title: Sumoylation regulates nuclear localization and function of zinc finger transcription factor ZIC3.
abstract: ZIC3, an X-linked zinc finger transcription factor, was the first identified gene involved in establishing normal left-right patterning in humans. Mutations in the Zic3 gene in patients cause heterotaxy, which includes congenital heart defects. However, very little is known about how the function of the ZIC3 protein is regulated. Sumoylation is a posttranslational modification process in which a group of small ubiquitin-like modifier (SUMO) proteins is covalently attached to targets via a series of enzymatic reactions. Here, we report for the first time that sumoylation targets human ZIC3 primarily on the consensus lysine residue K248, which is critical for the nuclear retention of ZIC3. Consequently, SUMO modification potentiates the repressive activity of ZIC3 on the promoter of its target gene cardiac α-actin, and the mutation of lysine 248 to arginine (K248R) abolishes its repressive function. We further revealed that ZIC3 variants with mutations found in human patients with congenital anomalies exhibit aberrant sumoylation activity, which at least partially accounts for their cytoplasmic diffusion. Improved sumoylation of human disease-associated ZIC3 variants reestablishes their nuclear occupancy in the presence of SUMO E3 ligase and SUMO-1. Thus, the altered sumoylation status of ZIC3 underpins the developmental abnormalities associated with these ZIC3 mutants. The SUMO targeting consensus sequence in ZIC3 is highly conserved in its paralogs and orthologs, pointing to sumoylation as a general mechanism underlying the functional control of ZIC proteins. This study provides a potential therapeutic strategy to regain the normal subcellular distribution and function of ZIC3 mutants by restoring SUMO conjugation.
authors.affiliation: The Center for Stem Cell Engineering, Texas Heart Institute, Houston, TX 77030, USA; Department of Biology and Biochemistry, University of Houston, Houston, TX 77204, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Chen
authors.affiliation: Institute of Biosciences and Technology, Texas A&M University Health Science Center, Houston, TX 77030, USA.
authors.forename: Yanlin
authors.initials: Y
authors.lastname: Ma
authors.affiliation: The Center for Stem Cell Engineering, Texas Heart Institute, Houston, TX 77030, USA.
authors.forename: Ling
authors.initials: L
authors.lastname: Qian
authors.affiliation: The Center for Stem Cell Engineering, Texas Heart Institute, Houston, TX 77030, USA. Electronic address: junwang@heart.thi.tmc.edu.
authors.forename: Jun
authors.initials: J
authors.lastname: Wang
mesh_terms: D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D000595:Amino Acid Sequence; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D006367:HeLa Cells; D018398:Homeodomain Proteins / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008239:Lysine / Q000378:metabolism; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000378:metabolism; D021381:Protein Transport / Q000187:drug effects; D025841:Small Ubiquitin-Related Modifier Proteins / Q000378:metabolism; D013347:Subcellular Fractions / Q000378:metabolism; D013379:Substrate Specificity / Q000187:drug effects; D058207:Sumoylation / Q000187:drug effects; D014157:Transcription Factors / Q000737:chemistry / Q000378:metabolism*
chemical_list: D005231:Fatty Acids, Unsaturated; D018398:Homeodomain Proteins; D050505:Mutant Proteins; D025841:Small Ubiquitin-Related Modifier Proteins; D014157:Transcription Factors; C491595:ZIC3 protein, human; D008239:Lysine; C038753:leptomycin B
keywords: Nuclear import/export; PIAS; SUMO; ZIC3