scholarly journals A clathrin-dependent pathway leads to KRas signaling on late endosomes en route to lysosomes

2009 ◽  
Vol 184 (6) ◽  
pp. 863-879 ◽  
Author(s):  
Albert Lu ◽  
Francesc Tebar ◽  
Blanca Alvarez-Moya ◽  
Cristina López-Alcalá ◽  
Maria Calvo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Intracellular Trafficking ◽  
Yellow Fluorescent Protein ◽  
Mitogen Activated Protein Kinase ◽  
Ras Signaling ◽  
Ras Proteins ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Signal Output ◽  
Dependent Pathway

Ras proteins are small guanosine triphosphatases involved in the regulation of important cellular functions such as proliferation, differentiation, and apoptosis. Understanding the intracellular trafficking of Ras proteins is crucial to identify novel Ras signaling platforms. In this study, we report that epidermal growth factor triggers Kirsten Ras (KRas) translocation onto endosomal membranes (independently of calmodulin and protein kinase C phosphorylation) through a clathrin-dependent pathway. From early endosomes, KRas but not Harvey Ras or neuroblastoma Ras is sorted and transported to late endosomes (LEs) and lysosomes. Using yellow fluorescent protein–Raf1 and the Raichu-KRas probe, we identified for the first time in vivo–active KRas on Rab7 LEs, eliciting a signal output through Raf1. On these LEs, we also identified the p14–MP1 scaffolding complex and activated extracellular signal-regulated kinase 1/2. Abrogation of lysosomal function leads to a sustained late endosomal mitogen-activated protein kinase signal output. Altogether, this study reveals novel aspects about KRas intracellular trafficking and signaling, shedding new light on the mechanisms controlling Ras regulation in the cell.

scholarly journals Endosomal Dynamics of Met Determine Signaling Output

2003 ◽  
Vol 14 (4) ◽  
pp. 1346-1354 ◽  
Author(s):  
Dean E. Hammond ◽  
Stephanie Carter ◽  
John McCullough ◽  
Sylvie Urbé ◽  
George Vande Woude ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cell Surface ◽  
Receptor Activation ◽  
Mitogen Activated Protein Kinase ◽  
Proteasomal Activity ◽  
Late Endosomes ◽  
Early Endosomes ◽  
Mitogen Activated Protein ◽  
The Face ◽  
Kinase Cascade

Proteasomal activity is required for Met receptor degradation after acute stimulation with hepatocyte growth factor (HGF). Inhibition of proteasomal activity with lactacystin leads to a block in the endocytic trafficking of Met such that the receptor fails to reach late endosomes/lysosomes, where degradation by acid-dependent proteases takes place ( Hammond et al., 2001 ). In this article, we have biochemically determined Met internalization rates from the cell surface and shown that lactacystin does not inhibit the initial HGF-dependent internalization step of Met. Instead, it promotes the recycling pathway from early endosomes at the expense of sorting to late endosomes, thereby ensuring rapid return of internalized Met to the cell surface. We have used this perturbation of Met endosomal sorting by lactacystin to examine the consequences for HGF-dependent signaling outputs. In control cells HGF-dependent receptor autophosphorylation reaches a maximal level over 5–10 min but then attenuates over the ensuing 50 min. Furthermore, Met dephosphorylation can be kinetically dissociated from Met degradation. In lactacystin-treated cells, we observe a failure of Met dephosphorylation as well as Met degradation. Elements of the mitogen-activated protein kinase cascade, downstream of receptor activation, show a normal kinetic profile of phosphorylation, indicating that the mitogen-activated protein kinase pathway can attenuate in the face of sustained receptor activation. The HGF-dependent phosphorylation of a receptor substrate that is localized to clathrin-coated regions of sorting endosomes, Hrs, is dramatically reduced by lactacystin treatment. Reduction of cellular Hrs levels by short interfering RNA modestly retards Met degradation and markedly prevents the attenuation of Met phosphorylation. HGF-dependent Hrs phosphorylation and Met dephosphorylation may provide signatures for retention of the receptor in coated regions of the endosome implicated in sorting to lysosomes.

scholarly journals Zamzam water protects cancer cells from chemotherapy-induced apoptosis via mitogen-activated protein kinase-dependent pathway

2019 ◽  
Vol 118 ◽  
pp. 109376
Author(s):  
Abdul Khalid Siraj ◽  
Rafia Begum ◽  
Roxanne Melosantos ◽  
Wafaa Albalawy ◽  
Jehan Abboud ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cancer Cells ◽  
Mitogen Activated Protein Kinase ◽  
Mitogen Activated Protein ◽  
Induced Apoptosis ◽  
Dependent Pathway

scholarly journals The Mitogen-activated Protein Kinase p38 Links Shiga Toxin-dependent Signaling and Trafficking

2008 ◽  
Vol 19 (1) ◽  
pp. 95-104 ◽  
Author(s):  
Sébastien Wälchli ◽  
Sigrid S. Skånland ◽  
Tone F. Gregers ◽  
Silje U. Lauvrak ◽  
Maria L. Torgersen ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Golgi Apparatus ◽  
Shiga Toxin ◽  
Intracellular Transport ◽  
Mitogen Activated Protein Kinase ◽  
Dependent Manner ◽  
Early Endosomes ◽  
Chemical Inhibitors ◽  
Mitogen Activated Protein ◽  
Interfering Rna

Shiga toxin (Stx) binds to the cell, and it is transported via endosomes and the Golgi apparatus to the endoplasmic reticulum and cytosol, where it exerts its toxic effect. We have recently shown that Stx activates the tyrosine kinase Syk, which in turn induces clathrin phosphorylation and up-regulates Stx uptake. Here, we show that toxin-induced signaling can also regulate another step in intracellular Stx transport. We demonstrate that transport of Stx to the Golgi apparatus is dependent on the mitogen-activated protein kinase p38. Treatment of cells with chemical inhibitors or small interfering RNA targeting p38 inhibited Stx transport to the Golgi and reduced Stx toxicity. This p38 dependence is specific to Stx, because transport of the related toxin ricin was not affected by p38 inhibition. Stx rapidly activated p38, and recruited it to early endosomes in a Ca2+-dependent manner. Furthermore, agonist-induced oscillations in cytosolic Ca2+levels were inhibited upon Stx stimulation, possibly reflecting Stx-dependent local alterations in cytosolic Ca2+levels. Intracellular transport of Stx is Ca2+dependent, and we provide evidence that Stx activates a signaling cascade involving cross talk between Ca2+and p38, to regulate its trafficking to the Golgi apparatus.

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