Abstract 13283: Mitochondrial DNA Damage and Remodelling of Nucleoid Bodies in Pulmonary Artery Smooth Muscle Cells From Human Patients With Pulmonary Arterial Hypertension
Bibliographic record
Abstract
Introduction: Pulmonary arterial hypertension (PAH) is an obstructive pulmonary vasculopathy characterized by pulmonary artery smooth muscle cell (PASMC) hyperproliferation. PAH-PASMC have mitochondrial defects, including increased fragmentation, and increased production of reactive oxygen species (ROS). Mitochondrial-derived ROS can cause DNA damage. Mitochondrial DNA (mtDNA) is surrounded by replication proteins which form nucleoid bodies (NB). Hypothesis: We hypothesize that mtDNA damage is increased and NB structure altered in human PAH PASMC. Methods & Results: We profiled mtDNA and NB composition and integrity in control and PAH PASMC (n = 5/group). mtDNA content was assessed via confocal immunofluorescence of discrete extranuclear double-stranded DNA colocalized with mitochondria. Lower mtDNA content was observed in PAH PASMC vs control (1.8±0.2 vs 3.5±0.2 mtDNAs/μm 3 mitochondria, p<0.0001). Reduced mtDNA in PAH vs control was validated by qPCR (0.69±0.07 vs 1.00±0.07 ng mtDNA/μg cellular protein, n=4-5, p=0.0182). siRNA targeting of Mitofusin2 (Mfn2) in normal PASMC to mimic the mitochondrial fragmentation of PAH, reduced total mtDNA compared to control (1.05±0.06 vs 3.5±0.2 mtDNA/μm 3 mitochondria, n=9, p<0.0001), suggesting increased fission reduces mtDNA expression. Amplification of an 8.8kb mtDNA fragment, a measure of mtDNA damage, revealed increased damage in PAH vs control (14.3±3.9 vs 28.7±2.4 pg mtDNA, n=4, p=0.02). PAH PASMC exhibited higher expression of NB proteins vs control (n=5/measurement): TFAM (+96.7±23.3%, p=0.0032), SSBP (+63.4±14.4%, p=0.0023), and POLG (+59.0±24.0%, p=0.0397). These results were confirmed via immunoblotting for TFAM (+161.9±39.3%, n=4-5, p=0.0045) . Immunofluorescence verified increased TFAM in PAH PASMC vs control. Conclusions: We report a paradoxical upregulation of NB proteins despite reduced mtDNA content and elevated mtDNA damage in PAH. We speculate there is an unsuccessful compensatory attempt to restore mtDNA levels by increasing the expression of mtDNA’s replication apparatus in PAH PASMC.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.004 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".