The adipogenic transcriptional cofactor ZNF638 interacts with splicing regulators and influences alternative splicing

• Published in: Journal of lipid research Vol. 55; no. 9; pp. 1886 - 1896
• Main Authors: Du, Chen, Ma, Xinran, Meruvu, Sunitha, Hugendubler, Lynne, Mueller, Elisabetta
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.09.2014; The American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: 3T3-L1 Cells; Active Transport, Cell Nucleus; adipocyte differentiation; Adipogenesis; Alternative Splicing; Animals; Cell Line, Tumor; DNA-Binding Proteins; HEK293 Cells; Humans; Mice; minigene reporter; nuclear speckles; Protein Isoforms - genetics; Protein Isoforms - metabolism; Protein Structure, Tertiary; RNA Precursors - genetics; RNA Precursors - metabolism; RNA-Binding Proteins; Transcription Factors - physiology; transcriptional coactivator; minigene reporter; transcriptional coactivator; nuclear speckles; adipocyte differentiation
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M047555

Increasing evidence indicates that transcription and alternative splicing are coordinated processes; however, our knowledge of specific factors implicated in both functions during the process of adipocyte differentiation is limited. We have previously demonstrated that the zinc finger protein ZNF638 plays a role as a transcriptional coregulator of adipocyte differentiation via induction of PPARγ in cooperation with CCAAT/enhancer binding proteins (C/EBPs). Here we provide new evidence that ZNF638 is localized in nuclear bodies enriched with splicing factors, and through biochemical purification of ZNF638's interacting proteins in adipocytes and mass spectrometry analysis, we show that ZNF638 interacts with splicing regulators. Functional analysis of the effects of ectopic ZNF638 expression on a minigene reporter demonstrated that ZNF638 is sufficient to promote alternative splicing, a function enhanced through its recruitment to the minigene promoter at C/EBP responsive elements via C/EBP proteins. Structure-function analysis revealed that the arginine/serine-rich motif and the C-terminal zinc finger domain required for speckle localization are necessary for the adipocyte differentiation function of ZNF638 and for the regulation of the levels of alternatively spliced isoforms of lipin1 and nuclear receptor co-repressor 1. Overall, our data demonstrate that ZNF638 participates in splicing decisions and that it may control adipogenesis through regulation of the relative amounts of differentiation-specific isoforms.