complex cellular interactions within the pulmonary vasculature in vivo.
• Potential Off-Target Effects: Pharmacological interventions targeting lactylation or the ALDOB–DRP1 axis may have broader metabolic consequences that require careful assessment for translational relevance.

Nonetheless, the integration of multi-omics, functional, and in vivo approaches strengthens the study’s validity and transferability to future research aiming to modulate smooth muscle cell proliferation and mitochondrial dynamics in pulmonary vascular disease.

Protocol Parameters

• Hypoxia Induction: Expose PASMCs to 1% O₂ for 24–72 hours to model PH-like metabolic reprogramming.
• Lactylation Manipulation: Overexpress wild-type, K87-lactylation-deficient, or K87-lactylation-mimetic ALDOB constructs to dissect causal effects, as outlined in the reference study.
• Cell Proliferation Assay with PDGF-BB: Stimulate PASMCs with 2–10 ng/ml murine recombinant PDGF-BB for 24–48 hours to assess proliferation responses, as recommended in internal protocol guides.
• Mitochondrial Fission Analysis: Use immunofluorescence and live-cell imaging to quantify DRP1 localization and mitochondrial morphology following genetic or pharmacological manipulation.
• Delactylase Modulation: Modulate SIRT1 activity using siRNA knockdown or pharmacological inhibitors/activators to assess impact on ALDOB K87 lactylation status and downstream readouts.

Research Support Resources

For researchers aiming to replicate or extend these findings, the use of defined recombinant growth factors is essential for controlled PASMC proliferation assays. The PDGF-BB, murine recombinant protein (SKU P1048) from APExBIO provides a highly pure, biologically validated tool for stimulating smooth muscle and connective tissue cell proliferation, with an ED50 of less than 2 ng/ml as confirmed by proliferation of BALB/c 3T3 cells. This reagent can facilitate standardized cell proliferation workflows in PH-related metabolic and mitochondrial studies. For detailed assay strategies and troubleshooting, consult internal workflow resources linked above.