Mechanisims of nuclear self-assembly

Introduction

Shape and function of the vertebrate nucleus depend on the choreographed interplay between lipids, proteins, and DNA to form the nuclear envelope. Even small molecular changes, such as point mutations in the proteins of the nuclear envelope (the lamina), cause detrimental human diseases including premature aging, cancer, and heart disease.

To date, a clear, mechanistically compelling explanation for the dynamic coupling of lipids, proteins, and DNA to safeguard nuclear shape and function is still missing. We here propose to build minimal, synthetic nuclei (‘Organelloids’) bottom-up as a tool to study the self-assembly of a functional nucleus.

Recent Discoveries

We recently discovered the conserved molecular machinery that ensures the assembly of the nuclear envelope in open vertebrate mitosis. Our data point to uncharacterized fundamental mechanisms that couple the following processes:

1. The fusion of lipid-membrane sheets into a continuous nuclear membrane.
2. The formation of the lamina.
3. The organization of chromatin in the same chain of events.

Proposal Overview

In this proposal, we will leverage our recent advances in reconstitution to build ‘Organelloids’ to recapitulate the shape and function of the membrane-lamina-chromatin confluence.

Using these nuclear Organelloids, we will resolve the nuclear assembly process in high resolution by applying integrated structural biology and determine the unknown biophysical principles that drive the self-organization of individual molecules into one functional organelle.

Goals and Implications

Our strategy will reveal the unknown hierarchical relationship between lipids, proteins, and DNA and produce detailed mechanistic models for the formation and coupling of functional subdomains that are commonly observed in the nuclear membrane, the lamina, and chromatin.

With cell models and top-down approaches, we ultimately aim to define the fundamental principles that govern nuclear biogenesis with implications for health and disease.