Search bioRxiv⌕ Search
Home/Archive/bioRxiv

bioRxiv · 10.1101/2023.11.10.566530

m6A RNA modification of mHtt intron 1 regulates the generation of Htt1a in Huntington's Disease

Pupak, A.·Navarro, I. R.·Sathasivam, K.·Essmann, A.·Singh, A.·Del Toro, D.·Gines, S.·Bates, G. P.·Vang Orom, U. A.·Marti, E.·Brito, V.
View original source ↗Export metadata ↓

Abstract

Huntingtons disease (HD) is a dominantly inherited neurodegenerative disorder caused by an expanded, somatically unstable CAG repeat in the first exon of the huntingtin gene (HTT). In the presence of an expanded CAG repeat, huntingtin mRNA undergoes an aberrant processing that generates HTT1a transcripts with exon 1 and intron 1 sequences, which encodes the aggregation-prone and pathogenic HTTexon 1 protein. The regulatory mechanisms that contribute to the production of HTT1a are not fully understood. In a previous transcriptome-wide m6A landscape study performed in Hdh+/Q111 knock-in mice, we have found that the proximal region of intron 1 to exon1-intron 1 splice site in Htt RNA is highly modified by m6A. Several pieces of evidence have demonstrated that m6A is involved in RNA processing and splicing. Therefore, in this study we set out to explore the impact of m6A RNA modifications in the generation of Htt1a. We show in the striatum of Hdh+/Q111 mice that m6A is enriched in intronic sequences 5 to the cryptic poly (A) sites (IpA1 and IpA2) at 680 and 1145 bp into intron 1 as well as in Htt1a polyadenylated mRNA. We also verified the presence of specific m6A-modified sites near the 5 exon1-intron1 splice donor site. Intronic HTT m6A methylation was recapitulated in human samples showing a significantly increased methylation ratio in HD putamen post-mortem samples and in HD fibroblast cell lines from pre-symptomatic and symptomatic patients. In order to test the hypothesis that the m6A modification is involved in mutant Htt RNA processing, we performed a pharmacological inhibition of METTL3 and a targeted demethylation of Htt intron 1 in HD cells using a dCas13-ALKBH5 system. We found that Htt1a transcript levels in HD cells are regulated by METTL3 and by methylation status in Htt intron 1. Site-specific manipulation with an RNA editing system resulted in decreased expression levels of Htt1a, which was accompanied by a reduction in DNA damage, a major hallmark in HD. Finally, we propose that m6A methylation in intron 1 is likely dependent on the expanded CAG repeats. These findings provide insight into the role of m6A in the generation of the aberrantly spliced mutant Htt transcripts with important implications for therapeutic strategies.

Explore related subjects

neurosciencePreprint

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Pupak, A., Navarro, I. R., Sathasivam, K., Essmann, A., Singh, A., Del Toro, D., Gines, S., Bates, G. P., Vang Orom, U. A., Marti, E., Brito, V.. 2023-11-10. m6A RNA modification of mHtt intron 1 regulates the generation of Htt1a in Huntington's Disease. https://doi.org/10.1101/2023.11.10.566530

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

Same Movements, Different Skills: How Context Shapes Learning in Humans and Neural Networks

What determines whether experiences are integrated into shared representations or split? Motor skill learning offers a revealing test: when two tasks require an identical sequence of movements, both intuition and theory suggest that practice in one should generalize to the other. Yet we find that changing context can make identical movements different skills. In simple recurrent networks trained on the same sequence across contexts, splitting was greatest when strong contextual inputs coincided with a high initial weight scale; neither alone sufficed. Greater representational separation coincided with separate context-specific learning curves. Humans practicing the same finger sequence while alternating between two performance-irrelevant contexts likewise exhibited context-specific curves, rather than the single continuous trajectory observed when practicing in a single context. State-space modeling favored split learning states in humans and very weakly coupled states in the most context-dependent networks. These findings have broader implications for understanding how learning generalizes across contexts.

neuroscience↗
bioRxiv2026

Postpartum resource scarcity reshapes maternal care, offspring prioritization, and the steroid-sensitive medial preoptic area

Parental care requires balancing offspring needs with environmental constraints, yet how resource scarcity alters the organization of maternal responses remains poorly understood. Here, we examined maternal behavior, offspring prioritization, and steroid receptor-associated extracellular matrix organization in postpartum rats exposed to limited bedding and nesting (LBN) or control conditions with ample nesting materials. LBN increased pup-directed and reduced self-directed behaviors but also increased behavioral entropy, a measure of behavioral fragmentation, indicating less predictable caregiving sequences. LBN dams preferentially retrieved male pups first, whereas control dams preferentially retrieved females first. LBN also increased the proportion of pup-investigation time directed toward males compared with controls. In offspring on postnatal day 10, corticosterone was elevated in female but not male LBN pups, a pattern that paralleled the maternal male bias. To identify associated neurobiological changes, we assessed steroid receptors and extracellular matrix organization in the medial preoptic area (mPOA), a key region for maternal behavior. LBN increased numbers of estrogen receptor (ER)- and androgen receptor (AR)-immunoreactive cells, reduced perineuronal net (PNN) abundance, and decreased receptor-positive cell enwrapment. Because PNNs constrain structural plasticity, these findings suggest that the postpartum environment alters the organization of steroid receptor-associated extracellular matrix, potentially modulating experience-dependent plasticity in neurosteroid-sensitive circuits. In sum, LBN increases the levels of maternal engagement while reshaping its temporal organization and allocation, accompanied by selective remodeling of steroid-sensitive preoptic architecture. Therefore, maternal adaptation to adversity may be better understood as changes in caregiving allocation strategies rather than a simple gain or loss of maternal care.

neuroscience↗
bioRxiv2026

The Computational Grammar of Human Behaviour in a Biological Environment

Human behaviour unfolds as an extended stream of spontaneous actions shaped by environmental demands and the agent's goals. The organisation of these actions, situated between setting abstract goals and concrete movement execution, remains poorly characterised. Here, we introduce DynaClade, an unsupervised temporal action segmentation algorithm for human full-body motion capture data, and apply it to freely moving participants navigating ecologically realistic risky foraging environments in virtual reality. DynaClade identifies discrete actions whose kinematic characteristics and spatial distributions correspond to environmental affordances, supporting the validity of the approach. Among these actions, we discovered a hitherto undescribed movement pattern defined by increased body sway without locomotion. Action sequences were highly non-random and showed clear history dependence beyond first-order Markov structure, most of which was explained by a second-order prediction. This higher-order structure was well captured in a hidden Markov model, in which some of the observed actions were associated with more than one latent state. Each of these latent states corresponded to the same action in a distinct action context. These findings suggest that spontaneous human actions are predominantly selected based on the current action and context, rather than following pre-planned or habitually assembled sequences.

neuroscience↗