Mechanistic understanding towards how progerin contributes to premature ageing

The nuclear lamina is a meshwork of lamin proteins that underlie the inner nuclear membrane and confer mechanical stability to the nuclear envelope. Mutations in lamins are associated with many disorders, including Progeria, a fatal premature ageing disease.

In progeroid cells, expression of a truncated form of lamin A, named progerin, drastically deforms the nuclear envelope, causing premature cellular senescence.

However, the underlying molecular mechanisms remain unclear.The nuclear pore complexes (NPCs) enable selective transport across the nuclear envelope.

The diameter of the NPC central channel and the resulting nucleocytoplasmic exchange is governed by membrane tension, which is predicted to alter in the progeroid nuclei.

Therefore, I postulate that the structural integrity of the NPCs is disrupted in progeroid cells, as a result of the deformed nuclear envelope, and/or direct interaction with progerin.

This may lead to further deregulation of nuclear transport that potentially drives cellular senescence.I aim to investigate whether the NPCs indeed undergo compositional and conformational change in Progeria patient-derived primary cells, and to what extent nuclear transport is impacted. To do so, I will apply in cellulo cryo-electron tomography to unveil the molecular organisation of the progeroid NPCs.

I will further employ fluorescence microscopy-based cellular assays to identify proteins with nucleocytoplasmic mislocalisation.

The proposed work will have three major significances: (1) To date, in cellulo structures of the NPCs in disease states have rarely been examined.

Visualisation of the NPCs directly in patient-derived cells will provide pivotal insights into NPC biology. (2) Investigation of nuclear transport in progeroid cells will reveal the mechanisms contributing to premature ageing. (3) Since progerin is also produced during normal ageing, its mechanistic investigation may add to understanding of the natural ageing processes.