GqPCR-stimulated Dephosphorylation of AKT is Induced by an IGBP1-mediated PP2A Switch

Overview

Journal Cell Commun Signal

Publisher Biomed Central

Specialties Biochemistry
Cell Biology

Date 2022 Jan 9

PMID 34998390

Citations 6

Authors

Guy Nadel

Zhong Yao

Ehud Wainstein

Izel Cohen

Ido Ben-Ami

Amir Schajnovitz

Galia Maik-Rachline

Zvi Naor

Benjamin A Horwitz

Rony Seger

Affiliations

Soon will be listed here.

Abstract

Background: G protein-coupled receptors (GPCRs) usually regulate cellular processes via activation of intracellular signaling pathways. However, we have previously shown that in several cell lines, GqPCRs induce immediate inactivation of the AKT pathway, which leads to JNK-dependent apoptosis. This apoptosis-inducing AKT inactivation is essential for physiological functions of several GqPCRs, including those for PGF2α and GnRH.

Methods: Here we used kinase activity assays of PI3K and followed phosphorylation state of proteins using specific antibodies. In addition, we used coimmunoprecipitation and proximity ligation assays to follow protein-protein interactions. Apoptosis was detected by TUNEL assay and PARP1 cleavage.

Results: We identified the mechanism that allows the unique stimulated inactivation of AKT and show that the main regulator of this process is the phosphatase PP2A, operating with the non-canonical regulatory subunit IGBP1. In resting cells, an IGBP1-PP2Ac dimer binds to PI3K, dephosphorylates the inhibitory pSer608-p85 of PI3K and thus maintains its high basal activity. Upon GqPCR activation, the PP2Ac-IGBP1 dimer detaches from PI3K and thus allows the inhibitory dephosphorylation. At this stage, the free PP2Ac together with IGBP1 and PP2Aa binds to AKT, causing its dephosphorylation and inactivation.

Conclusion: Our results show a stimulated shift of PP2Ac from PI3K to AKT termed "PP2A switch" that represses the PI3K/AKT pathway, providing a unique mechanism of GPCR-stimulated dephosphorylation. Video Abstract.

Citing Articles

Genetic variation in patent foramen ovale: a case-control genome-wide association study.

Dong B, Li Y, Ai F, Geng J, Tang T, Peng W Front Genet. 2025; 15:1523304.

PMID: 39872005 PMC: 11769951. DOI: 10.3389/fgene.2024.1523304.

Special Issue: MAPK Signaling Cascades in Human Health and Diseases.

Seger R Int J Mol Sci. 2024; 25(20).

PMID: 39457006 PMC: 11509016. DOI: 10.3390/ijms252011226.

Microcystin-LR activates serine/threonine kinases and alters the phosphoproteome in human HepaRG cells.

Ikumawoyi V, Lynch K, Iverson D, Ridge Call M, Yue G, Prasad B Toxicon. 2024; 249:108072.

PMID: 39154757 PMC: 11402562. DOI: 10.1016/j.toxicon.2024.108072.

Phosphorylation of PP2Ac by PKC is a key regulatory step in the PP2A-switch-dependent AKT dephosphorylation that leads to apoptosis.

Nadel G, Yao Z, Hacohen-Lev-Ran A, Wainstein E, Maik-Rachline G, Ziv T Cell Commun Signal. 2024; 22(1):154.

PMID: 38419089 PMC: 10900696. DOI: 10.1186/s12964-024-01536-7.

JNK Cascade-Induced Apoptosis-A Unique Role in GqPCR Signaling.

Nadel G, Maik-Rachline G, Seger R Int J Mol Sci. 2023; 24(17).

PMID: 37686335 PMC: 10487481. DOI: 10.3390/ijms241713527.

References

Trockenbacher A, Suckow V, Foerster J, Winter J, Krauss S, Ropers H . MID1, mutated in Opitz syndrome, encodes an ubiquitin ligase that targets phosphatase 2A for degradation. Nat Genet. 2001; 29(3):287-94. DOI: 10.1038/ng762. View

Murata K, Wu J, Brautigan D . B cell receptor-associated protein alpha4 displays rapamycin-sensitive binding directly to the catalytic subunit of protein phosphatase 2A. Proc Natl Acad Sci U S A. 1997; 94(20):10624-9. PMC: 23426. DOI: 10.1073/pnas.94.20.10624. View

Hemmings B . Akt signaling: linking membrane events to life and death decisions. Science. 1997; 275(5300):628-30. DOI: 10.1126/science.275.5300.628. View

Kraus S, Naor Z, Seger R . Intracellular signaling pathways mediated by the gonadotropin-releasing hormone (GnRH) receptor. Arch Med Res. 2001; 32(6):499-509. DOI: 10.1016/s0188-4409(01)00331-9. View

Rubinfeld H, Hanoch T, Seger R . Identification of a cytoplasmic-retention sequence in ERK2. J Biol Chem. 1999; 274(43):30349-52. DOI: 10.1074/jbc.274.43.30349. View

Vanhaesebroeck B, Stephens L, Hawkins P . PI3K signalling: the path to discovery and understanding. Nat Rev Mol Cell Biol. 2012; 13(3):195-203. DOI: 10.1038/nrm3290. View

Levi N, Hanoch T, Benard O, Rozenblat M, Harris D, Reiss N . Stimulation of Jun N-terminal kinase (JNK) by gonadotropin-releasing hormone in pituitary alpha T3-1 cell line is mediated by protein kinase C, c-Src, and CDC42. Mol Endocrinol. 1998; 12(6):815-24. DOI: 10.1210/mend.12.6.0120. View

Song M, Salmena L, Pandolfi P . The functions and regulation of the PTEN tumour suppressor. Nat Rev Mol Cell Biol. 2012; 13(5):283-96. DOI: 10.1038/nrm3330. View

Lambrecht C, Haesen D, Sents W, Ivanova E, Janssens V . Structure, regulation, and pharmacological modulation of PP2A phosphatases. Methods Mol Biol. 2013; 1053:283-305. DOI: 10.1007/978-1-62703-562-0_17. View

10.

Prickett T, Brautigan D . Cytokine activation of p38 mitogen-activated protein kinase and apoptosis is opposed by alpha-4 targeting of protein phosphatase 2A for site-specific dephosphorylation of MEK3. Mol Cell Biol. 2007; 27(12):4217-27. PMC: 1900036. DOI: 10.1128/MCB.00067-07. View

11.

Bennin D, Don A, Brake T, McKenzie J, Rosenbaum H, Ortiz L . Cyclin G2 associates with protein phosphatase 2A catalytic and regulatory B' subunits in active complexes and induces nuclear aberrations and a G1/S phase cell cycle arrest. J Biol Chem. 2002; 277(30):27449-67. DOI: 10.1074/jbc.M111693200. View

12.

Kraus S, Levy G, Hanoch T, Naor Z, Seger R . Gonadotropin-releasing hormone induces apoptosis of prostate cancer cells: role of c-Jun NH2-terminal kinase, protein kinase B, and extracellular signal-regulated kinase pathways. Cancer Res. 2004; 64(16):5736-44. DOI: 10.1158/0008-5472.CAN-04-1156. View

13.

Carpenter C, Auger K, Duckworth B, Hou W, Schaffhausen B, Cantley L . A tightly associated serine/threonine protein kinase regulates phosphoinositide 3-kinase activity. Mol Cell Biol. 1993; 13(3):1657-65. PMC: 359478. DOI: 10.1128/mcb.13.3.1657-1665.1993. View

14.

Offermanns S, Toombs C, Hu Y, Simon M . Defective platelet activation in G alpha(q)-deficient mice. Nature. 1997; 389(6647):183-6. DOI: 10.1038/38284. View

15.

New D, Wu K, Kwok A, Wong Y . G protein-coupled receptor-induced Akt activity in cellular proliferation and apoptosis. FEBS J. 2007; 274(23):6025-36. DOI: 10.1111/j.1742-4658.2007.06116.x. View

16.

Wang L, Summers S . Measuring insulin-stimulated phosphatidyl-inositol 3-kinase activity. Methods Mol Med. 2003; 83:127-36. DOI: 10.1385/1-59259-377-1:127. View

17.

Plotnikov A, Flores K, Maik-Rachline G, Zehorai E, Kapri-Pardes E, Berti D . The nuclear translocation of ERK1/2 as an anticancer target. Nat Commun. 2015; 6:6685. DOI: 10.1038/ncomms7685. View

18.

Kraus S, Naor Z, Seger R . Gonadotropin-releasing hormone in apoptosis of prostate cancer cells. Cancer Lett. 2006; 234(2):109-23. DOI: 10.1016/j.canlet.2005.02.038. View

19.

Hong I, Cheung A, Leung P . Gonadotropin-releasing hormones I and II induce apoptosis in human granulosa cells. J Clin Endocrinol Metab. 2008; 93(8):3179-85. DOI: 10.1210/jc.2008-0127. View

20.

Seshacharyulu P, Pandey P, Datta K, Batra S . Phosphatase: PP2A structural importance, regulation and its aberrant expression in cancer. Cancer Lett. 2013; 335(1):9-18. PMC: 3665613. DOI: 10.1016/j.canlet.2013.02.036. View