scholarly journals 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

2001 ◽  
Vol 276 (37) ◽  
pp. 34880-34887 ◽  
Author(s):  
Göran Hjälm ◽  
R. John MacLeod ◽  
Olga Kifor ◽  
Naibedya Chattopadhyay ◽  
Edward M. Brown
Keyword(s):  
Protein Kinase ◽  
Mitogen Activated Protein Kinase ◽  
Filamin A ◽  
Calcium Sensing Receptor ◽  
Calcium Sensing ◽  
Mitogen Activated Protein ◽  
Carboxyl Terminal

Regulation of MAP kinase by calcium-sensing receptor in bovine parathyroid and CaR-transfected HEK293 cells

2001 ◽  
Vol 280 (2) ◽  
pp. F291-F302 ◽  
Author(s):  
Olga Kifor ◽  
R. John MacLeod ◽  
Ruben Diaz ◽  
Mei Bai ◽  
Toru Yamaguchi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Combined Treatment ◽  
Cell Types ◽  
Serine Phosphorylation ◽  
Mitogen Activated Protein Kinase ◽  
Hek293 Cells ◽  
Calcium Sensing ◽  
Cytosolic Phospholipase ◽  
Extracellular Signal ◽  
Mitogen Activated Protein

Regulation of the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway by the extracellular calcium (Cao 2+)-sensing receptor (CaR) was investigated in bovine parathyroid and CaR-transfected human embryonic kidney (HEKCaR) cells. Elevating Cao 2+ or adding the selective CaR activator NPS R-467 elicited rapid, dose-dependent phosphorylation of ERK1/2. These phosphorylations were attenuated by pretreatment with pertussis toxin (PTX) or by treatment with the phosphotyrosine kinase (PTK) inhibitors genistein and herbimycin, the phosphatidylinositol-specific phospholipase C (PI-PLC) inhibitor U-73122, or the protein kinase C (PKC) inhibitor GF109203X and were enhanced by the PKC activator phorbol 12-myristate 13-acetate. Combined treatment with PTX and inhibitors of both PKC and PTK nearly abolished high Cao 2+-evoked ERK1/2 activation in HEKCaR cells, demonstrating CaR-mediated coupling via both Gq and Gi. High Cao 2+ increased serine phosphorylation of the 85-kDa cytosolic phospholipase A2(cPLA2) in both parathyroid and HEKCaR cells. The selective mitogen-activated protein kinase (MAPK) inhibitor PD98059 abolished high-Cao 2+-induced ERK1/2 activation and reduced cPLA2 phosphorylation in both cell types, documenting MAPK's role in cPLA2 activation. Thus our data suggest that the CaR activates MAPK through PKC, presumably through Gq/11-mediated activation of PI-PLC, as well as through Gi- and PTK-dependent pathway(s) in bovine parathyroid and HEKCaR cells and indicate the importance of MAPK in cPLA2 activation.

Filamin A and Parafibromin Expression in Parathyroid Carcinoma

2021 ◽  
Author(s):  
Sara Storvall ◽  
Helena Leijon ◽  
Eeva M Ryhänen ◽  
Tiina Vesterinen ◽  
Ilkka Heiskanen ◽  
...  
Keyword(s):  
Parathyroid Carcinoma ◽  
Mitogen Activated Protein Kinase ◽  
Proliferation Index ◽  
Filamin A ◽  
Ki 67 ◽  
Mapk Signalling Pathway ◽  
Calcium Sensing ◽  
Mitogen Activated Protein ◽  
Benign Tumours ◽  
Parathyroid Tumours

Objective: Parathyroid carcinoma (PC), atypical parathyroid tumors (APT) and parathyroid adenoma (PA) present with hypercalcemia. Diminished calcium-sensing receptor (CaSR) expression is reported in PC but is rare in benign tumours. Filamin A (FLNA) binds to the CaSR and activates the mitogen-activated protein kinase (MAPK) signalling pathway. FLNA is related to tumour aggressiveness in several cancers, but its role in parathyroid neoplasia is unknown. Design: We examined FLNA, CaSR and parafibromin expression in PCs (n = 32), APTs (n = 44) and PAs (n = 77) and investigated their potential as diagnostic and/or prognostic markers. Methods: Tissue microarray slides were immunohistochemically stained with FLNA, CaSR and parafibromin. Staining results were correlated with detailed clinical data. Results: All tumours stained positively for CaSR, with two tumours (one PC and one APT) showing diminished expression. Carcinomas were characterized by increased cytoplasmic FLNA expression compared to APTs and PAs (p = 0.004). FLNA expression was not correlated with Ki-67 proliferation index or loss of parafibromin expression. Cytoplasmic FLNA expression was also associated with higher serum calcium, PTH concentrations and male sex (p = 0.014, p = 0.017 and p = 0.049, respectively). Using a combined marker score, we found that parathyroid tumours with low FLNA expression and positive parafibromin staining were extremely likely to be benign (p < 0.001). Conclusion: Cytoplasmic and membranous FLNA expression is increased in parathyroid carcinomas compared to benign tumours. A combined FLNA and parafibromin expression score shows potential as a prognostic predictor of indolent behaviour in parathyroid neoplasms.

Filamin associates with stress signalling kinases MKK7 and MKK4 and regulates JNK activation

2010 ◽  
Vol 427 (2) ◽  
pp. 237-245 ◽  
Author(s):  
Kentaro Nakagawa ◽  
Misato Sugahara ◽  
Tokiwa Yamasaki ◽  
Hiroaki Kajiho ◽  
Shinya Takahashi ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Terminal Region ◽  
Mitogen Activated Protein Kinase ◽  
Actin Binding ◽  
Filamin A ◽  
Binding Region ◽  
Splice Isoforms ◽  
Mitogen Activated Protein ◽  
Jnk Activation

SAPK/JNK (stress-activated protein kinase/c-Jun N-terminal kinase) belongs to the MAPK (mitogen-activated protein kinase) family and is important in many biological contexts. JNK activation is regulated by phosphorylation of specific tyrosine and threonine residues sequentially catalysed by MKK4 and MKK7, which are both dual-specificity MAPKKs (MAPK kinases). Previously, we reported that tyrosine-phosphorylation of JNK by MKK4 precedes threonine-phosphorylation by MKK7, and that both are required for synergistic JNK activation. In the present study, we identify the actin-binding protein-280 (Filamin A) as a presumed ‘binder’ protein that can bind to MKK7, as well as to MKK4, connecting them in close proximity. We show that Filamin family members A, B and C interact with MKK4 and MKK7, but not with JNK. Filamin A binds to an N-terminal region (residues 31–60) present in the MKK7γ and MKK7β splice isoforms, but cannot bind to MKK7α which lacks these amino acids. This same N-terminal region is crucial for the intracellular co-localization of MKK7γ with actin stress fibres and Filamin A. Experiments using Filamin-A-deletion mutants revealed that the MKK7-binding region of Filamin A differs from its MKK4-binding region, and that MKK7γ (but not MKK7α) can form a complex with Filamin A and MKK4. Finally, we used Filamin-A-deficient cells to show that Filamin A enhances MKK7 activation and is important for synergistic stress-induced JNK activation in vivo. Thus Filamin A is a novel member of the group of scaffold proteins whose function is to link two MAPKKs together and promote JNK activation.

Sign in / Sign up

Export Citation Format

Share Document