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Basic Characteristics of Mutations
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Mutation Site
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H73E |
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Mutation Site Sentence
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Attenuation of phosphorylated AKT (pAKT) by E7 was independent of the Rb degradation function of E7 but could be ablated by a missense mutation in the E7 carboxy terminus, H73E, thereby defining a novel structure-function phenotype for E7. |
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Mutation Level
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Amino acid level |
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Mutation Type
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Nonsynonymous substitution |
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Gene/Protein/Region
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E7 |
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Standardized Encoding Gene
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E7
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Genotype/Subtype
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HPV16 |
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Viral Reference
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-
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Functional Impact and Mechanisms
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Disease
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Uterine Cervical Neoplasms
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Immune
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- |
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Target Gene
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-
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Clinical and Epidemiological Correlations
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Clinical Information
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- |
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Treatment
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- |
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Location
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- |
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Literature Information
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PMID
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27030265
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Title
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The Human Papillomavirus 16 E7 Oncoprotein Attenuates AKT Signaling To Promote Internal Ribosome Entry Site-Dependent Translation and Expression of c-MYC
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Author
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Strickland SW,Vande Pol S
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Journal
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Journal of virology
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Journal Info
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2016 May 27;90(12):5611-5621
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Abstract
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While the role of high-risk human papillomavirus (HPV) oncoproteins E6 and E7 in targeting p53 and retinoblastoma (Rb) has been intensively studied, how E6 and E7 manipulate cellular signaling cascades to promote the viral life cycle and cancer development is less understood. Keratinocytes containing the episomal HPV-16 genome had decreased activation of AKT, which was phenocopied by HPV-16 E7 expression alone. Attenuation of phosphorylated AKT (pAKT) by E7 was independent of the Rb degradation function of E7 but could be ablated by a missense mutation in the E7 carboxy terminus, H73E, thereby defining a novel structure-function phenotype for E7. Downstream of AKT, reduced phosphorylation of p70 S6K and 4E-BP1 was also observed in E7-expressing keratinocytes, which coincided with an increase in internal ribosomal entry site (IRES)-dependent translation that enhanced the expression of several cellular proteins, including MYC, Bax, and the insulin receptor. The decrease in pAKT mediated by E7 is in contrast to the widely observed increase of pAKT in invasive cervical cancers, suggesting that the activation of AKT signaling could be acquired during the progression from initial productive infections to invasive carcinomas. IMPORTANCE: HPV causes invasive cervical cancers through the dysregulation of the cell cycle regulators p53 and Rb, which are degraded by the viral oncoproteins E6 and E7, respectively. Signaling cascades contribute to cancer progression and cellular differentiation, and how E6 and E7 manipulate those pathways remains unclear. The phosphoinositol 3-kinase (PI3K)/AKT pathway regulates cellular processes, including proliferation, cell survival, and cell differentiation. Surprisingly, we found that HPV-16 decreased the phosphorylation of AKT (pAKT) and that this is a function of E7 that is independent of the Rb degradation function. This is in contrast to the observed increase in AKT signaling in nearly 80% of cervical cancers, which typically show an acquired mutation within the PI3K/AKT cascade leading to constitutive activation of the pathway. Our observations suggest that multiple changes in the activation and effects of AKT signaling occur in the progression from productive HPV infections to invasive cervical cancers.
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Sequence Data
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-
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