scholarly journals The Molecular Biology of Vestibular Schwannomas and Its Association with Hearing Loss: A Review

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Erika Celis-Aguilar ◽  
Luis Lassaletta ◽  
Miguel Torres-Martín ◽  
F. Yuri Rodrigues ◽  
Manuel Nistal ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Growth Factor ◽  
Molecular Biology ◽  
Cyclin D1 ◽  
Vestibular Schwannoma ◽  
Molecular Mechanisms ◽  
Platelet Derived Growth Factor ◽  
Common Symptom ◽  
The Past ◽  
New Evidence

Hearing loss is the most common symptom in patients with vestibular schwannoma (VS). In the past, compressive mechanisms caused by the tumoral mass and its growth have been regarded as the most likely causes of the hearing loss associated with VS. Interestingly, new evidence proposes molecular mechanisms as an explanation for such hearing loss. Among the molecular mechanisms proposed are methylation of TP73, negative expression of cyclin D1, expression of B7-H1, increased expression of the platelet-derived growth factor A, underexpression of PEX5L, RAD54B, and PSMAL, and overexpression of CEA. Many molecular mechanisms are involved in vestibular schwannoma development; we review some of these mechanisms with special emphasis on hearing loss associated with vestibular schwannoma.

Cellular crosstalk mediated by platelet-derived growth factor BB and transforming growth factor β during hepatic injury activates hepatic stellate cells

2018 ◽  
Vol 96 (8) ◽  
pp. 728-741 ◽  
Author(s):  
Sowmya Mekala ◽  
SubbaRao V. Tulimilli ◽  
Ramasatyaveni Geesala ◽  
Kanakaraju Manupati ◽  
Neha R. Dhoke ◽  
...  
Keyword(s):  
Growth Factor ◽  
Hepatic Stellate Cells ◽  
Hepg2 Cells ◽  
Molecular Mechanisms ◽  
Transforming Growth Factor ◽  
Stellate Cells ◽  
Transforming Growth Factor Β ◽  
Platelet Derived Growth Factor ◽  
Hepatic Tissue

Apoptotic hepatocytes release factors that activate hepatic stellate cells (HSCs), thereby inducing hepatic fibrosis. In the present study, in vivo and in vitro injury models were established using acetaminophen, ethanol, carbon tetrachloride, or thioacetamide. Histology of hepatotoxicant-induced diseased hepatic tissue correlated with differential expression of fibrosis-related genes. A marked increase in co-staining of transforming growth factor β receptor type II (TGFRIIβ) – desmin or α-smooth muscle actin – platelet-derived growth factor receptor β (PDGFRβ), markers of activated HSCs, in liver sections of these hepatotoxicant-treated mice also depicted an increase in Annexin V – cytokeratin expressing hepatocytes. To understand the molecular mechanisms of disease pathology, in vitro experiments were designed using the conditioned medium (CM) of hepatotoxicant-treated HepG2 cells supplemented to HSCs. A significant increase in HSC proliferation, migration, and expression of fibrosis-related genes and protein was observed, thereby suggesting the characteristics of an activated phenotype. Treating HepG2 cells with hepatotoxicants resulted in a significant increase in mRNA expression of platelet-derived growth factor BB (PDGF-BB) and transforming growth factor β (TGFβ). CM supplemented to HSCs resulted in increased phosphorylation of PDGFRβ and TGFRIIβ along with its downstream effectors, extracellular signal-related kinase 1/2 and focal adhesion kinase. Neutralizing antibodies against PDGF-BB and TGFβ effectively perturbed the hepatotoxicant-treated HepG2 cell CM-induced activation of HSCs. This study suggests PDGF-BB and TGFβ as potential molecular targets for developing anti-fibrotic therapeutics.

p38 MAP kinase negatively regulates cyclin D1 expression in airway smooth muscle cells

2001 ◽  
Vol 280 (5) ◽  
pp. L955-L964 ◽  
Author(s):  
Kristen Page ◽  
Jing Li ◽  
Marc B. Hershenson
Keyword(s):  
Growth Factor ◽  
Map Kinase ◽  
Cyclin D1 ◽  
Growth Regulation ◽  
P38 Map Kinase ◽  
Dominant Negative ◽  
Platelet Derived Growth Factor ◽  
Airway Smooth Muscle Cells ◽  
Erk Activation ◽  
Erk Phosphorylation

We have demonstrated that platelet-derived growth factor (PDGF) stimulates p38 mitogen-activated protein (MAP) kinase activation in bovine tracheal myocytes, suggesting that p38 is involved in growth regulation. We therefore examined whether p38 regulates expression of cyclin D1, a G1 cyclin required for cell cycle traversal. The chemical p38 inhibitors SB-202190 and SB-203580 each increased basal and PDGF-induced cyclin D1 promoter activity and protein abundance. Overexpression of a dominant negative allele of MAP kinase kinase-3 (MKK3), an upstream activator of p38α, had similar effects. Conversely, active MKK3 and MKK6, both of which increase p38α activity, each decreased transcription from the cyclin D1 promoter. Together, these data demonstrate that p38 negatively regulates cyclin D1 expression. We tested whether p38 regulates cyclin D1 expression via inhibition of extracellular signal-regulated kinase (ERK) activation. Chemical inhibitors of p38 induced modest ERK phosphorylation and activation. However, dominant negative MKK3 was insufficient to activate ERK, and active MKK3 and MKK6 did not attenuate platelet-derived growth factor-mediated ERK activation. These data are consistent with the notion that p38α negatively regulates cyclin D1 expression via an ERK-independent pathway.

Interaction of EGFR and IGF-1R signals to modulate the anti-proliferative and biochemical responses of head and neck squamous cancer (HNSCC) cells to EGFR inhibitors

2007 ◽  
Vol 25 (18_suppl) ◽  
pp. 6045-6045 ◽  
Author(s):  
C. Y. Thomas ◽  
M. Jameson ◽  
A. Beckler
Keyword(s):  
Cell Cycle ◽  
Growth Factor ◽  
Cyclin D1 ◽  
Molecular Mechanisms ◽  
Egfr Inhibitors ◽  
Secondary Source ◽  
Growth Factor Signaling ◽  
Egfr Inhibition ◽  
Biochemical Responses ◽  
Rb Phosphorylation

6045 Background: Epidermal growth factor receptor (EGFR) inhibitors improve the efficacy of radiotherapy for HNSCC and as single-agents induce tumor responses or stabilization in a minority of patients. The molecular mechanisms that dictate the spectrum of observed responses are not well understood. Methods/Results: Exposure of the HNSCC lines SCC-9 and SCC-25 in vitro to the EGFR inhibitors PD158780, lapitinib, or cetuximab suppressed cell proliferation and cell cycle progression into S-phase. Immunoblots showed that PD158780 inhibited autocrine activation of the EGFR, reduced phosphorylation of the downstream signaling proteins AKT and Erk, and affected cell cycle regulatory molecules (reduced Rb phosphorylation, decreased cyclin D1 levels, and induced p27kip1). However, stimulation of the cells with an insulin-like growth factor-1 (IGF-1) analog produced a dose-dependent resistance to the anti-proliferative effects of the EGFR inhibitors. The resistance of SCC-25 cells correlated with IGF-1-induced maintenance of AKT and Rb phosphorylation and cyclin D1 expression. Conversely, the EGFRs also acted downstream of the activated IGF-1 receptors as concomitant EGFR inhibition dampened the proliferative response of the cells, reduced Erk phosphorylation and increased p27kip1 expression. Experiments with the metalloproteinase inhibitor TAPI-2 suggested that the IGF-1 activates the EGFRs through proteolytic cleavage of precursor forms of EGFR ligands. Conclusions: The proliferative and biochemical responses of HNSCC cells to EGFR inhibitors are influenced by cross-talk between the EGFR and IGF-1 receptors. One implication of this work is that the clinical response of HNSCCs to EGFR inhibitors may depend on the relative contribution of autocrine EGFR signaling to activation of specific downstream growth factor signaling pathways, whether or not these receptors are the primary or secondary source of these signals. No significant financial relationships to disclose.

scholarly journals Pentoxifylline Inhibits Platelet-Derived Growth Factor-Stimulated Cyclin D1 Expression in Mesangial Cells by Blocking Akt Membrane Translocation

2003 ◽  
Vol 64 (4) ◽  
pp. 811-822 ◽  
Author(s):  
Shuei-Liong Lin ◽  
Ruey-Hwa Chen ◽  
Yung-Ming Chen ◽  
Wen-Chih Chiang ◽  
Tun-Jun Tsai ◽  
...  
Keyword(s):  
Growth Factor ◽  
Cyclin D1 ◽  
Mesangial Cells ◽  
Platelet Derived Growth Factor ◽  
Membrane Translocation

Inducible platelet-derived growth factor D-chain expression by angiotensin II and hydrogen peroxide involves transcriptional regulation by Ets-1 and Sp1

Blood ◽  
2006 ◽  
Vol 107 (6) ◽  
pp. 2322-2329 ◽  
Author(s):  
Mary Yanxia Liu ◽  
Melanie Eyries ◽  
Chunyan Zhang ◽  
Fernando S. Santiago ◽  
Levon M. Khachigian
Keyword(s):  
Angiotensin Ii ◽  
Growth Factor ◽  
Mrna Expression ◽  
Molecular Mechanisms ◽  
Transcriptional Start Site ◽  
Cell Types ◽  
Platelet Derived Growth Factor ◽  
Dna Binding Domain ◽  
Start Site ◽  
Extension Analysis

AbstractPlatelet-derived growth factor D-chain (PDGF-D) is the newest member of the PDGF family of mitogens and chemoattractants expressed in a wide variety of cell types, including vascular smooth muscle cells (SMCs). The molecular mechanisms regulating PDGF-D transcription are not known. Primer extension analysis mapped a single transcriptional start site to the ccAGCGC motif with several potential Ets motifs located upstream. Ets-1, but not Ets-1 bearing only the DNA-binding domain, activates the PDGF-D promoter and mRNA expression in SMCs. Ets site D3 (–470GGAT–467) is singly required for basal and Ets-1–inducible PDGF-D promoter-dependent expression. D3 supports the interaction of endogenous and recombinant Ets-1 and Sp1. Sp1, like Ets-1, induces PDGF-D transcription and mRNA expression, which is blocked by mutant Ets-1. H2O2 stimulates Ets-1, but not Sp1, and activates D3-dependent PDGF-D transcription. Ets-1 and Sp1 siRNA block peroxide-inducible PDGF-D expression. Angiotensin II (ATII) induction of PDGF-D and Ets-1 was blocked by prior incubation of the cells with PEG-catalase, but not BSA, indicating that ATII-inducible Ets-1 and PDGF-D expression is mediated via H2O2. Thus, 2 separate trans-acting factors regulate PDGF-D transcription, alone and in response to oxidative stress.

Distinct functional classes of PDGFRB pathogenic variants in primary familial brain calcification

2021 ◽  
Author(s):  
Sandrine Lenglez ◽  
Ariane Sablon ◽  
Gilles Fénelon ◽  
Anne Boland ◽  
Jean-François Deleuze ◽  
...  
Keyword(s):  
Growth Factor ◽  
Molecular Mechanisms ◽  
Residual Activity ◽  
Receptor Expression ◽  
Platelet Derived Growth Factor ◽  
Incomplete Penetrance ◽  
Loss Of Function ◽  
Primary Familial Brain Calcification ◽  
Brain Calcification ◽  
The Impact

Abstract Platelet-derived growth factor receptor beta (PDGFRB) is one of the genes associated with primary familial brain calcification (PFBC), an inherited neurological disease (OMIM:173410). Genetic analysis of patients and families revealed at least 13 PDGFRB heterozygous missense variants, including two novel ones described in the present report. Limited experimental data published on five of these variants had suggested that they decrease the receptor activity. No functional information was available on the impact of variants located within the receptor extracellular domains. Here, we performed a comprehensive molecular analysis of PDGFRB variants linked to PFBC. Mutated receptors were transfected in various cell lines to monitor receptor expression, signaling, mitogenic activity, and ligand binding. Four mutants caused a complete loss of tyrosine kinase activity in multiple assays. One of the novel variants, p.Pro154Ser, decreased the receptor expression and abolished binding of platelet-derived growth factor (PDGF-BB). Others showed a partial loss of function related to reduced expression or signaling. Combining clinical, genetic and molecular data, we consider nine variants as pathogenic or likely pathogenic, three as benign or likely benign and one as a variant of unknown significance. We discuss the possible relationship between the variant residual activity, incomplete penetrance, brain calcification and neurological symptoms. In conclusion, we identified distinct molecular mechanisms whereby PDGFRB variants may result in a receptor loss of function. This work will facilitate genetic counselling in PFBC.

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