Publications by Year: 2026

Prescription opioid abuse remains a critical public health concern and is a major risk factor for the development of opioid use disorder (OUD). Thus, there is an urgent need to better understand the neurobiological mechanisms underlying OUD in order to develop therapeutics and address the ongoing opioid epidemic. In this study, we hypothesized that microRNAs regulate gene expression changes following oxycodone self-administration. To test our hypothesis, we utilized a long-access drug self-administration paradigm in rats. Briefly, adult male Sprague-Dawley rats were trained to self-administer oxycodone (0.15mg/kg/infusion) or saline and were sacrificed 24h (withdrawal) following the last self-administration session. Brains were collected and the nucleus accumbens (NAc) was extracted and was processed for small RNA and RNA sequencing. We found that oxycodone self-administration changed the expression of 40 genes and 16 mature microRNAs (miRNAs). Bioinformatic predictions revealed that opioid-regulated genes are predicted targets of differentially regulated miRNAs, suggesting that miRNAs contribute to opioid-mediated transcriptomic changes in the NAc. Furthermore, we validated some of these findings in an independent cohort of male and female rats and across different stages of the addiction cycle. We identified miRNAs that are dynamically regulated during oxycodone withdrawal, as well as others that exhibit sustained regulation across different stages of the addiction cycle. Taken together, our data show that miRNAs may contribute to opioid-regulated gene expression and point to the therapeutic potential of miRNAs for OUD.

Cancer genes are classically categorized as oncogenes or tumor suppressors based on whether gain or loss of function promotes malignancy. Here we show that oncogene-imposed dosage constraints can produce mutations that mimic tumor suppressor loss yet mark essential genes. In acute promyelocytic leukemia (APL), the transcription factor EBF3 gene harbors recurrent heterozygous loss-of-function mutations, a tumor suppressor signature, and is essential for APL survival. We resolve this paradox by showing that while PML::RARA, the fusion oncoprotein defining APL, drives EBF3 expression, excess EBF3 suppresses proliferation. Patient mutations reduce EBF3 activity through heterozygous inactivation, optimizing its expression within a corridor bounded by fitness constraints at both extremes. PML::RARA activates EBF3 via a p300-dependent intronic enhancer, and p300 inhibition exploits this constraint by suppressing EBF3 below the viability threshold. Our findings reveal that oncogenes can impose dosage constraints that drive adaptive mutations conventionally misclassified as tumor suppressor loss, with implications for interpreting cancer genomes.

BACKGROUND: The African green monkey (AGM) is increasingly used as a model for early-stage Alzheimer's disease (AD), with cerebrospinal fluid (CSF) targeted for biomarker discovery and longitudinal disease monitoring of shifts in the central nervous system. MicroRNAs (miRNAs) are particularly informative indicators of early neuropathological change. Despite the complementary value of an early-stage disease model and a molecular marker capable of capturing early change, the miRNA composition (miRNome) of AGM remains undefined. We established the AGM CSF miRNome from antemortem samples using miRNA sequencing and a qRT-PCR-based array. We also developed a hierarchical annotation pipeline to classify miRNAs as either family-conserved or unclassified and to assess sequence alignment across humans and other species.

RESULTS: We used untargeted miRNA sequencing to characterize the AGM CSF miRNome and identified 205 miRNAs that could be classified into three family-conserved categories: canonical, noncanonical, and 3'-terminal variants. Of these, 150 were also detected using a human-targeted qRT-PCR array, providing independent support for the sequence-derived miRNome. Sequencing abundance and qRT-PCR array Ct values showed significant cross-platform concordance overall, although concordance was lower for 3'-terminal isomiRs than for canonical miRNAs. Comparison with human GTEx tissue-expression data indicated that several human homologs of AGM CSF miRNAs exhibited brain-preferential expression. Notably, predicted targets of many of these miRNAs were enriched for pathways implicated in neurodegenerative disease. Finally, we identified 20 unclassified candidates that could not be assigned to established miRNA families, two of which we propose as putatively novel miRNAs.

CONCLUSION: The AGM CSF miRNome is substantially conserved with the human miRNome but also contains 3'-terminal isomiRs and unclassified miRNA candidates. AGM CSF contains miRNAs homologous to human miRNAs associated with AD and other neuropathologies, highlighting the translational potential of this model. However, our study also reveals challenges related to species-specific sequence variation and reduced cross-platform concordance for isomiRs. Thus, comparative studies will be needed to validate the functional and biomarker relevance of these miRNAs across species. More generally, this initial miRNome provides a reference resource for future studies of miRNAs in AGM across disease-related, physiological, experimental, and evolutionary contexts.

UNLABELLED: Many aged individuals accumulate advanced Alzheimer's disease (AD) neuropathology without cognitive decline, signifying potent endogenous resilience mechanisms. Mimicking resilience to AD may offer new therapeutic opportunities by emulating endogenous neuroprotection, but the molecular pathways that underpin resilience remain largely unknown. MicroRNAs (miRNAs)-small noncoding RNA molecules that post-transcriptionally regulate gene expression-influence neuronal and glial processes associated with development, aging, and AD neurodegeneration but their role in resilience has not been characterized. We investigated resilience-associated miRNAs and their targeted programs in the dorsolateral prefrontal cortex of post-mortem human brains. We analyzed matched miRNA and messenger RNA (mRNA) expression across resilient, AD, and control subjects from the Religious Order Study and Memory and Aging Project (ROSMAP) cohort. Nine miRNAs were differentially expressed in resilience compared with AD, including previously unreported miR-362-3p and miR-433-3p and new resilience-associated roles for known AD-related miRNAs, including neuronal miR-132-3p and miR-129-5p. By analyzing miRNA activity across AD progression, we found additional cognitive-associated miRNAs (e.g., miR-335-5p and miR-19b) and one plaque-restricted miRNA (miR-199a-5p). Sex-specific miRNA dysregulation was observed: miR-7-5p showed male-specific upregulation in AD versus resilience and suggested sex-specific differences in AD patients. Integrated co-expression and target-enrichment analyses linked resilience-associated miRNAs to pathways that were associated with cognitive decline, including transforming growth factor β, Rho guanosine triphosphatases, and neurotransmitter receptor regulation. We also report restricted co-activity in AD subjects for miR-362-3p with inflammatory pathways, including tumor necrosis factor and Toll-like receptor signaling. These results demonstrate systematic involvement of miRNAs across neuronal and glial programs of AD resilience, cognitive decline, and sex-specific regulation. Our study provides an important resource for discovery of actionable regulatory programs that could lead to new therapies, based on endogenous molecules, that emulate natural resilience to AD.

KEY POINTS: Nine distinct cortical microRNA (miRNA) signatures correlate with resilience to Alzheimer's disease (AD)-related cognitive decline, pointing to endogenous regulatory programs that may help preserve cognitive function.At the miRNA level, resilient brains show minimal or no detectable differences to healthy individuals, despite the profound pathological differences, supporting the idea that resilience reflects preserved molecular homeostasis rather than a separate disease state.Some miRNA signatures are specific to a certain pathology (e.g., one linked to amyloid-β plaques independently of tau pathology and cognitive decline), helping to disentangle the regulation of these processes.Sex-specific miRNA dysregulation in AD suggests that resilience-linked pathways may be regulated differently in males and females, reinforcing the value of sex-stratified analyses and the potential for differential therapeutic strategies.Integrative miRNA-pathway analysis highlights candidate regulatory networks involved in inflammation, matrisome, and cellular stress responses, providing a framework for resilience-linked therapeutic targets.

Aging of the human brain is characterized by widespread changes in gene expression regulated in part by microRNAs (miRNAs). We present a lifespan miRNA atlas of the human dorsolateral prefrontal cortex generated from small RNA sequencing of 113 postmortem samples spanning 18 to 100 years of age. Differential expression analysis revealed progressive age-associated remodeling of miRNA expression, with the strongest differences observed between old and young individuals. Among the significantly altered miRNAs, miR-34a-5p emerged as one of the most robustly upregulated miRNAs in the aged cortex, alongside additional aging-associated miRNAs including miR-155-5p, miR-132-3p, miR-212-3p, miR-449a, and members of the miR-302 family. This atlas provides a resource for investigating miRNA dysregulation and small RNA regulatory networks during human cortical aging.

Oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) employs a biphasic life cycle consisting of latency and lytic replication to achieve lifelong infection. Despite its essential role in KSHV persistence and tumorigenicity, much remains unknown about how KSHV lytic reactivation is regulated. Leveraging high-throughput transcriptomics, we identify microRNA-31-5p (miRNA-31-5p) as a key regulator of KSHV lytic reactivation, capable of modulating expression of KSHV lytic genes and progression through the lytic cascade. Mechanistically, miR-31-5p controls the KSHV lytic switch by regulating expression of the RNA-binding protein KHDRBS3. miR-31-5p-mediated KHDRBS3 repression results in decreased nascent transcription of crucial viral lytic genes including the main KSHV transcription factor RTA. We characterize KHDRBS3 as a major host factor that is critical for KSHV lytic replication and uncover its key role in KSHV lytic gene transcription. Our results highlight a pivotal role for the miR-31-5p/KHDRBS3 axis in modulating KSHV reactivation and provide insights into gene-expression regulation of lytic KSHV.

Cutaneous melanoma, a highly aggressive and therapy-resistant skin cancer, is characterized by its remarkable cellular plasticity, enabling tumour cells to switch between different phenotypic states. This plasticity contributes to tumour heterogeneity and is regulated by key transcription factors. Long non-coding RNAs (lncRNAs) are emerging as crucial regulators in melanoma progression, yet much remains to be explored regarding their role in phenotype switching. In this study, we analysed long non-coding RNAs (lncRNAs) across different murine melanoma cell lines, identifying a set of lncRNAs potentially involved in regulating melanoma phenotypic state through cis-regulation of neighbouring protein-coding genes. We demonstrated that the lncRNA Dlx4os regulates genes associated with melanoma plasticity, favouring a mesenchymal-like, undifferentiated state. Dlx4os knockdown redirected melanoma cells to a more differentiated and less malignant phenotype, confirmed by differential expression of phenotypic state markers (Sox10, Mitf, Tgfβ, Sox6, Mlana), reduced their invasive and migratory potential, and delayed tumour progression in vivo. Furthermore, we identified a human orthologue of Dlx4os. Our findings highlight the potential of Dlx4os as both a biomarker and therapeutic target, capable of modulating melanoma's phenotypic plasticity to influence treatment response and metastasis.

Peptide nucleic acid (PNA) is a synthetic mimic of DNA where the deoxyribose-phosphodiester backbone is replaced with N-(2-aminoethyl) glycine units. The lack of deoxyribose-phosphodiester bonds enhances enzymatic stability and improves binding affinity of PNA with complementary DNA and RNA strands. To enhance target binding, conformational stability, and pharmacological activity, several chemical modifications have been introduced into PNA. Modified PNAs have demonstrated promising preclinical potential as antisense and anti-gene agents, supporting their use in diverse biomedical applications. The limited in vivo biodistribution and cellular uptake of PNA have significantly hindered its clinical development. Enhancing PNA biodistribution using nanoformulations and bioconjugate-based delivery strategies has resulted in substantial in vivo pharmacological effects. Further, with advancements in chemistry and delivery techniques, PNA holds promise in treating genetic diseases, metabolic disorders, cancers, and infectious diseases. This review summarizes PNA's pharmacological mechanisms, chemical modifications, delivery strategies, and therapeutic applications while addressing limitations for clinical translation.

The human prefrontal cortex (PFC), whose laminar organization is essential for cognitive function, is among the first regions to show age-related functional decline1,2. Single-cell sequencing studies revealed cell type-dependent aging effects but lacked spatial specificity3-6. Spatial transcriptomics (ST) advanced our molecular understanding of the human PFC7, yet whether aging-driven changes differ across PFC layers remains unclear. Here, we performed whole-transcriptome ST on postmortem PFC from 37 individuals across the adult lifespan. We mapped cortical layers and revealed aging mechanisms across layers. This represents one of the largest and most comprehensive lifespan ST analysis of the human PFC brain, offering crucial insight into how the brain ages and identifying potential molecular targets to mitigate cognitive aging and extend healthspan.

BRCA1/2 -mutated breast cancers exhibit homologous recombination deficiency (HRD), making them initially sensitive to poly(ADP-ribose) polymerase (PARP) inhibitors. However, 40-70% of patients develop resistance, necessitating combination strategies and predictive biomarkers. We first investigated approaches to overcome PARP resistance and then explored spatial microRNA (miRNA) profiling as a prognostic tool. Using the K14-Cre Brca1 f/f Trp53 f/f model with tumors that acquired PARP resistance, we evaluated PARP inhibitor combinations with either PI3K inhibition or Poly(I:C) in vivo . Both combinations improved antitumor activity compared to PARP inhibition alone. Next, to predict resistance we applied a sensitive assay that quantifies and spatially profiles miRNA expression in situ onto FFPE sections from tumors treated for 10 days using nanoliter well arrays with functionalized hydrogel posts. We developed a spatial miRNA analysis framework integrating latent Dirichlet allocation (LDA) and principal component analysis (PCA) to develop "topics" that stratify early tumors as either PARP inhibitor-sensitive or - resistant and distinguish their treatment regimens. We also incorporated immune architecture using Structural Similarity Index Measure (SSIM) maps that revealed co-localization of immune infiltration and miRNA topics. This integrative approach highlights how miRNA-based spatial analysis can predict PARP inhibitor resistance and provide a promising biomarker to inform therapeutic strategies for BRCA1/2- related breast cancers.