In today’s new edition of JCB, Klingberg et al. reveal that latent TGF-β1 complexes become primed for activation when myofibroblasts remodel the extracellular matrix into extended fibrils during wound healing. As explained in this week’s In Focus, TGF-β1 complexes incorporated into these fibrils come under strain and are therefore more susceptible to being pulled apart and activated by myofibroblast-mediated contractility, an event that can lead to tissue fibrosis.
Dolat et al. show that septin filaments crosslink actin stress fibers at the front of migrating epithelial cells and transmit tension to promote focal adhesion maturation and cell motility. More here.
Nandi et al. describe how a caspase and a kinase combine to regulate the levels of a protein that stimulates autophagy. The researchers discover that a Drosophila protein called Acinus is cleaved by the caspase Dcp-1, but is stabilized by the kinase Akt. As summarized here, cleavage-resistant forms of Acinus boost autophagy and extend the life spans of mutant flies, probably due to the protective effects of this cellular degradation pathway. Indeed, cleavage-resistant Acinus mutants even protect flies from the neurodegeneration associated with aggregation-prone Huntingtin protein.
And Gao et al. reveal that a cytosolic protein called CLUH promotes mitochondrial biogenesis by binding to mRNAs encoding mitochondrial proteins. The expression of several of these proteins is reduced in cells lacking CLUH, leading the authors to suggest that CLUH helps ensure that mitochondrial proteins are translated near to mitochondria so that they can be quickly imported into the organelle. More here.
And in this month’s biosights video podcast, Roland Wedlich-Söldner discusses his recent paper describing how non-confluent epithelial cells form long, dynamic microvilli on their apical surfaces, which connect to an underlying cortical actomyosin network. If you missed it last issue, you can also read Robert Fischer’s commentary on the paper here.
That’s all for today but, as always, you can find lots of other interesting papers by visiting our full table of contents here.
Cover image of the extracellular matrix assembled by human dermal fibroblasts © 2014 Klingberg et al.