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Liver pre-metastatic niche, resulting from fibronectin overexpression by hepatic stellate cells in response to TGFβ produced by von Kupffer cells activated by pancreatic tumour-derived exosomes.p816
Control of stem cell activity is essential for accurate regeneration. Pathogen- or chemical-induced intestinal damage is now shown to recruit haemocytes expressing bone morphogenetic protein signals that stimulate proliferation of intestinal stem cells and subsequently induce their quiescence, in conjunction with muscle-derived bone morphogenetic proteins. A temporal switch in expression of Type I receptors enables this two-phase response.
Cancer cells are known to secrete exosomes with pro-metastatic effects. Pancreatic-cancer-derived exosomes are now shown to promote liver metastasis by eliciting pre-metastatic niche formation through a multi-step process. This involves uptake of exosome-derived factors by liver Kupffer cells and hepatic stellate cell activation to generate a fibrotic microenvironment with immune cell infiltrates that favours metastasis.
A major controversy in the field of chromosome research has been whether condensin is required for achieving the highly compacted state of chromatin fibres in mitosis and meiosis. Through genetic experiments in mouse oocytes, condensin is now found to be indispensable for meiotic chromosome assembly by mediating chromosome compaction and disentanglement of sister chromatids and by conferring rigidity to chromosomes.
Qin, Pei and colleagues report that autophagy is induced early during somatic cell reprogramming into induced pluripotent stem cells. mTORC1 and autophagy control reprogramming efficiency by modulating mitochondrial architecture and p62 levels.
Nance and colleagues report that the E-cadherin HMR-1 recruits the RhoGAP PAC-1 to cell–cell contact and thereby drives symmetry breaking in C. elegans embryos.
Jasper and colleagues report that following intestinal damage in Drosophila, haemocytes recruited to the intestine secrete Dpp, promoting intestinal stem cell proliferation and, at later stages of regeneration, the re-establishment of intestinal stem cell quiescence.
Itoh and colleagues find that the membrane-bending protein FBP17 is released from membranes at the leading edge of migrating cells following increased tension involving a feedback loop, in which FBP17 also promotes tension through actin protrusion formation.
Cuervo and colleagues find that perilipin proteins associated with lipid droplets are degraded by chaperone-mediated autophagy to facilitate recruitment of the lipolytic machinery to lipid droplets.
By inactivating condensin I or II before the first meiotic division in mouse oocytes, Nasmyth and colleagues demonstrate that condensin is needed for chromatin thread formation and chromosome rigidity.
Whitmarsh and colleagues identify a nuclear form of the mitochondrial enzyme, CLK-1 in C. elegans and COQ7 in human cells, respectively, that senses reactive oxygen species and regulates gene expression.
Gutkind and colleagues delineate a tumour suppressive signalling pathway involving the Gαs G protein and the PKA kinase, which inhibits pro-tumorigenic Yap and Shh signalling in epidermal stem cells.
Roose and colleagues report that the RasGRP1 and SOS1 guanine nucleotide exchange factors have opposing roles downstream of the EGFR, with RasGRP1 restricting SOS1-induced KRAS-ERK activation and suppressing intestinal tumorigenesis.
Lyden and colleagues report that pancreatic cancer-derived exosomes induce a pre-metastatic niche in the liver by promoting TGFβ secretion from Kupffer cells, leading to fibronectin production in hepatic stellate cells and macrophage recruitment.
