Nuclear pore complex distribution on the nuclear envelope: insights into curvature, chromatin, and actin contributions

The Nuclear Pore Complex (NPC) is an ancestral feature of eukaryotic cells, essential for the exchange of material and information between cytoplasm and nucleoplasm. While, typical eukaryotic cells harbor thousands of NPCs covering the nucleus surface, a quantitative characterization of their spatial distribution remains lacking. Taking advantage of super-resolution microscopy, we imaged and segmented individual NPCs in myoblast cells to reconstruct the nuclear surface. Our spatial statistics analysis of NPCs on the nuclear surface reveals the existence of a 400nm repulsion length between NPCs, likely reflecting the mesh size of the underlying lamin network. Furthermore, we identify three key correlates of NPC density. (1) Myoblast actin fibres, which can indent the nucleus, correlate with a decrease in NPC surface density, contrary to what was reported in previous studies; (2) Regions of the nuclear envelope near large heterochromatin domains exhibit reduced NPC surface density; and (3) There is a non-monotonous relationship between NPC density and the nuclear envelope curvature. This last observation is consistent with the existence of NPC-preferred curvature suggesting curvature sensing properties. In conclusion, this study provides new insights into the spatial distribution of NPCs, shedding light on possible new determinants of NPC spatial distribution.