Identification of a new site of sumoylation on Tel (ETV6) uncovers a PIAS-dependent mode of regulating Tel function.
Cell proliferation and differentiation are governed by a finely controlled balance between repression and activation of gene expression. The vertebrate Ets transcriptional repressor Tel (ETV6) and its invertebrate orthologue Yan, play pivotal roles in cell fate determination although the precise mechanisms by which repression of gene expression by these factors is achieved are not clearly defined. Here, we report the identification and characterization of the primary site of sumoylation of Tel, lysine 11 (K11), which is highly conserved in vertebrates (except Danio rerio). We demonstrate that in cells PIAS3 binds to Tel and stimulates sumoylation of K11 in the nucleus. Both Tel monomers and oligomers are efficiently sumoylated on K11 in vitro; but in cells only Tel oligomers are found conjugated with SUMO, whereas sumoylation of Tel monomers is transitory and appears to sensitize them for proteasomal degradation. Mechanistically, sumoylation of K11 inhibits repression of gene expression by full-length Tel. In accordance with this observation, we found that sumoylation impedes Tel association with DNA. By contrast, a Tel isoform lacking K11 (TelM43) is strongly repressive. This isoform results from translation from an alternative initiation codon (M43) that is common to all Tel proteins that also contain the K11 sumoylation consensus site. We find that PIAS3 may have a dual, context-dependent influence on Tel; it mediates Tel sumoylation, but it also augments Tel's repressive function in a sumoylation-independent fashion. Our data support a model that suggests that PIAS-mediated sumoylation of K11 and the emergence of TelM43 in early vertebrates are linked and that this serves to refine spatiotemporal control of gene expression by Tel by establishing a pool of Tel molecules that are available either to be recycled to reinforce repression of gene expression or are degraded in a regulated fashion.
Roukens
M Guy
MG
Signaling and Transcription Laboratory, Department of Molecular Cell Biology, Leiden University Medical Center, Einthovenweg 20, P.O. Box 9600, 2300 RC Leiden, The Netherlands.
Alloul-Ramdhani
Mariam
M
Vertegaal
Alfred C O
AC
Anvarian
Zeinab
Z
Balog
Crina I A
CI
Deelder
André M
AM
Hensbergen
Paul J
PJ
Baker
David A
DA
D000595:Amino Acid Sequence; D000818:Animals; D001704:Biopolymers; D001859:Bone Neoplasms / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor / Q000378:metabolism; D017124:Conserved Sequence; D006801:Humans; D008239:Lysine / Q000737:chemistry; D018832:Molecular Chaperones / Q000502:physiology*; D008969:Molecular Sequence Data; D012516:Osteosarcoma / Q000378:metabolism / Q000473:pathology; D050828:Protein Inhibitors of Activated STAT / Q000502:physiology*; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D050783:Proto-Oncogene Proteins c-ets / Q000737:chemistry* / Q000502:physiology; D012097:Repressor Proteins / Q000737:chemistry* / Q000502:physiology; D025842:SUMO-1 Protein / Q000378:metabolism*; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D014714:Vertebrates / Q000235:genetics / Q000378:metabolism; D000097764:ETS Translocation Variant 6 Protein
D001704:Biopolymers; D008239:Lysine; D018832:Molecular Chaperones; D050828:Protein Inhibitors of Activated STAT; D050783:Proto-Oncogene Proteins c-ets; D012097:Repressor Proteins; D025842:SUMO-1 Protein; D025841:Small Ubiquitin-Related Modifier Proteins; D000097764:ETS Translocation Variant 6 Protein; C484745:PIAS3 protein, human; C117909:SUMO2 protein, human