Endocytosis of MPO in Marginal Cells Is Regulated by PKC, Protein Phosphatase, ERK and PI3-K Signaling Cascades, but Not by PKA and MEK Signaling Cascades.
Summary of "Endocytosis of MPO in Marginal Cells Is Regulated by PKC, Protein Phosphatase, ERK and PI3-K Signaling Cascades, but Not by PKA and MEK Signaling Cascades."
Endocytosis of marginal cells plays a key role in maintaining the homeostasis of endocytosis and function of the organ of Corti. How the signaling cascade is involved in the regulation of endocytosis is an important issue at present. To investigate the regulation of endocytosis in marginal cells of the stria vascularis by the signaling network, we perfused MPO, an endocytosis tracer, with PMA, OA, staurosporin, PAO, PD98059, SB20580 or wortmannin into the cochlear duct. After 30 min endolymphatic perfusion, the tissues were fixed and the distribution of MPO was examined by electron microscopy. We explored the functions of PKC, RTK, PI3-K, PTP, and PP1/2A in MPO endocytosis and defined the MPO endocytic route. MPO endocytosis was strongly dependent on PKC, ERK, PTP, PP1/2A and PI3-K signaling networks, but not on PKA and MEK signaling networks. The MPO endocytic pathways are clathrin-, GPI-AP-, and caveolae-independent.
Department of Otolaryngology, Faculty of Medicine, University of Tokyo, Tokyo, Japan.
This article was published in the following journal.
Name: ORL; journal for oto-rhino-laryngology and its related specialties
Medical and Biotech [MESH] Definitions
Map Kinase Signaling System
An intracellular signaling system involving the MAP kinase cascades (three-membered protein kinase cascades). Various upstream activators, which act in response to extracellular stimuli, trigger the cascades by activating the first member of a cascade, MAP KINASE KINASE KINASES; (MAPKKKs). Activated MAPKKKs phosphorylate MITOGEN-ACTIVATED PROTEIN KINASE KINASES which in turn phosphorylate the MITOGEN-ACTIVATED PROTEIN KINASES; (MAPKs). The MAPKs then act on various downstream targets to affect gene expression. In mammals, there are several distinct MAP kinase pathways including the ERK (extracellular signal-regulated kinase) pathway, the SAPK/JNK (stress-activated protein kinase/c-jun kinase) pathway, and the p38 kinase pathway. There is some sharing of components among the pathways depending on which stimulus originates activation of the cascade.
Protein Tyrosine Phosphatase, Non-receptor Type 6
A Src-homology domain-containing protein tyrosine phosphatase found in the CYTOSOL of hematopoietic cells. It plays a role in signal transduction by dephosphorylating signaling proteins that are activated or inactivated by PROTEIN-TYROSINE KINASES.
Protein Phosphatase 2
A phosphoprotein phosphatase subtype that is comprised of a catalytic subunit and two different regulatory subunits. At least two genes encode isoforms of the protein phosphatase catalytic subunit, while several isoforms of regulatory subunits exist due to the presence of multiple genes and the alternative splicing of their mRNAs. Protein phosphatase 2 acts on a broad variety of cellular proteins and may play a role as a regulator of intracellular signaling processes.
Protein Tyrosine Phosphatase, Non-receptor Type 2
A subtype of non-receptor protein tyrosine phosphatase that is closely-related to PROTEIN TYROSINE PHOSPHATASE, NON-RECEPTOR TYPE 1. Alternative splicing of the mRNA for this phosphatase results in the production at two gene products, one of which includes a C-terminal nuclear localization domain that may be involved in the transport of the protein to the CELL NUCLEUS. Although initially referred to as T-cell protein tyrosine phosphatase the expression of this subtype occurs widely.
Transcription Factor 7-like 2 Protein
A transcription factor that takes part in WNT signaling pathway. The activity of the protein is regulated via its interaction with BETA CATENIN. Transcription factor 7-like 2 protein plays an important role in the embryogenesis of the PANCREAS and ISLET CELLS.
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