Time for a quick roundup of some of the highlights from the latest issue of JCB…
Lawrimore et al. reveal that loops of pericentric chromatin repel each other to generate tension between sister centromeres independently of the mitotic spindle. As explained in this week’s In Focus, the structure of this pericentric chromatin spring may also allow it to act as a shock absorber that can buffer the variable forces generated by dynamic spindle microtubules.
Henne et al. reveal that a protein linked to human neurological disease helps tether vacuoles to the ER in budding yeast. Mutations in human sorting nexin 14 cause an autosomal-recessive form of cerebellar ataxia. Henne et al. find that similar mutations in the yeast homolog, Mdm1, disrupt this protein’s localization to ER-vacuole contact sites, which appears to result in impaired sphingolipid metabolism.
Zhao et al. reveal that the microRNA miR-7 suppresses gastric cancer by inhibiting pro-oncogenic NF-kB signaling. The researchers also find, however, that the NF-kB pathway can inhibit miR-7 expression as part of a feedback signaling loop. Chronic Helicobacter pylori infection is a major risk factor for gastric cancer, and co-culturing the bacterium with gastric epithelial cells activated NF-kB signaling and downregulated miR-7, a potentially key step in gastric cell transformation. More here.
And Hendrix et al. use a series of fluorescence fluctuation imaging techniques to reveal that HIV-1 particles start assembling in the cytoplasm of infected cells. As summarized here, the viral polyprotein Gag starts to oligomerize on viral RNAs in the cytoplasm, before the particles associate with the plasma membrane to complete their assembly into new viral particles.
Meanwhile, in this month’s biobytes podcast, you can hear author Vibe Oestergaard describe how a protein called TopBP1 protects the genome during mitosis (Pedersen et al.), and David Williams explain how defects in phagosome transport lead to age-related macular degeneration (Jiang et al.). Listen below or subscribe in iTunes!
And, of course, there are plenty of other interesting papers, reviews and features for you to discover by visiting our full table of contents page here!
Cover image showing the increased contacts formed between vacuoles and nuclear ER upon Mdm1 overexpression © 2015 Henne et al.