Evolving Spindlin1 Small Molecule Inhibitors Using Protein Microarrays

Using a library of tagged UNC1215 analogs, we screened a protein domain microarray of methyl-lysine effector molecules to rapidly detect compounds with novel binding profiles. Using this approach, we identified a compound (EML405) that acquired a novel interaction with the Tudor domain-containing protein Spindlin1 (SPIN1). Structural studies revealed that the symmetric nature of EML405 allows it to simultaneously engage two of SPIN1’s Tudor domains, and also facilitated the rational synthesis of more selective SPIN1 inhibitor (EML631). The EML631 compound engages SPIN1 in cells, blocks its ability to “read” H3K4me3 marks, and inhibits its transcriptional coactivator activity. RNA-seq of control, SPIN1 siRNA knockdown (24 hour post-transfection) and EML631 treated (10 mM, 3 days) T778 cells