Endocytosis of cationized ferritin in marginal cells of the stria vascularis is regulated by protein kinase, protein phosphatase, and MEK/ERK and PI3-K signaling pathways.
Otol Neurotol 2011;
32:856-62. [PMID:
21358558 DOI:
10.1097/mao.0b013e318210b8ad]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
HYPOTHESIS
The endocytosis of cationized ferritin (CF) via a clathrin-mediated pathway is regulated by a signaling network.
BACKGROUND
Marginal cells showed the active endocytosis of CF via a clathrin-mediated pathway. The internalization of receptors through the clathrin-mediated pathway is an important regulatory event in signal transduction. Numerous kinases are involved in endocytosis, and each endocytic route is subjected to high-order regulation by cellular signaling mechanisms.
METHODS
CF was infused into the cochlear duct with phorbol 12-myristate 13 acetate, okadaic acid, staurosporin, phenylarsine oxide, PD98059, SB20580 and wortmannin. Endocytic activity was measured at 30 minutes post-infusion by transmission electron microscopy.
RESULTS
The endocytosis of CF was stimulated by a protein kinase C activator (phorbol 12-myristate 13 acetate) and a protein kinase A activator (8-bromoadenosine-3', 5'-cyclic monophosphate). It was inhibited by protein phosphatase inhibitors (okadaic acid and phenylarsine oxide), mitogen-activated protein kinase/extracellular signal-related kinase inhibitors (PD98059 and SB20580), and a phosphatidylinositol 3-kinase inhibitor (wortmannin).
CONCLUSION
Our previous study showed the endocytosis of microperoxidase to be strongly dependent on protein kinase C, protein phosphatase, extracellular signal-related kinase, and phosphatidylinositol 3-kinase signaling networks but not on protein kinase A and mitogen-activated protein kinase signaling networks. The present study indicated that the signaling cascade regulating CF's internalization differed from the cascade for microperoxidase's endocytosis.
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