101. Fem1b promotes ubiquitylation and suppresses transcriptional activity of Gli1.
- Author
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Gilder AS, Chen YB, Jackson RJ 3rd, Jiang J, and Maher JF
- Subjects
- Animals, Caenorhabditis elegans metabolism, Caenorhabditis elegans Proteins genetics, Caenorhabditis elegans Proteins metabolism, Carrier Proteins genetics, Cell Cycle Proteins genetics, DNA-Binding Proteins metabolism, HEK293 Cells, Humans, Immunoprecipitation, Kruppel-Like Transcription Factors genetics, Kruppel-Like Transcription Factors metabolism, Mice, NIH 3T3 Cells, Neoplasms metabolism, Transcription Factors genetics, Ubiquitin-Protein Ligase Complexes, Zinc Finger Protein GLI1, Carrier Proteins metabolism, Cell Cycle Proteins metabolism, Transcription Factors metabolism, Transcription, Genetic, Ubiquitination
- Abstract
The mammalian Fem1b gene encodes a homolog of FEM-1, a protein in the sex-determination pathway of the nematode Caenorhabditis elegans. Fem1b and FEM-1 proteins each contain a VHL-box motif that mediates their interaction with certain E3 ubiquitin ligase complexes. In C. elegans, FEM-1 negatively regulates the transcription factor TRA-1, and functions as an E3 ubiquitin ligase substrate recognition subunit to target TRA-1 for ubiquitylation. TRA-1 is homologous to the mammalian Gli1 protein, a transcription factor that mediates Hedgehog signaling as well as having Hedgehog-independent functions. Whether the interaction between nematode FEM-1 and TRA-1 proteins is conserved, between corresponding mammalian homologs, has not been reported. Herein, we show that Fem1b interacts with Gli1 within cells, and directly binds Gli1. Fem1b also promotes ubiquitylation of Gli1, suppresses transcriptional activation by Gli1, and attenuates an oncogenic Gli1 autoregulatory loop in cancer cells, all dependent on the VHL-box of Fem1b. These findings have implications for understanding the cellular functions of Fem1b, and the regulation of Gli1 oncoprotein activity., (Copyright © 2013 Elsevier Inc. All rights reserved.)
- Published
- 2013
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