The Calcium-Sensing Receptor Stimulates JNK in MDCK Cells

Arthur, John M.; Lawrence, Martha S.; Payne, Cameron R.; Rane, Madhavi J.; McLeish, Kenneth R.

doi:10.1006/bbrc.2000.3226

Cited by 39 publications

(23 citation statements)

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“…The CaR acts pleiotropically via G q , G i , and G 12/13 proteins [reviewed by Ward (45)] to elicit various intracellular signaling pathways including activation of MAPKs (1,13,26,31). Feedback regulation of signaling through the CaR is believed to occur and to be mediated via direct phosphorylation of the receptor by PKC (2,24).…”

mentioning

confidence: 99%

Evidence for a functional calcium-sensing receptor that modulates myogenic tone in rat subcutaneous small arteries

Ohanian¹,

Gatfield²,

Ward³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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), and, recently, a receptor that senses changes in Ca 2ϩ , the calcium-sensing receptor (CaR), has been detected in vascular tissue. We investigated whether the CaR is involved in the regulation of myogenic tone in rat subcutaneous small arteries. Immunoblot analysis using a monoclonal antibody against the CaR demonstrated its presence in rat subcutaneous arteries. To determine whether the CaR was functionally active, segments of artery (Ͻ250 m internal diameter) mounted in a pressure myograph with an intraluminal pressure of 70 mmHg were studied after the development of myogenic tone. Increasing Ca o 2ϩ concentration ([Ca 2ϩ ]o) cumulatively from 0.5 to 10 mM induced an initial constriction (0.5-2 mM) followed by dilation (42 Ϯ 5% loss of tone). The dose-dependent dilation was mimicked by other known CaR agonists including magnesium (1-10 mM) and the aminoglycosides neomycin (0.003-10 mM) and kanamycin (0.003-3 mM). PKC activation with the phorbol ester phorbol-12,13-dibutyrate (20nM) inhibited the dilation induced by high [Ca 2ϩ ]o or neomycin, whereas inhibition of PKC with GF109203X (10 M) increased the responses to Ca o 2ϩ or neomycin, consistent with the role of PKC as a negative regulator of the CaR. We conclude that rat subcutaneous arteries express a functionally active CaR that may be involved in the modulation of myogenic tone and hence the regulation of peripheral vascular resistance. vascular smooth muscle; magnesium; aminoglycosides; contractility; peripheral vascular resistance THE EXTRACELLULAR CALCIUM-SENSING RECEPTOR (CaR) is a G protein-coupled receptor capable of sensing changes in extracellular calcium (Ca o 2ϩ ) concentration ([Ca 2ϩ ] o ). Primarily, the CaR regulates calcium homeostasis by suppressing parathyroid hormone secretion and renal Ca 2ϩ reabsorption. In addition, the CaR is also expressed in tissues and cell types outside the calcium homeostatic system including neural and cardiovascular tissues [reviewed by Brown and Macleod (8)]. However, the functional significance of the receptor in these noncalcium homeostatic tissues remains unclear.Calcium is an important regulator of contractility. Elevated intracellular calcium (Ca i 2ϩ ) levels stimulate smooth muscle contraction (17), and Ca o 2ϩ is required for the maintenance of myogenic tone (14), the intrinsic contractile activity of arterial wall smooth muscle that represents an important determinant of vascular resistance. The response to Ca o 2ϩ varies between artery type with some tissues showing contraction and others relaxation (3, 22, 35, 49 -51), but, in either case, these studies demonstrate that arteries can sense changes in [Ca 2ϩ ] o . In this regard, CaR expression has been reported in the perivascular sensory nerves of rat small mesenteric (10), basilar, renal, and coronary arteries (43). Increasing [Ca 2ϩ ] o (1.25-5 mM) induced a concentration-dependent relaxation of rat small mesenteric arteries precontracted with norepinephrine that was dependent on intact perivascular nerves (10,34,44) and associated...

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confidence: 99%

Evidence for a functional calcium-sensing receptor that modulates myogenic tone in rat subcutaneous small arteries

Ohanian¹,

Gatfield²,

Ward³

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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“…The receptor stimulates phospholipases C, A 2 , and D (4), inhibits adenylate cyclase through pertussis toxin-sensitive and -insensitive mechanisms (2) and activates several mitogen-activated protein kinase (MAPK) cascades (5)(6)(7)(8). The latter include the p42/44 (ERK1/2) (5,8) and p38 MAPK (6) cascades as well as the c-Jun NH 2 -terminal kinase pathway (7).…”

mentioning

confidence: 99%

Filamin-A Binds to the Carboxyl-terminal Tail of the Calcium-sensing Receptor, an Interaction That Participates in CaR-mediated Activation of Mitogen-activated Protein Kinase

Hjälm¹,

Macleod

Kifor

et al. 2001

Journal of Biological Chemistry

169

139

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The G protein-coupled, extracellular calcium-sensing receptor (CaR) regulates parathyroid hormone secretion and parathyroid cellular proliferation as well as the functions of diverse other cell types. The CaR resides in caveolae-plasma membrane microdomains containing receptors and associated signaling molecules that are thought to serve as cellular "message centers." An additional mechanism for coordinating cellular signaling is the presence of scaffold proteins that bind and organize components of signal transduction cascades. With the use of the yeast two-hybrid system, we identified filamin-A (an actin-cross-linking, putative scaffold protein that binds mitogen-activated protein kinase (MAPK) components activated by the CaR) as an intracellular binding partner of the CaR's carboxyl (COOH)-terminal tail. A direct interaction of the two proteins was confirmed by an in vitro binding assay. Moreover, confocal microscopy combined with two color immunofluorescence showed co-localization of the CaR and filamin-A within parathyroid cells as well as HEK-293 cells stably transfected with the CaR. Deletion mapping localized the sites of interaction between the two proteins to a stretch of 60 amino acid residues within the distal portion of the CaR's COOH-terminal tail and domains 14 and 15 in filamin-A, respectively. Finally, introducing the portion of filamin-A interacting with the CaR into CaR-transfected HEK-293 cells using protein transduction with a His-tagged, Tat-filamin-A fusion protein nearly abolished CaR-mediated activation of ERK1/2 MAPK but had no effect on ERK1/2 activity stimulated by ADP. Therefore, the binding of the CaR's COOH-terminal tail to filamin-A may contribute to its localization in caveolae, link it to the actin-based cytoskeleton, and participate in CaR-mediated activation of MAPK.

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“…This indicates that the CaR induces apoptosis via a G␣ i -dependent signaling pathway. Using GST-c-Jun 1-79 as a substrate and analyzing kinase activity in vitro, similar results, that the CaR stimulates JNK through a pertussis toxin-sensitive G protein pathway, were also observed in MDCK cells (26). The regulation of MAPK activities is a fundamental cellular process in cell proliferation, differentiation, and apoptosis that is essential for embryonic development and tissue homeostasis (52).…”

Section: Discussionmentioning

confidence: 71%

“…The CaR plays a central role in the regulation of MAPK signaling cascades (1,26,27). To test the hypothesis that CaR-induced apoptosis may involve the stimulation of SAPK/JNK, we examined the effect of the CaR on this signaling pathway.…”

Section: The Car Activates the Sapk/jnk Pathwaymentioning

confidence: 99%

“…The CaR acting via G ␣ i has been shown to activate ERK1/2 in a variety of cell lines, including fibroblasts, osteoblasts, parathyroid cells, HEK 293 cells, and MDCK cells (1). In in vitro kinase assays using glutathione S -transferase (GST)-c-Jun as the substrate, the CaR stimulates JNK through a pertussis toxin-sensitive G protein pathway in MDCK cells (26). Recently, one report showed that the CaR also activates p38 MAPK in the regulation of a Ca 2 ϩ -activated K ϩ channel (27).…”

mentioning

confidence: 99%

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