Upregulation of cAMP is a new functional signal pathway of Klotho in endothelial cells.
We measured angiotensin I-converting enzyme (ACE) activity in a human endothelial cell to characterize the intracellular signal pathways of Klotho. COS-1 cells transfected with naked mouse membrane-form klotho plasmid DNA (pCAGGS-klotho) translated proper Klotho protein. This translated Klotho protein was secreted into the culture medium. Furthermore, ACE activity in human umbilical vein endothelial cells (HUVEC) was upregulated when HUVEC were co-cultured with COS-1 cells that were pre-transfected with pCAGGS-klotho. The conditioned medium from COS-1 cells pre-transfected with pCAGGS-klotho also dose-dependently upregulated ACE in HUVEC. In addition, the conditioned medium induced time- and dose-dependent enhancement of cAMP production in HUVEC. Rp-cAMP, an inhibitor of cAMP-dependent protein kinase A (PKA), inhibited the upregulation of ACE by Klotho protein. Our results suggest that mouse membrane-form Klotho protein acts as a humoral factor to increase ACE activity in HUVEC via a cAMP-PKA-dependent pathway. These findings may provide a new insight into the mechanism of Klotho protein.
Yang
Jin
J
Department of Geriatric Medicine, Osaka University Graduate School of Medicine, 2-2 Yamadaoka, Suita 565-0871, Japan.
Matsukawa
Naomichi
N
Rakugi
Hiromi
H
Imai
Michio
M
Kida
Iwao
I
Nagai
Michiko
M
Ohta
Junsuke
J
Fukuo
Keisuke
K
Nabeshima
Yo-ichi
Y
Ogihara
Toshio
T
D000818:Animals; D019556:COS Cells; D018920:Coculture Techniques; D017077:Culture Media, Conditioned; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000378:metabolism*; D005966:Glucuronidase; D006801:Humans; D000090265:Klotho Proteins; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D007703:Peptidyl-Dipeptidase A / Q000378:metabolism; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation / Q000502:physiology*
D017077:Culture Media, Conditioned; D008565:Membrane Proteins; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D005966:Glucuronidase; D000090265:Klotho Proteins; D007703:Peptidyl-Dipeptidase A