scholarly journals Distinct regulation of autophagic activity by Atg14L and Rubicon associated with Beclin 1–phosphatidylinositol-3-kinase complex

2009 ◽  
Vol 11 (4) ◽  
pp. 468-476 ◽  
Author(s):  
Yun Zhong ◽  
Qing Jun Wang ◽  
Xianting Li ◽  
Ying Yan ◽  
Jonathan M. Backer ◽  
...  
Keyword(s):  
Beclin 1 ◽  
Phosphatidylinositol 3 Kinase ◽  
Autophagic Activity ◽  
Phosphatidylinositol 3

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 Atg38 is required for autophagy-specific phosphatidylinositol 3-kinase complex integrity

2013 ◽  
Vol 203 (2) ◽  
pp. 299-313 ◽  
Author(s):  
Yasuhiro Araki ◽  
Wei-Chi Ku ◽  
Manami Akioka ◽  
Alexander I. May ◽  
Yu Hayashi ◽  
...  
Keyword(s):  
Complex I ◽  
Protein Complexes ◽  
Pi3 Kinase ◽  
Phosphatidylinositol 3 Kinase ◽  
C Terminus ◽  
Physical Linkage ◽  
N Terminus ◽  
Autophagic Activity ◽  
Biochemical Analyses ◽  
Phosphatidylinositol 3

Autophagy is a conserved eukaryotic process of protein and organelle self-degradation within the vacuole/lysosome. Autophagy is characterized by the formation of an autophagosome, for which Vps34-dervied phosphatidylinositol 3-phosphate (PI3P) is essential. In yeast, Vps34 forms two distinct protein complexes: complex I, which functions in autophagy, and complex II, which is involved in protein sorting to the vacuole. Here we identify and characterize Atg38 as a stably associated subunit of complex I. In atg38Δ cells, autophagic activity was significantly reduced and PI3-kinase complex I dissociated into the Vps15–Vps34 and Atg14–Vps30 subcomplexes. We find that Atg38 physically interacted with Atg14 and Vps34 via its N terminus. Further biochemical analyses revealed that Atg38 homodimerizes through its C terminus and that this homodimer formation is indispensable for the integrity of complex I. These data suggest that the homodimer of Atg38 functions as a physical linkage between the Vps15–Vps34 and Atg14–Vps30 subcomplexes to facilitate complex I formation.

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.

Possibility of distinct insulin-signaling pathways beyond phosphatidylinositol 3-kinase-mediating glucose transport and lipogenesis

Diabetes ◽  
1998 ◽  
Vol 47 (2) ◽  
pp. 179-185 ◽  
Author(s):  
R. W. Stevenson ◽  
D. K. Kreutter ◽  
K. M. Andrews ◽  
P. E. Genereux ◽  
E. M. Gibbs
Keyword(s):  
Signaling Pathways ◽  
Glucose Transport ◽  
Insulin Signaling ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatidylinositol 3
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