ALDOB K87 Lactylation Regulates Mitochondrial Fission in Pulmonary Hypertension

Study Background and Research Question

Pulmonary hypertension (PH) is a severe cardiopulmonary disorder characterized by progressive vascular remodeling, increased pulmonary arterial pressure, and eventual right ventricular failure. Despite advances in vasodilator-based therapies, the 5-year survival rate for PH remains below 65%, largely because existing treatments do not reverse occlusive arteriopathy or prevent pathological proliferation of pulmonary artery smooth muscle cells (PASMCs) (Yi et al., 2026). Recent research has highlighted the role of metabolic reprogramming in PASMCs—specifically, a shift from oxidative phosphorylation to aerobic glycolysis (the Warburg effect)—in driving these pathological changes. However, the molecular signals linking metabolic shifts to mitochondrial dynamics and cell proliferation in PH are not fully understood.

Key Innovation from the Reference Study

The study by Yi and colleagues introduces a critical mechanistic insight: the lactylation of aldolase B (ALDOB) at lysine 87 (K87) serves as a molecular switch that drives mitochondrial fission and metabolic reprogramming in PH. This work is the first to demonstrate that nonhistone protein lactylation—a post-translational modification previously known mainly for its epigenetic roles—regulates the activity of metabolic enzymes in vascular disease settings. Their findings establish the lactate–ALDOB–DRP1 axis as a central pathway linking hypoxia-induced metabolic changes to mitochondrial fragmentation and PASMC proliferation (Yi et al., 2026).

Methods and Experimental Design Insights

The investigators employed a comprehensive multi-modal approach to characterize lactylation dynamics and its downstream effects:

• Lactylomic Profiling: Hypoxic human PASMCs were subjected to mass spectrometry-based lactylome sequencing, revealing a pronounced increase in ALDOB K87 lactylation.
• Rodent PH Models: Findings were validated in established rodent models of PH, confirming the conservation of ALDOB K87 hyperlactylation in vivo.
• Functional Assays: The team used genetic manipulation (lactylation-mimetic and non-lactylatable ALDOB mutants) and pharmacological interventions to assess mitochondrial dynamics, PASMC proliferation, and PH progression.
• Protein Interaction Studies: Co-immunoprecipitation and molecular biology techniques were used to map the interaction between lactylated ALDOB, dynamin-related protein 1 (DRP1), and the SUMOylation machinery.

For cell proliferation measurements, protocols such as the 5-ethynyl-2'-deoxyuridine imaging kit, which enable sensitive cell cycle S-phase DNA synthesis measurement, are often employed, although this specific methodology was not explicitly detailed in the main paper.

Protocol Parameters

• Hypoxic treatment of PASMCs: Typically 1% O₂ for 24–72 hours to induce metabolic reprogramming and lactylation events.
• Lactylome sequencing: Protein extraction and trypsin digestion followed by enrichment for lactylated peptides and LC-MS/MS analysis.
• In vivo PH induction: Chronic hypoxia or monocrotaline administration in rodents, with assessment of pulmonary artery pressure and right ventricular hypertrophy.
• Mitochondrial fission assays: Fluorescence microscopy with mitochondrial markers to assess fragmentation.
• Cell proliferation analyses: BrdU or EdU-based assays, flow cytometry, and Ki-67 immunofluorescence (see internal resources for EdU-specific workflows).

Core Findings and Why They Matter

The study's central discovery is that hypoxia-induced ALDOB K87 lactylation amplifies glycolytic flux in PASMCs, resulting in a self-reinforcing loop of lactate production and protein lactylation (Yi et al., 2026). Mechanistically, lactylated ALDOB recruits DRP1 to mitochondria by promoting its deSUMOylation via sentrin/SUMO-specific peptidase 3 (SENP3), triggering mitochondrial fission. This process drives PASMC proliferation, migration, and phenotypic switching—core features of vascular remodeling in PH. Importantly, sirtuin 1 (SIRT1) acts as a delactylase for ALDOB, and its downregulation in PH sustains this pathological axis. In vivo, both genetic and pharmacological suppression of ALDOB lactylation attenuated mitochondrial fission and PH progression, while lactylation-mimetic mutants exaggerated disease features.

By defining this lactate–ALDOB–DRP1 axis, the study bridges metabolic reprogramming with mitochondrial structural changes, providing a molecular explanation for the persistent PASMC proliferation underlying PH. This mechanistic insight not only deepens our understanding of PH biology but also suggests novel intervention points distinct from the conventional focus on vasodilation.

Comparison with Existing Internal Articles

Recent internal resources highlight the utility of the 5-ethynyl-2'-deoxyuridine imaging kit (EdU Imaging Kits (Cy5)) for sensitive and morphology-preserving cell proliferation assays. For example, the article "EdU Imaging Kits (Cy5): Benchmarking S-Phase DNA Synthesis Detection" details how EdU assays leverage click chemistry for artifact-free, high-specificity DNA synthesis measurement—essential for quantifying PASMC proliferation in metabolic and genotoxicity research. Another internal review ("EdU Imaging Kits (Cy5): Advanced Click Chemistry for Cell Cycle Analysis") discusses the advantages of fluorescence microscopy and flow cytometry DNA replication assays using EdU over traditional BrdU methods, particularly in preserving antigen binding and nuclear integrity.

Although the reference study does not explicitly detail EdU-based quantification, such approaches are highly compatible with the cellular assays required to dissect metabolic and proliferation dynamics in PH models. The referenced internal articles provide practical guidelines for integrating these techniques into workflows investigating epigenetic and metabolic regulation.

Limitations and Transferability

While the findings establish ALDOB K87 lactylation as a central regulator in rodent and cell-based PH models, several limitations warrant consideration:

• The translational relevance to human PH patients, particularly across diverse etiologies, remains to be validated in clinical studies.
• Potential off-target consequences of targeting ALDOB lactylation or DRP1-mediated fission are not fully characterized and may influence mitochondrial function in other tissues.
• The study primarily focuses on PASMCs; contributions from endothelial cells and fibroblasts in vascular remodeling should be systematically addressed in future work.

Nevertheless, the mechanistic clarity and multi-modal validation enhance the robustness and transferability of these findings, offering a foundation for further translational exploration.

Research Support Resources

For researchers aiming to study cell proliferation, metabolic regulation, or genotoxicity assessment in the context of pulmonary hypertension and mitochondrial dynamics, sensitive and specific DNA synthesis tools are essential. The EdU Imaging Kits (Cy5) (SKU K1076) from APExBIO provide a reliable alternative to traditional BrdU assays, enabling precise quantification of S-phase DNA synthesis without harsh denaturation, thus preserving cell morphology and antigenicity. These kits are well-suited for fluorescence microscopy and flow cytometry applications, as outlined in several internal workflow articles. Incorporating such tools can support advanced investigation into the links between metabolic reprogramming, mitochondrial fission, and pathological cell proliferation.