ESCRT-III/Vps4 Controls Heterochromatin-Nuclear Envelope Attachments.

Area of Science:

• Cell Biology
• Molecular Biology
• Genetics

Background:

• Eukaryotic genome organization relies on inner nuclear membrane (INM) protein interactions.
• Mechanisms controlling chromatin tethering to the INM and its role in nuclear envelope (NE) remodeling during mitosis are not fully understood.

Purpose of the Study:

• To investigate the regulation of chromatin-INM tethering during interphase.
• To determine the contribution of this process to NE remodeling in mitosis.

Main Methods:

• Utilized the fission yeast Schizosaccharomyces japonicus, which exhibits NE breakdown and reformation during mitosis.
• Employed genetic and cell biological approaches to probe protein interactions and cellular processes.

Main Results:

• Demonstrated that the ESCRT-III/Vps4 machinery remodels heterochromatin attachments to the INM-localized Lem2-Nur1 complex during interphase.
• Showed that impaired ESCRT-III/Vps4 function results in persistent chromosome-INM association throughout mitosis.
• Found that failure to release Lem2-Nur1 from heterochromatin at mitotic exit obstructs the re-establishment of nucleocytoplasmic compartmentalization.

Conclusions:

• Identified the Lem2-Nur1 complex as a substrate for the nuclear ESCRT machinery.
• Established a link between dynamic chromosome tethering to the INM and the establishment of nuclear compartmentalization.