ZFP30 promotes adipogenesis through the KAP1-mediated activation of a retrotransposon-derived Pparg2 enhancer

Wanze Chen,Michael Imbeault,Bart Deplancke,Tenagne Delessa,Marco Cassano,Eugenia V Pankevich,Petra C Schwalie,Suk Min Jang,Didier Trono,Carine Gubelmann,Sunil K Raghav,Julie Russeil,Christian Wolfrum,Riccardo Dainese,Julien Duc

doi:10.1038/s41467-019-09803-9

Abstract

Krüppel-associated box zinc finger proteins (KZFPs) constitute the largest family of mammalian transcription factors, but most remain completely uncharacterized. While initially proposed to primarily repress transposable elements, recent reports have revealed that KFZPs contribute to a wide variety of other biological processes. Using murine and human in vitro and in vivo models, we demonstrate here that one poorly studied KZFP, ZFP30, promotes adipogenesis by directly targeting and activating a retrotransposon-derived Pparg2 enhancer. Through mechanistic studies, we further show that ZFP30 recruits the co-regulator KRAB-associated protein 1 (KAP1), which, surprisingly, acts as a ZFP30 co-activator in this adipogenic context. Our findings provide an understanding of both adipogenic and KZFP-KAP1 complex-mediated gene regulation, showing that the KZFP-KAP1 axis can also function in a non-repressive manner.

Highlights

Krüppel-associated box zinc finger proteins (KZFPs) constitute the largest family of mammalian transcription factors, but most remain completely uncharacterized
Given that the core white and brown adipogenic differentiation programs are largely shared[32], we isolated a clonal subline from an immortalized murine-derived brown pre-adipocyte cell line (IBA)[33]. We found that these subcloned IBA cells constitute a suitable model alternative to 3T3-L1 cells given that they (i) do not express the brown adipocyte marker gene uncoupling protein 1 (Ucp1) when differentiated (Supplementary Fig. 1B), (ii) accumulate large amounts of lipids when induced with the adipogenic induction cocktail MDI (3-isobutyl-1-methylxanthine, dexamethasone, and insulin), and (iii) maintain a high differentiation potential even after long-term culture
Our study reveals that the poorly characterized KZFP ZFP3056,57 is important for adipogenesis across different mouse pre-adipocyte cell lines, an in vivo mouse model and ex vivo human cells, firmly establishing it as a pro-adipogenic transcription factor (TF)

Summary

Introduction

Krüppel-associated box zinc finger proteins (KZFPs) constitute the largest family of mammalian transcription factors, but most remain completely uncharacterized. Using murine and human in vitro and in vivo models, we demonstrate here that one poorly studied KZFP, ZFP30, promotes adipogenesis by directly targeting and activating a retrotransposon-derived Pparg[2] enhancer. We have recently uncovered one poorly studied KZFP, ZFP30, as a top hit in a large-scale TF overexpression screen aimed at identifying novel pro-adipogenic regulators[20] This finding suggests that ZFP30 may be a far unrecognized component of the adipogenic regulatory network. The principal network components are the TFs C/EBPβ and C/EBPδ that activate the expression of the adipogenic master regulators C/EBPα and PPARγ22,23 The latter TF, which is present as two isoforms (PPARγ1 and PPARγ2) with only PPARγ2 being restricted to adipose tissue[24], is both necessary and sufficient for adipogenesis since it directly regulates the majority of adipocytespecific genes[25]. Our results provide a functional characterization of the KZFP ZFP30, revealing its target landscape, DNA-binding specificity, detailed mode of action at the Pparg[2] locus in the context of adipogenesis, and evolutionary relation with specific retrotransposons

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