MiRNA-181c inhibits EGFR-signaling-dependent MMP9 activation via suppressing Akt phosphorylation in glioblastoma

Epidermal growth factor (EGF) receptor (EGFR) controls many aspects of cell physiology via the activation of intracellular signaling pathways. Aberrant EGFR signaling and overexpression of EGFR is a characteristic of various cancer types. Ligandbound EGFR elicits phosphorylation of Gab1, which activates phosphatidylinositol-3-kinase (PI3K), which in turn leads to Akt phosphorylation and activation. Akt is a central regulator of cell survival and metabolism. Rapidly upon binding EGF, the receptor is recruited to clathrin-coated pits (CCPs), eventually leading to EGFR endocytosis. As such, receptor-proximal EGFR signaling occurs while the receptor is enriched with CCPs at the plasma membrane. We have recently found that clathrin, but not receptor endocytosis, is required for EGF-stimulated phosphorylation of Akt, yet how clathrin controls EGFR signaling at the plasma membrane remains poorly understood. Clathrin interacts with and recruits numerous proteins to the plasma membrane. To examine how specific clathrin-interacting proteins may underlie the requirement for clathrin in EGFR signaling, I have examined the role of TOM1L1, which interacts with clathrin, EGFR and Src-family kinases (SFKs) through distinct domains. SiRNA gene silencing of TOM1L1 impairs EGF-stimulated Akt phosphorylation, as did expression of a dominant-interfering mutant of TOM1L1 deficient in clathrin binding. Using fluorescent labeling of clathrin, TOM1L1 and other signaling intermediates coupled to total internal reflection fluorescence microscopy; I found that CCPs are enriched in TOM1L1 and phosphorylated Gab1 upon EGF stimulation. These findings indicate that the clathrin-binding adaptor TOM1L1 regulates EGF-stimulated Akt phosphorylation, thus revealing a novel molecular mechanism of regulation of EGFR signaling at the plasma membrane.

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Epidermal growth factor receptor expression and signaling are essential in glutamine's cytoprotective mechanism in heat-stressed intestinal epithelial-6 cells

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.00418.2012 ◽

2013 ◽

Vol 304 (5) ◽

pp. G543-G552 ◽

Cited By ~ 15

Author(s):

Stefanie Niederlechner ◽

Christine Baird ◽

Benjamin Petrie ◽

Erhard Wischmeyer ◽

Paul E. Wischmeyer

Keyword(s):

Small Interfering Rna ◽

Growth Factor Receptor ◽

Intestinal Epithelial ◽

Egfr Signaling ◽

Cellular Protection ◽

Akt Phosphorylation ◽

Egfr Expression ◽

Epidermal Growth ◽

Interfering Rna

Epidermal growth factor receptor (EGFR) expression and signaling can induce cellular protection after intestinal inflammation. l-Glutamine (GLN) is known to prevent apoptosis after intestinal injury by activating MAPK and phosphatidylinositol 3-kinase (PI3-K)/Akt pathways. However, the role of EGFR expression and signaling in GLN-mediated cellular protection in intestinal epithelial-6 (IEC-6) cells after heat stress (HS) is unknown. To address the role of EGFR in GLN-mediated protection, IEC-6 cells were treated with GLN in the presence or absence of EGFR small interfering RNA, the EGFR tyrosine kinase inhibitor AG1478, the ERK1/2 inhibitor PD98059, the p38MAPK inhibitor SB203580, or the PI3-K/Akt inhibitor LY294002 under basal and HS conditions. GLN-mediated cell survival was measured using 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium assay. Phosphorylated and/or total levels of EGFR, cleaved caspase-3, poly(ADP-ribose) polymerase-1, ERK1/2, p38MAPK, and Akt were assessed by Western blotting. We showed that HS induced a decrease in total, cytoplasmic, and nuclear EGFR levels in IEC-6 cells, which was prevented by GLN supplementation, leading to attenuated apoptosis via EGFR small interfering RNA. Furthermore, the protective effect of GLN was lessened by AG1478, PD98059, and LY294002 but was not affected by SB203580. AG1478 attenuated GLN-mediated increases in ERK1/2 and decreases in p38MAPK phosphorylation. However, AG1478 had no effect on GLN-mediated augmentations in Akt phosphorylation. In summary, EGFR expression was important in the protective mechanism of GLN, as well as GLN-mediated activation of EGFR tyrosine kinase activity. GLN-mediated EGFR signaling activated ERK1/2 and decreased p38MAPK signaling. However, GLN-mediated Akt phosphorylation after HS seems to be independent of EGFR signaling.

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Regulation of epidermal growth factor receptor signaling by clathrin-coated membrane microdomains

10.32920/ryerson.14668404 ◽

2021 ◽

Author(s):

Camilo Garay

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Tyrosine Kinases ◽

Egf Receptor ◽

Akt Signaling ◽

Membrane Microdomains ◽

Egfr Signaling ◽

Coated Pits ◽

Akt Phosphorylation ◽

Epidermal Growth

The phosphatidylinositol-3-kinase (PI3K)-Akt signaling axis controls cell survival, proliferation and metabolism, and is activated by receptor tyrosine kinases (RTKs) such as the epidermal growth factor (EGF) receptor (EGFR). In addition to activation of PI3K-Akt signaling, the binding of EGF to its receptor results in rapid recruitment of EGFR to clathrin-coated pits (CCPs) followed by eventual EGFR internalization. Hence, receptor-proximal activation of signaling intermediates occurs while EGFR resides within CCPs; however, whether CCPs are required for EGFR signaling remains poorly understood. Using a combination of pharmacological inhibition and siRNA gene silencing of clathrin, we have examined how clathrin controls EGF-stimulated activation of Akt. We find that perturbation of clathrin, but not of EGFR endocytosis by perturbation of dynamin leads to disruption of EGF-stimulated Akt phosphorylation. This indicates that clathrin acts in a function separate from its role in endocytosis to regulate EGFR signaling at the plasma membrane. The EGF-stimulated phosphorylation of the signaling intermediate Gab1, but not that of EGFR itself, was also abrogated upon disruption of clathrin. We then utilized total internal reflection fluorescence microscopy (TIRF-M) to examine the hierarchy of recruitment of EGFR signaling components to CCPs. Collectively, these findings suggest a role for clathrin as a central regulator of EGFR signaling leading to Gab1 and Akt phosphorylation.

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Impaired Glycolysis Promotes Alcohol Exposure-Induced Apoptosis in HEI-OC1 Cells via Inhibition of EGFR Signaling

International Journal of Molecular Sciences ◽

10.3390/ijms21020476 ◽

2020 ◽

Vol 21 (2) ◽

pp. 476 ◽

Cited By ~ 1

Author(s):

Hyunsook Kang ◽

Seong Jun Choi ◽

Kye Hoon Park ◽

Chi-Kyou Lee ◽

Jong-Seok Moon

Keyword(s):

Hearing Loss ◽

Growth Factor Receptor ◽

Alcohol Exposure ◽

Metabolic Dysfunction ◽

Egfr Signaling ◽

Akt Phosphorylation ◽

Egfr Inhibition ◽

Glycolytic Activity ◽

Epidermal Growth ◽

Induced Apoptosis

Glucose metabolism is an important metabolic pathway in the auditory system. Chronic alcohol exposure can cause metabolic dysfunction in auditory cells during hearing loss. While alcohol exposure has been linked to hearing loss, the mechanism by which impaired glycolysis promotes cytotoxicity and cell death in auditory cells remains unclear. Here, we show that the inhibition of epidermal growth factor receptor (EGFR)-induced glycolysis is a critical mechanism for alcohol exposure-induced apoptosis in HEI-OC1 cells. The cytotoxicity via apoptosis was significantly increased by alcohol exposure in HEI-OC1 cells. The glycolytic activity and the levels of hexokinase 1 (HK1) were significantly suppressed by alcohol exposure in HEI-OC1 cells. Mechanistic studies showed that the levels of EGFR and AKT phosphorylation were reduced by alcohol exposure in HEI-OC1 cells. Notably, HK1 expression and glycolytic activity was suppressed by EGFR inhibition in HEI-OC1 cells. These results suggest that impaired glycolysis promotes alcohol exposure-induced apoptosis in HEI-OC1 cells via the inhibition of EGFR signaling.

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Clathrin and TOM1L1 regulate epidermal growth factor receptor signaling at the plasma membrane

10.32920/ryerson.14644383 ◽

2021 ◽

Author(s):

Gurjeet Singh Judge

Keyword(s):

Plasma Membrane ◽

Growth Factor ◽

Epidermal Growth Factor ◽

Intracellular Signaling ◽

Fluorescent Labeling ◽

Cell Physiology ◽

Egfr Signaling ◽

Coated Pits ◽

Akt Phosphorylation ◽

Epidermal Growth

Epidermal growth factor (EGF) receptor (EGFR) controls many aspects of cell physiology via the activation of intracellular signaling pathways. Aberrant EGFR signaling and overexpression of EGFR is a characteristic of various cancer types. Ligandbound EGFR elicits phosphorylation of Gab1, which activates phosphatidylinositol-3-kinase (PI3K), which in turn leads to Akt phosphorylation and activation. Akt is a central regulator of cell survival and metabolism. Rapidly upon binding EGF, the receptor is recruited to clathrin-coated pits (CCPs), eventually leading to EGFR endocytosis. As such, receptor-proximal EGFR signaling occurs while the receptor is enriched with CCPs at the plasma membrane. We have recently found that clathrin, but not receptor endocytosis, is required for EGF-stimulated phosphorylation of Akt, yet how clathrin controls EGFR signaling at the plasma membrane remains poorly understood. Clathrin interacts with and recruits numerous proteins to the plasma membrane. To examine how specific clathrin-interacting proteins may underlie the requirement for clathrin in EGFR signaling, I have examined the role of TOM1L1, which interacts with clathrin, EGFR and Src-family kinases (SFKs) through distinct domains. SiRNA gene silencing of TOM1L1 impairs EGF-stimulated Akt phosphorylation, as did expression of a dominant-interfering mutant of TOM1L1 deficient in clathrin binding. Using fluorescent labeling of clathrin, TOM1L1 and other signaling intermediates coupled to total internal reflection fluorescence microscopy; I found that CCPs are enriched in TOM1L1 and phosphorylated Gab1 upon EGF stimulation. These findings indicate that the clathrin-binding adaptor TOM1L1 regulates EGF-stimulated Akt phosphorylation, thus revealing a novel molecular mechanism of regulation of EGFR signaling at the plasma membrane.

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Regulation of epidermal growth factor receptor signaling by clathrin-coated membrane microdomains

10.32920/ryerson.14668404.v1 ◽

2021 ◽

Author(s):

Camilo Garay

Keyword(s):

Growth Factor ◽

Epidermal Growth Factor ◽

Tyrosine Kinases ◽

Egf Receptor ◽

Akt Signaling ◽

Membrane Microdomains ◽

Egfr Signaling ◽

Coated Pits ◽

Akt Phosphorylation ◽

Epidermal Growth

The phosphatidylinositol-3-kinase (PI3K)-Akt signaling axis controls cell survival, proliferation and metabolism, and is activated by receptor tyrosine kinases (RTKs) such as the epidermal growth factor (EGF) receptor (EGFR). In addition to activation of PI3K-Akt signaling, the binding of EGF to its receptor results in rapid recruitment of EGFR to clathrin-coated pits (CCPs) followed by eventual EGFR internalization. Hence, receptor-proximal activation of signaling intermediates occurs while EGFR resides within CCPs; however, whether CCPs are required for EGFR signaling remains poorly understood. Using a combination of pharmacological inhibition and siRNA gene silencing of clathrin, we have examined how clathrin controls EGF-stimulated activation of Akt. We find that perturbation of clathrin, but not of EGFR endocytosis by perturbation of dynamin leads to disruption of EGF-stimulated Akt phosphorylation. This indicates that clathrin acts in a function separate from its role in endocytosis to regulate EGFR signaling at the plasma membrane. The EGF-stimulated phosphorylation of the signaling intermediate Gab1, but not that of EGFR itself, was also abrogated upon disruption of clathrin. We then utilized total internal reflection fluorescence microscopy (TIRF-M) to examine the hierarchy of recruitment of EGFR signaling components to CCPs. Collectively, these findings suggest a role for clathrin as a central regulator of EGFR signaling leading to Gab1 and Akt phosphorylation.

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Increased cardiac microvascular permeability and activation of cardiac endothelial nitric oxide synthase in high tidal volume ventilation-induced lung injury

Asian Biomedicine ◽

10.2478/abm-2010-0004 ◽

2010 ◽

Vol 4 (1) ◽

pp. 27-36

Author(s):

Ming-Jui Hung ◽

Ming-Yow Hung ◽

Wen-Jin Cherng ◽

Li-Fu Li

Keyword(s):

Nitric Oxide ◽

Nitric Oxide Synthase ◽

Lung Injury ◽

Tidal Volume ◽

Endothelial Nitric Oxide Synthase ◽

Microvascular Permeability ◽

Akt Phosphorylation ◽

Enos Phosphorylation ◽

Oxide Synthase ◽

Endothelial Nitric Oxide

Abstract Background: Positive pressure ventilation with large tidal volumes has been shown to cause lung injury via the serine/threonine kinase-protein kinase B (Akt) and endothelial nitric oxide synthase (eNOS)-pathways. However, the effects of high tidal volume (VT) ventilation on the heart are unclear. Objectives: Evaluate the effect of VT ventilation on the cardiac vascular permeability and intracellular Akt and eNOS signaling pathway. Methods: C57BL/6 and Akt knock-out (heterozygotes, +/−) mice were exposed to high VT (30 mL/kg) mechanical ventilation with room air for one and/or five hours. Results: High VT ventilation increased cardiac microvascular permeability and eNOS phosphorylation in a timedependent manner. Serum cardiac troponin I was increased after one hour of high VT ventilation. Cardiac Akt phosphorylation was accentuated after one hour and attenuated after five hours of high VT ventilation. Pharmacological inhibition of Akt with LY294002 and high VT ventilation of Akt+/− mice attenuated cardiac Akt phosphorylation, but not eNOS phosphorylation. Conclusion: High VT ventilation increased cardiac myocardial injury, microvascular permeability, and eNOS phosphorylation. Involvement of cardiac Akt in high VT ventilation was transient.

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