Selective loss of substrate recognition induced by the tumour-associated D294G point mutation in protein kinase Cα

Prévostel, Corinne; Alvaro, Véronique; Vallentin, Alice; Martin, Annick; Jaken, Susan; Joubert, Dominique

doi:10.1042/bj3340393

Cited by 15 publications

(13 citation statements)

References 29 publications

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“…1D). Thus, one of the major cell biological defects of the PKCa-D294G mutant is the loss of tight membrane binding even upon treatment of TPA, consistent with the proposition by others that this mutant may have reduced stability of membrane association (5,9).…”

Section: Resultssupporting

confidence: 64%

The PKCα-D294G Mutant Found in Pituitary and Thyroid Tumors Fails to Transduce Extracellular Signals

Zhu

Dong²,

Tan³

et al. 2005

Cancer Research

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Protein kinase C (PKC) is a key regulator of cell proliferation, differentiation, and apoptosis and is one of the drug targets of anticancer therapy. Recently, a single point mutation (D294G) in PKCA has been found in pituitary and thyroid tumors with more invasive phenotype. Although the PKCA-D294G mutant is implicated in the progression of endocrine tumors, no apparent biochemical/cell biological abnormalities underlying tumorigenesis with this mutant have been found. We report here that the PKCA-D294G mutant is unable to bind to cellular membranes tightly despite the fact that it translocates to the membrane as efficiently as the wild-type PKCA upon treatment of phorbol ester. The impaired membrane binding is associated with this mutant's inability to transduce several antitumorigenic signals as it fails to mediate phorbol ester-stimulated translocation of myristoylated alanine-rich protein kinase C substrate (MARCKS), to activate mitogen-activated protein kinase and to augment melatonin-stimulated neurite outgrowth. Thus, the PKCA-D294G is a loss-of-function mutation. We propose that the wild-type PKCA may play important antitumorigenic roles in the progression of endocrine tumors. Therefore, developing selective activators instead of inhibitors of PKCA might provide effective pharmacological interventions for the treatment of certain endocrine tumors. (Cancer Res 2005; 65(11): 4520-4)

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Section: Resultssupporting

confidence: 64%

The PKCα-D294G Mutant Found in Pituitary and Thyroid Tumors Fails to Transduce Extracellular Signals

Zhu

Dong²,

Tan³

et al. 2005

Cancer Research

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“…Journal of Cell Science 117 (1) A cell-cell contact-induced signal responsible for the selectivity The D294G mutation induces a selective loss in the recognition of substrates exhibiting anchoring protein properties without affecting PKCα catalytic activity (Prevostel et al, 1998). This suggests that the selectivity of PKCα targeting to cellcell contacts might be mediated through protein-protein interactions.…”

Section: Discussionmentioning

confidence: 99%

“…Very little is known about the function of this region. In a previous study, we have established that the D294G mutation induces a selective loss in the recognition of substrates with properties of anchoring proteins (Prevostel et al, 1998). Recently, Parsons et al (Parsons et al, 2002) have identified a binding motif for β1 integrin within the PKCα V3 region that is critical for directed tumour cell migration.…”

Section: Introductionmentioning

confidence: 99%

Targeting of PKCα and ϵ in the pituitary: a highly regulated mechanism involving a GD(E)E motif of the V3 region

Quittau-Prévostel

Delaunay

Collazos

et al. 2004

Journal of Cell Science

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Protein kinase C (PKC) has been implicated in the control of intercellular adhesion. Our previous observation demonstrating that activated PKC alpha (PKCα is selectively targeted to cell-cell contacts of pituitary GH3B6 cells supports these findings. The relevance of this observation is further strengthened by the present data establishing that this targeting selectivity also occurs in the pituitary gland. Moreover, a new mechanism involved in the control of PKC targeting is unravelled. We demonstrate that a three amino acid motif located in the V3 region of α and epsilon (ϵ (GDE/GEE respectively) is essential for the targeting selectivity of these isoforms because: (1) this motif is absent in delta (δ) and mutated in the natural D294GPKCα mutant, which do not exhibit such selectivity, and (2) a GEE to GGE mutation abolishes the selectivity of targeting to cell-cell contacts for ϵ, as it does for the D294G PKCα mutant. Thus the GD(E)E motif may be part of a consensus sequence able to interact with shuttle and/or anchoring proteins. GFP-tagged deletion mutants also reveal a new function for the pseudosubstrate in the cytoplasmic sequestration. Together, these data underline the complexity of PKC subcellular targeting in the pituitary, determined by the cell-cell contact, at least for α and ϵ

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“…In GH3B6 cells, the fact that PKC␣ relocated to the cytoplasm before the [Ca 2ϩ ] i decreased to baseline levels (52) also indicates that cPKC activation is not always phase locked with variations in calcium concentration as suggested in many studies, such as that of Violin et al, who also showed the coincidence of PKC substrate phosphorylation with calcium oscillations (54). In addition, we have shown that the selective targeting of PKC␣ to cell-cell contacts is probably finely regulated at the molecular level, since the natural D294G point mutation (located in the V3 region of the enzyme and thus not involved in calcium or DAG binding), previously identified in human pituitary and thyroid tumors (2,40,41), abolished the selective accumulation of PKC␣ at the cell-cell contact (51). The same result was obtained when this mutation was introduced in the PKCε coding sequence (43).…”

mentioning

confidence: 85%

A Spatiotemporally Coordinated Cascade of Protein Kinase C Activation Controls Isoform-Selective Translocation

Collazos

Diouf

Guérineau

et al. 2006

Molecular and Cellular Biology

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In pituitary GH3B6 cells, signaling involving the protein kinase C (PKC) multigene family can self-organize into a spatiotemporally coordinated cascade of isoform activation. Indeed, thyrotropin-releasing hormone (TRH) receptor activation sequentially activated green fluorescent protein (GFP)-tagged or endogenous PKC␤1, PKC␣, PKC, and PKC␦, resulting in their accumulation at the entire plasma membrane (PKC␤ and -␦) or selectively at the cell-cell contacts (PKC␣ and -). The duration of activation ranged from 20 s for PKC␣ to 20 min for PKC. PKC␣ and -selective localization was lost in the presence of Gö6976, suggesting that accumulation at cell-cell contacts is dependent on the activity of a conventional PKC. Constitutively active, dominant-negative PKCs and small interfering RNAs showed that PKC␣ localization is controlled by PKC␤1 activity and is calcium independent, while PKC localization is dependent on PKC␣ activity. PKC␦ was independent of the cascade linking PKC␤1, -␣, and -. Furthermore, PKC␣, but not PKC, is involved in the TRH-induced ␤-catenin relocation at cell-cell contacts, suggesting that PKC is not the unique functional effector of the cascade. Thus, TRH receptor activation results in PKC␤1 activation, which in turn initiates a calcium-independent but PKC␤1 activity-dependent sequential translocation of PKC␣ and -. These results challenge the current understanding of PKC signaling and raise the question of a functional dependence between isoforms.Space and time parameters are intimately linked to the biological function of proteins and are pivotal in the organization and functioning of living matter. Particularly important in the case of intracellular signaling networks, this spatiotemporal constraint determines the modalities by which a given protein interacts with its partners in order to exchange information. Efforts are currently being made to translate the experimental evidence of this plasticity into a visualization concept of dynamic signaling networks (4,22). A degree of complexity is added when different isoforms of a protein coexist within the same cell and when they all potentially respond to the same stimulus, which is the case of the protein kinase C (PKC) family.The PKC family is composed of at least 11 isoforms. Several isoforms usually coexist within a given cell type, and each isoform is thought to mediate distinct cellular functions leading to proliferation, differentiation, apoptosis, or secretion. PKC function requires its translocation to a membrane compartment. The current understanding of PKC translocation/ activation has been largely based on the work of Oancea and Meyer (34), who presented conventional PKCs (cPKCs) and novel PKCs (nPKCs) as molecular machines responsible for decoding calcium and/or diacylglycerol (DAG)-mediated signals. Several observations suggest, however, that other, as yet unknown, parameters are involved in the temporal organization of PKC signaling. Indeed, despite similarities in sequence and cofactor regulation by DAG and Ca 2ϩ , the conventional P...

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Selective loss of substrate recognition induced by the tumour-associated D294G point mutation in protein kinase Cα

Cited by 15 publications

References 29 publications

The PKCα-D294G Mutant Found in Pituitary and Thyroid Tumors Fails to Transduce Extracellular Signals

The PKCα-D294G Mutant Found in Pituitary and Thyroid Tumors Fails to Transduce Extracellular Signals

Targeting of PKCα and ϵ in the pituitary: a highly regulated mechanism involving a GD(E)E motif of the V3 region

A Spatiotemporally Coordinated Cascade of Protein Kinase C Activation Controls Isoform-Selective Translocation

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