SF3B1K700E rewires splicing of cell cycle regulators

Mai Baker1,2, Eden Engel3,4, Aveksha Sharma3

  • 1Department of Biochemistry and Molecular Biology, The Institute for Medical Research Israel-Canada, Faculty of Medicine, The Hebrew University of Jerusalem, Jerusalem 9112102, Israel mib.sal89@gmail.com maayan.salton@mail.huji.ac.il.

RNA (New York, N.Y.)
|December 24, 2025
PubMed

Insights

Mutations in SF3B1 (a spliceosome component) disrupt RNA splicing, affecting cell cycle control and promoting cancer. The SF3B1K700E mutation specifically alters splicing of G2/M regulators like ARPP19, impacting cell division and patient survival.

Area of Science:

  • Molecular Biology
  • Cancer Biology
  • Genetics

Background:

  • Pre-mRNA splicing is vital for cellular homeostasis and tightly regulated, especially for cell cycle progression.
  • SF3B1, a spliceosome component, is crucial for alternative splicing and frequently mutated in cancers.
  • The SF3B1K700E mutation disrupts splicing and cell cycle control, contributing to tumorigenesis.

Purpose of the Study:

  • To investigate the impact of SF3B1K700E mutation on RNA splicing patterns.
  • To identify splicing alterations linked to the SF3B1K700E mutation and their functional consequences.
  • To explore the relationship between SF3B1-dependent splicing, cell cycle regulation, and cancer development.

Main Methods:

  • RNA sequencing (RNA-seq) of K562 erythroleukaemia cells expressing wild-type or SF3B1K700E.
  • siRNA-mediated depletion of SF3B1 in HeLa cells to validate mutation-dependent splicing signatures.
  • Pharmacological inhibition of DYRK1A and serine/threonine phosphatases.
  • Functional assays including ectopic expression of ARPP19-long isoform.
  • Analysis of TCGA-AML cohort data.

Main Results:

  • Identified 763 high-confidence splicing alterations in SF3B1K700E cells, enriched for G2/M regulators (e.g., ARPP19, ENSA, STAG2, ECT2).
  • Increased inclusion of ARPP19 exon 2 leads to ARPP19-long isoform, inhibiting PP2A-B55 and promoting mitosis.
  • A subset of SF3B1K700E-linked splicing changes were observed upon SF3B1 depletion, indicating a mutation-specific spliceosomal signature.
  • Kinase-phosphatase signaling (DYRK1A, phosphatases) influences ARPP19 exon 2 inclusion.
  • Ectopic ARPP19-long expression accelerated mitotic exit; high ARPP19-long levels correlated with poorer survival in AML patients.

Conclusions:

  • SF3B1K700E mutation drives specific splicing alterations impacting cell cycle regulators.
  • The ARPP19-long isoform plays a role in mitotic progression and is linked to adverse outcomes in AML.
  • SF3B1-dependent splicing dysregulation is a key mechanism in cancer development, offering potential therapeutic targets.

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