Garcia, C. D. | bioRxiv Science

bioRxiv2025

A field-focused systems approach reveals mRNA covalent modifications linked to sorghum growth and development under drought stress

RNA Covalent Modifications (RCMs) are post-transcriptional chemical alterations that influence RNA stability and translation efficiency, thus play critical roles in eukaryotic growth and development. However, their role in regulating plant performance under abiotic stress remain largely unexplored. Here, we integrated multi-omics data in six Sorghum bicolor accessions under water-limiting conditions in the field to explore the relationship between RCMs and drought response. Within a stress and photosynthesis-associated gene co-expression module, we identified SbDUS2, a member of family of enzymes, conserved across eukaryotes, which catalyzes the reduction of uracil to dihydrouridine (DHU) on RNA molecules. DHU-modified transcripts in this module were enriched for photosynthetic functions and showed strong correlation with photosynthetic traits. To elucidate the function of this RCM, we characterized loss of function dus2 mutants in the genetic model, Arabidopsis thaliana. Under control conditions, these DHU-deficient mutants exhibited impaired germination and delayed development. Furthermore, when exposed to heat or water-limiting conditions, these mutants showed significantly reduced net CO2 assimilation and survival. Using multiple transcriptome-wide RNA stability assays, we demonstrated that transcripts associated with lower DHU level in a dus2 background generally exhibited increased stability compared to Col-0 controls. Particularly, lack of DUS2 led to the hyperstability of photosynthesis-related transcripts, impeding their turnover and likely preventing proper photosynthetic acclimation during stress. We propose a model based on these data where DHU acts as a critical post-transcriptional regulator marking mRNAs for rapid turnover under stress, highlighting an overlooked regulatory layer contributing to plant resilience.

plant biology↗

bioRxiv2023

Validation of σ2R/TMEM97 as a neuropathic pain target: Specificity, human expression and mechanism of action.

The Sigma 2 receptor ({sigma}2R) was described pharmacologically more than three decades ago, but its molecular identity remained obscure until recently when it was identified as transmembrane protein 97 (TMEM97). We and others have shown that {sigma}2R/TMEM97 ligands alleviate mechanical hypersensitivity in mouse neuropathic pain models with a time course wherein maximal anti-nociceptive effect is approximately 24 hours following dosing. We sought to understand this unique anti-neuropathic pain effect by addressing two key questions: do these {sigma}2R/TMEM97 compounds act selectively via the receptor, and what is their downstream mechanism on nociceptive neurons? Using male and female conventional knockout (KO) mice for Tmem97, we find that a new {sigma}2R/TMEM97 binding compound, FEM-1689, requires the presence of the gene to produce anti-nociception in the spared nerve injury model in mice. Using primary mouse dorsal root ganglion (DRG) neurons, we demonstrate that FEM-1689 inhibits the integrated stress response (ISR) and promotes neurite outgrowth via a {sigma}2R/TMEM97-specific action. We extend the clinical translational value of these findings by showing that FEM-1689 reduces ISR and p-eIF2 levels in human sensory neurons and that it alleviates the pathogenic engagement of ISR by methylglyoxal. We also demonstrate that {sigma}2R/TMEM97 is expressed in human nociceptors and satellite glial cells. These results validate {sigma}2R/TMEM97 as a promising target for further development for the treatment of neuropathic pain. Significance StatementNeuropathic pain is a major medical problem that is poorly treated with existing therapeutics. Our findings demonstrate that targeting {sigma}2R/TMEM97 with a newly described modulator reduces pain hypersensitivity in a mouse model with exquisite selectivity. We also identify integrated stress response (ISR) inhibition as a potential mechanism of action that links the receptor to cellular signaling events that have preclinical and clinical validation for pain relief. Our work suggests that {sigma}2R/TMEM97 can be selectively engaged by specific small molecules to produce ISR inhibition in a subset of cells that are critical for neuropathic pain. {sigma}2R/TMEM97-targeted therapeutics thus have the potential to offer effective pain relief without engagement of opioid receptors.

neuroscience↗