Lecture-hall cartoon depictions aside, the nucleus is not a
balloon. Rather, its architecture is defined by a specialized
cytoskeleton (the nuclear lamina) consisting of proteins known
as lamins. These proteins give structure to the nuclear envelope
during interphase; during cell division, a complex dance of
phosphorylation and dephosphorylation causes them to disassemble
(allowing for chromosome segregation into the daughter nuclei)
and then reassemble following cytokinesis. Derangement of the
lamina might be expected to cause serious trouble for the cell.
Indeed, an extensive body of work over the past 5 years has
clearly demonstrated that a particular mutation in the lamin A
gene (LMNA) results in severe nuclear malformation. In humans,
this mutation gives rise to a devastating disease, Hutchinson-
Gilford progeria syndrome (HGPS). (For earlier articles on HGPS,
see here and here). Two new papers, published back-to-back in
the most recent issue of PNAS, describe the impact of the HGPS
lamin A mutant protein