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Melemedjian, O.

Publications and source records attributed to Melemedjian, O..

2 recordsLinked to original sources

Transcript architecture predetermines m6A remodeling and sensory neuron vulnerability in chemotherapy-induced peripheral neuropathy

Whether individual transcripts carry intrinsic features that predetermine their response to perturbations is unknown. Here we used nanopore direct RNA sequencing of male mouse dorsal root ganglia (DRG) to simultaneously profile N6-methyladenosine (m6A) modifications, poly(A) tail dynamics, and full-length isoform identity from mice treated with bortezomib, a proteasome inhibitor that causes painful peripheral neuropathy. Machine learning revealed that transcript-intrinsic features predetermine the magnitude of perturbation-induced m6A loss (R{superscript 2} = 0.983). Expression level contributed just 2.6% of predictive importance. Bortezomib removed a fixed [~]73.5% fraction of m6A marks, meaning absolute loss scaled linearly with baseline density and a transcripts epitranscriptomic fate was encoded in its architecture before drug exposure. Unsupervised clustering identified four response programs where the dominant m6A erosion cluster enriched for oxidative phosphorylation (OXPHOS, p = 1.0 x 10-{superscript 1}) and proteasome (p = 2.8 x 10-{superscript 1}) genes, recapitulating bortezomibs established mechanisms without prior biological knowledge. Isoform-resolved analysis uncovered m6A remodeling patterns suggesting post-transcriptional regulation of glycolytic and OXPHOS genes, and Western blot confirmed protein-level suppression of OXPHOS components. Integration with single-nuclei sequencing showed sensory neurons carried 2.2-fold greater m6A loss burden than non-neuronal cells, a direct consequence of architectural determinism applied to cell-type-specific transcriptomes. These findings establish that epitranscriptomic bortezomib response is predetermined by transcript architecture, with pathway specificity and cell-type vulnerability emerging as downstream consequences of intrinsic RNA structure.

neuroscience↗

Sex-dependent changes in insular cortex connectivity in a rat model of comorbid pain

Temporomandibular disorder (TMD) and irritable bowel syndrome (IBS) are two highly comorbid, nociplastic pain conditions that belong to a broader group of commonly co-occurring chronic pain conditions. Most of these chronic overlapping pain conditions (COPCs), including TMD and IBS, disproportionately affect females and are highly stress sensitive. Our previous study illustrated sex differences in brain activity during colorectal distension specific to our model of comorbid pain hypersensitivity (CPH), in which masseter muscle inflammation followed by restraint stress elicits IBS-like visceral hypersensitivity. Since insular cortex (Ins) activity increased in female CPH rats only and abnormal Ins activity has been identified in TMD and IBS patients, we sought to characterize patterns of Ins-based functional connectivity (FC) by performing functional MRI (fMRI) scans at baseline, 1 week, and 7 weeks post-injury/stress in groups of male and female Sprague-Dawley rats randomized to the following conditions: CPH, stress-induced hypersensitivity (SIH), Complete Freunds Adjuvant (CFA)-induced masseter muscle inflammation, and naive. CPH females displayed extensive Ins FC with brain regions in the cortex and limbic system, including the thalamus. Compared to CPH males, CPH females showed robust insular-thalamo connectivity at week seven, a time point where visceral hypersensitivity and referred pain-like behavior persists in CPH females but not males. This trend is also apparent in CPH females week seven versus week one Ins FC, whereas CPH males tend to decrease Ins FC broadly. These findings potentially suggest sensitization within the insular-thalamo and -cortical networks in CPH females, warranting future investigation of Ins circuit involvement in comorbid pain.

neuroscience↗