ALDOB K87 Lactylation Orchestrates Mitochondrial Fission in PH

Study Background and Research Question

Pulmonary hypertension (PH) is a progressive and life-threatening disorder characterized by pulmonary vascular remodeling, occlusive arteriopathy, and eventual right ventricular failure. Despite recent advances, the molecular drivers of the abnormal proliferation and migration of pulmonary artery smooth muscle cells (PASMCs)—key contributors to vascular remodeling—remain incompletely understood. The role of metabolic reprogramming, particularly the shift from oxidative phosphorylation to aerobic glycolysis (the Warburg effect), in PH pathogenesis is increasingly recognized. However, the mechanistic bridge connecting these metabolic shifts to cellular phenotypes and vascular pathology is not fully elucidated (paper).

Key Innovation from the Reference Study

The paper by Yi et al. introduces a novel post-translational modification—lactylation of aldolase B (ALDOB) at lysine 87 (K87)—as a pivotal molecular switch in the regulation of mitochondrial dynamics and metabolic reprogramming in PH. This study is the first to demonstrate that hypoxia-induced ALDOB-K87 lactylation recruits dynamin-related protein 1 (DRP1) to mitochondria, thereby promoting mitochondrial fission. This mechanistic insight highlights a lactate–ALDOB–DRP1 axis that links heightened glycolytic activity and lactate accumulation to pathological PASMC proliferation and vascular remodeling in PH (paper).

Methods and Experimental Design Insights

To dissect the role of ALDOB lactylation, the authors employed integrated lactylomic proteomic profiling in hypoxic human PASMCs and validated their findings in rodent models of PH. Key methodological components included:

• Lactylome sequencing to identify and quantify protein lactylation sites, particularly ALDOB-K87.
• Genetic manipulation of ALDOB (including lactylation-mimetic and -deficient mutants) to examine causal roles in mitochondrial dynamics and cell proliferation.
• Pharmacological and genetic interventions targeting ALDOB lactylation, with assessment of mitochondrial morphology, DRP1 recruitment, and PASMC proliferation under hypoxic conditions.
• Functional validation in vivo using rodent models of PH to test the impact of ALDOB lactylation modulation on disease progression.

The study also leveraged immunoprecipitation and immunoblotting to probe protein interactions, and high-resolution microscopy to quantify mitochondrial fission events.

Core Findings and Why They Matter

The study’s principal findings can be summarized as follows:

1. ALDOB-K87 lactylation is upregulated in hypoxic PASMCs and PH rodent models. This modification amplifies glycolytic flux and lactate accumulation, creating a feed-forward loop that sustains lactylation and metabolic reprogramming (paper).
2. Lactylated ALDOB recruits DRP1 via a SUMOylation-dependent mechanism. Specifically, ALDOB lactylation facilitates DRP1 deSUMOylation by sentrin/SUMO-specific peptidase 3 (SENP3), thereby enabling DRP1 translocation to mitochondria and promoting mitochondrial fragmentation—a process essential for PASMC proliferation and phenotypic switching.
3. Sirtuin 1 (SIRT1) acts as a delactylase for ALDOB, but is downregulated in PH. This loss of SIRT1 further sustains the pathological ALDOB lactylation state.
4. Genetic or pharmacological inhibition of ALDOB lactylation attenuates mitochondrial fission and vascular remodeling in vivo. Conversely, lactylation-mimetic ALDOB mutants worsen PH phenotypes, confirming the functional importance of this pathway.

These findings provide a mechanistic explanation for the long-observed metabolic reprogramming and enhanced proliferation of PASMCs in PH, extending beyond the classical view of energy metabolism to implicate post-translational protein modifications in disease progression. By linking glycolytic flux and lactate metabolism to mitochondrial dynamics, the study opens new avenues for targeted interventions aimed at halting or reversing pathological vascular remodeling.

Comparison with Existing Internal Articles

Several internal articles have addressed related facets of pulmonary vascular remodeling, cell proliferation, and the molecular underpinnings of PH:

• "ALDOB K87 Lactylation Drives Mitochondrial Fission in PH" provides a concise summary of the reference study, emphasizing the centrality of ALDOB lactylation in mitochondrial dynamics and smooth muscle proliferation. The current article expands on these findings by offering a detailed methodological and mechanistic context.
• "ALDOB K87 Lactylation Orchestrates Mitochondrial Fission in PH" similarly highlights the connection between post-translational modification and vascular remodeling, but the present discussion delves deeper into the signaling axis and therapeutic implications.
• For researchers interested in experimental approaches to smooth muscle cell proliferation, "PDGF-BB, Murine Recombinant Protein: Advanced Mechanisms and Applications in Vascular Remodeling Research" discusses the mitogenic effects of PDGF-BB signaling via PDGFR-α and PDGFR-β, complementing the mechanistic insights from the ALDOB study with established growth factor paradigms.

Together, these resources provide a comprehensive context for understanding how metabolic and growth factor signaling converge in PH pathogenesis.

Limitations and Transferability

While the reference study offers a compelling mechanistic framework, several limitations and considerations should be noted:

• Translational Relevance: Most mechanistic insights were derived from cell culture systems (human PASMCs) and rodent PH models. Although these models are highly informative, their direct applicability to human PH patients requires further clinical validation (paper).
• Specificity of the ALDOB-DRP1 Axis: The study focuses on ALDOB-K87 lactylation, but other glycolytic enzymes and post-translational modifications may also contribute to mitochondrial dynamics in PH—a question for future research.
• Therapeutic Targeting: Pharmacological strategies to modulate protein lactylation are still in their infancy, with off-target effects and delivery challenges yet to be fully addressed.

These caveats underscore the need for further studies, particularly those integrating proteomic, genomic, and clinical approaches.

Protocol Parameters

• cell proliferation assay | ED50 < 2 ng/ml (PDGF-BB, murine recombinant protein) | murine BALB/c 3T3 cells | Confirms mitogenic potency for proliferation studies | product_spec
• reconstitution buffer | 100 mM acetic acid with 0.1% BSA | applicable for recombinant PDGF-BB in vitro use | Ensures solubility and protein stability | product_spec
• storage conditions | 4°C (1 week) or -20°C (long-term, reconstituted) | general laboratory workflows | Maintains biological activity and reproducibility | product_spec
• growth factor dose range | 0.1–1.0 mg/ml (stock solution) | recommended for pilot optimization in cell-based assays | Enables titration for cell-specific responses | workflow_recommendation

Research Support Resources

For researchers aiming to explore PDGF-BB mitogen activity, smooth muscle cell proliferation, or elucidate growth factor signaling in vascular remodeling, validated reagents such as PDGF-BB, murine recombinant protein (SKU P1048) can facilitate rigorous cell proliferation assays and mechanistic studies. As highlighted above, this reagent is confirmed for mitogenic activity in murine cell lines and supports reproducibility in research use applications (source: product_spec). For detailed workflow optimization, consult the manufacturer's guidelines and internal reviews, such as "Optimizing Cell Proliferation Assays with PDGF-BB, murine recombinant protein".

Outlook

The discovery of ALDOB-K87 lactylation as a regulator of mitochondrial fission and metabolic reprogramming significantly advances our understanding of PH pathogenesis. This work paves the way for targeted approaches that disrupt pathological metabolic-epigenetic coupling, with the potential to mitigate abnormal PASMC proliferation and vascular remodeling. As research progresses, integrating these mechanistic insights with established growth factor pathways may yield more effective intervention strategies for pulmonary hypertension (paper).