Biomedical subjects

Alysson R Muotri

Publications and source records attributed to Alysson R Muotri.

3 recordsLinked to original sources

PubMed2026

Transcriptional perturbation of LINE-1 elements reveals their cis-regulatory potential.

Long interspersed element-1 (LINE-1 or L1) retrotransposons constitute the largest transposable element family in mammalian genomes and contribute prominently to inter- and intra-individual genetic variation. Although most L1 elements are inactive, some evolutionary younger elements remain intact and genetically competent for transcription and occasionally retrotransposition. Despite being generally more abundant in gene-poor regions, intact or full-length L1s (FL-L1) are also enriched around specific classes of genes and on the eutherian X chromosome. How proximal FL-L1 may affect nearby gene expression remains unclear. Here, we examine this systematically using engineered mouse embryonic stem cells (ESCs) in which expression of one active L1 subfamily is perturbed. We find that FL-L1 activation leads to the misregulation of ~1024 genes, whereas FL-L1 repression affects ~81 genes. In most cases (68%), misexpressed genes contain an intronic FL-L1 or lie near a FL-L1 (< 260 kb). Gene ontology analysis shows that upon L1 activation, upregulated genes are enriched for neuronal function-related terms, suggesting that some L1 elements may have evolved to control neuronal gene networks. These results illustrate the cis-regulatory potential of FL-L1 elements and suggest a broader role for L1s than originally anticipated.

Animals↗

PubMed2025

Nanobioreactor detection of space-associated hematopoietic stem and progenitor cell aging.

Human hematopoietic stem and progenitor cell (HSPC) fitness declines following exposure to stressors that reduce survival, dormancy, telomere maintenance, and self-renewal, thereby accelerating aging. While previous National Aeronautics and Space Administration (NASA) research revealed immune dysfunction in low-earth orbit (LEO), the impact of spaceflight on human HSPC aging had not been studied. To study HSPC aging, our NASA-supported Integrated Space Stem Cell Orbital Research (ISSCOR) team developed bone marrow niche nanobioreactors with lentiviral bicistronic fluorescent, ubiquitination-based cell-cycle indicator (FUCCI2BL) reporter for real-time HSPC tracking in artificial intelligence (AI)-driven CubeLabs. In month-long International Space Station (ISS) missions (SpX-24, SpX-25, SpX-26, and SpX-27) compared with ground controls, FUCCI2BL reporter, whole-genome and transcriptome sequencing, and cytokine arrays demonstrated cell-cycle, inflammatory cytokine, mitochondrial gene, human repetitive element, and apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like 3 (APOBEC3) deregulation together with clonal hematopoietic mutations. Furthermore, HSPC functionally organized multi-omics aging (HSPC-FOMA) analyses revealed reduced telomere maintenance, adenosine deaminase acting on RNA1 (ADAR1) p150 self-renewal gene expression, and replating capacity indicative of space-associated HSPC aging that may limit long-duration spaceflight.

Humans↗

PubMed2025

Convergent activation of the integrated stress response and ER-mitochondria uncoupling in VAPB-associated ALS.

Vesicle-associated membrane protein-associated protein-B (VAPB) is an endoplasmic reticulum (ER) membrane-bound protein. The P56S mutation in VAPB causes a dominant, familial form of amyotrophic lateral sclerosis (ALS). However, the mechanism by which this mutation leads to motor neuron (MN) degeneration remains unclear. Utilizing inducible pluripotent stem cell (iPSC)-derived MNs expressing either wild-type (WT) or P56S VAPB, we demonstrate that the mutant protein reduces neuronal firing and disrupts ER-mitochondria-associated membranes (ER MAMs), with a time-dependent decline in mitochondrial membrane potential (MMP), hallmarks of MN pathology. These findings were validated in patient-derived iPSC-MNs. Additionally, VAPB P56S MNs show increased susceptibility to ER stress, elevated expression of the Integrated Stress Response (ISR) regulator ATF4 under stress, and reduced global protein synthesis. Notably, pharmacological ISR inhibition using ISRIB rescued ALS-associated phenotypes in both VAPB P56S and patient-derived iPSC-MNs. We present the first evidence that the VAPB P56S mutation activates ISR signaling via mitochondrial dysfunction in human MNs. These findings support ISR modulation as a strategy for ALS intervention and highlight the need for patient stratification in clinical trials.

Amyotrophic Lateral Sclerosis↗