title: Lens epithelium-derived growth factor deSumoylation by Sumo-specific protease-1 regulates its transcriptional activation of small heat shock protein and the cellular response.
abstract: Lens epithelium-derived growth factor (LEDGF), a ubiquitously expressed nuclear protein, acts by interacting with DNA and protein and is involved in widely varying cellular functions. Despite its importance, the mechanism(s) that regulate naturally occurring LEDGF activity are unidentified. In the present study, we report that LEDGF is constitutively Sumoylated, and that the dynamical regulatory mechanism(s) (i.e. Sumoylation and deSumoylation) act as a molecular switch in modulating the DNA-binding and transcriptional activity of LEDGF with the functional consequences. Using bioinformatics analysis coupled with in vitro and in vivo Sumoylation assays, we found that lysine (K) 364 of LEDGF was Sumoylated, repressing its transcriptional activity. Conversely, mutation of K364 to arginine (R) or deSumoylation by small ubiquitin-like modifier (Sumo)-specific protease-1, a nuclear deSumoylase, enhanced the transactivation capacity of LEDGF and its cellular abundance. The enhancements were directly correlated with an increase in the DNA-binding activity and small heat shock protein transcription of LEDGF, whereas the process was reversed in cells overexpressing Sumo1. Interestingly, cells expressing Sumoylation-deficient pEGFP-K364R protein showed increased cellular survival compared to wild-type LEDGF protein. The findings provide insights into the regulation and regulatory functions of LEDGF in Sumoylation-dependent transcriptional control that may be essential for modifying the physiology of cells to maintain cellular homeostasis. These studies also provide new evidence of the important role of post-translational modification in controlling LEDGF function.
authors: Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, NE, USA.
authors: Keiichi
authors: K
authors: Ishihara
authors: Nigar
authors: N
authors: Fatma
authors: Biju
authors: B
authors: Bhargavan
authors: Bhavana
authors: B
authors: Chhunchha
authors: Eri
authors: E
authors: Kubo
authors: Sanjib
authors: S
authors: Dey
authors: Yoshihiro
authors: Y
authors: Takamura
authors: Anil
authors: A
authors: Kumar
authors: Dhirendra P
authors: DP
authors: Singh
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D017931:DNA Primers; D010450:Endopeptidases / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000235:genetics*; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D058207:Sumoylation; D015533:Transcriptional Activation
chemical_list: D017931:DNA Primers; D006360:Heat-Shock Proteins; D036341:Intercellular Signaling Peptides and Proteins; C119380:lens epithelium-derived growth factor; D010450:Endopeptidases; C404512:SENP1 protein, human; D003546:Cysteine Endopeptidases