title: SIPL1-facilitated PTEN ubiquitination contributes to its association with PTEN.
abstract: PTEN is post-translationally modified by ubiquitin via association with multiple E3 ubiquitin ligases, including NEDD4-1, XIAP, and WWP2. Despite the rapid progress made in researching the impact of ubiquitination on PTEN function, our understanding remains fragmented. Building on the previously observed interaction between SIPL1 and PTEN, we report here that SIPL1 promotes PTEN polyubiquitination via lysine 48 (K48)-independent polyubiquitin chains. Substitution of the K48 residue of ubiquitin with arginine (R) enhanced SIPL1-mediated PTEN polyubiquitination. In contrast, the K63R substitution significantly reduced it. The ubiquitin-like (UBL) domain is required for SIPL1-induced PTEN polyubiquitination. This post-translational modification promoted the association of SIPL1 with PTEN. Elevated amounts of the SIPL1/PTEN complex were precipitated in 293T cells co-transfected with PTEN, SIPL1, and ubiquitin compared to cells co-transfected with SIPL1 and PTEN only. Additionally, formation of the SIPL1/PTEN complex was inhibited when either lysine-less (K0) ubiquitin or K63R ubiquitin was co-transfected together with SIPL1+PTEN. The PTEN component in the SIPL1/PTEN complex contained polyubiquitin chains. The ubiquitination reaction may play a structural role, stabilizing the SIPL1/PTEN complex, as a ubiquitin binding-defective SIPL1 mutant (TFLV) is proficient in PTEN association. Collectively, we demonstrate that SIPL1 binds PTEN and enhances PTEN polyubiquitination which in turn promotes the interaction between SIPL1 and PTEN.
authors.affiliation: Division of Nephrology, Department of Medicine, McMaster University, Canada; Father Sean O'Sullivan Research Institute, St. Joseph's Hospital, Hamilton, Ontario, Canada.
authors.forename: Jason
authors.initials: J
authors.lastname: De Melo
authors.affiliation: Division of Nephrology, Department of Medicine, McMaster University, Canada; Father Sean O'Sullivan Research Institute, St. Joseph's Hospital, Hamilton, Ontario, Canada.
authors.forename: Xiaozeng
authors.initials: X
authors.lastname: Lin
authors.affiliation: Division of Nephrology, Department of Medicine, McMaster University, Canada; Father Sean O'Sullivan Research Institute, St. Joseph's Hospital, Hamilton, Ontario, Canada; Massachusetts General Hospital (MGH), Harvard Medical School, Boston, MA 02114, USA.
authors.forename: Lizhi
authors.initials: L
authors.lastname: He
authors.affiliation: Division of Nephrology, Department of Medicine, McMaster University, Canada; Father Sean O'Sullivan Research Institute, St. Joseph's Hospital, Hamilton, Ontario, Canada; The Genetics Laboratory, Institute of Women and Children's Health, Longgang District, Shenzhen, Guangdong, PR China.
authors.forename: Fengxiang
authors.initials: F
authors.lastname: Wei
authors.affiliation: Department of Oncology, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Pierre
authors.initials: P
authors.lastname: Major
authors.affiliation: Division of Nephrology, Department of Medicine, McMaster University, Canada; Father Sean O'Sullivan Research Institute, St. Joseph's Hospital, Hamilton, Ontario, Canada. Electronic address: damut@mcmaster.ca.
authors.forename: Damu
authors.initials: D
authors.lastname: Tang
mesh_terms: D001120:Arginine / Q000378:metabolism; D002460:Cell Line; D057809:HEK293 Cells; D006801:Humans; D008239:Lysine / Q000378:metabolism; D051059:PTEN Phosphohydrolase / Q000378:metabolism*; D025821:Polyubiquitin / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D011499:Protein Processing, Post-Translational / Q000502:physiology; D017434:Protein Structure, Tertiary; D014162:Transfection / Q000379:methods; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism; D054875:Ubiquitination / Q000502:physiology*; D014452:Ubiquitins / Q000378:metabolism*
chemical_list: C575183:SHARPIN protein, human; D025801:Ubiquitin; D014452:Ubiquitins; D025821:Polyubiquitin; D001120:Arginine; D044767:Ubiquitin-Protein Ligases; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; D008239:Lysine
keywords: PTEN; Protein–protein interaction; SIPL1/sharpin; Ubiquitination