Université de Fribourg

Multilayered control of protein turnover by torc1 and atg1

Hu, Zehan ; Raucci, Serena ; Jaquenoud, Malika ; Hatakeyama, Riko ; Stumpe, Michael ; Rohr, Rudolf ; Reggiori, Fulvio ; Virgilio, Claudio De ; Dengjel, Jörn

In: Cell Reports, 2019, vol. 28, no. 13, p. 3486-3496.e6

The target of rapamycin complex 1 (TORC1) is a master regulator of cell homeostasis, which promotes anabolic reactions and synchronously inhibits catabolic processes such as autophagy-mediated protein degradation. Its prime autophagy target is Atg13, a subunit of the Atg1 kinase complex that acts as the gatekeeper of canonical autophagy. To study whether the activities of TORC1 and Atg1 are...

Université de Fribourg

Spatially distinct pools of TORC1 balance protein homeostasis

Hatakeyama, Riko ; Péli-Gulli, Marie-Pierre ; Hu, Zehan ; Jaquenoud, Malika ; Osuna, Guillermo Miguel Garcia ; Sardu, Alessandro ; Dengjel, Jörn ; Virgilio, Claudio De

In: Molecular Cell, 2019, vol. 73, no. 2, p. 325-338.e8

The eukaryotic TORC1 kinase is a homeostatic controller of growth that integrates nutritional cues and mediates signals primarily from the surface of lysosomes or vacuoles. Amino acids activate TORC1 via the Rag GTPases that combine into structurally conserved multi-protein complexes such as the EGO complex (EGOC) in yeast. Here we show that Ego1, which mediates membrane-anchoring of EGOC via...

Université de Fribourg

TORC1 coordinates the conversion of Sic1 from a target to an inhibitor of cyclin-CDK-Cks1

Moreno-Torres, Marta ; Jaquenoud, Malika ; Péli-Gulli, Marie-Pierre ; Nicastro, Raffaele ; Virgilio, Claudio De

In: Cell Discovery, 2017, vol. 3, p. 17012

Eukaryotic cell cycle progression through G1–S is driven by hormonal and growth- related signals that are transmitted by the target of rapamycin complex 1 (TORC1) pathway. In yeast, inactivation of TORC1 restricts G1–S transition due to the rapid clearance of G1 cyclins (Cln) and the stabilization of the B-type cyclin (Clb) cyclin- dependent kinase (CDK) inhibitor Sic1. The latter mechanism...

Université de Fribourg

TORC1 controls G1-S cell cycle transition in yeast via Mpk1 and the greatwall kinase pathway

Moreno-Torres, Marta ; Jaquenoud, Malika ; De Virgilio, Claudio

In: Nature Communications, 2015, vol. 6, p. 8256

The target of rapamycin complex 1 (TORC1) pathway couples nutrient, energy and hormonal signals with eukaryotic cell growth and division. In yeast, TORC1 coordinates growth with G₁–S cell cycle progression, also coined as START, by favouring the expression of G₁ cyclins that activate cyclin-dependent protein kinases (CDKs) and by destabilizing the CDK inhibitor Sic1. Following TORC1...

Université de Fribourg

TORC1 regulates Pah1 phosphatidate phosphatase activity via the Nem1/Spo7 protein phosphatase complex

Dubots, Emmanuelle ; Cottier, Stéphanie ; Péli-Gulli, Marie-Pierre ; Jaquenoud, Malika ; Bontron, Séverine ; Schneiter, Roger ; Virgilio, Claudio De

In: PLoS ONE, 2014, vol. 9, no. 8, p. e104194

The evolutionarily conserved target of rapamycin complex 1 (TORC1) controls growth-related processes such as protein, nucleotide, and lipid metabolism in response to growth hormones, energy/ATP levels, and amino acids. Its deregulation is associated with cancer, type 2 diabetes, and obesity. Among other substrates, mammalian TORC1 directly phosphorylates and inhibits the phosphatidate phosphatase...

Université de Fribourg

Yeast endosulfines control entry into quiescence and chronological life span by inhibiting protein phosphatase 2A

Bontron, Séverine ; Jaquenoud, Malika ; Vaga, Stefania ; Talarek, Nicolas ; Bodenmiller, Bernd ; Aebersold, Ruedi ; De Virgilio, Claudio

In: Cell Reports, 2012, vol. 3, no. 1, p. 16–22

The TORC1 and PKA protein kinases are central elements of signaling networks that regulate eukaryotic cell proliferation in response to growth factors and/or nutrients. In yeast, attenuation of signaling by these kinases following nitrogen and/or carbon limitation activates the protein kinase Rim15, which orchestrates the initiation of a reversible cellular quiescence program to ensure normal...

Université de Fribourg

Leucyl-tRNA synthetase controls TORC1 via the EGO complex

Bonfils, Grégory ; Jaquenoud, Malika ; Bontron, Séverine ; Ostrowicz, Clemens ; Ungermann, Christian ; De Virgilio, Claudio

In: Molecular Cell, 2012, vol. 46, no. 1, p. 105–110

The target of rapamycin complex 1 (TORC1) is an essential regulator of eukaryotic cell growth that responds to growth factors, energy levels, and amino acids. The mechanisms through which the preeminent amino acid leucine signals to the TORC1-regulatory Rag GTPases, which activate TORC1 within the yeast EGO complex (EGOC) or the structurally related mammalian Rag-Ragulator complex, remain...

Université de Fribourg

Initiation of the TORC1-regulated G0 program requires Igo1/2, which license specific mRNAs to evade degradation via the 5'-3' mRNA decay pathway

Talarek, Nicolas ; Cameroni, Elisabetta ; Jaquenoud, Malika ; Luo, Xuan ; Bontron, Séverine ; Lippman, Soyeon ; Devgan, Geeta ; Snyder, Michael ; Broach, James R. ; De Virgilio, Claudio

In: Molecular Cell, 2010, vol. 38, no. 3, p. 345-355

Eukaryotic cell proliferation is controlled by growth factors and essential nutrients, in the absence of which cells may enter into a quiescent (G0) state. In yeast, nitrogen and/or carbon limitation causes downregulation of the conserved TORC1 and PKA signaling pathways and, consequently, activation of the PAS kinase Rim15, which orchestrates G0 program initiation and ensures proper life span by...

Université de Fribourg

The Gup1 homologue of Trypanosoma brucei is a GPI glycosylphosphatidylinositol remodelase

Jaquenoud, Malika ; Pagac, Martin ; Signorell, Aita ; Benghezal, Mohammed ; Jelk, Jennifer ; Bütikofer, Peter ; Conzelmann, Andreas

In: Molecular Microbiology, 2008, vol. 67, no. 1, p. 202-212

Glycosylphosphatidylinositol (GPI) lipids of Trypanosoma brucei undergo lipid remodelling, whereby longer fatty acids on the glycerol are replaced by myristate (C14:0). A similar process occurs on GPI proteins of Saccharomyces cerevisiae where Per1p first deacylates, Gup1p subsequently reacylates the anchor lipid, thus replacing a shorter fatty acid by C26:0. Heterologous expression...

Université de Fribourg

GUP1 of Saccharomyces cerevisiae Encodes an O-Acyltransferase Involved in Remodeling of the GPI Anchor

Bosson, Régine ; Jaquenoud, Malika ; Conzelmann, Andreas

In: Molecular Biology of the Cell, 2006, vol. 17, no. 6, p. 2636-2645

The anchors of mature glycosylphosphatidylinositol (GPI)-anchored proteins of Saccharomyces cerevisiae contain either ceramide or diacylglycerol with a C26:0 fatty acid in the sn2 position. The primary GPI lipid added to newly synthesized proteins in the ER consists of diacylglycerol with conventional C16 and C18 fatty acids. Here we show that GUP1 is essential for the synthesis of...