Identification of FBXO25-interacting proteins using an integrated proteomics approach

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• FBXO25 is a human F-box protein involved in the SCF1 ubiquitin ligase complex.
• SCF1 targets proteins for degradation via the ubiquitin-proteasome system.
• FBXO25 has been observed to accumulate in novel subnuclear structures, termed FBXO25-associated nuclear domains (FAND).

Purpose of the Study:

• To identify novel FBXO25 interacting partners.
• To investigate the composition and regulation of FAND.
• To explore the functional role of FBXO25 and FAND in nuclear processes.

Main Methods:

• Two-step affinity purification followed by mass spectrometry (MS).
• Classical two-hybrid screening.
• In vitro transcription assays using FBXO25 antibodies.

Main Results:

• Identified 132 novel potential FBXO25 interacting partners.
• Beta-actin was identified as an FBXO25 interactor, localizing to FAND.
• Actin polymerization inhibitors disrupted FAND, suggesting actin's role in their organization.
• FBXO25 antibodies inhibited RNA polymerase II transcription in vitro.

Conclusions:

• FBXO25 forms novel nuclear compartments (FAND) influenced by nuclear actin organization.
• FBXO25 and FAND are implicated in regulating nuclear functions, including transcription.
• These findings provide new insights into the function of FAND and FBXO25 in the nucleus.