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The yeast cell wall integrity pathway signals from recycling endosomes upon elimination of phosphatidylinositol (4,5)-bisphosphate by mammalian phosphatidylinositol 3-kinase.

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Fernández Acero, Teresa and Rodríguez Escudero, Isabel and Molina, María and Cid, Víctor J. (2015) The yeast cell wall integrity pathway signals from recycling endosomes upon elimination of phosphatidylinositol (4,5)-bisphosphate by mammalian phosphatidylinositol 3-kinase. Cellular signalling, 27 (11). pp. 2272-84. ISSN 0898-6568

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Official URL: http://dx.doi.org/10.1016/j.cellsig.2015.08.004



Abstract

Phosphatidylinositol (4,5)-bisphosphate [PtdIns(4,5)P2] is essential for recognition of the plasma membrane inner leaf by protein complexes. We expressed mammalian class I phosphoinositide 3-kinase (PI3K) in Saccharomyces cerevisiae to eliminate PtdIns(4,5)P2 by its conversion into PtdIns(3,4,5)P3, a lipid naturally missing in this yeast. This led to loss of actin function and endocytosis defects, causing a blockage in polarized secretion. Also, the cell wall integrity (CWI) mitogen-activated protein kinase (MAPK) pathway was activated, triggering a typical transcriptional response. In the absence of PtdIns(4,5)P2 at the plasma membrane, the Pkc1 protein kinase upstream the CWI MAPK module localized to post-Golgi endosomes marked by SNARE Snc1 and Rab GTPases Ypt31 and Ypt32. Other components at the head of the pathway, like the mechanosensor Wsc1, the GTPase Rho1 and its activator the GDP/GTP exchange factor Rom2, co-localized with Pkc1 in these compartments. Chemical inhibition of PI3K proved that both CWI activation and Pkc1 relocation to endosomes are reversible. These results suggest that the CWI pathway is able to respond to loss of plasma membrane identity from recycling endosomes.


Item Type:Article
Uncontrolled Keywords:Yeast, MAPK signaling, Pkc1, Phosphoinositides, Endosomes, PI3K
Subjects:Medical sciences > Pharmacy > Microbiology
ID Code:33656
Deposited On:26 Nov 2015 13:20
Last Modified:29 Nov 2015 14:51

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