Browse
Submit Data
Databases
API
Help

Dataset Information

27 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Structure of the phosphoinositide 3-kinase (PI3K) p110γ-p101 complex reveals molecular mechanism of GPCR activation.

ABSTRACT: The class IB phosphoinositide 3-kinase (PI3K), PI3Kγ, is a master regulator of immune cell function and a promising drug target for both cancer and inflammatory diseases. Critical to PI3Kγ function is the association of the p110γ catalytic subunit to either a p101 or p84 regulatory subunit, which mediates activation by G protein-coupled receptors. Here, we report the cryo-electron microscopy structure of a heterodimeric PI3Kγ complex, p110γ-p101. This structure reveals a unique assembly of catalytic and regulatory subunits that is distinct from other class I PI3K complexes. p101 mediates activation through its Gβγ-binding domain, recruiting the heterodimer to the membrane and allowing for engagement of a secondary Gβγ-binding site in p110γ. Mutations at the p110γ-p101 and p110γ-adaptor binding domain interfaces enhanced Gβγ activation. A nanobody that specifically binds to the p101-Gβγ interface blocks activation, providing a novel tool to study and target p110γ-p101-specific signaling events in vivo.

SUBMITTER: Rathinaswamy MK

PROVIDER: S-EPMC8397274 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Structure of the phosphoinositide 3-kinase p110-p101 complex reveals molecular mechanism of GPCR activation

Project description:The class IB phosphoinositide 3-kinase (PI3K), PI3K, is a master regulator of immune cell function, and is a promising drug target for both inflammatory diseases and cancer. Critical to PI3K function is the association of the p110 catalytic subunit to either a p101 or p84 regulatory subunit, which mediates regulation by G-protein coupled receptors (GPCRs). Here, we report the first structure of a heterodimeric PI3K complex, p110-p101. This structure revealed a unique mode of assembly of catalytic and regulatory subunits distinct from that of other class I PI3K complexes. Multiple oncogenic mutations mapped to these novel interfaces led to increased activation by G. p101 mediates activation through its G binding domain, recruiting the complex to the membrane and allowing for engagement of a secondary site in p110. A nanobody that specifically binds to this p101-G interface blocks activation providing a novel tool to study p101-specific signaling events in vivo.

2021-09-22 | PXD025209 | Pride

Gβγ is a direct regulator of endogenous p101/p110γ and p84/p110γ PI3Kγ complexes in mouse neutrophils.

Project description:The PI3Kγ isoform is activated by Gi-coupled GPCRs in myeloid cells, but the extent to which the two endogenous complexes of PI3Kγ, p101/p110γ and p84/p110γ, receive direct regulation through Gβγ or indirect regulation through RAS and the sufficiency of those inputs is controversial or unclear. We generated mice with point mutations that prevent Gβγ binding to p110γ (RK552DD) or to p101 (VVKR777AAAA) and investigated the effects of these mutations in primary neutrophils and in mouse models of neutrophilic inflammation. Loss of Gβγ binding to p110γ substantially reduced the activation of both p101/p110γ and p84/p110γ in neutrophils by various GPCR agonists. Loss of Gβγ binding to p101 caused more variable effects, depending on both the agonist and cellular response, with the biggest reductions seen in PIP3 production by primary neutrophils in response to LTB4 and MIP-2 and in the migration of neutrophils during thioglycolate-induced peritonitis or MIP2-induced ear pouch inflammation. We also observed that p101VVKR777AAAA neutrophils showed enhanced p84-dependent ROS responses to fMLP and C5a, suggesting that competition may exist between p101/p110γ and p84/p110γ for Gβγ subunits downstream of GPCR activation. GPCRs did not activate p110γ in neutrophils from mice lacking both the p101 and p84 regulatory subunits, indicating that RAS binding to p110γ is insufficient to support GPCR activation in this cell type. These findings define a direct role for Gβγ subunits in activating both of the endogenous PI3Kγ complexes and indicate that the regulatory PI3Kγ subunit biases activation toward different GPCRs.

| S-EPMC7610408 | biostudies-literature

Roles of G beta gamma in membrane recruitment and activation of p110 gamma/p101 phosphoinositide 3-kinase gamma.

Project description:Receptor-regulated class I phosphoinositide 3-kinases (PI3K) phosphorylate the membrane lipid phosphatidylinositol (PtdIns)-4,5-P2 to PtdIns-3,4,5-P3. This, in turn, recruits and activates cytosolic effectors with PtdIns-3,4,5-P3-binding pleckstrin homology (PH) domains, thereby controlling important cellular functions such as proliferation, survival, or chemotaxis. The class IB p110 gamma/p101 PI3K gamma is activated by G beta gamma on stimulation of G protein-coupled receptors. It is currently unknown whether in living cells G beta gamma acts as a membrane anchor or an allosteric activator of PI3K gamma, and which role its noncatalytic p101 subunit plays in its activation by G beta gamma. Using GFP-tagged PI3K gamma subunits expressed in HEK cells, we show that G beta gamma recruits the enzyme from the cytosol to the membrane by interaction with its p101 subunit. Accordingly, p101 was found to be required for G protein-mediated activation of PI3K gamma in living cells, as assessed by use of GFP-tagged PtdIns-3,4,5-P3-binding PH domains. Furthermore, membrane-targeted p110 gamma displayed basal enzymatic activity, but was further stimulated by G beta gamma, even in the absence of p101. Therefore, we conclude that in vivo, G beta gamma activates PI3K gamma by a mechanism assigning specific roles for both PI3K gamma subunits, i.e., membrane recruitment is mediated via the noncatalytic p101 subunit, and direct stimulation of G beta gamma with p110 gamma contributes to activation of PI3K gamma.

| S-EPMC2172741 | biostudies-literature

Different inhibition of G??-stimulated class IB phosphoinositide 3-kinase (PI3K) variants by a monoclonal antibody. Specific function of p101 as a G??-dependent regulator of PI3K? enzymatic activity.

Project description:Class IB phosphoinositide 3-kinases ? (PI3K?) are second-messenger-generating enzymes downstream of signalling cascades triggered by G-protein-coupled receptors (GPCRs). PI3K? variants have one catalytic p110? subunit that can form two different heterodimers by binding to one of a pair of non-catalytic subunits, p87 or p101. Growing experimental data argue for a different regulation of p87-p110? and p101-p110? allowing integration into distinct signalling pathways. Pharmacological tools enabling distinct modulation of the two variants are missing. The ability of an anti-p110? monoclonal antibody [mAb(A)p110?] to block PI3K? enzymatic activity attracted us to characterize this tool in detail using purified proteins. In order to get insight into the antibody-p110? interface, hydrogen-deuterium exchange coupled to MS (HDX-MS) measurements were performed demonstrating binding of the monoclonal antibody to the C2 domain in p110?, which was accompanied by conformational changes in the helical domain harbouring the G??-binding site. We then studied the modulation of phospholipid vesicles association of PI3K? by the antibody. p87-p110? showed a significantly reduced G??-mediated phospholipid recruitment as compared with p101-p110?. Concomitantly, in the presence of mAb(A)p110?, G?? did not bind to p87-p110?. These data correlated with the ability of the antibody to block G??-stimulated lipid kinase activity of p87-p110? 30-fold more potently than p101-p110?. Our data argue for differential regulatory functions of the non-catalytic subunits and a specific G??-dependent regulation of p101 in PI3K? activation. In this scenario, we consider the antibody as a valuable tool to dissect the distinct roles of the two PI3K? variants downstream of GPCRs.

| S-EPMC4655608 | biostudies-literature

Structure of the CaMKIIdelta/calmodulin complex reveals the molecular mechanism of CaMKII kinase activation.

Project description:UnlabelledLong-term potentiation (LTP), a long-lasting enhancement in communication between neurons, is considered to be the major cellular mechanism underlying learning and memory. LTP triggers high-frequency calcium pulses that result in the activation of Calcium/Calmodulin (CaM)-dependent kinase II (CaMKII). CaMKII acts as a molecular switch because it remains active for a long time after the return to basal calcium levels, which is a unique property required for CaMKII function. Here we describe the crystal structure of the human CaMKIIdelta/Ca2+/CaM complex, structures of all four human CaMKII catalytic domains in their autoinhibited states, as well as structures of human CaMKII oligomerization domains in their tetradecameric and physiological dodecameric states. All four autoinhibited human CaMKIIs were monomeric in the determined crystal structures but associated weakly in solution. In the CaMKIIdelta/Ca2+/CaM complex, the inhibitory region adopted an extended conformation and interacted with an adjacent catalytic domain positioning T287 into the active site of the interacting protomer. Comparisons with autoinhibited CaMKII structures showed that binding of calmodulin leads to the rearrangement of residues in the active site to a conformation suitable for ATP binding and to the closure of the binding groove for the autoinhibitory helix by helix alphaD. The structural data, together with biophysical interaction studies, reveals the mechanism of CaMKII activation by calmodulin and explains many of the unique regulatory properties of these two essential signaling molecules.Enhanced versionThis article can also be viewed as an enhanced version in which the text of the article is integrated with interactive 3-D representations and animated transitions. Please note that a web plugin is required to access this enhanced functionality. Instructions for the installation and use of the Web plugin are available in Text S1.

| S-EPMC2910593 | biostudies-literature

Structure of the LKB1-STRAD-MO25 complex reveals an allosteric mechanism of kinase activation.

Project description:The LKB1 tumor suppressor is a protein kinase that controls the activity of adenosine monophosphate-activated protein kinase (AMPK). LKB1 activity is regulated by the pseudokinase STRADalpha and the scaffolding protein MO25alpha through an unknown, phosphorylation-independent, mechanism. We describe the structure of the core heterotrimeric LKB1-STRADalpha-MO25alpha complex, revealing an unusual allosteric mechanism of LKB1 activation. STRADalpha adopts a closed conformation typical of active protein kinases and binds LKB1 as a pseudosubstrate. STRADalpha and MO25alpha promote the active conformation of LKB1, which is stabilized by MO25alpha interacting with the LKB1 activation loop. This previously undescribed mechanism of kinase activation may be relevant to understanding the evolution of other pseudokinases. The structure also reveals how mutations found in Peutz-Jeghers syndrome and in various sporadic cancers impair LKB1 function.

| S-EPMC3518268 | biostudies-literature

Unveiling molecular insights into the mechanism of activation of oncogenic phosphoinositide 3-kinase mutants.

Project description: Not available

| S-EPMC9897451 | biostudies-literature

A nuclear phosphoinositide kinase complex regulates p53.

Project description:The tumour suppressor p53 (encoded by TP53) protects the genome against cellular stress and is frequently mutated in cancer. Mutant p53 acquires gain-of-function oncogenic activities that are dependent on its enhanced stability. However, the mechanisms by which nuclear p53 is stabilized are poorly understood. Here, we demonstrate that the stability of stress-induced wild-type and mutant p53 is regulated by the type I phosphatidylinositol phosphate kinase (PIPKI-α (also known as PIP5K1A)) and its product phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2). Nuclear PIPKI-α binds to p53 upon stress, resulting in the production and association of PtdIns(4,5)P2 with p53. PtdIns(4,5)P2 binding promotes the interaction between p53 and the small heat shock proteins HSP27 (also known as HSPB1) and αB-crystallin (also known as HSPB5), which stabilize nuclear p53. Moreover, inhibition of PIPKI-α or PtdIns(4,5)P2 association results in p53 destabilization. Our results point to a previously unrecognized role of nuclear phosphoinositide signalling in regulating p53 stability and implicate this pathway as a promising therapeutic target in cancer.

| S-EPMC7017954 | biostudies-literature

Molecular mechanism of GPCR-mediated arrestin activation.

Project description:Despite intense interest in discovering drugs that cause G-protein-coupled receptors (GPCRs) to selectively stimulate or block arrestin signalling, the structural mechanism of receptor-mediated arrestin activation remains unclear1,2. Here we reveal this mechanism through extensive atomic-level simulations of arrestin. We find that the receptor's transmembrane core and cytoplasmic tail-which bind distinct surfaces on arrestin-can each independently stimulate arrestin activation. We confirm this unanticipated role of the receptor core, and the allosteric coupling between these distant surfaces of arrestin, using site-directed fluorescence spectroscopy. The effect of the receptor core on arrestin conformation is mediated primarily by interactions of the intracellular loops of the receptor with the arrestin body, rather than the marked finger-loop rearrangement that is observed upon receptor binding. In the absence of a receptor, arrestin frequently adopts active conformations when its own C-terminal tail is disengaged, which may explain why certain arrestins remain active long after receptor dissociation. Our results, which suggest that diverse receptor binding modes can activate arrestin, provide a structural foundation for the design of functionally selective ('biased') GPCR-targeted ligands with desired effects on arrestin signalling.

| S-EPMC6294333 | biostudies-literature

A Complex Interplay of Anionic Phospholipid Binding Regulates 3'-Phosphoinositide-Dependent-Kinase-1 Homodimer Activation.

Project description:3'-Phosphoinositide-dependent-Kinase-1 (PDK1) is a master regulator whereby its PI3-kinase-dependent dysregulation in human pathologies is well documented. Understanding the direct role for PtdIns(3,4,5)P3 and other anionic phospholipids in the regulation of PDK1 conformational dynamics and its downstream activation remains incomplete. Using advanced quantitative-time-resolved imaging (Fluorescence Lifetime Imaging and Fluorescence Correlation Spectroscopy) and molecular modelling, we show an interplay of antagonistic binding effects of PtdIns(3,4,5)P3 and other anionic phospholipids, regulating activated PDK1 homodimers. We demonstrate that phosphatidylserine maintains PDK1 in an inactive conformation. The dysregulation of the PI3K pathway affects the spatio-temporal and conformational dynamics of PDK1 and the activation of its downstream substrates. We have established a new anionic-phospholipid-dependent model for PDK1 regulation, depicting the conformational dynamics of multiple homodimer states. We show that the dysregulation of the PI3K pathway perturbs equilibrium between the PDK1 homodimer conformations. Our findings provide a role for the PtdSer binding site and its previously unrewarding role in PDK1 downregulation, suggesting a possible therapeutic strategy where the constitutively active dimer conformer of PDK1 may be rendered inactive by small molecules that drive it to its PtdSer-bound conformer.

| S-EPMC6787260 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data