Human G protein-coupled Receptor 30 (GPR30) is N -glycosylated and N-terminal Domain Asparagine 44 is Required for Receptor Structure and Activity

GPR30, or G protein-coupled estrogen receptor (GPER), is a G protein-coupled receptor (GPCR) that is currently attracting considerable attention in breast cancer and cardiometabolic regulation. The receptor was reported to be a novel membrane estrogen receptor mediating rapid non-genomic responses. However, questions remain about both the cognate ligand and the subcellular localization of receptor activity. Here, we used HEK293 cells ectopically expressing N-terminally FLAG-tagged human GPR30 and three unique antibodies (Ab) specifically targeting the receptor N-terminal domain (N-domain) to investigate the role of N -glycosylation in receptor maturation and activity, the latter assayed by constitutive receptor-stimulated ERK1/2 activity. GPR30 expression was complex with receptor species spanning from about 40 kDa to higher molecular masses and localized in the endoplasmatic reticulum (ER), the plasma membrane (PM), and endocytic vesicles. The receptor contains three conserved asparagines, Asn25, Asn32, and Asn44, in consensus N -glycosylation motifs, all in the N-domain, and PNGase F treatment showed that at least one of them is N -glycosylated. Mutating Asn44 to isoleucine inactivated the receptor, yielding a unique receptor species at about 20 kDa that was recognized by Ab only in a denatured state. On the other hand, mutating Asn25 or Asn32 either individually or in combination, or truncating successively N-domain residues 1-42, had no significant effect either on receptor structure, maturation, or activity. Thus, Asn44 in the GPR30 N-domain is required for receptor structure and activity, whereas N-domain residues 1-42, including specifically Asn25 and Asn32, do not play any major structural or functional roles

Requirement for direct cross-talk between B1 and B2 kinin receptors for the proliferation of androgen-insensitive prostate cancer PC3 cells.

Stimulation of endogenous kinin receptors promotes growth of androgen-independent prostate cancer PC3 cells via activation of the mitogenic extracellular-signal-regulated kinase (ERK) pathway. In the present study, we show that kinin-mediated mitogenic signalling and prostate-cell growth involves two subtypes of bradykinin (BK) receptors, B1R and B2R. Specific stimulation of either B1R or B2R by their respective agonists des-Arg(9)-BK and Lys-BK promoted ERK activation and cell growth, whereas selective blockade with specific antagonists des-Arg(9)-[Leu(8)]BK and Hoe 140 respectively obliterated this effect, indicating the presence of both receptor subtypes. However, blockade of B1R also inhibited B2R-mediated ERK activation and cell growth, and, similarly, antagonism of B2R inhibited the B1R-mediated response. Furthermore, both B1R and B2R agonists promoted internalization of B1R, whereas both receptor antagonists blocked this effect. The B1R ligands des-Arg(9)-BK and des-Arg(9)-[Leu(8)]BK had no effect on the binding of BK to B2R, as demonstrated by radioligand competitive binding studies. However, blockade of either B1R or B2R impaired the ability of the reciprocal receptor to produce inositol phosphates, suggesting that the interaction between B1R and B2R is proximal to activation of phospholipase C. These results provide evidence for the existence of B1R-B2R complexes in prostate cancer PC3 cells and demonstrate that antagonism of one receptor interferes with the signalling ability of the other, possibly at the level of receptor-Galpha(q) protein coupling. Selective inhibition of B1R, which is up-regulated in injured and cancerous tissue, may be beneficial for the treatment of advanced prostate cancer

Plasma membrane expression of G protein-coupled estrogen receptor (GPER)/G protein-coupled receptor 30 (GPR30) is associated with worse outcome in metachronous contralateral breast cancer

Background G protein-coupled estrogen receptor (GPER), or G protein-coupled receptor 30 (GPR30), is reported to mediate non-genomic estrogen signaling. GPR30 associates with breast cancer (BC) outcome and may contribute to tamoxifen resistance. We investigated the expression and prognostic significance of GPR30 in metachronous contralateral breast cancer (CBC) as a model of tamoxifen resistance. Methods Total GPR30 expression (GPR30TOT) and plasma membrane-localized GPR30 expression (GPR30PM) were analyzed by immunohistochemistry in primary (BC1; nBC1 = 559) and contralateral BC (BC2; nBC2 = 595), and in lymph node metastases (LGL; nLGL1 = 213; nLGL2 = 196). Death from BC (BCD), including BC death or death after documented distant metastasis, was used as primary end-point. Results GPR30PM in BC2 and LGL2 were associated with increased risk of BCD (HRBC2 = 1.7, p = 0.03; HRLGL2 = 2.0; p = 0.02). In BC1 and BC2, GPR30PM associated with estrogen receptor (ER)-negativity (pBC1<0.0001; pBC2<0.0001) and progesterone receptor (PR)-negativity (pBC1 = 0.0007; pBC2<0.0001). The highest GPR30TOT and GPR30PM were observed in triple-negative BC. GPR30PM associated with high Ki67 staining in BC1 (p<0.0001) and BC2 (p<0.0001). GPR30TOT in BC2 did not associate with tamoxifen treatment for BC1. However, BC2 that were diagnosed during tamoxifen treatment were more likely to express GPR30PM than BC2 diagnosed after treatment completion (p = 0.01). Furthermore, a trend was observed that patients with GPR30PM in an ER-positive BC2 had greater benefit from tamoxifen treatment. Conclusion PM-localized GPR30 staining is associated with increased risk of BC death when expressed in BC2 and LGL2. Additionally, PM-localized GPR30 correlates with prognostic markers of worse outcome, such as high Ki67 and a triple-negative subtype. Therefore, PM-localized GPR30 may be an interesting new target for therapeutic exploitation. We found no clear evidence that total GPR30 expression is affected by tamoxifen exposure during development of metachronous CBC, or that GPR30 contributes to tamoxifen resistance

Kinin receptor expression during Staphylococcus aureus infection

An inappropriate host response to invading bacteria is a critical parameter that often aggravates the outcome of an infection. Staphylococcus aureus is a major human Gram-positive pathogen that causes a wide array of community- and hospital-acquired diseases ranging from superficial skin infections to severe conditions such as staphylococcal toxic shock. Here we find that S aureus induces inflammatory reactions by modulating the expression and response of the B1 and B2 receptors, respectively. This process is initiated by a chain of events, involving staphylococcal-induced cytokine release from monocytes, bacteria-triggered contact activation, and conversion of bradykinin to its metabolite desArg9bradykinin. The data of the present study implicate an important and previously unknown role for kinin receptor regulation in S aureus infections

Breast cancer hypoxia in relation to prognosis and benefit from radiotherapy after breast-conserving surgery in a large, randomised trial with long-term follow-up

BACKGROUND: Breast-conserving surgery followed by radiotherapy is part of standard treatment for early-stage breast cancer. Hypoxia is common in cancer and may affect the benefit of radiotherapy. Cells adapt to hypoxic stress largely via the transcriptional activity of hypoxia-inducible factor (HIF)-1α. Here, we aim to determine whether tumour HIF-1α-positivity and hypoxic gene-expression signatures associated with the benefit of radiotherapy, and outcome.METHODS: Tumour HIF-1α-status and expression of hypoxic gene signatures were retrospectively analysed in a clinical trial where 1178 women with primary T1-2N0M0 breast cancer were randomised to receive postoperative radiotherapy or not and followed 15 years for recurrence and 20 years for breast cancer death.RESULTS: The benefit from radiotherapy was similar in patients with HIF-1α-positive and -negative primary tumours. Both ipsilateral and any breast cancer recurrence were more frequent in women with HIF-1α-positive primary tumours (hazard ratio, HR0-5 yrs1.9 [1.3-2.9], p = 0.003 and HR0-5 yrs = 2.0 [1.5-2.8], p < 0.0001). Tumour HIF-1α-positivity is also associated with increased breast cancer death (HR0-10 years 1.9 [1.2-2.9], p = 0.004). Ten of the 11 investigated hypoxic gene signatures correlated positively to HIF-1α-positivity, and 5 to increased rate/risk of recurrence.CONCLUSIONS: The benefit of postoperative radiotherapy persisted in patients with hypoxic primary tumours. Patients with hypoxic primary breast tumours had an increased risk of recurrence and breast cancer death

Gper1 activation is essential for E2-mediated cardioprotection.

<p><b>A.</b> Recordings of left ventricular developed pressure (LVDP) comparing heart activity from wild-type (WT) animals not subjected to ischemia/reperfusion (Sham) with the function of hearts subjected to the ischemia reperfusion (I/R) protocol under the continuous presence of vehicle (control) or 40 nM E2 in KH buffer. In sham hearts, function stabilizes at about 30–40 min after mounting and is stable for at least 2 hours. In hearts subjected to I/R (middle and bottom traces), E2 improved recovery from ischemia (during reperfusion) compared to control. <b>B-D.</b> LVDP traces from hearts of Esr1, Esr2 and Gper1 knockouts (-/-) subjected to I/R. Only in Gper1^-/- hearts, E2 lost its ability to improve functional recovery (<b>E</b>). n = 6–8 hearts/ group.</p

Salvage mechanisms triggered by E2 via Gper1 during I/R.

<p>E2 binding to Gper1 may initially trigger protein kinase C (PKC) translocation. PKC could directly or via activation of MEK_1/2/ERK_1/2 pathway increase phosphorylation of GSK-3β, which in turn would inhibit mPTP opening resulting in cardioprotection. Chelerythrine chloride, inhibitor of PKC translocation; U0126, inhibitor of the MEK_1/2/ERK_1/2-pathway; and LY294002, inhibitor of PI-3K. E2 through Gper1 can also induce a transient activation of PI-3K/Akt pathway, but this activation does not play an important role in the acute E2 induced cardioprotection after I/R. Black arrows, pathways demonstrated in this work. Dashed arrows, putative pathways.?, unknown target.</p