title: LAMTOR2-mediated modulation of NGF/MAPK activation kinetics during differentiation of PC12 cells.
abstract: LAMTOR2 (p14), a part of the larger LAMTOR/Ragulator complex, plays a crucial role in EGF-dependent activation of p42/44 mitogen-activated protein kinases (MAPK, ERK1/2). In this study, we investigated the role of LAMTOR2 in nerve growth factor (NGF)-mediated neuronal differentiation. Stimulation of PC12 (rat adrenal pheochromocytoma) cells with NGF is known to activate the MAPK. Pharmacological inhibition of MEK1 as well as siRNA-mediated knockdown of both p42 and p44 MAPK resulted in inhibition of neurite outgrowth. Contrary to expectations, siRNA-mediated knockdown of LAMTOR2 effectively augmented neurite formation and neurite length of PC12 cells. Ectopic expression of a siRNA-resistant LAMTOR2 ortholog reversed this phenotype back to wildtype levels, ruling out nonspecific off-target effects of this LAMTOR2 siRNA approach. Mechanistically, LAMTOR2 siRNA treatment significantly enhanced NGF-dependent MAPK activity, and this effect again was reversed upon expression of the siRNA-resistant LAMTOR2 ortholog. Studies of intracellular trafficking of the NGF receptor TrkA revealed a rapid colocalization with early endosomes, which was modulated by LAMTOR2 siRNA. Inhibition of LAMTOR2 and concomitant destabilization of the remaining members of the LAMTOR complex apparently leads to a faster release of the TrkA/MAPK signaling module and nuclear increase of activated MAPK. These results suggest a modulatory role of the MEK1 adapter protein LAMTOR2 in NGF-mediated MAPK activation required for induction of neurite outgrowth in PC12 cells.
authors.affiliation: Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Bettina
authors.initials: B
authors.lastname: Thauerer
authors.affiliation: Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria; Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Paul
authors.initials: P
authors.lastname: Voegele
authors.affiliation: Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Natascha
authors.initials: N
authors.lastname: Hermann-Kleiter
authors.affiliation: Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Nikolaus
authors.initials: N
authors.lastname: Thuille
authors.affiliation: Division of Cell Biology, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Mariana E G
authors.initials: ME
authors.lastname: de Araujo
authors.affiliation: Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Martin
authors.initials: M
authors.lastname: Offterdinger
authors.affiliation: Division of Cell Genetics, Department for Pharmacology and Genetics, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Gottfried
authors.initials: G
authors.lastname: Baier
authors.affiliation: Division of Cell Biology, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Lukas A
authors.initials: LA
authors.lastname: Huber
authors.affiliation: Division of Neurobiochemistry, CCB-Biocenter, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Baier-Bitterlich
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000502:physiology; D011992:Endosomes / Q000378:metabolism; D007700:Kinetics; D048369:MAP Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D020932:Nerve Growth Factor / Q000235:genetics / Q000378:metabolism*; D016716:PC12 Cells; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C426009:LAMTOR2 protein, mouse; D011506:Proteins; D020932:Nerve Growth Factor; D020928:Mitogen-Activated Protein Kinases; D048369:MAP Kinase Kinase 1
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