Nuclear Actin Puncta in Senescent Cells

Both cellular senescence and the nuclear actin cytoskeleton participate in a plethora of physiological and pathological activities. However, their connection remains elusive. Recently, it is becoming increasingly apparent that filamentous actin plays important functions within the nucleus. Particularly, micron-scaled actin filaments (hereinafter referred to as F-actin) in the nucleus are of the essence in DNA damage repair, cell fate determination and age-related diseases etc. Latrunculin B (latB), a pharmaceutically applicable macrolide, can induce nuclear F-actin assembly. Now it is unclear how the nuclear actin skeleton responds to latB stimulation in senescent cells. Here, by time-lapse images, Doxo-induced senescent IMR-90 cells showed a large number of nuclear actin puncta, then the nuclear actin puncta become brighter and larger in size upon latB treatment. Some actin puncta even served as the elongation bases for the nuclear F-actin. Therefore, our results link the nuclear actin skeleton to cell aging and reveal the effect of latB treatment on the nuclear actin skeleton in aging cells.