title: Human spot 14 protein interacts physically and functionally with the thyroid receptor.
abstract: Spot 14 (S14) is a small acidic protein with no sequence similarity to other mammalian gene products. Its biochemical function is elusive. Recent studies have shown that, in some cancers, human S14 (hS14) localizes to the nucleus and is amplified, suggesting that it plays a role in the regulation of lipogenic enzymes during tumorigenesis. In this study, we purified untagged hS14 protein and then demonstrated, using various biochemical methods, including analytic ultracentrifugation, that hS14 might form a homodimer. We also found several lines of evidence to suggest physical and functional interactions between hS14 and the thyroid hormone receptor (TR). The ubiquitous expression of hS14 in various cell lines and its cell-type-dependent functions demonstrated in this study suggest that it acts as a positive or negative cofactor of the TR to regulate malic enzyme gene expression. These findings provide a molecular rationale for the role of hS14 in TR-dependent transcriptional activation of the expression of specific genes.
authors.affiliation: Department of Biochemistry, National Defense Medical Center, Taipei 114, Taiwan, ROC.
authors.forename: Wei-Yuan
authors.initials: WY
authors.lastname: Chou
authors.forename: Yi-Shan
authors.initials: YS
authors.lastname: Cheng
authors.forename: Ching-Liang
authors.initials: CL
authors.lastname: Ho
authors.forename: Shu-Ting
authors.initials: ST
authors.lastname: Liu
authors.forename: Pei-Yao
authors.initials: PY
authors.lastname: Liu
authors.forename: Chen-Chin
authors.initials: CC
authors.lastname: Kuo
authors.forename: Hui-Ping
authors.initials: HP
authors.lastname: Chang
authors.forename: Yu-Hou
authors.initials: YH
authors.lastname: Chen
authors.forename: Gu-Gang
authors.initials: GG
authors.lastname: Chang
authors.forename: Shih-Ming
authors.initials: SM
authors.lastname: Huang
mesh_terms: D002460:Cell Line; D006801:Humans; D008291:Malate Dehydrogenase / Q000378:metabolism*; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D025941:Protein Interaction Mapping; D011988:Receptors, Thyroid Hormone / Q000737:chemistry* / Q000378:metabolism*; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D009687:Nuclear Proteins; D011988:Receptors, Thyroid Hormone; C051065:THRSP protein, human; D014157:Transcription Factors; D008291:Malate Dehydrogenase; C495394:malic enzyme 2; human