Regulation of survivin protein stability by USP35 is evolutionarily conserved.

Survivin is the key component of the chromosomal passenger complex and plays important roles in the regulation of cell division. Survivin has also been implicated in the regulation of apoptosis and tumorigenesis. Although the survivin protein has been reported to be degraded by a ubiquitin/proteasome-dependent mechanism, whether there is a DUB that is involved in the regulation of its protein stability is largely unknown. Using an expression library containing 68 deubiquitinating enzymes, we found that ubiquitin-specific-processing protease 35 (USP35) regulates survivin protein stability in an enzymatic activity-dependent manner. USP35 interacted with and promoted the deubiquitination of the survivin protein. USP38, an ortholog of USP35 encoded by the human genome, is also able to regulate survivin protein stability. Moreover, we found that the deubiquitinating enzyme DUBAI, the Drosophila homolog of human USP35, is able to regulate the protein stability of Deterin, the Drosophila homolog of survivin. Interestingly, USP35 also regulated the protein stability of Aurora B and Borealin which are also the component of the chromosomal passenger complex. By regulating protein stabilities of chromosomal passenger complex components, USP35 regulated cancer cell proliferation. Taken together, our work uncovered an evolutionarily conserved relationship between USP35 and survivin that might play an important role in cell proliferation.