Protein Kinase C-Dependent Supply of Secretory Granules to the Plasma Membrane

Receptor desensitization occurs through receptor internalization and targeting to endosomes, a prerequisite for sorting and degradation. Such trafficking processes may not be restricted to membrane associated receptors but may also play an important role in the downregulation of cytoplasmic transducers such as protein kinase C (PKC). It is demonstrated here that acute TPA exposure induces the transport of activated PKC(alpha) from the plasma membrane to endosomes. This process requires PKC activity and catalytically competent PKC can even promote a similar process for a truncated regulatory domain PKC(α) protein. It is established that PKC(α) is targeted to the endosome compartment as an active kinase, where it colocalizes with annexin I, a substrate of PKC. Thus, PKC(alpha) downregulation shares features with plasma membrane associated receptor sorting and degradation. However, it is shown that PKC(α) delivery to the endosome compartment is not a Rab5 mediated process in contrast to the well characterised internalisation of the transferrin receptor. An alternative route for PKC(alpha) is evidenced by the finding that the cholesterol binding drugs nystatin and filipin, known to inhibit caveolae mediated trafficking, are able to block PKC(alpha) traffic and down regulation. Consistent with this, the endosomes where PKC(alpha) is found also contain caveolin. It is concluded that the initial step in desensitisation of PKC(alpha) involves active delivery to endosomes via a caveolae mediated process.

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Protein Kinase C: Plasma Membrane to Nucleus

Plasma Membrane Oxidoreductases in Control of Animal and Plant Growth ◽

10.1007/978-1-4684-8029-0_42 ◽

1988 ◽

pp. 383-393

Author(s):

Anant N. Malviya ◽

Ahmed Masmoudi ◽

Gérard Labourdette ◽

Marcel Mersel ◽

Patrick Rogue ◽

...

Keyword(s):

Plasma Membrane ◽

Protein Kinase C ◽

Protein Kinase ◽

Kinase C

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Mammalian Homologue of the Caenorhabditis elegans UNC-76 Protein Involved in Axonal Outgrowth Is a Protein Kinase C ζ–interacting Protein

The Journal of Cell Biology ◽

10.1083/jcb.144.3.403 ◽

1999 ◽

Vol 144 (3) ◽

pp. 403-411 ◽

Cited By ~ 62

Author(s):

Shun'ichi Kuroda ◽

Noritaka Nakagawa ◽

Chiharu Tokunaga ◽

Kenji Tatematsu ◽

Katsuyuki Tanizawa

Keyword(s):

Plasma Membrane ◽

Protein Kinase C ◽

Caenorhabditis Elegans ◽

Protein Kinase ◽

Rat Brain ◽

Axonal Outgrowth ◽

Yeast Two Hybrid ◽

Interacting Protein ◽

Kinase C ◽

Two Hybrid

By the yeast two-hybrid screening of a rat brain cDNA library with the regulatory domain of protein kinase C ζ (PKCζ) as a bait, we have cloned a gene coding for a novel PKCζ-interacting protein homologous to the Caenorhabditis elegans UNC-76 protein involved in axonal outgrowth and fasciculation. The protein designated FEZ1 (fasciculation and elongation protein zeta-1) consisting of 393 amino acid residues shows a high Asp/Glu content and contains several regions predicted to form amphipathic helices. Northern blot analysis has revealed that FEZ1 mRNA is abundantly expressed in adult rat brain and throughout the developmental stages of mouse embryo. By the yeast two-hybrid assay with various deletion mutants of PKC, FEZ1 was shown to interact with the NH2-terminal variable region (V1) of PKCζ and weakly with that of PKCε. In the COS-7 cells coexpressing FEZ1 and PKCζ, FEZ1 was present mainly in the plasma membrane, associating with PKCζ and being phosphorylated. These results indicate that FEZ1 is a novel substrate of PKCζ. When the constitutively active mutant of PKCζ was used, FEZ1 was found in the cytoplasm of COS-7 cells. Upon treatment of the cells with a PKC inhibitor, staurosporin, FEZ1 was translocated from the cytoplasm to the plasma membrane, suggesting that the cytoplasmic translocation of FEZ1 is directly regulated by the PKCζ activity. Although expression of FEZ1 alone had no effect on PC12 cells, coexpression of FEZ1 and constitutively active PKCζ stimulated the neuronal differentiation of PC12 cells. Combined with the recent finding that a human FEZ1 protein is able to complement the function of UNC-76 necessary for normal axonal bundling and elongation within axon bundles in the nematode, these results suggest that FEZ1 plays a crucial role in the axon guidance machinery in mammals by interacting with PKCζ.

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Entry of the Two Infectious Forms of Vaccinia Virus at the Plasma Membane Is Signaling-Dependent for the IMV but Not the EEV

Molecular Biology of the Cell ◽

10.1091/mbc.11.7.2497 ◽

2000 ◽

Vol 11 (7) ◽

pp. 2497-2511 ◽

Cited By ~ 127

Author(s):

Jacomine Krijnse Locker ◽

Annett Kuehn ◽

Sibylle Schleich ◽

Gaby Rutter ◽

Heinrich Hohenberg ◽

...

Keyword(s):

Plasma Membrane ◽

Protein Kinase C ◽

Protein Kinase ◽

Cell Surface ◽

Vaccinia Virus ◽

Hela Cells ◽

Signaling Cascade ◽

Enveloped Virus ◽

Kinase C ◽

Mature Virus

The simpler of the two infectious forms of vaccinia virus, the intracellular mature virus (IMV) is known to infect cells less efficiently than the extracellular enveloped virus (EEV), which is surrounded by an additional, TGN-derived membrane. We show here that when the IMV binds HeLa cells, it activates a signaling cascade that is regulated by the GTPase rac1 and rhoA, ezrin, and both tyrosine and protein kinase C phosphorylation. These cascades are linked to the formation of actin and ezrin containing protrusions at the plasma membrane that seem to be essential for the entry of IMV cores. The identical cores of the EEV also appear to enter at the cell surface, but surprisingly, without the need for signaling and actin/membrane rearrangements. Thus, in addition to its known role in wrapping the IMV and the formation of intracellular actin comets, the membrane of the EEV seems to have evolved the capacity to enter cells silently, without a need for signaling.

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