Stable knockdown or over expression of the SPOP-substrate ZMYND11 in Y87C SPOP-mutant and control VCaP cells

SPOP is known to bind to serine/theronine-rich degrons on substrate proteins. We identified two degron sequences within the PWWP and MYND domain of ZMYND11, a novel SPOP substrate, and investigated whether ZMYND11 may contribute to the transcriptional output of mutant SPOP in VCaP cancer cells. Indeed, a significant subset of SPOP mutant-induced gene expression changes were reverted by stable knockdown of ZMYND11 in Y87C SPOP-mutant VCaP cells. Conversely, we over-expressed wild type HA-ZMYND11 and degron-deficient ZMYND11 mutants in control VCaP cells. While all constructs where robustly over-expressed at the mRNA level, only the degron-deficient variants yielded a robust increase in ZMYND11 protein expression. Degron mutant-induced transcriptional perturbations partially mimicked SPOP mutant-induced gene expression changes, suggesting that ZMYND11 is sufficient to recapitulate certain features of mutant SPOP.