SUV39H1 Orchestrates Centromeric Methylation Dynamics in Mitosis

Abstract

Histone methylation performs multiple functions such as DNA replication, transcription regulation, heterochromatin formation, and chromatin condensation. How this methylation gradient is orchestrated in the centromere during chromosome segregation is not known. Here we examine the temporal dynamics of protein methylation in the centromere by SUV39H1 methyltransferase, a key mitotic regulator, using fluorescence resonance energy transfer‐based sensors in living HeLa cells and immunofluorescence of native SUV39H1 substrates. A quantitative analysis of methylation dynamics, using centromere‐targeted sensors, reveals a temporal change during chromosome segregation. These dynamics result in an accurate chromosome congression to and alignment at the equator as an inhibition of methylation dynamics using SUV39H1 inhibitor perturbs chromosome congression in living HeLa cells. Surprisingly, this inhibition of methylation results in a brief increase in Aurora B kinase activity and an enrichment of microtubule depolymerase MCAK in the centromere with a concomitant kinetochore‐microtubule destabilization and a reduced tension across the sister kinetochores with ultimate chromosome misalignments. We reason that SUV39H1 generates a gradient of methylation marks at the kinetochore that provides spatiotemporal information essential for accurate chromosome segregation in mitosis. Currently, we are uncovering the kinetochore substrates of SUV39H1 and understand how methylation of non‐histone proteins regulates kinetochore microtubule dynamics and chromosome plasticity in mitosis.