The Chromatin-Associated Phf12 Protein Maintains Nucleolar Integrity and Prevents Premature Cellular Senescence

Area of Science:

• Molecular Biology
• Genetics
• Cell Biology

Background:

• Pf1 (plant homeodomain zinc finger protein 12) is a member of the PHD zinc finger protein family.
• Pf1 interacts with a chromatin complex including MRG15, Sin3B, and HDAC1, functioning as a transcriptional modulator.
• The precise biological role of Pf1 has remained largely undetermined.

Purpose of the Study:

• To investigate the physiological role of Pf1 through the generation of knockout mice.
• To elucidate the function of Pf1 in embryonic development and cellular processes.

Main Methods:

• Generation and analysis of Pf1 knockout mice.
• Assessment of mouse embryonic fibroblasts (MEFs) for proliferation, senescence, and DNA damage markers (bromodeoxyuridine incorporation, SA-β-Gal, γ-H2A.X).
• Transcriptomic and proteomic analyses to identify Pf1-regulated pathways and interacting proteins.

Main Results:

• Pf1 deficiency results in mid- to late-gestation embryonic lethality.
• Loss of Pf1 impairs MEF proliferation, induces cellular senescence, and is associated with DNA double-strand breaks.
• Pf1 impacts ribosome biogenesis pathways and leads to abnormal nucleolar structure.
• Proteomic analysis identified ribosome biogenesis proteins within Pf1-interacting complexes.

Conclusions:

• Pf1 is crucial for embryonic viability and maintaining cellular homeostasis.
• The Pf1-associated chromatin complex plays a significant, previously unrecognized role in regulating ribosome biogenesis and preventing cellular senescence.
• These findings uncover a novel function for Pf1 in fundamental cellular pathways.