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Pietro de camilli

Joshua A Lees, Mirko Messa, Elizabeth Wen Sun, Heather Wheeler, Federico Torta, Markus R Wenk, Pietro De Camilli, Karin M Reinisch
Insulin is released by β cells in pulses regulated by calcium and phosphoinositide signaling. Here, we describe how transmembrane protein 24 (TMEM24) helps coordinate these signaling events. We showed that TMEM24 is an endoplasmic reticulum (ER)-anchored membrane protein whose reversible localization to ER-plasma membrane (PM) contacts is governed by phosphorylation and dephosphorylation in response to oscillations in cytosolic calcium. A lipid-binding module in TMEM24 transports the phosphatidylinositol 4,5-bisphosphate [PI(4,5)P2] precursor phosphatidylinositol between bilayers, allowing replenishment of PI(4,5)P2 hydrolyzed during signaling...
February 17, 2017: Science
Roni Levin, Gerald R V Hammond, Tamas Balla, Pietro De Camilli, Gregory D Fairn, Sergio Grinstein
We analyzed the distribution, fate, and functional role of phosphatidylinositol 4-phosphate (PtdIns4P) during phagosome formation and maturation. To this end, we used genetically encoded probes consisting of the PtdIns4P-binding domain of the bacterial effector SidM. PtdIns4P was found to undergo complex, multiphasic changes during phagocytosis. The phosphoinositide, which is present in the plasmalemma before engagement of the target particle, is transiently enriched in the phagosomal cup. Soon after the phagosome seals, PtdIns4P levels drop precipitously due to the hydrolytic activity of Sac2 and phospholipase C, becoming undetectable for ∼10 min...
January 1, 2017: Molecular Biology of the Cell
Kazunori Inoue, Daniel M Balkin, Lijuan Liu, Ramiro Nandez, Yumei Wu, Xuefei Tian, Tong Wang, Robert Nussbaum, Pietro De Camilli, Shuta Ishibe
Lowe syndrome and Dent disease are two conditions that result from mutations of the inositol 5-phosphatase oculocerebrorenal syndrome of Lowe (OCRL) and share the feature of impaired kidney proximal tubule function. Genetic ablation of Ocrl in mice failed to recapitulate the human phenotypes, possibly because of the redundant functions of OCRL and its paralog type 2 inositol polyphosphate-5-phosphatase (INPP5B). Germline knockout of both paralogs in mice results in early embryonic lethality. We report that kidney tubule-specific inactivation of Inpp5b on a global Ocrl-knockout mouse background resulted in low molecular weight proteinuria, phosphaturia, and acidemia...
November 28, 2016: Journal of the American Society of Nephrology: JASN
Bruno Antonny, Christopher Burd, Pietro De Camilli, Elizabeth Chen, Oliver Daumke, Katja Faelber, Marijn Ford, Vadim A Frolov, Adam Frost, Jenny E Hinshaw, Tom Kirchhausen, Michael M Kozlov, Martin Lenz, Harry H Low, Harvey McMahon, Christien Merrifield, Thomas D Pollard, Phillip J Robinson, Aurélien Roux, Sandra Schmid
The large GTPase dynamin is the first protein shown to catalyze membrane fission. Dynamin and its related proteins are essential to many cell functions, from endocytosis to organelle division and fusion, and it plays a critical role in many physiological functions such as synaptic transmission and muscle contraction. Research of the past three decades has focused on understanding how dynamin works. In this review, we present the basis for an emerging consensus on how dynamin functions. Three properties of dynamin are strongly supported by experimental data: first, dynamin oligomerizes into a helical polymer; second, dynamin oligomer constricts in the presence of GTP; and third, dynamin catalyzes membrane fission upon GTP hydrolysis...
September 26, 2016: EMBO Journal
Katia Hardies, Yiying Cai, Claude Jardel, Anna C Jansen, Mian Cao, Patrick May, Tania Djémié, Caroline Hachon Le Camus, Kathelijn Keymolen, Tine Deconinck, Vikas Bhambhani, Catherine Long, Samin A Sajan, Katherine L Helbig, Arvid Suls, Rudi Balling, Ingo Helbig, Peter De Jonghe, Christel Depienne, Pietro De Camilli, Sarah Weckhuysen
SYNJ1 encodes a polyphosphoinositide phosphatase, synaptojanin 1, which contains two consecutive phosphatase domains and plays a prominent role in synaptic vesicle dynamics. Autosomal recessive inherited variants in SYNJ1 have previously been associated with two different neurological diseases: a recurrent homozygous missense variant (p.Arg258Gln) that abolishes Sac1 phosphatase activity was identified in three independent families with early onset parkinsonism, whereas a homozygous nonsense variant (p.Arg136*) causing a severe decrease of mRNA transcript was found in a single patient with intractable epilepsy and tau pathology...
September 2016: Brain: a Journal of Neurology
Rui Dong, Yasunori Saheki, Sharan Swarup, Louise Lucast, J Wade Harper, Pietro De Camilli
VAP (VAPA and VAPB) is an evolutionarily conserved endoplasmic reticulum (ER)-anchored protein that helps generate tethers between the ER and other membranes through which lipids are exchanged across adjacent bilayers. Here, we report that by regulating PI4P levels on endosomes, VAP affects WASH-dependent actin nucleation on these organelles and the function of the retromer, a protein coat responsible for endosome-to-Golgi traffic. VAP is recruited to retromer budding sites on endosomes via an interaction with the retromer SNX2 subunit...
July 14, 2016: Cell
Lars Demmel, Katy Schmidt, Louise Lucast, Katharina Havlicek, Armin Zankel, Tina Koestler, Viktoria Reithofer, Pietro de Camilli, Graham Warren
No abstract text is available yet for this article.
June 1, 2016: Journal of Cell Science
Yasunori Saheki, Xin Bian, Curtis M Schauder, Yujin Sawaki, Michal A Surma, Christian Klose, Frederic Pincet, Karin M Reinisch, Pietro De Camilli
Acute metabolic changes in plasma membrane (PM) lipids, such as those mediating signalling reactions, are rapidly compensated by homeostatic responses whose molecular basis is poorly understood. Here we show that the extended synaptotagmins (E-Syts), endoplasmic reticulum (ER) proteins that function as PtdIns(4,5)P2- and Ca(2+)-regulated tethers to the PM, participate in these responses. E-Syts transfer glycerolipids between bilayers in vitro, and this transfer requires Ca(2+) and their lipid-harbouring SMP domain...
May 2016: Nature Cell Biology
Karin M Reinisch, Pietro De Camilli
SMP-domains are found in proteins that localize to membrane contact sites. Elucidation of the properties of these proteins gives clues as to the molecular bases underlying processes that occur at such sites. Described here are recent discoveries concerning the structure, function, and regulation of the Extended-Synaptotagmin proteins and ERMES complex subunits, SMP-domain proteins at endoplasmic reticulum (ER)-plasma membrane and ER-mitochondrial contacts, respectively. They act as tethers contributing to the architecture of these sites and as lipid transporters that convey glycerolipids between apposed membranes...
August 2016: Biochimica et Biophysica Acta
Jeremy M Baskin, Xudong Wu, Romain Christiano, Michael S Oh, Curtis M Schauder, Elisabetta Gazzerro, Mirko Messa, Simona Baldassari, Stefania Assereto, Roberta Biancheri, Federico Zara, Carlo Minetti, Andrea Raimondi, Mikael Simons, Tobias C Walther, Karin M Reinisch, Pietro De Camilli
Genetic defects in myelin formation and maintenance cause leukodystrophies, a group of white matter diseases whose mechanistic underpinnings are poorly understood. Hypomyelination and congenital cataract (HCC), one of these disorders, is caused by mutations in FAM126A, a gene of unknown function. We show that FAM126A, also known as hyccin, regulates the synthesis of phosphatidylinositol 4-phosphate (PtdIns(4)P), a determinant of plasma membrane identity. HCC patient fibroblasts exhibit reduced PtdIns(4)P levels...
January 2016: Nature Cell Biology
Jeeyun Chung, Federico Torta, Kaori Masai, Louise Lucast, Heather Czapla, Lukas B Tanner, Pradeep Narayanaswamy, Markus R Wenk, Fubito Nakatsu, Pietro De Camilli
Lipid transfer between cell membrane bilayers at contacts between the endoplasmic reticulum (ER) and other membranes help to maintain membrane lipid homeostasis. We found that two similar ER integral membrane proteins, oxysterol-binding protein (OSBP)-related protein 5 (ORP5) and ORP8, tethered the ER to the plasma membrane (PM) via the interaction of their pleckstrin homology domains with phosphatidylinositol 4-phosphate (PI4P) in this membrane. Their OSBP-related domains (ORDs) harbored either PI4P or phosphatidylserine (PS) and exchanged these lipids between bilayers...
July 24, 2015: Science
Olof Idevall-Hagren, Alice Lü, Beichen Xie, Pietro De Camilli
The extended synaptotagmins (E-Syts) are ER proteins that act as Ca(2+)-regulated tethers between the ER and the plasma membrane (PM) and have a putative role in lipid transport between the two membranes. Ca(2+) regulation of their tethering function, as well as the interplay of their different domains in such function, remains poorly understood. By exposing semi-intact cells to buffers of variable Ca(2+) concentrations, we found that binding of E-Syt1 to the PI(4,5)P2-rich PM critically requires its C2C and C2E domains and that the EC50 of such binding is in the low micromolar Ca(2+) range...
September 2, 2015: EMBO Journal
Edward L Huttlin, Lily Ting, Raphael J Bruckner, Fana Gebreab, Melanie P Gygi, John Szpyt, Stanley Tam, Gabriela Zarraga, Greg Colby, Kurt Baltier, Rui Dong, Virginia Guarani, Laura Pontano Vaites, Alban Ordureau, Ramin Rad, Brian K Erickson, Martin Wühr, Joel Chick, Bo Zhai, Deepak Kolippakkam, Julian Mintseris, Robert A Obar, Tim Harris, Spyros Artavanis-Tsakonas, Mathew E Sowa, Pietro De Camilli, Joao A Paulo, J Wade Harper, Steven P Gygi
Protein interactions form a network whose structure drives cellular function and whose organization informs biological inquiry. Using high-throughput affinity-purification mass spectrometry, we identify interacting partners for 2,594 human proteins in HEK293T cells. The resulting network (BioPlex) contains 23,744 interactions among 7,668 proteins with 86% previously undocumented. BioPlex accurately depicts known complexes, attaining 80%-100% coverage for most CORUM complexes. The network readily subdivides into communities that correspond to complexes or clusters of functionally related proteins...
July 16, 2015: Cell
Swetha Gowrishankar, Peng Yuan, Yumei Wu, Matthew Schrag, Summer Paradise, Jaime Grutzendler, Pietro De Camilli, Shawn M Ferguson
Through a comprehensive analysis of organellar markers in mouse models of Alzheimer's disease, we document a massive accumulation of lysosome-like organelles at amyloid plaques and establish that the majority of these organelles reside within swollen axons that contact the amyloid deposits. This close spatial relationship between axonal lysosome accumulation and extracellular amyloid aggregates was observed from the earliest stages of β-amyloid deposition. Notably, we discovered that lysosomes that accumulate in such axons are lacking in multiple soluble luminal proteases and thus are predicted to be unable to efficiently degrade proteinaceous cargos...
July 14, 2015: Proceedings of the National Academy of Sciences of the United States of America
Fubito Nakatsu, Mirko Messa, Ramiro Nández, Heather Czapla, Yixiao Zou, Stephen M Strittmatter, Pietro De Camilli
The recruitment of inositol phosphatases to endocytic membranes mediates dephosphorylation of PI(4,5)P2, a phosphoinositide concentrated in the plasma membrane, and prevents its accumulation on endosomes. The importance of the conversion of PI(4,5)P2 to PtdIns during endocytosis is demonstrated by the presence of both a 5-phosphatase and a 4-phosphatase (Sac domain) module in the synaptojanins, endocytic PI(4,5)P2 phosphatases conserved from yeast to humans and the only PI(4,5)P2 phosphatases in yeast. OCRL, another 5-phosphatase that couples endocytosis to PI(4,5)P2 dephosphorylation, lacks a Sac domain...
April 13, 2015: Journal of Cell Biology
Tim Willinger, Matthew Staron, Shawn M Ferguson, Pietro De Camilli, Richard A Flavell
Prolonged T-cell receptor (TCR) signaling is required for the proliferation of T lymphocytes. Ligation of the TCR activates signaling, but also causes internalization of the TCR from the cell surface. How TCR signaling is sustained for many hours despite lower surface expression is unknown. Using genetic inhibition of endocytosis, we show here that TCR internalization promotes continued TCR signaling and T-lymphocyte proliferation. T-cell-specific deletion of dynamin 2, an essential component of endocytosis, resulted in reduced TCR signaling strength, impaired homeostatic proliferation, and the inability to undergo clonal expansion in vivo...
April 7, 2015: Proceedings of the National Academy of Sciences of the United States of America
Rubén Fernández-Busnadiego, Yasunori Saheki, Pietro De Camilli
The close apposition between the endoplasmic reticulum (ER) and the plasma membrane (PM) plays important roles in Ca(2+) homeostasis, signaling, and lipid metabolism. The extended synaptotagmins (E-Syts; tricalbins in yeast) are ER-anchored proteins that mediate the tethering of the ER to the PM and are thought to mediate lipid transfer between the two membranes. E-Syt cytoplasmic domains comprise a synaptotagmin-like mitochondrial-lipid-binding protein (SMP) domain followed by five C2 domains in E-Syt1 and three C2 domains in E-Syt2/3...
April 21, 2015: Proceedings of the National Academy of Sciences of the United States of America
Roberta Fiume, Yvette Stijf-Bultsma, Zahid H Shah, Willem Jan Keune, David R Jones, Julian Georg Jude, Nullin Divecha
Phosphatidylinositol-5-phosphate (PtdIns5P)-4-kinases (PIP4Ks) are stress-regulated lipid kinases that phosphorylate PtdIns5P to generate PtdIns(4,5)P₂. There are three isoforms of PIP4Ks: PIP4K2A, 2B and 2C, which localise to different subcellular compartments with the PIP4K2B isoform being localised predominantly in the nucleus. Suppression of PIP4K expression selectively prevents tumour cell growth in vitro and prevents tumour development in mice that have lost the tumour suppressor p53. p53 is lost or mutated in over 70% of all human tumours...
June 2015: Biochimica et Biophysica Acta
Antonella De Matteis, Pietro De Camilli
No abstract text is available yet for this article.
June 2015: Biochimica et Biophysica Acta
Jeeyun Chung, Fubito Nakatsu, Jeremy M Baskin, Pietro De Camilli
Plasma membrane PI4P is an important direct regulator of many processes that occur at the plasma membrane and also a biosynthetic precursor of PI(4,5)P2 and its downstream metabolites. The majority of this PI4P pool is synthesized by an evolutionarily conserved complex, which has as its core the PI 4-kinase PI4KIIIα (Stt4 in yeast) and also comprises TTC7 (Ypp1 in yeast) and the peripheral plasma membrane protein EFR3. While EFR3 has been implicated in the recruitment of PI4KIIIα via TTC7, the plasma membrane protein Sfk1 was also shown to participate in this targeting and activity in yeast...
March 2015: EMBO Reports
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