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Heidelberg, Germany

Zitouni S.,Instituto Gulbenkian Of Ciencia | Francia M.,Instituto Gulbenkian Of Ciencia | Leal F.,Instituto Gulbenkian Of Ciencia | Montenegro Gouveia S.,Instituto Gulbenkian Of Ciencia | And 16 more authors.
Current Biology | Year: 2016

Centrioles are essential for the assembly of both centrosomes and cilia. Centriole biogenesis occurs once and only once per cell cycle and is temporally coordinated with cell-cycle progression, ensuring the formation of the right number of centrioles at the right time. The formation of new daughter centrioles is guided by a pre-existing, mother centriole. The proximity between mother and daughter centrioles was proposed to restrict new centriole formation until they separate beyond a critical distance. Paradoxically, mother and daughter centrioles overcome this distance in early mitosis, at a time when triggers for centriole biogenesis Polo-like kinase 4 (PLK4) and its substrate STIL are abundant. Here we show that in mitosis, the mitotic kinase CDK1-CyclinB binds STIL and prevents formation of the PLK4-STIL complex and STIL phosphorylation by PLK4, thus inhibiting untimely onset of centriole biogenesis. After CDK1-CyclinB inactivation upon mitotic exit, PLK4 can bind and phosphorylate STIL in G1, allowing pro-centriole assembly in the subsequent S phase. Our work shows that complementary mechanisms, such as mother-daughter centriole proximity and CDK1-CyclinB interaction with centriolar components, ensure that centriole biogenesis occurs once and only once per cell cycle, raising parallels to the cell-cycle regulation of DNA replication and centromere formation. Zitouni, Francia et al. explore the mechanisms coupling the cell cycle to centrosome biogenesis, and show that in mitosis, CDK1 competes with PLK4, the trigger of centriole biogenesis, for binding to its substrate STIL. PLK4 binding and phosphorylation of STIL occurs only upon CDK1 activity drop at mitotic exit, leading to centriole biogenesis onset. © 2016 Elsevier Ltd.

Lima-Mendez G.,Catholic University of Leuven | Lima-Mendez G.,Center for the Biology of Disease | Lima-Mendez G.,Vrije Universiteit Brussel | Faust K.,Catholic University of Leuven | And 105 more authors.
Science | Year: 2015

Species interaction networks are shaped by abiotic and biotic factors. Here, as part of the Tara Oceans project, we studied the photic zone interactome using environmental factors and organismal abundance profiles and found that environmental factors are incomplete predictors of community structure. We found associations across plankton functional types and phylogenetic groups to be nonrandomly distributed on the network and driven by both local and global patterns. We identified interactions among grazers, primary producers, viruses, and (mainly parasitic) symbionts and validated networkgenerated hypotheses using microscopy to confirm symbiotic relationships. We have thus provided a resource to support further research on ocean food webs and integrating biological components into ocean models. © 2015, American Association for the Advancement of Science. All rights reserved.

Ukken F.P.,University of Cologne | Ukken F.P.,University of Wisconsin - Madison | Aprill I.,Directors Research | JayaNandanan N.,Directors Research | And 2 more authors.
PLoS ONE | Year: 2014

A key element in the regulation of subcellular branching and tube morphogenesis of the Drosophila tracheal system is the organization of the actin cytoskeleton by the ERM protein Moesin. Activation of Moesin within specific subdomains of cells, critical for its interaction with actin, is a tightly controlled process and involves regulatory inputs from membrane proteins, kinases and phosphatases. The kinases that activate Moesin in tracheal cells are not known. Here we show that the Sterile-20 like kinase Slik, enriched at the luminal membrane, is necessary for the activation of Moesin at the luminal membrane and regulates branching and subcellular tube morphogenesis of terminal cells. Our results reveal the FGF-receptor Breathless as an additional necessary cue for the activation of Moesin in terminal cells. Breathless-mediated activation of Moesin is independent of the canonical MAP kinase pathway. © 2014 Ukken et al.

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