scholarly journals Characterization of VPS34-IN1, a selective inhibitor of Vps34, reveals that the phosphatidylinositol 3-phosphate-binding SGK3 protein kinase is a downstream target of class III phosphoinositide 3-kinase

2014 ◽  
Vol 463 (3) ◽  
pp. 413-427 ◽  
Author(s):  
Ruzica Bago ◽  
Nazma Malik ◽  
Michael J. Munson ◽  
Alan R. Prescott ◽  
Paul Davies ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Selective Inhibitor ◽  
Class Iii ◽  
Phosphate Binding ◽  
Downstream Target ◽  
Phosphoinositide 3 Kinase ◽  
Phosphatidylinositol 3

We characterize VPS34-IN, a potent and selective inhibitor of class III Vps34 PI3K. Using VPS34-IN1, we demonstrate that PtdIns(3)P, produced by Vps34 controls phosphorylation and activity of the SGK3 protein kinase.

scholarly journals Ca2+-regulated Pool of Phosphatidylinositol-3-phosphate Produced by Phosphatidylinositol 3-Kinase C2α on Neurosecretory Vesicles

2008 ◽  
Vol 19 (12) ◽  
pp. 5593-5603 ◽  
Author(s):  
Peter J. Wen ◽  
Shona L. Osborne ◽  
Isabel C. Morrow ◽  
Robert G. Parton ◽  
Jan Domin ◽  
...  
Keyword(s):  
Critical Role ◽  
Neurosecretory Cells ◽  
Secretory Vesicles ◽  
Endosomal Trafficking ◽  
Class Iii ◽  
Phosphatidylinositol 3 Kinase ◽  
Lipid Product ◽  
Phosphatidylinositol 3

Phosphatidylinositol-3-phosphate [PtdIns(3)P] is a key player in early endosomal trafficking and is mainly produced by class III phosphatidylinositol 3-kinase (PI3K). In neurosecretory cells, class II PI3K-C2α and its lipid product PtdIns(3)P have recently been shown to play a critical role during neuroexocytosis, suggesting that two distinct pools of PtdIns(3)P might coexist in these cells. However, the precise characterization of this additional pool of PtdIns(3)P remains to be established. Using a selective PtdIns(3)P probe, we have identified a novel PtdIns(3)P-positive pool localized on secretory vesicles, sensitive to PI3K-C2α knockdown and relatively resistant to wortmannin treatment. In neurosecretory cells, stimulation of exocytosis promoted a transient albeit large increase in PtdIns(3)P production localized on secretory vesicles sensitive to PI3K-C2α knockdown and expression of PI3K-C2α catalytically inactive mutant. Using purified chromaffin granules, we found that PtdIns(3)P production is controlled by Ca2+. We confirmed that PtdIns(3)P production from recombinantly expressed PI3K-C2α is indeed regulated by Ca2+. We provide evidence that a dynamic pool of PtdIns(3)P synthesized by PI3K-C2α occurs on secretory vesicles in neurosecretory cells, demonstrating that the activity of a member of the PI3K family is regulated by Ca2+ in vitro and in living neurosecretory cells.

Morphological characterization of Class III phosphoinositide 3-kinase during mouse brain development

2015 ◽  
Vol 49 (1) ◽  
pp. 28-33 ◽  
Author(s):  
Yutaka Inaguma ◽  
Hidenori Ito ◽  
Ikuko Iwamoto ◽  
Ayumi Matsumoto ◽  
Takanori Yamagata ◽  
...  
Keyword(s):  
Brain Development ◽  
Mouse Brain ◽  
Morphological Characterization ◽  
Class Iii ◽  
Phosphoinositide 3 Kinase ◽  
Mouse Brain Development

scholarly journals Class III phosphoinositide 3-kinase–Beclin1 complex mediates the amino acid-dependent regulation of autophagy in C2C12 myotubes

2003 ◽  
Vol 376 (3) ◽  
pp. 577-586 ◽  
Author(s):  
Amina TASSA ◽  
Marie Paule ROUX ◽  
Didier ATTAIX ◽  
Daniel M. BECHET
Keyword(s):  
Amino Acid ◽  
Protein Kinase ◽  
Glycogen Synthase ◽  
Amino Acid Starvation ◽  
Class I ◽  
C2c12 Myotubes ◽  
Dependent Manner ◽  
Class Iii ◽  
Mitogen Activated Protein ◽  
Phosphoinositide 3 Kinase

Increased proteolysis contributes to muscle atrophy that prevails in many diseases. Elucidating the signalling pathways responsible for this activation is of obvious clinical importance. Autophagy is a ubiquitous degradation process, induced by amino acid starvation, that delivers cytoplasmic components to lysosomes. Starvation markedly stimulates autophagy in myotubes, and the present studies investigate the mechanisms of this regulation. In C2C12 myotubes incubated with serum growth factors, amino acid starvation stimulated autophagic proteolysis independently of p38 and p42/p44 mitogen-activated protein kinases, but in a PI3K (phosphoinositide 3-kinase)-dependent manner. Starvation, however, did not alter activities of class I and class II PI3Ks, and was not sufficient to affect major signalling proteins downstream from class I PI3K (glycogen synthase kinase, Akt/protein kinase B and protein S6). In contrast, starvation increased class III PI3K activity in whole-myotube extracts. In fact, this increase was most pronounced for a population of class III PI3K that coimmunoprecipitated with Beclin1/Apg6 protein, a major determinant in the initiation of autophagy. Stimulation of proteolysis was reproduced by feeding myotubes with synthetic dipalmitoyl-PtdIns3P, the class III PI3K product. Conversely, protein transfection of anti-class III PI3K inhibitory antibody into starved myotubes inverted the induction of proteolysis. Therefore, independently of class I PI3K/Akt, protein S6 and mitogen-activated protein kinase pathways, amino acid starvation stimulates proteolysis in myotubes by regulating class III PI3K–Beclin1 autophagic complexes.

scholarly journals Loss of Class III Phosphoinositide 3-Kinase Vps34 Results in Cone Degeneration

Biology ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 384
Author(s):  
Ammaji Rajala ◽  
Feng He ◽  
Robert E. Anderson ◽  
Theodore G. Wensel ◽  
Raju V. S. Rajala
Keyword(s):  
Gene Knockout ◽  
Substantial Reduction ◽  
Photoreceptor Cells ◽  
Mouse Retina ◽  
Cone Photoreceptor ◽  
Class Iii ◽  
Cone Function ◽  
Rod Function ◽  
Phosphoinositide 3 Kinase ◽  
Phosphatidylinositol 3

The major pathway for the production of the low-abundance membrane lipid phosphatidylinositol 3-phosphate (PI(3)P) synthesis is catalyzed by class III phosphoinositide 3-kinase (PI3K) Vps34. The absence of Vps34 was previously found to disrupt autophagy and other membrane-trafficking pathways in some sensory neurons, but the roles of phosphatidylinositol 3-phosphate and Vps34 in cone photoreceptor cells have not previously been explored. We found that the deletion of Vps34 in neighboring rods in mouse retina did not disrupt cone function up to 8 weeks after birth, despite diminished rod function. Immunoblotting and lipid analysis of cones isolated from the cone-dominant retinas of the neural retina leucine zipper gene knockout mice revealed that both PI(3)P and Vps34 protein are present in mouse cones. To determine whether Vps34 and PI(3)P are important for cone function, we conditionally deleted Vps34 in cone photoreceptor cells of the mouse retina. Overall retinal morphology and rod function appeared to be unaffected. However, the loss of Vps34 in cones resulted in the loss of structure and function. There was a substantial reduction throughout the retina in the number of cones staining for M-opsin, S-opsin, cone arrestin, and peanut agglutinin, revealing degeneration of cones. These studies indicate that class III PI3K, and presumably PI(3)P, play essential roles in cone photoreceptor cell function and survival.

Sign in / Sign up

Export Citation Format

Share Document