Human stanniocalcin-1 interacts with nuclear and cytoplasmic proteins and acts as a SUMO E3 ligase.
Human stanniocalcin-1 (STC1) is a glycoprotein that has been implicated in different physiological process, including angiogenesis, apoptosis and carcinogenesis. Here we identified STC1 as a putative molecular marker for the leukemic bone marrow microenvironment and identified new interacting protein partners for STC1. Seven selected interactions retrieved from yeast two-hybrid screens were confirmed by GST-pull down assays in vitro. The N-terminal region was mapped to be the region that mediates the interaction with cytoplasmic, mitochondrial and nuclear proteins. STC1 interacts with SUMO-1 and several proteins that have been shown to be SUMOylated and localized to SUMOylation related nuclear bodies. Although STC1 interacts with SUMO-1 and has a high theoretical prediction score for a SUMOylation site, endogenous co-immunoprecipitation and in vitro SUMOylation assays with the purified recombinant protein could not detect STC1 SUMOylation. However, when we tested STC1 for SUMO E3 ligase activity, we found in an in vitro assay, that it significantly increases the SUMOylation of two other proteins. Confocal microscopic subcellular localization studies using both transfected cells and specific antibodies for endogenous STC1 revealed a cytoplasmic and nuclear deposition, the latter in the form of some specific dot-like substructure resembling SUMOylation related nuclear bodies. Together, these findings suggest a new role for STC1 in SUMOylation pathways, in nuclear bodies.
Laboratório Nacional de Biociências, Centro Nacional de Pesquisa em Energia e Materiais, Rua Giuseppe Máximo Scolfaro 10.000, CP6192, 13084-971 Campinas, SP, Brasil. marcost.santos@lnbio.org.br
Marcos Tadeu
MT
dos Santos
Daniel Maragno
DM
Trindade
Kaliandra de Almeida
Kde A
Gonçalves
Gustavo Costa
GC
Bressan
Filipe
F
Anastassopoulos
José Andres
JA
Yunes
Jörg
J
Kobarg
D003593:Cytoplasm / Q000378:metabolism*; D006023:Glycoproteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D047468:Immunoprecipitation; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D011485:Protein Binding; D025941:Protein Interaction Mapping / Q000379:methods*; D025842:SUMO-1 Protein / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D014407:Tumor Cells, Cultured; D020798:Two-Hybrid System Techniques; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*
D006023:Glycoproteins; D009687:Nuclear Proteins; D025842:SUMO-1 Protein; C051795:teleocalcin; D044767:Ubiquitin-Protein Ligases