title: APOBEC3 proteins inhibit human LINE-1 retrotransposition.
abstract: The human cytidine deaminase family APOBEC3 represents a novel group of proteins in the field of innate defense mechanisms that has been shown to be active against a variety of retroviruses. Here we examined whether members of the APO-BEC3 family have an impact on retrotransposition of human long interspersed nuclear elements (LINE-1s or L1s). Using a retrotransposition reporter assay in HeLa cells, we demonstrate that in the presence of transiently transfected APOBEC3A, L1 retrotransposition frequency was reduced by up to 85%. Although APOBEC3G and -3H did not influence L1 retrotransposition notably, expression of APOBEC3B, -3C, and -3F inhibited transposition by approximately 75%. Although reverse transcription of L1s occurs in the nucleus and APOBEC3 proteins are believed to act via DNA deamination during reverse transcription, activity against L1 retrotransposition was not correlated with nuclear localization of APOBEC3s. We demonstrate that APOBEC3C and APOBEC3B were endogenously expressed in HeLa cells. Accordingly, down-regulation of APOBEC3C by RNA interference enhanced L1 retrotransposition by approximately 78%. Sequence analyses of de novo L1 retrotransposition events that occurred in the presence of overexpressed APOBEC3 proteins as well as the analyses of pre-existing endogenous L1 elements did not reveal an enhanced rate of G-to-A transitions, pointing to a mechanism independent of DNA deamination. This study presents evidence for a role of host-encoded APOBEC3 proteins in the regulation of L1 retrotransposition.
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Heide
authors.initials: H
authors.lastname: Muckenfuss
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Hamdorf
authors.affiliation: Section Pr2/Retroelements, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Ulrike
authors.initials: U
authors.lastname: Held
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Perković
authors.affiliation: Section Pr2/Retroelements, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Löwer
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Cichutek
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany.
authors.forename: Egbert
authors.initials: E
authors.lastname: Flory
authors.affiliation: Section Pr2/Retroelements, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany. Electronic address: schgr@pei.de.
authors.forename: Gerald G
authors.initials: GG
authors.lastname: Schumann
authors.affiliation: Division of Medical Biotechnology, Paul-Ehrlich-Institut, Paul-Ehrlich-Strasse 51-59, D-63225 Langen, Germany. Electronic address: mueca@pei.de.
authors.forename: Carsten
authors.initials: C
authors.lastname: Münk
mesh_terms: D000071478:APOBEC Deaminases; D002467:Cell Nucleus; D003564:Cytidine Deaminase / Q000502:physiology; D043525:Cytosine Deaminase / Q000235:genetics / Q000502:physiology*; D006367:HeLa Cells; D006801:Humans; D007700:Kinetics; D020084:Long Interspersed Nucleotide Elements; D015778:Minor Histocompatibility Antigens; D020125:Mutation, Missense; D034741:RNA, Small Interfering / Q000494:pharmacology; D048348:Reverse Transcription; D014162:Transfection
chemical_list: D015778:Minor Histocompatibility Antigens; D034741:RNA, Small Interfering; D043525:Cytosine Deaminase; D000071478:APOBEC Deaminases; C502889:APOBEC3 proteins, human; C495794:APOBEC3B protein, human; D003564:Cytidine Deaminase