Biology subjects

Grellscheid, S.

Publications and source records attributed to Grellscheid, S..

3 recordsLinked to original sources

bioRxiv2026

Cell-autonomous restoration of splicing homeostasis and RP11 phenotype in patient-derived RPE and retinal organoids by PRPF31.AAV gene therapy

Mutations in PRPF31 gene cause retinitis pigmentosa type 11 (RP11) through haploinsufficiency, impairing spliceosome assembly and triggering progressive retinal degeneration. While gene augmentation holds therapeutic promise, key questions remain regarding the mechanistic basis of rescue and its therapeutic efficacy across all primarily affected human retinal cell types and disease stages. Here, we utilised patient-specific induced pluripotent stem cells (iPSCs)-derived retinal pigment epithelium (RPE) cells and three-dimensional retinal organoids (ROs) to determine the therapeutic mechanism of AAV-mediated PRPF31 delivery. Using the ShH10(Y445F) serotype to ensure robust dual targeting of RPE and photoreceptors, we demonstrated that PRPF31 transduction restores nuclear localisation, reorganises SC35+ nuclear speckles and enhances p-SF3B1 active spliceosome foci. Transcriptomic and proteomic profiling revealed a global rescue of splicing activity and upregulation of phagocytosis, protein aggregate clearance pathways, and mitochondrial proteins. These molecular shifts facilitated the clearance of proteotoxic cytoplasmic aggregates and reversed key functional deficits; specifically, they reinforced RPE apical-basal polarity, restored phagocytic capacity and normal ciliary morphology and incidence, and boosted light-evoked activity in photoreceptors. Combining gene therapy with rapamycin-mediated-autophagy activation conferred no additive benefit, identifying the restoration of splicing homeostasis as the critical therapeutic driver. Notably, substantial phenotypic rescue is achievable in mature RPE, supporting a broad clinical window for intervention. Collectively, these data provide a systems-level validation of ShH10(Y445F)-PRPF31 gene therapy and establish a mechanistic framework for its clinical translation in RP11.

molecular biology↗

bioRxiv2023

Traditional Norwegian Kveik Yeast: An Ancient Sister Group to Domesticated Saccharomyces cerevisiae

Kveik is the common name of yeast that has been used in traditional farmhouse brewing of western Norway for generations. Its fast fermentation, increased flocculation, temperature tolerance, and rich flavor profile have led to growing interest in recent years. Previous genetic analyses have shown that kveik forms a distinct group within the Saccharomyces cerevisiae tree and placed its origins within the Beer I clade of industrial brewing yeasts, although with signs of mixed ancestry. In this study, we revisited the phylogenetic position of kveik within the S. cerevisiae tree. We searched for traditional farm breweries in western Norway and collected ten samples of potential kveik yeast. Using Illumina whole genome shotgun sequencing, we reconstructed the phylogenetic tree of kveik based on de novo genome assemblies and variant calls of our new kveik samples, along with published wild and domesticated S. cerevisiae strains. We calibrated and used sequential computational experiments at different thresholds to determine the most probable phylogenetic position of kveik yeast. Previously sequenced kveik genotypes form a clade with our new samples clustering partially by place of origin. Our results indicate that kveik is indeed a compact clade within S. cerevisiae with significantly reduced polymorphism compared to common brewing yeasts and wild strains. Contrary to what was previously thought, our analyses support a more ancient divergence of kveik and place it closer to the root of the S. cerevisiae tree. In conclusion, our genetic analyses suggest that kveik is a unique and ancient yeast group, distinct from other domesticated S. cerevisiae strains. Considering a possible far east origin of kveik yeast, the apparent endemism to western Norway remains as a big paradox These findings have important implications for the understanding of yeast domestication and the use of kveik in modern brewing practices.

genomics↗

bioRxiv2022

MERISTEM-DEFECTIVE/DEFECTIVELY ORGANIZED TRIBUTARIES2 regulates the balance between stemness and differentiation in the root meristem through RNA splicing control.

Plants respond to environmental stresses through controlled stem cell maintenance and meristem activity. One level of transcriptional control is RNA alternative splicing. However the mechanistic link between stress, meristem function and RNA splicing is poorly understood. The MERISTEM-DEFECTIVE (MDF)/DEFECTIVELY ORGANIZED TRIBUTARIES (DOT2) gene of Arabidopsis encodes a SR-related family protein, required for meristem function and leaf vascularization, and is the likely orthologue of the human SART1 and yeast snu66 splicing factors. MDF is required for the correct splicing and expression of key transcripts associated with root meristem function. We identified RSZ33 and ACC1, both known to regulate cell patterning, as splicing targets required for MDF function in the meristem. MDF expression is modulated by osmotic and cold stress, associated with differential splicing and specific isoform accumulation and shuttling between nucleus and cytosol, and acts in part via a splicing target SR34. We propose a model in which MDF controls splicing in the root meristem to promote stemness and repress stress response and cell differentiation pathways. Summary statementThe protein MERISTEM-DEFECTIVE regulates Arabidopsis meristem function through its role as a splicing factor, mediated through splicing targets RSZ33, ACC1 and SR34.

plant biology↗