scholarly journals Autophagy requires endoplasmic reticulum targeting of the PI3-kinase complex via Atg14L

2010 ◽  
Vol 190 (4) ◽  
pp. 511-521 ◽  
Author(s):  
Kohichi Matsunaga ◽  
Eiji Morita ◽  
Tatsuya Saitoh ◽  
Shizuo Akira ◽  
Nicholas T. Ktistakis ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Mammalian Cells ◽  
Embryonic Stem ◽  
Pi3 Kinase ◽  
Class Iii ◽  
Autophagosome Formation ◽  
Membranous Structure ◽  
Er Targeting ◽  
Endoplasmic Reticulum Targeting ◽  
Phosphatidylinositol 3

Autophagy is a catabolic process that allows cells to digest their cytoplasmic constituents via autophagosome formation and lysosomal degradation. Recently, an autophagy-specific phosphatidylinositol 3-kinase (PI3-kinase) complex, consisting of hVps34, hVps15, Beclin-1, and Atg14L, has been identified in mammalian cells. Atg14L is specific to this autophagy complex and localizes to the endoplasmic reticulum (ER). Knockdown of Atg14L leads to the disappearance of the DFCP1-positive omegasome, which is a membranous structure closely associated with both the autophagosome and the ER. A point mutation in Atg14L resulting in defective ER localization was also defective in the induction of autophagy. The addition of the ER-targeting motif of DFCP1 to this mutant fully complemented the autophagic defect in Atg14L knockout embryonic stem cells. Thus, Atg14L recruits a subset of class III PI3-kinase to the ER, where otherwise phosphatidylinositol 3-phosphate (PI3P) is essentially absent. The Atg14L-dependent appearance of PI3P in the ER makes this organelle the platform for autophagosome formation.

scholarly journals Beclin 1 Forms Two Distinct Phosphatidylinositol 3-Kinase Complexes with Mammalian Atg14 and UVRAG

2008 ◽  
Vol 19 (12) ◽  
pp. 5360-5372 ◽  
Author(s):  
Eisuke Itakura ◽  
Chieko Kishi ◽  
Kinji Inoue ◽  
Noboru Mizushima
Keyword(s):  
Membrane Trafficking ◽  
Mammalian Cells ◽  
Coiled Coil ◽  
Pi3 Kinase ◽  
Beclin 1 ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Interacting Protein ◽  
Vacuolar Protein ◽  
Phosphatidylinositol 3

Class III phosphatidylinositol 3-kinase (PI3-kinase) regulates multiple membrane trafficking. In yeast, two distinct PI3-kinase complexes are known: complex I (Vps34, Vps15, Vps30/Atg6, and Atg14) is involved in autophagy, and complex II (Vps34, Vps15, Vps30/Atg6, and Vps38) functions in the vacuolar protein sorting pathway. Atg14 and Vps38 are important in inducing both complexes to exert distinct functions. In mammals, the counterparts of Vps34, Vps15, and Vps30/Atg6 have been identified as Vps34, p150, and Beclin 1, respectively. However, orthologues of Atg14 and Vps38 remain unknown. We identified putative mammalian homologues of Atg14 and Vps38. The Vps38 candidate is identical to UV irradiation resistance-associated gene (UVRAG), which has been reported as a Beclin 1-interacting protein. Although both human Atg14 and UVRAG interact with Beclin 1 and Vps34, Atg14, and UVRAG are not present in the same complex. Although Atg14 is present on autophagic isolation membranes, UVRAG primarily associates with Rab9-positive endosomes. Silencing of human Atg14 in HeLa cells suppresses autophagosome formation. The coiled-coil region of Atg14 required for binding with Vps34 and Beclin 1 is essential for autophagy. These results suggest that mammalian cells have at least two distinct class III PI3-kinase complexes, which may function in different membrane trafficking pathways.

scholarly journals PtdIns(4,5)P2 signaling regulates ATG14 and autophagy

2016 ◽  
Vol 113 (39) ◽  
pp. 10896-10901 ◽  
Author(s):  
Xiaojun Tan ◽  
Narendra Thapa ◽  
Yihan Liao ◽  
Suyong Choi ◽  
Richard A. Anderson
Keyword(s):  
Endoplasmic Reticulum ◽  
Functional Significance ◽  
Mammalian Cells ◽  
Beclin 1 ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Atg Proteins ◽  
Late Endosomes ◽  
Irradiation Resistance ◽  
Phosphatidylinositol 3

Autophagy is a regulated self-digestion pathway with fundamental roles in cell homeostasis and diseases. Autophagy is regulated by coordinated actions of a series of autophagy-related (ATG) proteins. The Barkor/ATG14(L)–VPS34 (a class III phosphatidylinositol 3-kinase) complex and its product phosphatidylinositol 3-phosphate [PtdIns(3)P] play key roles in autophagy initiation. ATG14 contains a C-terminal Barkor/ATG14(L) autophagosome-targeting sequence (BATS) domain that senses the curvature of PtdIns(3)P-containing membrane. The BATS domain also strongly binds PtdIns(4,5)P2, but the functional significance has been unclear. Here we show that ATG14 specifically interacts with type Iγ PIP kinase isoform 5 (PIPKIγi5), an enzyme that generates PtdIns(4,5)P2 in mammalian cells. Autophagosomes have associated PIPKIγi5 and PtdIns(4,5)P2 that are colocalized with late endosomes and the endoplasmic reticulum. PtdIns(4,5)P2 generation at these sites requires PIPKIγi5. Loss of PIPKIγi5 results in a loss of ATG14, UV irradiation resistance-associated gene, and Beclin 1 and a block of autophagy. PtdIns(4,5)P2 binding to the ATG14–BATS domain regulates ATG14 interaction with VPS34 and Beclin 1, and thus plays a key role in ATG14 complex assembly and autophagy initiation. This study identifies an unexpected role for PtdIns(4,5)P2 signaling in the regulation of ATG14 complex and autophagy.

scholarly journals Endoplasmic reticulum targeting fluorescent probes to image mobile Zn2+

2019 ◽  
Vol 10 (47) ◽  
pp. 10881-10887 ◽  
Author(s):  
Le Fang ◽  
Giuseppe Trigiante ◽  
Rachel Crespo-Otero ◽  
Chris S. Hawes ◽  
Michael P. Philpott ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Fluorescent Probes ◽  
Biological Processes ◽  
Er Targeting ◽  
Endoplasmic Reticulum Targeting

Two endoplasmic reticulum (ER) targeting probes were developed to image mobile Zn2+ to help understand Zn2+ related biological processes in the ER.

scholarly journals Autophagosome formation from membrane compartments enriched in phosphatidylinositol 3-phosphate and dynamically connected to the endoplasmic reticulum

2008 ◽  
Vol 182 (4) ◽  
pp. 685-701 ◽  
Author(s):  
Elizabeth L. Axe ◽  
Simon A. Walker ◽  
Maria Manifava ◽  
Priya Chandra ◽  
H. Llewelyn Roderick ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Dynamic Equilibrium ◽  
Membrane Vesicles ◽  
Amino Acid Starvation ◽  
Autophagosome Formation ◽  
Double Membrane ◽  
Dynamic Relationship ◽  
Golgi Membranes ◽  
Membrane Compartments ◽  
Phosphatidylinositol 3

Autophagy is the engulfment of cytosol and organelles by double-membrane vesicles termed autophagosomes. Autophagosome formation is known to require phosphatidylinositol 3-phosphate (PI(3)P) and occurs near the endoplasmic reticulum (ER), but the exact mechanisms are unknown. We show that double FYVE domain–containing protein 1, a PI(3)P-binding protein with unusual localization on ER and Golgi membranes, translocates in response to amino acid starvation to a punctate compartment partially colocalized with autophagosomal proteins. Translocation is dependent on Vps34 and beclin function. Other PI(3)P-binding probes targeted to the ER show the same starvation-induced translocation that is dependent on PI(3)P formation and recognition. Live imaging experiments show that this punctate compartment forms near Vps34-containing vesicles, is in dynamic equilibrium with the ER, and provides a membrane platform for accumulation of autophagosomal proteins, expansion of autophagosomal membranes, and emergence of fully formed autophagosomes. This PI(3)P-enriched compartment may be involved in autophagosome biogenesis. Its dynamic relationship with the ER is consistent with the idea that the ER may provide important components for autophagosome formation.

An endoplasmic reticulum-targeting fluorescent probe for the imaging of GSH in living cells

2019 ◽  
Vol 11 (29) ◽  
pp. 3736-3740 ◽  
Author(s):  
Cheng-Shi Jiang ◽  
Zhi-Qiang Cheng ◽  
Yong-Xi Ge ◽  
Jia-Li Song ◽  
Juan Zhang ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Fluorescent Probe ◽  
Living Cells ◽  
Er Targeting ◽  
Endoplasmic Reticulum Targeting

A new endoplasmic reticulum (ER)-targeting fluorescent probe (ER-G) was designed and applied for the detection of cellular GSH in the ER.

scholarly journals Spatial control of avidity regulates initiation and progression of selective autophagy

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
David M. Hollenstein ◽  
Mariya Licheva ◽  
Nicole Konradi ◽  
David Schweida ◽  
Hector Mancilla ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Nuclear Membrane ◽  
Vacuolar Membrane ◽  
Phosphatidylinositol 3 Kinase ◽  
Autophagosome Formation ◽  
Spatial Control ◽  
Selective Autophagy ◽  
Phagophore Assembly Site ◽  
Assembly Site ◽  
Phosphatidylinositol 3

AbstractAutophagosomes form at the endoplasmic reticulum in mammals, and between the vacuole and the endoplasmic reticulum in yeast. However, the roles of these sites and the mechanisms regulating autophagosome formation are incompletely understood. Vac8 is required for autophagy and recruits the Atg1 kinase complex to the vacuole. Here we show that Vac8 acts as a central hub to nucleate the phagophore assembly site at the vacuolar membrane during selective autophagy. Vac8 directly recruits the cargo complex via the Atg11 scaffold. In addition, Vac8 recruits the phosphatidylinositol 3-kinase complex independently of autophagy. Cargo-dependent clustering and Vac8-dependent sequestering of these early autophagy factors, along with local Atg1 activation, promote phagophore assembly site assembly at the vacuole. Importantly, ectopic Vac8 redirects autophagosome formation to the nuclear membrane, indicating that the vacuolar membrane is not specifically required. We propose that multiple avidity-driven interactions drive the initiation and progression of selective autophagy.

Silver-mediated direct C–H amination of BODIPYs for screening endoplasmic reticulum-targeting reagents

2018 ◽  
Vol 54 (26) ◽  
pp. 3219-3222 ◽  
Author(s):  
Huaxing Zhang ◽  
Xingyu Chen ◽  
Jingbo Lan ◽  
Yanhong Liu ◽  
Fulin Zhou ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Highly Efficient ◽  
Er Targeting ◽  
Endoplasmic Reticulum Targeting

A highly efficient Ag(i)-mediated direct C–H amination of BODIPYs is accomplished. BODIPYs 3q and 4b exhibit specific ER-targeting capacities.

Sign in / Sign up

Export Citation Format

Share Document