Time for a quick roundup of some of the highlights from today's new issue of JCB...
Kleiblova et al. identify mutations in the phosphatase Wip1 that enable cancer cells to foil the tumor suppressor p53. As explained in this week's In Focus, the mutations generate truncated versions of Wip1 that are more stable than the wild-type protein, and are therefore better able to inactivate p53 and permit cells to override the DNA damage checkpoint.
Snow et al. reveal that Progerin, a mutant form of lamin A expressed in Hutchinson-Gilford Progeria syndrome, disrupts the import of large protein cargoes into the nucleus by lowering the levels of nuclear RanGTPase. More here.
Civelekoglu-Scholey et al. model the dynamics of metaphase chromosomes in Ptk1 cells. As explained here, Ptk1 cells represent in unusual case in which chromosomes at the edge of the metaphase plate are immobile, whereas the ones in the central region oscillate. Civelekoglu-Scholey et al. reveal that these different behaviors are due to regional differences in the strength of the polar ejection forces that push chromosomes toward the cell equator.
And Graziano et al. report a new mechanism for controlling actin nucleation, identifying a budding yeast protein, Bil1, that activates the nucleation promoting factor Bud6, which, in turn, stimulates the formin Bnr1 to initiate actin cable assembly. As described in this summary, this is an unusual way of regulating actin assembly, as nucleation tends to be initiated by proteins working in pairs, rather than in groups of three.
And, finally for today, this month’sbiosights video podcast features Roberta Martinelli and Christopher Carman, who discuss their recent paper describing how a loss of tension inside endothelial cells induces the formation of ventral membrane protrusions that close the holes left by transmigrating leukocytes. You can watch it here or subscribe in iTunes and, if you'd like to discuss Martinelli et al.'s findings with your lab, you can download a “Journal Club Pack” – including a pdf of the paper and a PowerPoint file of their figures – by clicking here.
That's all for today, but you can find the full table of contents for today's new issue by clicking here.
Cover image of nuclear import in the presence and absence of progerin © 2013 Snow et al.