Biology subjects

Lee, M. F.

Publications and source records attributed to Lee, M. F..

3 recordsLinked to original sources

bioRxiv2022

Integrity of the minor spliceosome in the developing mouse hypothalamus determines neuronal subtype composition regulating energy balance.

While gene regulatory networks underlying hypothalamic development are being characterized, minor intron splicing remains unexplored. Here, we used Nkx2.1-Cre to ablate Rnu11, encoding the minor spliceosome-specific U11 snRNA, in the progenitors of the ventral diencephalon (VD), to study minor intron splicing in hypothalamic development and control of energy balance in mice. Loss of U11 resulted in aberrant minor intron splicing, mitotic stalling, apoptosis, and altered neurogenesis. Mutant mice exhibited gross dysgenesis of hypothalamic architecture, while single-cell RNA sequencing (scRNAseq) revealed aberrant composition of neuronal subtypes implicated in feeding and energy balance. Mutant weanlings failed to thrive, followed by rapid weight gain, resulting in obesity. Assessment of energy imbalance and pair-feeding demonstrated that hyperphagia in adult mutants initiates weight gain, and is compounded by metabolic dysfunction, ultimately resulting in obesity. Our findings suggest a key role of minor intron splicing in the developmental patterning of hypothalamic neuronal subtypes underlying energy balance.

neuroscience↗

bioRxiv2021

Trp53 ablation fails to prevent microcephaly in mouse pallium with impaired minor intron splicing

Mutations in minor spliceosome component RNU4ATAC, a small nuclear RNA (snRNA), are linked to primary microcephaly. We have reported that in the conditional knockout (cKO) mice for Rnu11, another minor spliceosome snRNA, minor intron splicing defect in minor intron-containing genes (MIGs) regulating cell cycle resulted in cell cycle defects, with a concomitant increase in {gamma}H2aX+ cells and p53-mediated apoptosis. Trp53 ablation in the Rnu11 cKO mice did not prevent microcephaly. However, RNAseq analysis of the double knockout (dKO) pallium reflected transcriptomic shift towards the control from the Rnu11 cKO. We found elevated minor intron retention and alternative splicing across minor introns in the dKO. Disruption of these MIGs resulted in cell cycle defects that were more severe and detected earlier in the dKO, but with delayed detection of {gamma}H2aX+ DNA damage. Thus, p53 might also play a role in causing DNA damage in the developing pallium. In all, our findings further refine our understanding of the role of the minor spliceosome in cortical development and identify MIGs underpinning microcephaly in minor spliceosome-related diseases.

developmental biology↗

bioRxiv2020

The minor and major spliceosome interact to regulate alternative splicing around minor introns

Mutations in minor spliceosome components are linked to diseases such as Roifman syndrome, Lowry-Wood syndrome, and early-onset cerebellar ataxia (EOCA). Here we report that besides increased minor intron retention, Roifman syndrome and EOCA can also be characterized by elevated alternative splicing (AS) around minor introns. Consistent with the idea that the assembly/activity of the minor spliceosome informs AS in minor intron-containing genes (MIGs), inhibition of all minor spliceosome snRNAs led to upregulated AS. Notably, alternatively spliced MIG isoforms were bound to polysomes in the U11-null dorsal telencephalon, which suggested that aberrant MIG protein expression could contribute to disease pathogenesis. In agreement, expression of an aberrant isoform of the MIG Dctn3 by in utero electroporation, affected radial glial cell divisions. Finally, we show that AS around minor introns is executed by the major spliceosome and is regulated by U11-59K of the minor spliceosome, which forms exon-bridging interactions with proteins of the major spliceosome. Overall, we extend the exon-definition model to MIGs and postulate that disruptions of exon-bridging interactions might contribute to disease severity and pathogenesis.

molecular biology↗