Gastrointestinal Hormones Cause Rapid c-Met Receptor Down-regulation by a Novel Mechanism Involving Clathrin-mediated Endocytosis and a Lysosome-dependent Mechanism

Hoffmann, K. Martin; Tapia, José A.; Berna, Marc J.; Thill, Michelle; Braunschweig, Till; Mantey, Samuel A.; Moody, Terry W.; Jensen, Robert T.

doi:10.1074/jbc.m602583200

Cited by 14 publications

(20 citation statements)

References 74 publications

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“…This model highlights the unique role of Src activation in contributing to the dual effects of CCK on Akt activation, in that its activation is essential for Akt stimulation with low doses of CCK, but is not important for the inhibitory effect of higher concentrations of CCK. In a recent study, these latter concentrations of CCK were reported to stimulate the degradation of c-Met in rat pancreatic acini [118]. In the present study, we report that similar concentrations of CCK inhibit PI3K and Akt activity in these cells, raising the possibility these effects could be caused by an effect on c-Met further downstream in the signal transduction pathway.…”

Section: Discussionsupporting

confidence: 63%

“…First, c-Met degradation after CCK follows a slow kinetic, starting at 10 minutes and reaching a maximum after 45 minutes [118], while Akt inhibition is maximal after only 2.5 minutes. Second, degradation of growth factor receptors after CCK is limited to c-Met, other growth factor receptors are not degraded [118]. As the latter effects are not regulated by c-Met, they cannot be mediated by CCK-induced c-Met degradation.…”

Section: Discussionmentioning

confidence: 99%

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Gastrointestinal growth factors and hormones have divergent effects on Akt activation

Berna

Tapia

Sancho

et al. 2009

Cellular Signalling

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Akt is a central regulator of apoptosis, cell growth and survival. Growth factors and some G-proteincoupled receptors (GPCR) regulate Akt. Whereas growth-factor activation of Akt has been extensively studied, the regulation of Akt by GPCR's, especially gastrointestinal hormones/ neurotransmitters, remains unclear. To address this area, in this study the effects of GI growth factors and hormones/neurotransmitters were investigate in rat pancreatic acinar cells which are high responsive to these agents. Pancreatic acini expressed Akt and 5 of 7 known pancreatic growth-factors stimulate Akt phosphorylation (T308, S473) and translocation. These effects are mediated by p85 phosphorylation and activation of PI3K. GI hormones increasing intracellular cAMP had similar effects. However, GI-hormones/neurotransmitters[CCK, bombesin,carbachol] activating phospholipase C (PLC) inhibited basal and growth-factor-stimulated Akt activation. Detailed studies with CCK, which has both physiological and pathophysiological effects on pancreatic acinar cells at different concentrations, demonstrated CCK has a biphasic effect: at low concentrations(pM) stimulating Akt by a Src-dependent mechanism and at higher concentrations(nM) inhibited basal and stimulated Akt translocation, phosphorylation and activation, by de-phosphorylating p85 resulting in decreasing PI3K activity. This effect required activation of both limbs of the PLC-pathway and a protein tyrosine phosphatase, but was not mediated by p44/42 MAPK, Src or activation of a serine phosphatase. Akt inhibition by CCK was also found in vivo and in Panc-1 cancer cells where it inhibited serum-mediated rescue from apoptosis. These results demonstrate that GI growth factors as well as gastrointestinal hormones/neurotransmitters with different cellular basis of action can all regulate Akt phosphorylation in pancreatic acinar cells. This regulation is complex with phospholipase C agents such as CCK, because both stimulatory and inhibitory effects can be seen, which are mediated by different mechanisms.

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Section: Discussionsupporting

confidence: 63%

Section: Discussionmentioning

confidence: 99%

Gastrointestinal growth factors and hormones have divergent effects on Akt activation

Berna

Tapia

Sancho

et al. 2009

Cellular Signalling

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“…After treating isolated pancreatic acini with or without stimulants as indicated, cells were fixed, transferred to glass slides and blocked as previously described [28], then slides were incubated with a rabbit anti-pT538 PKCθ antibody and a mouse anti-cadherin antibody at a dilution of 1:500 overnight at 4 °C. Reactivity was demonstrated by incubation with an Alexa 488-conjugated anti-rabbit or with an Alexa 555-conjugated anti-mouse secondary antibody, respectively, at a dilution of 1:500 for 2 hours RT.…”

Section: Methodsmentioning

confidence: 99%

“…Negative controls consisted of replacement of primary antibody with an isotype-matched control. Slides were analyzed as previously reported [28]. …”

Section: Methodsmentioning

confidence: 99%

PKCθ activation in pancreatic acinar cells by gastrointestinal hormones/neurotransmitters and growth factors is needed for stimulation of numerous important cellular signaling cascades

Sancho

Berna

Thill

et al. 2011

Biochimica et Biophysica Acta (BBA) - Molecular Cell Research

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The novel PKCθ isoform is highly expressed in T-cells, brain and skeletal muscle and originally thought to have a restricted distribution. It has been extensively studied in T-cells and shown to be important for apoptosis, T-cell activation and proliferation. Recent studies showed its presence in other tissues and importance in insulin signaling, lung surfactant secretion, intestinal barrier permeability, platelet and mast-cell functions. However, little information is available for PKCθ activation by gastrointestinal(GI) hormones/neurotransmitters and growth factors. In the present study we used rat pancreatic acinar cells to explore their ability to activate PKCθ and the possible interactions with important cellular mediators of their actions. Particular attention was paid to cholecystokinin(CCK), a physiological regulator of pancreatic function and important in pathological processes affecting acinar function, like pancreatitis. PKCθ-protein/mRNA were present in the pancreatic acini, and T538-PKCθ phosphorylation/activation was stimulated only by hormones/neurotransmitters activating phospholipase C. PKCθ was activated in time- and dose-related manner by CCK, mediated 30% by high-affinity CCKA-receptor activation. CCK stimulated PKCθ translocation from cytosol to membrane. PKCθ inhibition (by pseudostrate-inhibitor or dominant negative) inhibited CCK- and TPA-stimulation of PKD, Src, RafC, PYK2, p125FAK and IKKα/β, but not basal/stimulated enzyme secretion. Also CCK- and TPA-induced PKCθ activation produced an increment in PKCθ’s direct association with AKT, RafA, RafC and Lyn. These results show for the first time PKCθ presence in pancreatic acinar cells, its activation by some GI hormones/neurotransmitters and involvement in important cell signaling pathways mediating physiological responses (enzyme secretion, proliferation, apoptosis, cytokine expression, and pathological responses like pancreatitis and cancer growth).

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“…Blocking the proteasomal or lysosomal degradation pathways individually was unable to greatly prevent 2BP-induced c-Met loss. Multiple reports detail the paradoxical effects these degradation pathways have on c-Met trafficking and stability [46–48]. We find it likely that distinct intracellular pools of c-Met are degraded through different, possibly compensatory, pathways.…”

Section: Discussionmentioning

confidence: 65%

Palmitoylation regulates the intracellular trafficking and stability of c-Met

et al. 2016

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c-Met is a receptor tyrosine kinase whose activity can promote both mitogenic and motogenic phenotypes involved in tissue development and cancer progression. Herein, we report the first evidence that c-Met is palmitoylated and that palmitoylation facilitates its trafficking and stability. Inhibition of palmitoylation reduced the expression of c-Met in multiple cancer cell lines post-transcriptionally. Using surface biotinylation, confocal microscopy, and metabolic labeling we determined that inhibition of palmitoylation reduces the stability of newly synthesized c-Met and causes accumulation at the Golgi. Acyl-biotin exchange and click chemistry-based palmitate labeling indicated the c-Met β-chain is palmitoylated, and site-directed mutagenesis revealed two likely cysteine palmitoylation sites. Moreover, by monitoring palmitoylation kinetics during the biosynthesis and trafficking of c-Met, we revealed that stable palmitoylation occurs in the endoplasmic reticulum prior to cleavage of the 170 kDa c-Met precursor to the mature 140 kDa form. Our data suggest palmitoylation is required for egress from the Golgi for transport to the plasma membrane. These findings introduce palmitoylation as a critical modification of c-Met, providing a novel therapeutic target for c-Met-driven cancers.

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Gastrointestinal Hormones Cause Rapid c-Met Receptor Down-regulation by a Novel Mechanism Involving Clathrin-mediated Endocytosis and a Lysosome-dependent Mechanism

Cited by 14 publications

References 74 publications

Gastrointestinal growth factors and hormones have divergent effects on Akt activation

Gastrointestinal growth factors and hormones have divergent effects on Akt activation

PKCθ activation in pancreatic acinar cells by gastrointestinal hormones/neurotransmitters and growth factors is needed for stimulation of numerous important cellular signaling cascades

Palmitoylation regulates the intracellular trafficking and stability of c-Met

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