scholarly journals Phorbol-12-myristate 13-acetate inhibits Nephronectin gene expression via Protein kinase C alpha and c-Jun/c-Fos transcription factors

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mitsuhiro Kinoshita ◽  
Atsushi Yamada ◽  
Kiyohito Sasa ◽  
Kaori Ikezaki ◽  
Tatsuo Shirota ◽  
...  

AbstractNephronectin (Npnt) is an extracellular matrix protein and ligand of integrin α8β1 known to promote differentiation of osteoblasts. A search for factors that regulate Npnt gene expression in osteoblasts revealed that phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), had a strong effect to suppress that expression. Research was then conducted to elucidate the signaling pathway responsible for regulation of Npnt gene expression by PMA in osteoblasts. Treatment of MC3T3-E1 cells with PMA suppressed cell differentiation and Npnt gene expression. Effects were noted at a low concentration of PMA, and were time- and dose-dependent. Furthermore, treatment with the PKC signal inhibitor Gö6983 inhibited down-regulation of Npnt expression, while transfection with small interfering RNA (siRNA) of PKCα, c-Jun, and c-Fos suppressed that down-regulation. The present results suggest regulation of Npnt gene expression via the PKCα and c-Jun/c-Fos pathway.

2021 ◽  
Author(s):  
Mitsuhiro Kinoshita ◽  
Atsushi Yamada ◽  
Kiyohito Sasa ◽  
Kaori Ikezaki ◽  
Tatsuo Shirota ◽  
...  

Abstract Nephronectin (Npnt) is an extracellular matrix protein and ligand of integrin α8β1 known to promote differentiation of osteoblasts. A search for factors that regulate Npnt gene expression in osteoblasts revealed that phorbol 12-myristate 13-acetate (PMA), which activates protein kinase C (PKC), had a strong effect to suppress that expression. Research was then conducted to elucidate the signaling pathway responsible for regulation of Npnt gene expression by PMA in osteoblasts. Treatment of MC3T3-E1 cells with PMA suppressed cell differentiation and Npnt gene expression. Effects were noted at a low concentration of PMA, and were time- and dose-dependent. Furthermore, treatment with the PKC signal inhibitor Gö6983 inhibited down-regulation of Npnt expression, while transfection with small interfering RNA (siRNA) of PKCα, c-Jun, and c-Fos suppressed that down-regulation. The present results suggest regulation of Npnt gene expression via the PKCα and c-Jun/c-Fos pathway.


Hypertension ◽  
2008 ◽  
Vol 52 (3) ◽  
pp. 499-506 ◽  
Author(s):  
Jundong Jiao ◽  
Vivek Garg ◽  
Baofeng Yang ◽  
Terry S. Elton ◽  
Keli Hu

Vascular ATP-sensitive K + (K ATP ) channels are critical regulators of arterial tone and, thus, blood flow in response to local metabolic needs. They are important targets for clinically used drugs to treat hypertensive emergency and angina. It is known that protein kinase C (PKC) activation inhibits K ATP channels in vascular smooth muscles. However, the mechanism by which PKC inhibits the channel remains unknown. Here we report that caveolin-dependent internalization is involved in PKC-ε–mediated inhibition of vascular K ATP channels (Kir6.1 and SUR2B) by phorbol 12-myristate 13-acetate or angiotensin II in human embryonic kidney 293 cells and immortalized human saphenous vein vascular smooth muscle cells. We showed that Kir6.1 substantially overlapped with caveolin-1 at the cell surface. Cholesterol depletion with methyl-β-cyclodextrin significantly reduced, whereas overexpression of caveolin-1 largely enhanced, PKC-induced inhibition of Kir6.1/SUR2B currents. Importantly, we demonstrated that activation of PKC-ε caused internalization of K ATP channels, the effect that was blocked by depletion of cholesterol with methyl-β-cyclodextrin, expression of dominant-negative dynamin mutant K44E, or knockdown of caveolin-1 with small interfering RNA. Moreover, patch-clamp studies revealed that PKC-ε–mediated inhibition of the K ATP current induced by PMA or angiotensin II was reduced by a dynamin mutant, as well as small interfering RNA targeting caveolin-1. The reduction in the number of plasma membrane K ATP channels by PKC activation was further confirmed by cell surface biotinylation. These studies identify a novel mechanism by which the levels of vascular K ATP channels could be rapidly downregulated by internalization. This finding provides a novel mechanistic insight into how K ATP channels are regulated in vascular smooth muscle cells.


2012 ◽  
Vol 128 (1) ◽  
pp. 209-222 ◽  
Author(s):  
Dong-mei Wu ◽  
Jun Lu ◽  
Yuan-lin Zheng ◽  
Yan-qiu Zhang ◽  
Bin Hu ◽  
...  

1994 ◽  
Vol 22 (3) ◽  
pp. 291S-291S ◽  
Author(s):  
Victoria J. Wilson ◽  
Daniela Oddiah ◽  
Michael V. Sofroniew ◽  
Moeen K. Panni ◽  
Marcus Rattray

Sign in / Sign up

Export Citation Format

Share Document