title: The sirtuins promote Dishevelled-1 scaffolding of TIAM1, Rac activation and cell migration.
abstract: Rac1-GTPases serve as intermediary cellular switches, which conduct transient and constitutive signals from upstream cues, including those from Ras oncoproteins. Although the sirtuin1 (SIRT1) deacetylase is overexpressed in several human cancers and has recently been linked to cancer cell motility as a context-dependent regulator of multiple pathways, its role in Rac1 activation has not been reported. Similarly, SIRT2 has been demonstrated to be upregulated in some cancers; however, studies have also reported its role in tumor suppression. Here, we demonstrate that SIRT1 and SIRT2 positively regulate the levels of Rac1-GTP and the activity of T-cell lymphoma invasion and metastasis 1 (TIAM1), a Rac guanine nucleotide exchange factor (GEF). Transient inhibition of SIRT1 and SIRT2 resulted in increased acetylation of TIAM1, whereas chronic SIRT2 knockdown resulted in enhanced acetylation of TIAM1. SIRT1 regulates Dishevelled (DVL) protein levels in cancer cells, and DVL along with TIAM1 are known to augment Rac activation; however, SIRT1 or 2 has not been previously linked with TIAM1. We found that diminished sirtuin activity led to the disruption of the DVL1-TIAM1 interaction. We hence propose a model for Rac activation where SIRT1/2 positively modulates the DVL/TIAM1/Rac axis and promotes sustained pathway activation.
authors.affiliation: Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: M
authors.initials: M
authors.lastname: Saxena
authors.affiliation: Department of Microbiology and Immunology, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: S S
authors.initials: SS
authors.lastname: Dykes
authors.affiliation: Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: S
authors.initials: S
authors.lastname: Malyarchuk
authors.affiliation: Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: A E
authors.initials: AE
authors.lastname: Wang
authors.affiliation: 1] Department of Microbiology and Immunology, LSU Health Shreveport, Shreveport, LA, USA [2] Feist-Weiller Cancer Center, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Cardelli
authors.affiliation: 1] Department of Molecular and Cellular Physiology, LSU Health Shreveport, Shreveport, LA, USA [2] Feist-Weiller Cancer Center, LSU Health Shreveport, Shreveport, LA, USA.
authors.forename: K
authors.initials: K
authors.lastname: Pruitt
mesh_terms: D000107:Acetylation; D048868:Adaptor Proteins, Signal Transducing / Q000037:antagonists & inhibitors / Q000378:metabolism*; D002448:Cell Adhesion / Q000502:physiology; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism; D000072261:Dishevelled Proteins; D020662:Guanine Nucleotide Exchange Factors / Q000037:antagonists & inhibitors / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D010750:Phosphoproteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D056564:Sirtuin 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D056565:Sirtuin 2 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; D014157:Transcription Factors / Q000378:metabolism; D014162:Transfection; D020830:rac1 GTP-Binding Protein / Q000378:metabolism*
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D004268:DNA-Binding Proteins; C000606578:DVL1 protein, human; D000072261:Dishevelled Proteins; D020662:Guanine Nucleotide Exchange Factors; D010750:Phosphoproteins; C107953:RAC1 protein, human; C480633:SLC2A4RG protein, human; D000075684:T-Lymphoma Invasion and Metastasis-inducing Protein 1; C087334:TIAM1 protein, human; D014157:Transcription Factors; C447939:SIRT1 protein, human; C474199:SIRT2 protein, human; D056564:Sirtuin 1; D056565:Sirtuin 2; D020830:rac1 GTP-Binding Protein