Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.

The Karyopherin superfamily comprises nuclear transport proteins, involved in the shuttling of certain cargo proteins into and out of the nucleus. Karyopherin β1 (Kpnβ1) and Karyopherin α2 (Kpnα2) are importin proteins, which work in concert to transport their cargo into the nucleus. We previously i...

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Autores principales:	Pauline J van der Watt, Ellen Ngarande, Virna D Leaner
Formato:	article
Lenguaje:	EN
Publicado:	Public Library of Science (PLoS) 2011
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/782f73de7e1240b2a9311308a8d8b738
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spelling	oai:doaj.org-article:782f73de7e1240b2a9311308a8d8b7382021-11-18T07:33:55ZOverexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.1932-620310.1371/journal.pone.0027723https://doaj.org/article/782f73de7e1240b2a9311308a8d8b7382011-01-01T00:00:00Zhttps://www.ncbi.nlm.nih.gov/pmc/articles/pmid/22125623/?tool=EBIhttps://doaj.org/toc/1932-6203The Karyopherin superfamily comprises nuclear transport proteins, involved in the shuttling of certain cargo proteins into and out of the nucleus. Karyopherin β1 (Kpnβ1) and Karyopherin α2 (Kpnα2) are importin proteins, which work in concert to transport their cargo into the nucleus. We previously identified increased expression of Kpnβ1 and Kpnα2 in cervical tumours compared to normal epithelium and in transformed cells compared to their normal counterparts. This study therefore aimed to identify the transcription regulatory mechanisms associated with high Kpnβ1 and Kpnα2 levels in cancer cells. Kpnβ1 (-2013 to +100) and Kpnα2 (-1900 to +69) promoter fragments were separately cloned into the reporter vector, pGL3-basic, and luciferase assays revealed both as significantly more active in cancer and transformed cells compared to normal. A series of deletion constructs identified the -637 to -271 Kpnβ1 and -180 to -24 Kpnα2 promoter regions as responsible for the differential promoter activity, and a number of highly conserved E2F binding sites were identified within these regions. Mutation analysis confirmed the requirement of E2F sites for promoter activity, and ChIP analysis confirmed E2F2/Dp1 binding to the Kpnβ1 and Kpnα2 promoters in vivo. Dp1 inhibition resulted in decreased levels of the respective proteins, confirming the role of E2F in the overexpression of Kpnβ1 and Kpnα2 proteins in cancer. E2F activity is known to be deregulated in cervical cancer cells due to the inhibition of its repressor, Rb, by HPV E7. The inhibition of E7 using siRNA resulted in decreased Kpnβ1 and Kpnα2 promoter activities, as did the overexpression of Rb. In conclusion, this study is a first to show that elevated Kpnβ1 and Kpnα2 expression in cancer cells correlates with altered transcriptional regulation associated with deregulated E2F/Rb activities.Pauline J van der WattEllen NgarandeVirna D LeanerPublic Library of Science (PLoS)articleMedicineRScienceQENPLoS ONE, Vol 6, Iss 11, p e27723 (2011)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q Pauline J van der Watt Ellen Ngarande Virna D Leaner Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
description	The Karyopherin superfamily comprises nuclear transport proteins, involved in the shuttling of certain cargo proteins into and out of the nucleus. Karyopherin β1 (Kpnβ1) and Karyopherin α2 (Kpnα2) are importin proteins, which work in concert to transport their cargo into the nucleus. We previously identified increased expression of Kpnβ1 and Kpnα2 in cervical tumours compared to normal epithelium and in transformed cells compared to their normal counterparts. This study therefore aimed to identify the transcription regulatory mechanisms associated with high Kpnβ1 and Kpnα2 levels in cancer cells. Kpnβ1 (-2013 to +100) and Kpnα2 (-1900 to +69) promoter fragments were separately cloned into the reporter vector, pGL3-basic, and luciferase assays revealed both as significantly more active in cancer and transformed cells compared to normal. A series of deletion constructs identified the -637 to -271 Kpnβ1 and -180 to -24 Kpnα2 promoter regions as responsible for the differential promoter activity, and a number of highly conserved E2F binding sites were identified within these regions. Mutation analysis confirmed the requirement of E2F sites for promoter activity, and ChIP analysis confirmed E2F2/Dp1 binding to the Kpnβ1 and Kpnα2 promoters in vivo. Dp1 inhibition resulted in decreased levels of the respective proteins, confirming the role of E2F in the overexpression of Kpnβ1 and Kpnα2 proteins in cancer. E2F activity is known to be deregulated in cervical cancer cells due to the inhibition of its repressor, Rb, by HPV E7. The inhibition of E7 using siRNA resulted in decreased Kpnβ1 and Kpnα2 promoter activities, as did the overexpression of Rb. In conclusion, this study is a first to show that elevated Kpnβ1 and Kpnα2 expression in cancer cells correlates with altered transcriptional regulation associated with deregulated E2F/Rb activities.
format	article
author	Pauline J van der Watt Ellen Ngarande Virna D Leaner
author_facet	Pauline J van der Watt Ellen Ngarande Virna D Leaner
author_sort	Pauline J van der Watt
title	Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
title_short	Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
title_full	Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
title_fullStr	Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
title_full_unstemmed	Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.
title_sort	overexpression of kpnβ1 and kpnα2 importin proteins in cancer derives from deregulated e2f activity.
publisher	Public Library of Science (PLoS)
publishDate	2011
url	https://doaj.org/article/782f73de7e1240b2a9311308a8d8b738
work_keys_str_mv	AT paulinejvanderwatt overexpressionofkpnb1andkpna2importinproteinsincancerderivesfromderegulatede2factivity AT ellenngarande overexpressionofkpnb1andkpna2importinproteinsincancerderivesfromderegulatede2factivity AT virnadleaner overexpressionofkpnb1andkpna2importinproteinsincancerderivesfromderegulatede2factivity
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Overexpression of Kpnβ1 and Kpnα2 importin proteins in cancer derives from deregulated E2F activity.

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