Gα12 is required for renal cystogenesis induced by <i>Pkd1</i> inactivation

Wu, Yong; Xu, Jin-Wen; El-Jouni, Wassim; Lu, Tzongshi; Li, Suyan; Wang, Qingyi; Tran, Mei; Barrera, Ivan; Bonventre, Joseph V.; Zhou, Jing; Denker, Bradley M.; Kong, Tianqing

doi:10.1242/jcs.190496

Cited by 22 publications

(24 citation statements)

References 65 publications

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“…Both inhibition (by sequestration) and activation of Ga-and Gbg-mediated signaling with effects on apoptosis, ion channel activity and transcription factor activation (AP-1, NFAT) have been reported for PC1 in cell-based assay systems (15)(16)(17)(18)(19)(20)(21)(22). Recent in vivo studies have shown that PC1-dependent regulation of G protein signaling is necessary for preventing cyst formation in the kidneys of mice and in the developing pronephros of Xenopus embryos (14,23,24). Together, these observations support a critical function of PC1 as a novel and non-canonical GPCR important in ADPKD pathophysiology.…”

Section: Introductionmentioning

confidence: 99%

Constitutive signaling by the C-terminal fragment of polycystin-1 is mediated by a tethered peptide agonist

Magenheimer

Munoz

Ravichandran

et al. 2021

Preprint

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Mutation of the PKD1 gene, encoding polycystin-1 (PC1), is the primary cause of autosomal dominant polycystic kidney disease. PC1 is an 11-transmembrane domain protein that binds and modulates the activity of multiple heterotrimeric G protein families and is thought to function as a non-canonical G protein-coupled receptor (GPCR). PC1 shares a conserved GPCR autoproteolysis inducing [GAIN] domain with the adhesion family of GPCRs, that promotes an auto-catalytic, cis-cleavage at the GPCR proteolysis site (GPS) located proximal to the first transmembrane domain. GPS cleavage divides these receptors into two associated ‘subunits’, the extracellular N-terminal (NTF) and transmembrane C-terminal (CTF) fragments. For the adhesion GPCRs, removal of the NTF leads to activation of G protein signaling as a result of the exposure and subsequent intramolecular binding of the extracellular N-terminal stalk of the CTF, i.e., the tethered cryptic ligand or tethered agonist model. Here, we test the hypothesis that PC1-mediated signaling is regulated by an adhesion GPCR-like, tethered agonist mechanism. Using cell-based reporter assays and mutagenesis of PC1 expression constructs, we show that the CTF form of PC1 requires the stalk for signaling activation and synthetic peptides derived from the PC1 stalk sequence can re-activate signaling by a ‘stalk-less’ CTF. In addition, we demonstrate that ADPKD-associated missense mutations within the PC1 stalk affect signaling and can inhibit GPS cleavage. These results provide a foundation for beginning to understand the molecular mechanism of G protein regulation by PC1 and suggest that a tethered agonist-mediated mechanism can contribute to PKD pathogenesis.SIGNIFICANCE STATEMENTMutations of the PKD1 gene, encoding polycystin-1, are the predominant cause of autosomal dominant polycystic kidney disease (ADPKD), a systemic disease that is the 4th leading cause of kidney failure. Polycystin-1 functions as an atypical GPCR capable of binding or activating heterotrimeric G proteins, which is essential for preventing renal cystogenesis. However, little is known regarding its regulation. Polycystin-1 shares structural features with the Adhesion family of GPCRs. In this work, we combined mutagenesis and cellular signaling assays which demonstrated that constitutive activation of signaling by polycystin-1 involves an Adhesion GPCR-like molecular mechanism. This study provides new knowledge regarding the structure-function relationships of polycystin-1 which will stimulate additional areas of investigation and reveal novel avenues of therapeutic intervention for ADPKD.

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Section: Introductionmentioning

confidence: 99%

Constitutive signaling by the C-terminal fragment of polycystin-1 is mediated by a tethered peptide agonist

Magenheimer

Munoz

Ravichandran

et al. 2021

Preprint

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“…PC1-inhibited apoptosis was linked to the phosphatidylinositol 3-kinase (PI3K)/Akt- and Gα 12 /Jun N-terminal kinases (JNKs)-dependent pathways 9 , 10 . Interestingly, it was found that G protein α12 (Gα12) is necessary for the cystogenesis induced by dysregulated PC1 because lack of Gα12 in mice abolished PC1-dependent cyst formation 11 . Despite the tremendous progress made during the past two decades, the molecular mechanisms underlying ADPKD pathogenesis remain controversial.…”

Section: Introductionmentioning

confidence: 99%

Polycystin-1 inhibits eIF2α phosphorylation and cell apoptosis through a PKR-eIF2α pathway

Tang

Wang

Yang

et al. 2017

Sci Rep

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Autosomal dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 or PKD2 which encodes polycystin-1 (PC1) and polycystin-2, respectively. PC1 was previously shown to slow cell proliferation and inhibit apoptosis but the underlying mechanisms remain elusive or controversial. Here we showed in cultured mammalian cells and Pkd1 knockout mouse kidney epithelial cells that PC1 and its truncation mutant comprising the last five transmembrane segments and the intracellular C-terminus (PC1-5TMC) down-regulate the phosphorylation of protein kinase R (PKR) and its substrate eukaryotic translation initiation factor 2 alpha (eIF2α). PKR is known to be activated by interferons and dsRNAs, inhibits protein synthesis and induces apoptosis. By co-immunoprecipitation experiments we found that PC1 truncation mutants associate with PKR, or with PKR and its activator PACT. Further experiments showed that PC1 and PC1-5TMC reduce phosphorylation of eIF2α through inhibiting PKR phosphorylation. Our TUNEL experiments using tunicamycin, an apoptosis inducer, and GADD34, an inhibitor of eIF2α phosphorylation, demonstrated that PC1-5TMC inhibits apoptosis of HEK293T cells in a PKR-eIF2α-dependent manner, with concurrent up- and down-regulation of Bcl-2 and Bax, respectively, revealed by Western blotting. Involvement of PC1-regulated eIF2α phosphorylation and a PKR-eIF2α pathway in cell apoptosis may be an important part of the mechanism underlying ADPKD pathogenesis.

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“…33,66). PC1 regulates PC2 channel activity and thus intracellular calcium homeostasis, and also plays a role in cell-cell/matrix interactions (21,32,68) and G protein-coupled signal trans-duction pathways (20,45). High expression of PC1 in the basal membranes of ureteric bud epithelia suggests the involvement of PC1 during early development of the metanephric kidney (7,25).…”

mentioning

confidence: 99%

Insights into cellular and molecular basis for urinary tract infection in autosomal-dominant polycystic kidney disease

Gao

Zhang

et al. 2017

American Journal of Physiology-Renal Physiology

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Urinary tract infection (UTI) is a broad term referring to an infection of the kidneys, ureters, bladder, and/or urethra. Because of its prevalence, frequent recurrence, and rising resistance to antibiotics, UTI has become a challenge in clinical practice. Autosomal-dominant polycystic kidney disease (ADPKD) is the most common monogenic disorder of the kidney and is characterized by the growth of fluid-filled cysts in both kidneys. Progressive cystic enlargement, inflammation, and interstitial fibrosis result in nephron loss with subsequent decline in kidney function. ADPKD patients frequently develop UTI; however, the cellular and molecular mechanisms responsible for the high UTI incidence in ADPKD patients remain virtually unaddressed. Emerging evidence suggests that α-intercalated cells (α-ICs) of the collecting ducts function in the innate immune defense against UTI. α-ICs inhibit bacterial growth by acidifying urine and secreting neutrophil gelatinase-associated lipocalin (NGAL) that chelates siderophore-containing iron. It is necessary to determine, therefore, if ADPKD patients with recurrent UTI have a reduced number and/or impaired function of α-ICs. Identification of the underlying cellular and molecular mechanisms may lead to the development of novel strategies to reduce UTI in ADPKD.

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Gα12 is required for renal cystogenesis induced by Pkd1 inactivation

Cited by 22 publications

References 65 publications

Constitutive signaling by the C-terminal fragment of polycystin-1 is mediated by a tethered peptide agonist

Constitutive signaling by the C-terminal fragment of polycystin-1 is mediated by a tethered peptide agonist

Polycystin-1 inhibits eIF2α phosphorylation and cell apoptosis through a PKR-eIF2α pathway

Insights into cellular and molecular basis for urinary tract infection in autosomal-dominant polycystic kidney disease

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