USP45 and Spindly are part of the same complex implicated in cell migration

Area of Science:

• Biochemistry
• Molecular Biology
• Cell Biology

Background:

• Ubiquitylation is a key post-translational modification regulating protein function.
• Deubiquitinating enzymes (DUBs), like USP45, reverse ubiquitylation.
• USP45's functions are largely uncharacterized beyond DNA repair and retinal differentiation.

Purpose of the Study:

• To identify novel targets of USP45.
• To elucidate the role of USP45 in regulating Spindly.
• To investigate USP45's function in cellular processes.

Main Methods:

• Mass spectrometry to identify USP45 interacting partners.
• Co-immunoprecipitation to confirm protein complex formation.
• Ubiquitin chain analysis and in vitro deubiquitylation assays.

Main Results:

• Spindly was identified as a novel USP45 target, forming a complex dependent on USP45's catalytic activity.
• USP45 preferentially cleaves K48-linked ubiquitin chains and potentially K6-linked chains.
• USP45 specifically removes mono-ubiquitylation from Spindly.
• USP45 was found to play a role in cell migration, a function also attributed to Spindly.

Conclusions:

• USP45 directly interacts with and deubiquitylates Spindly.
• USP45's enzymatic activity is crucial for its interaction with Spindly and regulation of its ubiquitylation status.
• USP45 contributes to cell migration, highlighting a shared functional role with Spindly.