Dynamic phosphorylation of CENP-N by CDK1 guides accurate chromosome segregation in mitosis

In mitosis,accurate chromosome segregation depends on the kinetochore,a supermolecular machinery that couples dynamic spin-dle microtubules to centromeric chromatin.However,the structure–activity relationship of the constitutive centromere-associated network(CCAN)during mitosis remains uncharacterized.Building on our recent cryo-electron microscopic analyses of human CCAN structure,we investigated how dynamic phosphorylation of human CENP-N regulates accurate chromosome segregation.Our mass spectrometric analyses revealed mitotic phosphorylation of CENP-N by CDK1,which modulates the CENP-L–CENP-N interaction for accurate chromosome segregation and CCAN organization.Perturbation of CENP-N phosphorylation is shown to prevent proper chromosome alignment and activate the spindle assembly checkpoint.These analyses provide mechanistic insight into a previously undefined link between the centromere–kinetochore network and accurate chromosome segregation.

Ultrastructural analysis of neuronal synapses using state-of-the-art nano-imaging techniques

Neuronal synapses are functional nodes in neural circuits.Their organization and activity define an individual＇s level of intelligence,emotional state and mental health.Changes in the structure and efficacy of synapses are the biological basis of learning and memory.However,investigation of the molecular architecture of synapses has been impeded by the lack of efficient techniques with sufficient resolution.Recent developments in state-of-the-art nano-imaging techniques have opened up a new window for dissecting the molecular organization of neuronal synapses with unprecedented resolution.Here,we review recent technological advances in nano-imaging techniques as well as their applications to the study of synapses,emphasizing super-resolution light microscopy and 3-dimensional electron tomography.