Activated human hydroxy‐carboxylic acid receptor‐3 signals to MAP kinase cascades via the PLC‐dependent PKC and MMP‐mediated EGFR pathways

Abstract

BACKGROUND AND PURPOSE3-Hydroxy-octanoate, recently identified as a ligand for, the orphan GPCR, HCA3, is of particular interest given its ability to treat lipid disorders and atherosclerosis. Here we demonstrate the pathway of HCA3-mediated activation of ERK1/2. EXPERIMENTAL APPROACHUsing CHO-K1 cells stably expressing HCA3 receptors and A431 cells, a human epidermoid cell line with high levels of endogenous expression of functional HCA3 receptors, HCA3-mediated activation of ERK1/2 was measured by Western blot. KEY RESULTSHCA3-mediated activation of ERK1/2 was rapid, peaking at 5 min, and was Pertussis toxin sensitive. Our data, obtained by time course analyses in combination with different kinase inhibitors, demonstrated that on agonist stimulation, HCA3 receptors evoked ERK1/2 activation via two distinct pathways, the PLC/PKC pathway at early time points (Յ2 min) and the MMP/ epidermal growth factor receptor (EGFR) transactivation pathway with a maximum response at 5 min. Furthermore, our present results also indicated that the bg-subunits of the Gi protein play a critical role in HCA3-activated ERK1/2 phosphorylation, whereas b-arrestins and Src were not required for ERK1/2 activation. CONCLUSIONS AND IMPLICATIONSWe have described the molecular mechanisms underlying the coupling of human HCA3 receptors to the ERK1/2 MAP kinase pathway in CHO-K1 and A431 cells, which implicate the Gi protein-initiated, PLC/PKC-and platelet-derived growth factor receptor/EGFR transactivation-dependent pathways. These observations may provide new insights into the pharmacological effects and the physiological functions modulated by the HCA3-mediated activation of ERK1/2. AbbreviationsADAM, a disintegrin and metalloproteinase; CRE, cAMP response element; EGFR, epidermal growth factor receptor;

Natural biased signaling of hydroxycarboxylic acid receptor 3 and G protein-coupled receptor 84

“…Activation of both, HCA 3 and GPR84, resulted in phosphorylation of extracellular-signal regulated kinase (ERK) ( Figure S6A, Table S2). We did not observe calcium signals upon stimulation of either receptor ( Figure S6B) which partially contrasts previous findings [42,43]. However, the previously reported calcium signals in HCA 3 -transfected CHO-K1 cells have been reported at very high agonist concentrations, i.e.…”

“…However, the previously reported calcium signals in HCA 3 -transfected CHO-K1 cells have been reported at very high agonist concentrations, i.e. 100 μM of the synthetic agonist 1-isopropylbenzotriazole-5-carboxylic acid (IPBT5CA) [42], which has been reported to activate HCA 3 with an EC 50 value of 0.4 μM [44]. Additionally, Gaidarov et al showed that GPR84 activation evoked calcium responses only in human macrophages but not in transfected HEK293 cells which is in line with our findings [43].…”

The gut microbiota suppresses insulin-mediated fat accumulation via the short-chain fatty acid receptor GPR43

“…5b). It is reported that G(i/o)βγ mediates to the PLC–PKC–ERK pathway34. GPR43-mediated suppression of insulin-induced Akt phosphorylation was effectively blocked by the treatment with U73122 (PLC inhibitor) and Go6983 (PKC inhibitor), but not U0126 (MEK inhibitor) (Fig.…”

A Gene Expression Profile of Peripheral Blood in Colorectal Cancer

“…Higher MDM2 expression has been reported in a variety of human stromal and epithelial malignancies, including colorectal cancers [33][34][35][36][37][38] . DUSP6, also known as MAPK phosphatase 3 (MKP3), inactivates MAPK1/ERK2 [39][40][41][42] . Elevated DUSP6 transcript levels have been reported as a risk factor for poor prognosis in non-small cell lung cancer patients [21] and tamoxifen resistance in breast cancer patients [43] .…”