WDTC1

WDTC1 is a conserved suppressor of fat accumulation that functions as a DDB1-CUL4-ROC1 (CRL4) substrate receptor (DCAF), coupling E3 ubiquitin ligase activity to transcriptional repression of adipogenic genes. Loss of the Drosophila ortholog adp increases triglyceride storage and promotes obesity, while gain-of-function specifically reduces the fat body, establishing WDTC1 as a dose-dependent regulator of lipid homeostasis (PMID:12717455). The CRL4^WDTC1 complex promotes histone H2AK119 monoubiquitylation at adipogenic loci; disruption of the WDTC1–DDB1 interface abolishes this chromatin mark and derepresses adipogenic gene expression, leading to enhanced triglyceride accumulation in 3T3-L1 cells (PMID:27113764).

1. 2003 High

   Identification of adp/WDTC1 as a conserved anti-obesity gene resolved the question of whether a single locus could dominantly suppress fat storage in metazoans, establishing the functional framework for all subsequent mechanistic work.

   Evidence Drosophila loss-of-function mutants (increased triglyceride, extended starvation survival) and gain-of-function transgenics (fat body reduction)

   PMID:12717455

   Open questions at the time

   • Molecular mechanism of fat suppression was unknown
   • No mammalian cellular or biochemical confirmation at this stage
   • Direct target genes or pathways not identified
2. 2016 High

   Demonstration that WDTC1 acts as a DCAF within the CRL4 E3 ligase to promote H2AK119 monoubiquitylation provided the molecular mechanism linking WDTC1 to transcriptional repression of adipogenic genes, explaining its anti-adipogenic activity.

   Evidence Co-IP of WDTC1–DDB1 interaction, mutagenesis of the binding interface, 3T3-L1 adipogenesis assays with triglyceride staining, and ChIP for H2AK119ub1

   PMID:27113764

   Open questions at the time

   • The direct substrate(s) ubiquitylated by CRL4^WDTC1 beyond histone H2A remain unidentified
   • Structural basis of WDTC1–DDB1 interaction and substrate recognition not resolved
   • In vivo mammalian loss-of-function phenotype (e.g., mouse knockout) not reported

• It remains unknown how CRL4^WDTC1 is recruited to specific adipogenic gene loci, whether WDTC1 ubiquitylates non-histone substrates relevant to fat metabolism, and whether its anti-adipogenic function is conserved in vivo in mammals.
• Locus-specific recruitment mechanism unknown
• Non-histone substrates not explored
• No mammalian in vivo genetic model reported