Summary L eucine R ich R epeat K inase 2 ( LRRK2 ) is the most commonly mutated gene in familial Parkinson’s disease (PD) 1 and is also linked to its idiopathic form 2 . LRRK2 is proposed to function in membrane trafficking 3 and co-localizes with microtubules 4 . Despite LRRK2’s fundamental importance for understanding and treating PD, there is limited structural information on it. Here we report the 3.5Å structure of the catalytic half of LRRK2, and an atomic model of microtubule-associated LRRK2 built using a reported 14Å cryo-electron tomography in situ structure 5 . We propose that the conformation of LRRK2’s kinase domain regulates its microtubule interaction, with a closed conformation favoring oligomerization on microtubules. We show that the catalytic half of LRRK2 is sufficient for filament formation and blocks the motility of the microtubule-based motors kinesin-1 and cytoplasmic dynein-1 in vitro . Kinase inhibitors that stabilize an open conformation relieve this interference and reduce LRRK2 filament formation in cells, while those that stabilize a closed conformation do not. Our findings suggest that LRRK2 can act as a roadblock for microtubule-based motors and have implications for the design of therapeutic LRRK2 kinase inhibitors.

Cyclophilins belong to the enzyme class of peptidyl prolyl cis/trans isomerases which catalyze the cis/trans isomerization of prolyl bonds in peptides and proteins in different folding states. Cyclophilins have been shown to be involved in a multitude of cellular functions like cell growth, proliferation, and motility. Among the 20 human cyclophilin isoenzymes, the two most abundant members of the cyclophilin family CypA and CypB exhibit specific cellular functions in several inflammatory diseases, cancer development and HCV replication. A small-molecule inhibitor on the basis of aryl 1-indanylketones has now been shown to discriminate between CypA and CypB in vitro. CypA binding of this inhibitor has been characterized by fluorescence anisotropy- and isothermal titration calorimetry-based cyclosporin competition assays. Inhibition of CypA- but not CypB-mediated chemotaxis of mouse CD4+ T cells by the inhibitor provided biological proof of discrimination in vivo.

Highlights d KI-ARv-03 reduces AR protein levels and AR-driven transcription d KI-ARv-03 is deduced to be a potent, ultraselective inhibitor of CDK9 d Optimization led to the orally bioavailable and selective CDK9 inhibitor KB-0742 d KB-0742 displays potent anti-tumor activity in cancer models in vitro and in vivo

Mammalian oocytes are arrested in the dictyate stage of meiotic prophase I for long periods of time, during which the high concentration of the p53 family member TAp63α sensitizes them to DNA damage-induced apoptosis. TAp63α is kept in an inactive and exclusively dimeric state but undergoes rapid phosphorylation-induced tetramerization and concomitant activation upon detection of DNA damage. Here we show that the TAp63α dimer is a kinetically trapped state. Activation follows a spring-loaded mechanism not requiring further translation of other cellular factors in oocytes and is associated with unfolding of the inhibitory structure that blocks the tetramerization interface. Using a combination of biophysical methods as well as cell and ovary culture experiments we explain how TAp63α is kept inactive in the absence of DNA damage but causes rapid oocyte elimination in response to a few DNA double strand breaks thereby acting as the key quality control factor in maternal reproduction.DOI: http://dx.doi.org/10.7554/eLife.13909.001