Related Experiment Video
Updated: Oct 19, 2025
Defining Gene Functions in Tumorigenesis by Ex vivo Ablation of Floxed Alleles in Malignant Peripheral Nerve Sheath Tumor Cells
Published on: August 25, 2021
Trp53 ablation fails to prevent microcephaly in mouse pallium with impaired minor intron splicing
Alisa K White1, Marybeth Baumgartner2, Madisen F Lee1
1Physiology and Neurobiology Department, University of Connecticut, Storrs, CT 06269, USA.
Abstract:
Minor spliceosome inhibition due to mutations in RNU4ATAC are linked to primary microcephaly. Ablation of Rnu11, which encodes a minor spliceosome snRNA, inhibits the minor spliceosome in the developing mouse pallium, causing microcephaly. There, cell cycle defects and p53-mediated apoptosis in response to DNA damage resulted in loss of radial glial cells (RGCs), underpinning microcephaly. Here, we ablated Trp53 to block cell death in Rnu11 cKO mice. We report that Trp53 ablation failed to prevent microcephaly in these double knockout (dKO) mice. We show that the transcriptome of the dKO pallium was more similar to the control compared with the Rnu11 cKO. We find aberrant minor intron splicing in minor intron-containing genes involved in cell cycle regulation, resulting in more severely impaired mitotic progression and cell cycle lengthening of RGCs in the dKO that was detected earlier than in the Rnu11 cKO. Furthermore, we discover a potential role of p53 in causing DNA damage in the developing pallium, as detection of γH2aX+ was delayed in the dKO. Thus, we postulate that microcephaly in minor spliceosome-related diseases is primarily caused by cell cycle defects.
Insights
Minor spliceosome defects cause microcephaly by impairing cell cycle progression in radial glial cells (RGCs). Blocking p53-mediated apoptosis did not prevent microcephaly, indicating cell cycle defects are the primary cause.
Area of Science:
- Developmental biology
- Molecular genetics
- Cell biology
Background:
- Mutations in RNU4ATAC cause primary microcephaly by inhibiting the minor spliceosome.
- Ablation of Rnu11, a minor spliceosome component, leads to microcephaly in mice due to cell cycle defects and p53-mediated apoptosis in radial glial cells (RGCs).
Purpose of the Study:
- To investigate the role of p53 in microcephaly caused by minor spliceosome inhibition.
- To determine if blocking p53-mediated apoptosis can prevent microcephaly in Rnu11-deficient mice.
Main Methods:
- Generated double knockout (dKO) mice by ablating Trp53 in Rnu11 conditional knockout (cKO) mice.
- Analyzed transcriptome, cell cycle progression, and DNA damage markers (γH2aX) in the developing pallium of control, Rnu11 cKO, and dKO mice.
Main Results:
- Trp53 ablation did not prevent microcephaly in Rnu11 cKO mice.
- Aberrant minor intron splicing in cell cycle-related genes caused more severe cell cycle defects and RGC mitotic progression impairment in dKO mice compared to Rnu11 cKO mice.
- p53-mediated DNA damage response (γH2aX detection) was delayed in dKO mice, suggesting a role for p53 in inducing DNA damage.
Conclusions:
- Microcephaly in minor spliceosome-related diseases is primarily driven by cell cycle defects, not p53-mediated apoptosis.
- The minor spliceosome plays a critical role in regulating cell cycle progression in developing neural stem cells.
More Related Videos
07:01Evaluation of Abnormal Growth-related Genes of Hematopoietic Stem and Progenitor Cells by Combining CRISPR/Cas9 Technology with Cell Counting
Published on: May 2, 2025
08:22A Novel Strategy Combining Array-CGH, Whole-exome Sequencing and In Utero Electroporation in Rodents to Identify Causative Genes for Brain Malformations
Published on: December 1, 2017