scholarly journals Assortment of Phosphatidylinositol 3-Kinase Complexes—Atg14p Directs Association of Complex I to the Pre-autophagosomal Structure in Saccharomyces cerevisiae

2006 ◽  
Vol 17 (4) ◽  
pp. 1527-1539 ◽  
Author(s):  
Keisuke Obara ◽  
Takayuki Sekito ◽  
Yoshinori Ohsumi
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Complex I ◽  
Regulatory Subunit ◽  
Biological Processes ◽  
Phosphatidylinositol 3 Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Complex Ii ◽  
Vacuolar Protein ◽  
Vacuolar Membranes ◽  
Phosphatidylinositol 3

In the yeast Saccharomyces cerevisiae, two similar phosphatidylinositol 3-kinase complexes (complexes I and II) function in distinct biological processes, complex I in autophagy and complex II in the vacuolar protein sorting via endosomes. Atg14p is only integrated into complex I, likely facilitating the function of complex I in autophagy. Deletion analysis of Atg14p revealed that N-terminal region containing the coiled-coil structures was essential and sufficient for autophagy. Atg14p localized to pre-autophagosomal structure (PAS) and vacuolar membranes, whereas Vps38p, a component specific to complex II, localized to endosomes and vacuolar membranes. Vps34p and Vps30p, components shared by the two complexes, localized to the PAS, vacuolar membranes, and several punctate structures that included endosomes. The localization of these components to the PAS was Atg14p dependent but not dependent on Vps38p. Conversely, localization of these proteins to endosomes required Vps38p but not Atg14p. Vps15p, regulatory subunit of the Vps34p complexes, localized to the PAS, vacuolar membranes, and punctate structures independent of both Atg14p and Vps38p. Together, these results indicate that complexes I and II function in distinct biological processes by localizing to specific compartments in a manner mediated by specific components of each complex, Atg14p and Vps38p, respectively.

scholarly journals Dynamics and architecture of the NRBF2-containing phosphatidylinositol 3-kinase complex I of autophagy

2016 ◽  
Vol 113 (29) ◽  
pp. 8224-8229 ◽  
Author(s):  
Lindsey N. Young ◽  
Kelvin Cho ◽  
Rosalie Lawrence ◽  
Roberto Zoncu ◽  
James H. Hurley
Keyword(s):  
Complex I ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Kinase ◽  
Negative Stain ◽  
Binding Factor ◽  
Hydrogen Deuterium ◽  
Negative Stain Electron Microscopy ◽  
Vacuolar Protein ◽  
Phosphatidylinositol 3

The class III phosphatidylinositol 3-kinase complex I (PI3KC3-C1) is central to autophagy initiation. We previously reported the V-shaped architecture of the four-subunit version of PI3KC3-C1 consisting of VPS (vacuolar protein sorting) 34, VPS15, BECN1 (Beclin 1), and ATG (autophagy-related) 14. Here we show that a putative fifth subunit, nuclear receptor binding factor 2 (NRBF2), is a tightly bound component of the complex that profoundly affects its activity and architecture. NRBF2 enhances the lipid kinase activity of the catalytic subunit, VPS34, by roughly 10-fold. We used hydrogen–deuterium exchange coupled to mass spectrometry and negative-stain electron microscopy to map NRBF2 to the base of the V-shaped complex. NRBF2 interacts primarily with the N termini of ATG14 and BECN1. We show that NRBF2 is a homodimer and drives the dimerization of the larger PI3KC3-C1 complex, with implications for the higher-order organization of the preautophagosomal structure.

The class III phosphatidylinositol 3-kinase Vps34 in Saccharomyces cerevisiae

2017 ◽  
Vol 398 (5-6) ◽  
pp. 677-685 ◽  
Author(s):  
Christina Reidick ◽  
Fahd Boutouja ◽  
Harald W. Platta
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Functional Role ◽  
Protein Sorting ◽  
Endocytic Trafficking ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Kinase ◽  
Vacuolar Protein ◽  
Phosphatidylinositol 3

Abstract The class III phosphatidylinositol 3-kinase Vps34 (vacuolar protein sorting 34) catalyzes for the formation of the signaling lipid phosphatidylinositol-3-phopsphate, which is a central factor in the regulation of autophagy, endocytic trafficking and vesicular transport. In this article, we discuss the functional role of the lipid kinase Vps34 in Saccharomyces cerevisiae.

Association with Longevity of Phosphatidylinositol 3-Kinase Regulatory Subunit 1 Gene Variants Stems from Protection against Mortality Risk in Men with Cardiovascular Disease

Gerontology ◽  
2021 ◽  
pp. 1-9
Author(s):  
Timothy A. Donlon ◽  
Randi Chen ◽  
Kamal H. Masaki ◽  
Bradley J. Willcox ◽  
Brian J. Morris
Keyword(s):  
Cardiovascular Disease ◽  
Life Span ◽  
Mortality Risk ◽  
Regulatory Subunit ◽  
Phosphatidylinositol 3 Kinase ◽  
Survival Curves ◽  
Genotypic Effect ◽  
Hazard Ratios ◽  
Phosphatidylinositol 3

<b><i>Introduction:</i></b> Genetic variation in the phosphatidylinositol 3-kinase reregulatory subunit 1 gene (<i>PIK3R1</i>) is associated with longevity. <b><i>Objective:</i></b> The aim of the study was to determine whether cardiovascular disease (CVD) affects this association. <b><i>Methods:</i></b> We performed a longitudinal study of longevity-associated <i>PIK3R1</i> single-nucleotide polymorphism <i>rs7709243</i> genotype by CVD status in 3,584 elderly American men of Japanese ancestry. <b><i>Results:</i></b> At baseline (1991–1993), 2,254 subjects had CVD and 1,314 did not. The follow-up until Dec 31, 2019 found that overall, men with a CVD had higher mortality than men without a CVD (<i>p</i> = 1.7 × 10<sup>−5</sup>). However, survival curves of CVD subjects differed according to <i>PIK3R1</i> genotype. Those with longevity-associated <i>PIK3R1 TT</i>/<i>CC</i> had survival curves similar to those of subjects without a CVD (<i>p</i> = 0.11 for <i>TT</i>/<i>CC</i>, and <i>p</i> = 0.054 for <i>TC</i>), whereas survival curves for CVD subjects with the <i>CT</i> genotype were significantly attenuated compared with survival curves of subjects without a CVD (<i>p</i> = 0.0000012 compared with <i>TT</i>/<i>CC</i>, and <i>p</i> = 0.0000028 compared with <i>TC</i>). Men without CVD showed no association of longevity-associated genotype with life span (<i>p</i> = 0.58). Compared to subjects without any CVD, hazard ratios for mortality risk were 1.26 (95% CI, 1.14–1.39; <i>p</i> = 0.0000043) for <i>CT</i> subject with CVD and 1.07 (95% CI 0.99–1.17; <i>p</i> = 0.097) for <i>CC</i>/<i>TT</i> subjects with CVD. There was no genotypic effect on life span for 1,007 subjects with diabetes and 486 with cancer. <b><i>Conclusion:</i></b> Our study provides novel insights into the basis for <i>PIK3R1</i> as a longevity gene. We suggest that the <i>PIK3R1</i> longevity genotype attenuates mortality risk in at-risk individuals by protection against cellular stress caused by CVD.

scholarly journals Phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog as therapeutic targets in breast cancer

Tumor Biology ◽  
2017 ◽  
Vol 39 (3) ◽  
pp. 101042831769552 ◽  
Author(s):  
Ebubekir Dirican ◽  
Mustafa Akkiprik
Keyword(s):  
Breast Cancer ◽  
Cancer Progression ◽  
Molecular Mechanisms ◽  
Breast Cancer Progression ◽  
Regulatory Subunit ◽  
Phosphatidylinositol 3 Kinase ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Kinase Pathway ◽  
Phosphatidylinositol 3

Breast cancer is the most commonly diagnosed cancer among women in Turkey and worldwide. It is considered a heterogeneous disease and has different subtypes. Moreover, breast cancer has different molecular characteristics, behaviors, and responses to treatment. Advances in the understanding of the molecular mechanisms implicated in breast cancer progression have led to the identification of many potential therapeutic gene targets, such as Breast Cancer 1/2, phosphatidylinositol 3-kinase catalytic subunit alpha, and tumor protein 53. The aim of this review is to summarize the roles of phosphatidylinositol 3-kinase regulatory subunit 1 (alpha) (alias p85α) and phosphatase and tensin homolog in breast cancer progression and the molecular mechanisms involved. Phosphatase and tensin homolog is a tumor suppressor gene and protein. Phosphatase and tensin homolog antagonizes the phosphatidylinositol 3-kinase/AKT signaling pathway that plays a key role in cell growth, differentiation, and survival. Loss of phosphatase and tensin homolog expression, detected in about 20%–30% of cases, is known to be one of the most common tumor changes leading to phosphatidylinositol 3-kinase pathway activation in breast cancer. Instead, the regulatory subunit p85α is a significant component of the phosphatidylinositol 3-kinase pathway, and it has been proposed that a reduction in p85α protein would lead to decreased negative regulation of phosphatidylinositol 3-kinase and hyperactivation of the phosphatidylinositol 3-kinase pathway. Phosphatidylinositol 3-kinase regulatory subunit 1 protein has also been reported to be a positive regulator of phosphatase and tensin homolog via the stabilization of this protein. A functional genetic alteration of phosphatidylinositol 3-kinase regulatory subunit 1 that results in reduced p85α protein expression and increased insulin receptor substrate 1 binding would lead to enhanced phosphatidylinositol 3-kinase signaling and hence cancer development. Phosphatidylinositol 3-kinase regulatory subunit 1 underexpression was observed in 61.8% of breast cancer samples. Therefore, expression/alternations of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog genes have crucial roles for breast cancer progression. This review will summarize the biological roles of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog in breast cancer, with an emphasis on recent findings and the potential of phosphatidylinositol 3-kinase regulatory subunit 1 and phosphatase and tensin homolog as a therapeutic target for breast cancer therapy.

scholarly journals Cloning and characterization of BCY1, a locus encoding a regulatory subunit of the cyclic AMP-dependent protein kinase in Saccharomyces cerevisiae.

1987 ◽  
Vol 7 (4) ◽  
pp. 1371-1377 ◽  
Author(s):  
T Toda ◽  
S Cameron ◽  
P Sass ◽  
M Zoller ◽  
J D Scott ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Carbon Sources ◽  
Regulatory Subunit ◽  
Dependent Protein Kinase ◽  
Yeast Saccharomyces Cerevisiae ◽  
Regulatory Subunits ◽  
Dependent Protein

We have cloned a gene (BCY1) from the yeast Saccharomyces cerevisiae that encodes a regulatory subunit of the cyclic AMP-dependent protein kinase. The encoded protein has a structural organization similar to that of the RI and RII regulatory subunits of the mammalian cyclic AMP-dependent protein kinase. Strains of S. cerevisiae with disrupted BCY1 genes do not display a cyclic AMP-dependent protein kinase in vitro, fail to grow on many carbon sources, and are exquisitely sensitive to heat shock and starvation.

scholarly journals Saccharomyces cerevisiae contains a Type II phosphoinositide 4-kinase

2003 ◽  
Vol 371 (2) ◽  
pp. 533-540 ◽  
Author(s):  
Shary N. SHELTON ◽  
Barbara BARYLKO ◽  
Derk D. BINNS ◽  
Bruce F. HORAZDOVSKY ◽  
Joseph P. ALBANESI ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Fluorescent Protein ◽  
Distinct Type ◽  
Type Ii ◽  
Yeast Saccharomyces Cerevisiae ◽  
Molar Ratios ◽  
Ionic Detergent ◽  
Km Value ◽  
Green Fluorescent ◽  
Vacuolar Membranes

The yeast Saccharomyces cerevisiae contains two known phosphoinositide 4-kinases (PI 4-kinases), which are encoded by PIK1 and STT4; both are essential. Pik1p is important for exocytic transport from the Golgi, whereas Stt4p plays a role in cell-wall integrity and cytoskeletal rearrangements. In the present study, we report that cells have a third PI 4-kinase activity encoded by LSB6, a protein identified previously in a two-hybrid screen as interacting with LAS17p. Although Pik1p and Stt4p are closely related members of the Type III class of PI 4-kinases, Lsb6p belongs to the distinct Type II class, based on its amino acid sequence, its sensitivity to inhibition by adenosine and its insensitivity to wortmannin. Lsb6p is the first fungal Type II enzyme cloned. The protein was expressed and purified from Sf9 cells and used to define kinetic parameters. As commonly observed for surface-active enzymes, activities varied both with substrate concentration and lipid/detergent molar ratios. Maximal activities of approx. 100min−1 were obtained at the PI/Triton X-100 ratio of 1:5. The Km value for ATP was 266μM, intermediate between the values reported for mammalian Type II and III kinases. Epitope-tagged protein, expressed in yeast, was entirely particulate, and about half of it could be extracted with non-ionic detergent. Lsb6p–green fluorescent protein was found both on vacuolar membranes and on the plasma membrane, suggesting a role in endocytic or exocytic pathways.

scholarly journals Statin-induced Ras Activation Integrates the Phosphatidylinositol 3-Kinase Signal to Akt and MAPK for Bone Morphogenetic Protein-2 Expression in Osteoblast Differentiation

2006 ◽  
Vol 282 (7) ◽  
pp. 4983-4993 ◽  
Author(s):  
Nandini Ghosh-Choudhury ◽  
Chandi Charan Mandal ◽  
Goutam Ghosh Choudhury
Keyword(s):  
Bone Morphogenetic Protein ◽  
Osteoblast Differentiation ◽  
Dominant Negative ◽  
Bone Morphogenetic Protein 2 ◽  
Regulatory Subunit ◽  
Type I ◽  
Dependent Manner ◽  
Phosphatidylinositol 3 Kinase ◽  
Morphogenetic Protein ◽  
Phosphatidylinositol 3

Lovastatin promotes osteoblast differentiation by increasing bone morphogenetic protein-2 (BMP-2) expression. We demonstrate that lovastatin stimulates tyrosine phosphorylation of the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K), leading to an increase in its kinase activity in osteoblast cells. Inhibition of PI3K ameliorated expression of the osteogenic markers alkaline phosphatase, type I collagen, osteopontin, and BMP-2. Expression of dominant-negative PI3K and PTEN, an inhibitor of PI3K signaling, significantly attenuated lovastatin-induced transcription of BMP-2. Akt kinase was also activated in a PI3K-dependent manner. However, our data suggest involvement of an additional signaling pathway. Lovastatin-induced Erk1/2 activity contributed to BMP-2 transcription. Inhibition of PI3K abrogated Erk1/2 activity in response to lovastatin, indicating the presence of a signal relay between them. We provide, as a mechanism of this cross-talk, the first evidence that lovastatin stimulates rapid activation of Ras, which associates with and activates PI3K in the plasma membrane, which in turn regulates Akt and Erk1/2 to induce BMP-2 expression for osteoblast differentiation.

scholarly journals Cloning of a novel, ubiquitously expressed human phosphatidylinositol 3-kinase and identification of its binding site on p85.

1993 ◽  
Vol 13 (12) ◽  
pp. 7677-7688 ◽  
Author(s):  
P Hu ◽  
A Mondino ◽  
E Y Skolnik ◽  
J Schlessinger
Keyword(s):  
Cell Cycle Progression ◽  
Phosphatidylinositol 3 Kinase ◽  
Intact Cells ◽  
Src Homology 2 ◽  
Genes Encoding ◽  
Src Homology ◽  
Acid Domain ◽  
Vacuolar Protein ◽  
Phosphatidylinositol 3

Phosphatidylinositol 3-kinase (PI 3-kinase) has been implicated as a participant in signaling pathways regulating cell growth by virtue of its activation in response to various mitogenic stimuli. Here we describe the cloning of a novel and ubiquitously expressed human PI 3-kinase. The 4.8-kb cDNA encodes a putative translation product of 1,070 amino acids which is 42% identical to bovine PI 3-kinase and 28% identical to Vps34, a Saccharomyces cerevisiae PI 3-kinase involved in vacuolar protein sorting. Human PI 3-kinase is also similar to Tor2, a yeast protein required for cell cycle progression. Northern (RNA) analysis demonstrated expression of human PI 3-kinase in all tissues and cell lines tested. Protein synthesized from an epitope-tagged cDNA had intrinsic PI 3-kinase activity and associated with the adaptor 85-kDa subunit of PI 3-kinase (p85) in intact cells, as did endogenous human PI 3-kinase. Coprecipitation assays showed that a 187-amino-acid domain between the two src homology 2 domains of p85 mediates interaction with PI 3-kinase in vitro and in intact cells. These results demonstrate the existence of different PI 3-kinase isoforms and define a family of genes encoding distinct PI 3-kinase catalytic subunits that can associate with p85.

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.

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