Lamin A / Progerin
Lamin A is a structural protein (an intermediate filament) and a major part of the nuclear lamina, the mesh just under your cell's inner nuclear membrane. It is essential for nuclear shape, organizing chromatin, DNA repair, and gene regulation. It is coded by the LMNA gene. Making mature lamin A takes processing: the precursor (prelamin A) gets farnesylated, then an enzyme (ZMPSTE24) cuts it to the finished form. Progerin is a broken version. It is a shortened, permanently farnesylated form, produced by a hidden splice-site mutation in LMNA, and it causes the premature-aging disease Hutchinson-Gilford progeria. Here is the wider point: progerin also builds up at low levels during normal aging. It disrupts nuclear architecture, the DNA-damage response, and heterochromatin. That makes it a model for studying how aging works at the nuclear envelope.
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Sources
- De Sandre-Giovannoli A, Bernard R, Cau P, et al.. (2003). Lamin A truncation in Hutchinson-Gilford progeria. *Science*doi:10.1126/science.1084125
- Varela I, Cadiñanos J, Pendás AM, et al.. (2005). Accelerated ageing in mice deficient in Zmpste24 protease is linked to p53 signalling activation. *Nature*doi:10.1038/nature04019