In today’s new issue of JCB, Couturier et al. reveal that the endocytic regulator Numb downregulates Notch signaling by sorting the Notch receptor and its binding partner Sanpodo to late endosomes and lysosomes during Drosophila sensory bristle morphogenesis. As described in this week’s In Focus, the researchers uncovered this pathway by dual tagging Notch and Sanpodo with both green and red fluorescent proteins, an approach that should prove useful for following the endocytic sorting of many other membrane proteins.
Norris et al. describe another useful new tool, specifically a technique to control the assembly of multiprotein complexes in vivo. The researchers use their approach to examine how different kinesin motor proteins affect each other’s function when assembled into a single transport complex. You can read more about the technique, and about how kinesin-1/kinesin-3 complexes move differently on different populations of microtubules, in this summary.
Meanwhile, Rošić et al. demonstrate that a non-coding RNA transcribed from repetitive satellite DNA sequences promotes kinetochore assembly and chromosome segregation during mitosis. The researchers find that SAT III RNA transcribed from the Drosophila X chromosome localizes to the centromeres of most mitotic chromosomes. Knocking down this RNA inhibits the recruitment of centromere and kinetochore proteins, causing defects in chromosome segregation. More here.
And Olsen et al. describe how the kinase complex mTORC2 acts downstream of the b3-adrenoceptor to stimulate translocation of the glucose transporter GLUT1 to the plasma membrane of brown adipocytes in order to promote glucose uptake. As explained here, brown adipose tissue can take up large amounts of glucose from the bloodstream to use as a fuel source to generate body heat, so stimulating this pathway may be an effective treatment for type II diabetes and obesity.
Today also sees the release of our latest biobytes podcast, which features the senior authors of two recent JCB papers. Vincent Archambault describes how the mitotic kinase Aurora B regulates Polo kinase during cytokinesis, and Kerry Bloom discusses the role of tRNA genes and tRNA regulatory proteins in organizing pericentric chromatin. You can listen to the podcast below or subscribe in iTunes.
That’s all for today, but there are, of course, lots of other papers for you to discover at our table of contents page here.
Cover image of dual-tagged Sanpodo protein in dividing cells in the notum of a Drosophila pupa © 2014 Couturier et al.