The sirtuins promote Dishevelled-1 scaffolding of TIAM1, Rac activation and cell migration

• Published in: Oncogene 2015-01, Vol.34 (2), p.188-198
• Main Authors: Saxena, M, Dykes, S S, Malyarchuk, S, Wang, A E, Cardelli, J A, Pruitt, K
• Format: Article
• Language: English
• Subjects: 631/67; 631/80/84; 631/80/86; Acetylation; Adaptor Proteins, Signal Transducing - antagonists & inhibitors; Adaptor Proteins, Signal Transducing - metabolism; Analysis; Apoptosis; Carcinogenesis; Care and treatment; Cell activation; Cell adhesion & migration; Cell Adhesion - physiology; Cell Biology; Cell Line, Tumor; Cell migration; Cell Movement - physiology; Cellular biology; Development and progression; Dishevelled protein; Dishevelled Proteins; DNA-Binding Proteins - metabolism; G proteins; Gene expression; Genetic aspects; Guanine; Guanine nucleotide exchange factor; Guanine Nucleotide Exchange Factors - antagonists & inhibitors; Guanine Nucleotide Exchange Factors - metabolism; Guanosine triphosphate; Health aspects; HEK293 Cells; Human Genetics; Humans; Internal Medicine; Kinases; Lymphocytes T; Medicine; Medicine & Public Health; Metastases; Non-Hodgkin's lymphomas; Oncology; original-article; Phosphoproteins - antagonists & inhibitors; Phosphoproteins - metabolism; rac1 GTP-Binding Protein - metabolism; Rac1 protein; Risk factors; Signal Transduction; SIRT1 protein; Sirtuin 1 - antagonists & inhibitors; Sirtuin 1 - metabolism; Sirtuin 2 - antagonists & inhibitors; Sirtuin 2 - metabolism; Sirtuins; T cells; T-cell lymphoma; T-Lymphoma Invasion and Metastasis-inducing Protein 1; Tiam1 protein; Transcription Factors - metabolism; Transfection; Tumor suppression
• ISSN: 0950-9232; 1476-5594
• DOI: 10.1038/onc.2013.549

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.