Characterization of Membrane Contact Sites for the Facilitation of Lipid Exchange at the Malaria Parasite - Red Blood Cell Interface

AbstractCoordinated assembly and disassembly of integrin-mediated focal adhesions (FAs) is essential for cell migration. Many studies have shown that FA disassembly requires Ca2+ influx, however our understanding of this process remains incomplete. Here we show that Ca2+ influx via STIM1/Orai1 calcium channels, which cluster near FAs, leads to activation of the GTPase Arf5 via the Ca2+-activated GEF IQSec1, and that both IQSec1 and Arf5 activation are essential for adhesion disassembly. We further show that IQSec1 forms a complex with the lipid transfer protein ORP3, and that Ca2+ influx triggers PKC-dependent translocation of this complex to ER/plasma membrane contact sites adjacent to FAs. In addition to allosterically activating IQSec1, ORP3 also extracts PI4P from the PM, in exchange for phosphatidylcholine. ORP3-mediated lipid exchange is also important for FA turnover. Together, these findings identify a new pathway that links calcium influx to FA turnover during cell migration.

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PI4P/PS countertransport by ORP10 at ER–endosome membrane contact sites regulates endosome fission

The Journal of Cell Biology ◽

10.1083/jcb.202103141 ◽

2021 ◽

Vol 221 (1) ◽

Author(s):

Asami Kawasaki ◽

Akiko Sakai ◽

Hiroki Nakanishi ◽

Junya Hasegawa ◽

Tomohiko Taguchi ◽

...

Keyword(s):

Membrane Trafficking ◽

Binding Protein ◽

Dependent Manner ◽

Oxysterol Binding Protein ◽

Membrane Contact Sites ◽

Contact Sites ◽

Lipid Exchange ◽

Membrane Contact ◽

Phosphatidylinositol 4

Membrane contact sites (MCSs) serve as a zone for nonvesicular lipid transport by oxysterol-binding protein (OSBP)-related proteins (ORPs). ORPs mediate lipid countertransport, in which two distinct lipids are transported counterdirectionally. How such lipid countertransport controls specific biological functions, however, remains elusive. We report that lipid countertransport by ORP10 at ER–endosome MCSs regulates retrograde membrane trafficking. ORP10, together with ORP9 and VAP, formed ER–endosome MCSs in a phosphatidylinositol 4-phosphate (PI4P)-dependent manner. ORP10 exhibited a lipid exchange activity toward its ligands, PI4P and phosphatidylserine (PS), between liposomes in vitro, and between the ER and endosomes in situ. Cell biological analysis demonstrated that ORP10 supplies a pool of PS from the ER, in exchange for PI4P, to endosomes where the PS-binding protein EHD1 is recruited to facilitate endosome fission. Our study highlights a novel lipid exchange at ER–endosome MCSs as a nonenzymatic PI4P-to-PS conversion mechanism that organizes membrane remodeling during retrograde membrane trafficking.

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Membrane contact sites promote lipid exchange

Science Signaling ◽

10.1126/scisignal.aad0886 ◽

2015 ◽

Vol 8 (387) ◽

pp. ec210-ec210

Author(s):

Stella M. Hurtley

Keyword(s):

Membrane Contact Sites ◽

Contact Sites ◽

Lipid Exchange ◽

Membrane Contact

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Inositol triphosphate-triggered calcium release blocks lipid exchange at endoplasmic reticulum-Golgi contact sites

Nature Communications ◽

10.1038/s41467-021-22882-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Mouhannad Malek ◽

Anna M. Wawrzyniak ◽

Peter Koch ◽

Christian Lüchtenborg ◽

Manuel Hessenberger ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Golgi Complex ◽

Calcium Release ◽

Inositol Triphosphate ◽

Vesicular Traffic ◽

Oxysterol Binding Protein ◽

Membrane Contact Sites ◽

Contact Sites ◽

Lipid Exchange ◽

Membrane Contact

AbstractVesicular traffic and membrane contact sites between organelles enable the exchange of proteins, lipids, and metabolites. Recruitment of tethers to contact sites between the endoplasmic reticulum (ER) and the plasma membrane is often triggered by calcium. Here we reveal a function for calcium in the repression of cholesterol export at membrane contact sites between the ER and the Golgi complex. We show that calcium efflux from ER stores induced by inositol-triphosphate [IP3] accumulation upon loss of the inositol 5-phosphatase INPP5A or receptor signaling triggers depletion of cholesterol and associated Gb3 from the cell surface, resulting in a blockade of clathrin-independent endocytosis (CIE) of Shiga toxin. This phenotype is caused by the calcium-induced dissociation of oxysterol binding protein (OSBP) from the Golgi complex and from VAP-containing membrane contact sites. Our findings reveal a crucial function for INPP5A-mediated IP3 hydrolysis in the control of lipid exchange at membrane contact sites.

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Inositol triphosphate-triggered calcium release blocks lipid exchange at endoplasmic reticulum-Golgi contact sites

10.21203/rs.3.rs-35925/v1 ◽

2020 ◽

Author(s):

Charles Malek ◽

Anna Maria Wawrzyniak ◽

Peter Koch ◽

Christian Lüchtenborg ◽

Manuel Hessenberger ◽

...

Keyword(s):

Endoplasmic Reticulum ◽

Golgi Complex ◽

Calcium Release ◽

Inositol Triphosphate ◽

Vesicular Traffic ◽

Membrane Contact Sites ◽

Contact Sites ◽

Lipid Exchange ◽

Membrane Contact ◽

Membrane Tethers

Abstract Vesicular traffic and membrane contact sites between organelles enable the exchange of proteins, lipids, and metabolites. Recruitment of membrane tethers to contact sites between the endoplasmic reticulum (ER) and the plasma membrane is often triggered by calcium. In contrast, we reveal here a function for calcium in the repression of cholesterol export at membrane contact sites between the ER and the Golgi complex. We show that calcium efflux from ER stores induced by inositol-triphosphate [IP3] accumulation upon loss of the inositol 5-phosphatase INPP5A or sustained receptor signaling triggers the depletion of cholesterol and associated complex glycosphingolipids from the cell surface, resulting in a blockade of clathrin-independent endocytosis (CIE) of bacterial toxins. This phenotype is caused by the calcium-induced dissociation of oxysterol binding protein (OSBP) from the Golgi complex and from VAP-containing membrane contact sites. Our findings reveal a crucial function for INPP5A-mediated IP3 hydrolysis in the control of lipid exchange at membrane contact sites.

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ER-Golgi membrane contact sites

Biochemical Society Transactions ◽

10.1042/bst20190537 ◽

2020 ◽

Vol 48 (1) ◽

pp. 187-197 ◽

Cited By ~ 2

Author(s):

Rossella Venditti ◽

Maria Chiara Masone ◽

Maria Antonietta De Matteis

Keyword(s):

Lipid Transfer ◽

Lipid Transfer Proteins ◽

Membrane Contact Sites ◽

Contact Sites ◽

Lipid Exchange ◽

Pathological Conditions ◽

The Sixties ◽

In Trans ◽

Membrane Contact ◽

Methodological Approaches

Membrane contact sites (MCSs) are sites where the membranes of two different organelles come into close apposition (10–30 nm). Different classes of proteins populate MCSs including factors that act as tethers between the two membranes, proteins that use the MCSs for their function (mainly lipid or ion exchange), and regulatory proteins and enzymes that can act in trans across the MCSs. The ER-Golgi MCSs were visualized by electron microscopists early in the sixties but have remained elusive for decades due to a lack of suitable methodological approaches. Here we report recent progress in the study of this class of MCSs that has led to the identification of their main morphological features and of some of their components and roles. Among these, lipid transfer proteins and lipid exchange have been the most studied and understood so far. However, many unknowns remain regarding their regulation and their role in controlling key TGN functions such as sorting and trafficking as well as their relevance in physiological and pathological conditions.

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Membrane Contact Sites: Complex Zones for Membrane Association and Lipid Exchange

Lipid Insights ◽

10.4137/lpi.s37190 ◽

2015 ◽

Vol 8s1 ◽

pp. LPI.S37190 ◽

Cited By ~ 3

Author(s):

Evan Quon ◽

Christopher T. Beh

Keyword(s):

Membrane Association ◽

Ion Transfer ◽

Lipid Transfer ◽

Membrane Contact Sites ◽

Contact Sites ◽

Protein Carriers ◽

Lipid Exchange ◽

Membrane Tethering ◽

Membrane Contact

Lipid transport between membranes within cells involves vesicle and protein carriers, but as agents of nonvesicular lipid transfer, the role of membrane contact sites has received increasing attention. As zones for lipid metabolism and exchange, various membrane contact sites mediate direct associations between different organelles. In particular, membrane contact sites linking the plasma membrane (PM) and the endoplasmic reticulum (ER) represent important regulators of lipid and ion transfer. In yeast, cortical ER is stapled to the PM through membrane-tethering proteins, which establish a direct connection between the membranes. In this review, we consider passive and facilitated models for lipid transfer at PM–ER contact sites. Besides the tethering proteins, we examine the roles of an additional repertoire of lipid and protein regulators that prime and propagate PM–ER membrane association. We conclude that instead of being simple mediators of membrane association, regulatory components of membrane contact sites have complex and multilayered functions.

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