In today’s new edition of JCB, Baßler et al. describe how a motor protein on immature ribosomes connects to a network of other molecules within the nascent organelles so that it can tug them into their final positions. As described in this week’s In Focus, the dynein-related motor Rea1 removes a protein called Rsa4 from immature ribosomes and, in the process, appears to reposition several other ribosomal components into their correct locations.
Fernandes et al. reveal that mutations in the Drosophila gene Skywalker, a homologue of a human gene linked to neurodegeneration and epilepsy, enhances the turnover of old synaptic vesicle-associated proteins. This increases the abundance of newer, more active synaptic vesicle proteins, which, by enhancing synaptic activity, could result in neurodegeneration. More here.
Juin et al. identify a receptor that allows cancer cells to recognize and break through type I collagen. As explained here, the collagen receptor DDR1 promotes the formation of actin-rich extensions called linear invadosomes by activating the small GTPase Cdc42 through its guanine nucleotide exchange factor Tuba. The linear invadosomes then degrade the extracellular collagen matrix to promote cance cell invasion.
And Sun et al. reveal that oscillating calcium levels help melanoma cells become invasive. Calcium waves induced by the proteins STIM1 and Orai1 stimulate invadosome protrusions and promote the delivery of a matrix metalloproteinase to the plasma membrane. More here.
And finally for today, Jones et al. reveal that dynein’s light intermediate chains are required to maintain centrosome integrity during mitosis, preventing the premature separation of mother-daughter centrioles and the formation of multipolar spindles. Senior authors Viki Allan and Sarah Woolner explain more in this month’s biosights video podcast, which you can watch below or subscribe to in iTunes.
That’s all for today, but you can find plenty more interesting papers by visiting our table of contents page here.
Cover image of linear invadosomes in a breast cancer cell © 2014 Juin et al.