1
|
The tumor suppressor role of salvador family WW domain-containing protein 1 (SAV1): one of the key pieces of the tumor puzzle. J Cancer Res Clin Oncol 2021; 147:1287-1297. [PMID: 33580421 DOI: 10.1007/s00432-021-03552-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 02/04/2021] [Indexed: 10/22/2022]
Abstract
PURPOSE In the complex tumor scenario, understanding the function of proteins with protumor or antitumor roles is essential to support advances in the cancer clinical area. Among them, the salvador family WW domain-containing protein 1 (SAV1) is highlighted. This protein plays a fundamental role in the tumor suppressor face of the Hippo pathway, which are responsible for controlling cell proliferation, organ size, development and tissue homeostasis. However, the functional dysregulation of this pathway may contribute to tumorigenesis and tumor progression. As SAV1 is a tumor suppressor scaffold protein, we explored the functions performed by SAV1 with its partners, the regulation of its expression, and its antitumor role in various types of cancer. METHODS We selected and analyzed 80 original articles and reviews from Pubmed that focuses on the study of SAV1 in cancer. RESULTS SAV1 interacts with several proteins, has different functions and acts as tumor suppressor by other mechanisms besides Hippo pathway. SAV1 expression regulation seems to occur by microRNAs and rarely by mutation or promoter methylation. It is downregulated in different types of cancer, which leads to cancer promotion and progression and is associated with poor prognosis. In vivo models have shown that the loss of SAV1 contributes to tumorigenesis. CONCLUSION SAV1 plays a relevant role as tumor suppressor in several types of cancer, highlighting SAV1 and the Hippo pathway's importance to cancer. Thus, encouraging further studies to include the SAV1 as a molecular key piece in cancer biology and in clinical approaches to cancer.
Collapse
|
2
|
Kato W, Nishio M, To Y, Togashi H, Mak TW, Takada H, Ohga S, Maehama T, Suzuki A. MOB1 regulates thymocyte egress and T-cell survival in mice in a YAP1-independent manner. Genes Cells 2019; 24:485-495. [PMID: 31125466 DOI: 10.1111/gtc.12704] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 05/05/2019] [Accepted: 05/14/2019] [Indexed: 01/31/2023]
Abstract
Mammalian STE20-like protein kinase 1/2 (MST1/2) and nuclear Dbf2-related kinase 1/2 (NDR1/2) are core components of Hippo signaling that are also known to be important regulators of lymphocyte trafficking. However, little is understood about the roles of other Hippo pathway molecules in these cells. Here, we present the first analysis of the function of Mps one binder kinase activator-1 (MOB1) in T lymphocytes in vivo. T-cell-specific double knockout (DKO) of MOB1A/B in mice [tMob1 DKO mice] reduces the number of naïve T cells in both the circulation and secondary lymphoid organs, but leads to an accumulation of CD4+ CD8- and CD4- CD8+ single-positive (SP) cells in the thymus. In vitro, naïve MOB1A/B-deficient T cells show increased apoptosis and display impaired trafficking capacity in response to the chemokine CCL19. These defects are linked to suppression of the activation of MST and NDR kinases, but are independent of the downstream transcriptional co-activator Yes-associated protein 1 (YAP1). Thus, MOB1 proteins play an important role in thymic egress and T-cell survival that is mediated by a pathway other than conventional Hippo-YAP1 signaling.
Collapse
Affiliation(s)
- Wakako Kato
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Hyogo, Japan.,Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.,Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Miki Nishio
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Hyogo, Japan.,Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Yoko To
- Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| | - Hideru Togashi
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Hyogo, Japan
| | - Tak Wah Mak
- The Campbell Family Institute for Breast Cancer Research, University Health Network, Toronto, Ontario, Canada
| | - Hidetoshi Takada
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan.,Department of Child Health, Faculty of Medicine, University of Tsukuba, Tsukuba, Japan
| | - Shouichi Ohga
- Department of Pediatrics, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Hyogo, Japan
| | - Akira Suzuki
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Hyogo, Japan.,Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan
| |
Collapse
|
3
|
Jiang J, Chang W, Fu Y, Gao Y, Zhao C, Zhang X, Zhang S. SAV1, regulated by microRNA-21, suppresses tumor growth in colorectal cancer. Biochem Cell Biol 2019; 97:91-99. [PMID: 30681889 DOI: 10.1139/bcb-2018-0034] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This study investigated the role and action of the Salvador 1 protein (SAV1, also called WW45) in colorectal cancer (CRC). For this, CRC SW480 and HCT116 cells were infected with lentiviruses of SAV1 overexpression vector (lenti-SAV1) and SAV1 short hairpin RNA (sh-SAV1) to overexpress and silence SAV1 respectively, or transfected with microRNA-21 (miR-21) mimic to overexpress miR-21. Relative mRNA levels of SAV1 and relative miR-21 levels in CRC tissues or cells were detected. The effects of SAV1 and miR-21 on cell proliferation and apoptosis were evaluated using the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay and annexin V – fluorescein isothiocyanate (FITC) – propidium iodide (PI) flow cytometry, respectively. Our results revealed that SAV1 was downregulated in CRC tissues compared with the adjacent noncancerous tissues. Furthermore, SAV1 overexpression inhibited proliferation and promoted apoptosis in SW480 and HCT116 cells, whereas knockdown of SAV1 exerted the opposite effect. Additionally, the tumorigenesis of SW480 cells in xenografted mice was significantly inhibited by SAV1 overexpression but promoted by SAV1 knockdown. MiR-21 levels significantly and negatively correlated with SAV1 expression in CRC tissues. More importantly, miR-21 overexpression significantly abolished the SAV1-mediated inhibition of proliferation and stimulation of apoptosis of SW480. In conclusion, SAV1 suppresses tumor growth in CRC and is regulated by miR-21.
Collapse
Affiliation(s)
- Jianwu Jiang
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of Henan Key Laboratory of Digestive Organ Transplantation, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of ZhengZhou Key Laboratory of Hepatobiliary & Pancreatic Diseases and Organ Transplantation, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Wei Chang
- Department of Intensive Care Unit, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Yang Fu
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Yongshun Gao
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Chunlin Zhao
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Xiefu Zhang
- Department of Gastrointestinal Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| | - Shuijun Zhang
- Department of Henan Key Laboratory of Digestive Organ Transplantation, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of Open and Key Laboratory of Hepatobiliary & Pancreatic Surgery and Digestive Organ Transplantation at Henan Universities, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of ZhengZhou Key Laboratory of Hepatobiliary & Pancreatic Diseases and Organ Transplantation, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
- Department of Hepatobiliary and Pancreatic Surgery, The First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, China
| |
Collapse
|
4
|
Goto H, Nishio M, To Y, Oishi T, Miyachi Y, Maehama T, Nishina H, Akiyama H, Mak TW, Makii Y, Saito T, Yasoda A, Tsumaki N, Suzuki A. Loss of Mob1a/b in mice results in chondrodysplasia due to YAP1/TAZ-TEAD-dependent repression of SOX9. Development 2018; 145:dev.159244. [PMID: 29511023 DOI: 10.1242/dev.159244] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 02/19/2018] [Indexed: 12/30/2022]
Abstract
Hippo signaling is modulated in response to cell density, external mechanical forces, and rigidity of the extracellular matrix (ECM). The Mps one binder kinase activator (MOB) adaptor proteins are core components of Hippo signaling and influence Yes-associated protein 1 (YAP1) and transcriptional co-activator with PDZ-binding motif (TAZ), which are potent transcriptional regulators. YAP1/TAZ are key contributors to cartilage and bone development but the molecular mechanisms by which the Hippo pathway controls chondrogenesis are largely unknown. Cartilage is rich in ECM and also subject to strong external forces - two upstream factors regulating Hippo signaling. Chondrogenesis and endochondral ossification are tightly controlled by growth factors, morphogens, hormones, and transcriptional factors that engage in crosstalk with Hippo-YAP1/TAZ signaling. Here, we generated tamoxifen-inducible, chondrocyte-specific Mob1a/b-deficient mice and show that hyperactivation of endogenous YAP1/TAZ impairs chondrocyte proliferation and differentiation/maturation, leading to chondrodysplasia. These defects were linked to suppression of SOX9, a master regulator of chondrogenesis, the expression of which is mediated by TEAD transcription factors. Our data indicate that a MOB1-dependent YAP1/TAZ-TEAD complex functions as a transcriptional repressor of SOX9 and thereby negatively regulates chondrogenesis.
Collapse
Affiliation(s)
- Hiroki Goto
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.,Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Miki Nishio
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.,Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Yoko To
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Tatsuya Oishi
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan
| | - Yosuke Miyachi
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan.,Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Tomohiko Maehama
- Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| | - Hiroshi Nishina
- Department of Developmental and Regenerative Biology, Medical Research Institute, Tokyo Medical and Dental University, Tokyo 113-8510, Japan
| | - Haruhiko Akiyama
- Department of Orthopaedic Surgery, Gifu University School of Medicine, Gifu 501-1194, Japan
| | - Tak Wah Mak
- Campbell Family Institute for Breast Cancer Research at the Princess Margaret Cancer Centre, University Health Network, Toronto M5G 2C1, Canada; Department of Medical Biophysics, University of Toronto, University Health Network, Toronto M5G 2C1, Canada
| | - Yuma Makii
- Department of Sensory and Motor System Medicine, Faculty of Medicine, University of Tokyo, Tokyo 113-8655, Japan
| | - Taku Saito
- Department of Sensory and Motor System Medicine, Faculty of Medicine, University of Tokyo, Tokyo 113-8655, Japan
| | - Akihiro Yasoda
- Department of Diabetes, Endocrinology and Nutrition, Kyoto University Graduate School of Medicine, Kyoto 606-8501, Japan
| | - Noriyuki Tsumaki
- Department of Cell Growth and Differentiation, Center for iPS Cell Research and Application, Kyoto University, Kyoto 606-8507, Japan
| | - Akira Suzuki
- Division of Cancer Genetics, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-8582, Japan .,Division of Molecular and Cellular Biology, Kobe University Graduate School of Medicine, Kobe, Hyogo 650-0017, Japan
| |
Collapse
|
5
|
Chen S, Wang H, Huang YF, Li ML, Cheng JH, Hu P, Lu CH, Zhang Y, Liu N, Tzeng CM, Zhang ZM. WW domain-binding protein 2: an adaptor protein closely linked to the development of breast cancer. Mol Cancer 2017; 16:128. [PMID: 28724435 PMCID: PMC5518133 DOI: 10.1186/s12943-017-0693-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Accepted: 07/10/2017] [Indexed: 01/27/2023] Open
Abstract
The WW domain is composed of 38 to 40 semi-conserved amino acids shared with structural, regulatory, and signaling proteins. WW domain-binding protein 2 (WBP2), as a binding partner of WW domain protein, interacts with several WW-domain-containing proteins, such as Yes kinase-associated protein (Yap), paired box gene 8 (Pax8), WW-domain-containing transcription regulator protein 1 (TAZ), and WW-domain-containing oxidoreductase (WWOX) through its PPxY motifs within C-terminal region, and further triggers the downstream signaling pathway in vitro and in vivo. Studies have confirmed that phosphorylated form of WBP2 can move into nuclei and activate the transcription of estrogen receptor (ER) and progesterone receptor (PR), whose expression were the indicators of breast cancer development, indicating that WBP2 may participate in the progression of breast cancer. Both overexpression of WBP2 and activation of tyrosine phosphorylation upregulate the signal cascades in the cross-regulation of the Wnt and ER signaling pathways in breast cancer. Following the binding of WBP2 to the WW domain region of TAZ which can accelerate migration, invasion and is required for the transformed phenotypes of breast cancer cells, the transformation of epithelial to mesenchymal of MCF10A is activated, suggesting that WBP2 is a key player in regulating cell migration. When WBP2 binds with WWOX, a tumor suppressor, ER transactivation and tumor growth can be suppressed. Thus, WBP2 may serve as a molecular on/off switch that controls the crosstalk between E2, WWOX, Wnt, TAZ, and other oncogenic signaling pathways. This review interprets the relationship between WBP2 and breast cancer, and provides comprehensive views about the function of WBP2 in the regulation of the pathogenesis of breast cancer and endocrine therapy in breast cancer treatment.
Collapse
Affiliation(s)
- Shuai Chen
- Department of Breast Surgery, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China
| | - Han Wang
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China
| | - Yu-Fan Huang
- Department of Breast Surgery, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, 361005, People's Republic of China
| | - Ming-Li Li
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China
| | - Jiang-Hong Cheng
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China
| | - Peng Hu
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China.,INNOVA Cell Theranostics/Clinics and TRANSLA Health Group, Yangzhou, Jiangsu, People's Republic of China
| | - Chuan-Hui Lu
- Department of Breast Surgery, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, 361005, People's Republic of China
| | - Ya Zhang
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China.,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China
| | - Na Liu
- Department of Breast Surgery, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, 361005, People's Republic of China
| | - Chi-Meng Tzeng
- Translational Medicine Research Center (TMRC), School of Pharmaceutical Science, Xiamen University, Xiamen, Fujian, 361005, People's Republic of China. .,Key Laboratory for Cancer T-Cell Therapeutics and Clinical Translation (CTCTCT), Xiamen, Fujian, 361005, People's Republic of China. .,INNOVA Cell Theranostics/Clinics and TRANSLA Health Group, Yangzhou, Jiangsu, People's Republic of China.
| | - Zhi-Ming Zhang
- Department of Breast Surgery, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian, 361005, People's Republic of China. .,Teaching Hospital of Fujian Medical University, Fuzhou, Fujian, 350004, People's Republic of China.
| |
Collapse
|
6
|
Valero V, Pawlik TM, Anders RA. Emerging role of Hpo signaling and YAP in hepatocellular carcinoma. J Hepatocell Carcinoma 2015; 2:69-78. [PMID: 27508196 PMCID: PMC4918286 DOI: 10.2147/jhc.s48505] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Hepatocellular carcinoma (HCC) is the sixth most common cancer and the third most common cause of cancer-related mortality worldwide. Due to the poor prognosis and limited therapeutic options, there is great interest in further understanding better the molecular underpinnings and potential molecular targets associated with HCC. The Hippo (Hpo) signaling pathway and YAP, its principal downstream effector, represent an innovative area of research in HCC. Pioneered in Drosophila melanogaster, the Hpo cascade controls tissue homeostasis including organ size, cell proliferation, apoptosis, as well as cell-cycle regulation and differentiation. This conserved kinase cascade in mammals depends on central control by the tumor suppressor mammalian sterile 20-like kinase 1/2 (Mst1/2). The Mst1/2 commences the downstream kinase cascade, ultimately activating the oncoprotein YAP and allowing its physical association with downstream targets to enhance the gene expression signatures that are involved in proliferation and survival. Alterations in YAP expression and defective regulation of other key Hpo pathway members, such as Mst1/2, Salvador, neurofibromatosis and Mer (Nf2/mer), large tumor suppressor homolog 1/2 (Lats1/2), and Mps one binder kinase activator-like 1A and 1B (Mob1) drive carcinogenesis in animal models. The dysregulation of the Hpo pathway – resulting in an unchecked activation of YAP – culminates in the development of a broad range of human tumor types, including HCC. The abrogation of Mst1/2-mediated YAP phosphorylation permits YAP entry into the nucleus in murine models and functions similarly in human HCCs. Chemoresistance mechanisms displayed by HCC tumors occur in a YAP-dependent manner. The HCC specimens exhibit YAP overexpression, and YAP serves as an independent prognostic marker for disease-free survival and overall survival in patients with HCC. Recently, the small molecule inhibitor, verteporfin has been shown to attenuate YAP activity in murine models, perhaps offering a novel therapeutic approach for patients with advanced HCC.
Collapse
Affiliation(s)
- Vicente Valero
- Department of Surgery, Division of Surgical Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Timothy M Pawlik
- Department of Surgery, Division of Surgical Oncology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert A Anders
- Department of Pathology, Sidney Kimmel Cancer Center, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| |
Collapse
|
7
|
Shi Z, Jiao S, Zhou Z. Structural dissection of Hippo signaling. Acta Biochim Biophys Sin (Shanghai) 2015; 47:29-38. [PMID: 25476203 DOI: 10.1093/abbs/gmu107] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Hippo pathway controls cell number and organ size by restricting cell proliferation and promoting apoptosis, and thus is a key regulator in development and homeostasis. Dysfunction of the Hippo pathway correlates with many pathological conditions, especially cancer. Hippo signaling also plays important roles in tissue regeneration and stem cell biology. Therefore, the Hippo pathway is recognized as a crucial target for cancer therapy and regeneration medicine. To date, structures of several key components in Hippo signaling have been determined. In this review, we summarize current available structural studies of the Hippo pathway, which may help to improve our understanding of its regulatory mechanisms, as well as to facilitate further functional studies and potential therapeutic interventions.
Collapse
|
8
|
A conserved serine residue regulates the stability of Drosophila Salvador and human WW domain-containing adaptor 45 through proteasomal degradation. Biochem Biophys Res Commun 2013; 433:538-41. [PMID: 23524264 DOI: 10.1016/j.bbrc.2013.03.023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 03/08/2013] [Indexed: 01/10/2023]
Abstract
The Hippo (Hpo) pathway is a conserved tumor suppressor pathway that controls organ size through the coordinated regulation of apoptosis and proliferation. Drosophila Salvador (Sav), which limits organ size, is a core component of the Hpo pathway. In this study, Ser-17 was shown to be important for the stability of Sav. Alanine mutation of Ser-17 promoted the proteasomal degradation of Sav. Destabilization and stabilization of the Sav protein mediated by alanine mutation of Ser-17 and by Hpo, respectively, were independent of each other. This implies that the stability of Sav is controlled by two mechanisms, one that is Ser-17-dependent and Hpo-independent, and another that is Ser-17-independent and Hpo-dependent. These dual mechanisms also regulated the human counterpart of Drosophila Sav, WW domain-containing adaptor 45 (WW45). The conservation of this regulation adds to its significance in normal physiology and tumorigenesis.
Collapse
|
9
|
Nishio M, Hamada K, Kawahara K, Sasaki M, Noguchi F, Chiba S, Mizuno K, Suzuki SO, Dong Y, Tokuda M, Morikawa T, Hikasa H, Eggenschwiler J, Yabuta N, Nojima H, Nakagawa K, Hata Y, Nishina H, Mimori K, Mori M, Sasaki T, Mak TW, Nakano T, Itami S, Suzuki A. Cancer susceptibility and embryonic lethality in Mob1a/1b double-mutant mice. J Clin Invest 2012; 122:4505-18. [PMID: 23143302 DOI: 10.1172/jci63735] [Citation(s) in RCA: 116] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Accepted: 09/13/2012] [Indexed: 12/31/2022] Open
Abstract
Mps one binder 1a (MOB1A) and MOB1B are key components of the Hippo signaling pathway and are mutated or inactivated in many human cancers. Here we show that intact Mob1a or Mob1b is essential for murine embryogenesis and that loss of the remaining WT Mob1 allele in Mob1a(Δ/Δ)1b(tr/+) or Mob1a(Δ/+)1b(tr/tr) mice results in tumor development. Because most of these cancers resembled trichilemmal carcinomas, we generated double-mutant mice bearing tamoxifen-inducible, keratinocyte-specific homozygous-null mutations of Mob1a and Mob1b (kDKO mice). kDKO mice showed hyperplastic keratinocyte progenitors and defective keratinocyte terminal differentiation and soon died of malnutrition. kDKO keratinocytes exhibited hyperproliferation, apoptotic resistance, impaired contact inhibition, enhanced progenitor self renewal, and increased centrosomes. Examination of Hippo pathway signaling in kDKO keratinocytes revealed that loss of Mob1a/b altered the activities of the downstream Hippo mediators LATS and YAP1. Similarly, YAP1 was activated in some human trichilemmal carcinomas, and some of these also exhibited MOB1A/1B inactivation. Our results clearly demonstrate that MOB1A and MOB1B have overlapping functions in skin homeostasis, and exert their roles as tumor suppressors by regulating downstream elements of the Hippo pathway.
Collapse
Affiliation(s)
- Miki Nishio
- Division of Cancer Genetics, Medical Institute of Bioregulation, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Mammalian ste20-like kinase and SAV1 promote 3T3-L1 adipocyte differentiation by activation of PPARγ. PLoS One 2012; 7:e30983. [PMID: 22292086 PMCID: PMC3266932 DOI: 10.1371/journal.pone.0030983] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2011] [Accepted: 12/29/2011] [Indexed: 11/19/2022] Open
Abstract
The mammalian ste20 kinase (MST) signaling pathway plays an important role in the regulation of apoptosis and cell cycle control. We sought to understand the role of MST2 kinase and Salvador homolog 1 (SAV1), a scaffolding protein that functions in the MST pathway, in adipocyte differentiation. MST2 and MST1 stimulated the binding of SAV1 to peroxisome proliferator-activated receptor γ (PPARγ), a transcription factor that plays a key role in adipogenesis. The interaction of endogenous SAV1 and PPARγ was detected in differentiating 3T3-L1 adipocytes. This binding required the kinase activity of MST2 and was mediated by the WW domains of SAV1 and the PPYY motif of PPARγ. Overexpression of MST2 and SAV1 increased PPARγ levels by stabilizing the protein, and the knockdown of SAV1 resulted in a decrease of endogenous PPARγ protein in 3T3-L1 adipocytes. During the differentiation of 3T3-L1 cells into adipocytes, MST2 and SAV1 expression began to increase at 2 days when PPARγ expression also begins to increase. MST2 and SAV1 significantly increased PPARγ transactivation, and SAV1 was shown to be required for the activation of PPARγ by rosiglitazone. Finally, differentiation of 3T3-L1 cells was augmented by MST2 and SAV1 expression and inhibited by knockdown of MST1/2 or SAV1. These results suggest that PPARγ activation by the MST signaling pathway may be a novel regulatory mechanism of adipogenesis.
Collapse
|
11
|
Mardin BR, Lange C, Baxter JE, Hardy T, Scholz SR, Fry AM, Schiebel E. Components of the Hippo pathway cooperate with Nek2 kinase to regulate centrosome disjunction. Nat Cell Biol 2010; 12:1166-76. [PMID: 21076410 PMCID: PMC3939356 DOI: 10.1038/ncb2120] [Citation(s) in RCA: 146] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2010] [Accepted: 10/15/2010] [Indexed: 12/25/2022]
Abstract
During interphase, centrosomes are held together by a proteinaceous linker that connects the proximal ends of the mother and daughter centriole. This linker is disassembled at the onset of mitosis in a process known as centrosome disjunction, thereby facilitating centrosome separation and bipolar spindle formation. The NIMA (never in mitosis A)-related kinase Nek2A is implicated in disconnecting the centrosomes through disjoining the linker proteins C-Nap1 and rootletin. However, the mechanisms controlling centrosome disjunction remain poorly understood. Here, we report that two Hippo pathway components, the mammalian sterile 20-like kinase 2 (Mst2) and the scaffold protein Salvador (hSav1), directly interact with Nek2A and regulate its ability to localize to centrosomes, and phosphorylate C-Nap1 and rootletin. Furthermore, we demonstrate that the hSav1-Mst2-Nek2A centrosome disjunction pathway becomes essential for bipolar spindle formation on partial inhibition of the kinesin-5 Eg5. We propose that hSav1-Mst2-Nek2A and Eg5 have distinct, but complementary functions, in centrosome disjunction.
Collapse
Affiliation(s)
- Balca R Mardin
- Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Allianz, Im Neuenheimer Feld 282, 69117 Heidelberg, Germany
| | | | | | | | | | | | | |
Collapse
|
12
|
Hirabayashi S, Nakagawa K, Sumita K, Hidaka S, Kawai T, Ikeda M, Kawata A, Ohno K, Hata Y. Threonine 74 of MOB1 is a putative key phosphorylation site by MST2 to form the scaffold to activate nuclear Dbf2-related kinase 1. Oncogene 2008; 27:4281-92. [DOI: 10.1038/onc.2008.66] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
|
13
|
Callus BA, Verhagen AM, Vaux DL. Association of mammalian sterile twenty kinases, Mst1 and Mst2, with hSalvador via C-terminal coiled-coil domains, leads to its stabilization and phosphorylation. FEBS J 2006; 273:4264-76. [PMID: 16930133 DOI: 10.1111/j.1742-4658.2006.05427.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Genetic screens in Drosophila have revealed that the serine/threonine kinase Hippo (Hpo) and the scaffold protein Salvador participate in a pathway that controls cell proliferation and apoptosis. Hpo most closely resembles the pro-apoptotic mammalian sterile20 kinases 1 and 2 (Mst1 and 2), and Salvador (Sav) has a human orthologue hSav (also called hWW45). Here we show that Mst and hSav heterodimerize in an interaction requiring the conserved C-terminal coiled-coil domains of both proteins. hSav was also able to homodimerize, but this did not require its coiled-coil domain. Coexpression of Mst and hSav led to phosphorylation of hSav and also increased its abundance. In vitro phosphorylation experiments indicate that the phosphorylation of Sav by Mst is direct. The stabilizing effect of Mst was much greater on N-terminally truncated hSav mutants, as long as they retained the ability to bind Mst. Mst mutants that lacked the C-terminal coiled-coil domain and were unable to bind to hSav, also failed to stabilize or phosphorylate hSav, whereas catalytically inactive Mst mutants that retained the ability to bind to hSav were still able to increase its abundance, although they were no longer able to phosphorylate hSav. Together these results show that hSav can bind to, and be phosphorylated by, Mst, and that the stabilizing effect of Mst on hSav requires its interaction with hSav but is probably not due to phosphorylation of hSav by Mst.
Collapse
|
14
|
Jin H, Valverde P, Chen J. Cloning of hamster osteopontin and expression distribution in normal tissues and experimentally induced oral squamous-cell carcinoma. Arch Oral Biol 2005; 51:236-45. [PMID: 16095557 DOI: 10.1016/j.archoralbio.2005.06.013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2005] [Revised: 06/06/2005] [Accepted: 06/22/2005] [Indexed: 12/25/2022]
Abstract
Osteopontin (OPN) is a non-collagenous extracellular matrix (ECM) protein expressed and secreted by several human cancers. This study investigated the expression pattern of OPN during development of oral squamous-cell carcinoma by using 7,12-dimethylbenz[a]anthracene (DMBA)-induced squamous-cell carcinomas in buccal pouch of syrian golden hamsters. We first identified the hamster OPN cDNA sequence by screening of a hamster calvariae cDNA library with a rat OPN cDNA probe. The resulting 1,449 bp of hamster OPN cDNA led to a deduced protein sequence of 305 amino acids containing several putative binding sites to integrins, CD44 receptors, calcium ions and hydroxyapatite, as well as multiple sites for phosphorylation, glycosylation and sulphation. Hamster OPN cDNA was then used as a probe to analyze the expression of OPN mRNA by Northern blot and in situ hybridization analyses of normal and malignant tissues. OPN mRNA was detected in several non-mineralized tissues as well as in mineralized tissues, but was not present in normal hamster buccal epithelium. DMBA-treated hamster buccal pouches expressed OPN mRNA as early as 4 weeks and displayed the highest level of expression at 15 weeks. The specimens treated with DMBA for 15 weeks exhibited histological features of squamous-cell carcinoma, presented microcrystalline deposits and showed OPN expression associated with malignant epithelium and tumor-associated macrophages. To summarize, our results suggest that buccal-pouch carcinogenesis of Syrian golden hamster may constitute an excellent experimental model to study the mechanisms by which OPN is associated with oral cancer pathogenesis, and to validate OPN-based therapeutic approaches to ameliorate oral cancer progression and metastasis.
Collapse
MESH Headings
- 9,10-Dimethyl-1,2-benzanthracene
- Amino Acid Sequence
- Animals
- Base Sequence
- Carcinogens
- Carcinoma, Squamous Cell/chemically induced
- Carcinoma, Squamous Cell/genetics
- Cloning, Molecular/methods
- Cricetinae
- DNA, Complementary/genetics
- DNA, Neoplasm/genetics
- Extracellular Matrix Proteins/analysis
- Extracellular Matrix Proteins/genetics
- Gene Expression Regulation, Neoplastic/genetics
- Male
- Mesocricetus
- Mouth Neoplasms/chemically induced
- Mouth Neoplasms/genetics
- Neoplasm Proteins/analysis
- Neoplasm Proteins/genetics
- Osteopontin
- RNA, Messenger/analysis
- RNA, Neoplasm/analysis
- Sequence Alignment/methods
- Sialoglycoproteins/analysis
- Sialoglycoproteins/genetics
- Tissue Distribution
Collapse
Affiliation(s)
- Hangqing Jin
- Department of Pediatric Dentistry, University of Texas Health Sciences Center at San Antonio, USA
| | | | | |
Collapse
|
15
|
Chan EHY, Nousiainen M, Chalamalasetty RB, Schäfer A, Nigg EA, Silljé HHW. The Ste20-like kinase Mst2 activates the human large tumor suppressor kinase Lats1. Oncogene 2005; 24:2076-86. [PMID: 15688006 DOI: 10.1038/sj.onc.1208445] [Citation(s) in RCA: 443] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Originally identified in Drosophila melanogaster, the Warts(Wts)/Lats protein kinase has been proposed to function with two other Drosophila proteins, Hippo (Hpo) and Salvador (Sav), in the regulation of cell cycle exit and apoptosis. In mammals, two candidate Warts/Lats homologs, termed Lats1 and Lats2, have been described, and the targeted disruption of LATS1 in mice increases tumor formation. Little, however, is known about the function and regulation of human Lats kinases. Here we report that human Mst2, a STE20-family member and purported Hpo ortholog, phosphorylates and activates both Lats1 and Lats2. Deletion analysis revealed that regulation of Lats1 occurs through the C-terminal, catalytic domain. Within this domain, two regulatory phosphorylation sites were identified by mass spectrometry. These sites, S909 in the activation loop and T1079 within a hydrophobic motif, have been highly conserved during evolution. Moreover, a direct interaction was observed between Mst2 and hWW45, a putative ortholog of Drosophila Sav. These results indicate that Mst2-like kinases regulate Lats kinase activities in an evolutionarily conserved regulatory pathway. Although the function of this pathway remains poorly understood in mammals, it is intriguing that, in Drosophila, it has been linked to development and tissue homeostasis.
Collapse
Affiliation(s)
- Eunice H Y Chan
- Department of Cell Biology, Max Planck Institute for Biochemistry, Am Klopferspitz 18, D-82152 Martinsried, Germany
| | | | | | | | | | | |
Collapse
|
16
|
Yoo NJ, Soung YH, Lee JW, Park WS, Kim SY, Nam SW, Han JH, Kim SH, Lee JY, Lee SH. Mutational analysis of salvador gene in human carcinomas. APMIS 2003; 111:595-8. [PMID: 12969014 DOI: 10.1034/j.1600-0463.2003.1110601.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
It is believed that clonal expansion and cancer growth is the result of the deregulation of proliferation and cell death. Recently, salvador, a molecule that can regulate both cell proliferation and cell death, was identified. It was also reported that human salvador (hWW45) is mutated in some cancer cell lines. However, there have been no data regarding salvador gene mutations in human cancer tissues. To explore the hypothesis that the salvador gene might be similarly mutated in human cancer tissues, we analyzed the entire coding region of the salvador gene for the detection of somatic mutations in a series of human cancer tissues, including carcinomas from stomach, colon, liver and lung. However, using SSCP analysis, no mutation in the coding and splicing regions could be detected in the cancers. The data presented here suggest that salvador is not frequently mutated in human carcinoma tissues and that the mutation might be tumor-type specific.
Collapse
Affiliation(s)
- Nam Jin Yoo
- Department of Pathology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Kamikubo Y, Takaori-Kondo A, Uchiyama T, Hori T. Inhibition of cell growth by conditional expression of kpm, a human homologue of Drosophila warts/lats tumor suppressor. J Biol Chem 2003; 278:17609-14. [PMID: 12624101 DOI: 10.1074/jbc.m211974200] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
kpm is a human serine/threonine kinase that is homologous to Drosophila tumor suppressor warts/lats and its mammalian homologue LATS1. In order to define the biological function of kpm, we generated stable transfectants of wild-type kpm (kpm-wt), a kinase-dead mutant of kpm (kpm-kd), and luciferase in HeLa Tet-Off cells under the tetracycline-responsive promoter. Western blot analysis showed that high levels of expression of kpm-wt as well as kpm-kd with an apparent mass of 150 kDa were induced after the removal of doxycycline. Induction of kpm-wt expression resulted in a marked decline in viable cell number measured by both trypan blue dye exclusion and MTT assay, whereas that of kpm-kd or luciferase had no effect. We then analyzed the cell cycle progression and apoptosis upon induction of kpm expression. 2-3 days after removal of doxycycline, cells underwent G(2)/M arrest, demonstrated by flow cytometric analysis of propidium iodide incorporation and MPM-2 reactivity. In vitro kinase assay showed that induction of kpm-wt led to down-regulation of kinase activity of the Cdc2-cyclin B complex, which was accompanied by an increase in the hyperphosphorylated form of Cdc2 and a change of phosphorylation status of Cdc25C. Furthermore, both DAPI staining and TUNEL assay showed that the proportion of apoptotic cells increased as kpm expression was induced. Taken together, these results indicate that kpm negatively regulates cell growth by inducing G(2)/M arrest and apoptotic cell death through its kinase activity.
Collapse
Affiliation(s)
- Yasuhiko Kamikubo
- Department of Hematology and Oncology, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | | | | | | |
Collapse
|
18
|
Pantalacci S, Léopold P, Tapon N. [Drosophila and cancer: proof by sav]. Med Sci (Paris) 2003; 19:149-51. [PMID: 12836609 DOI: 10.1051/medsci/2003192149] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
19
|
Kremerskothen J, Plaas C, Büther K, Finger I, Veltel S, Matanis T, Liedtke T, Barnekow A. Characterization of KIBRA, a novel WW domain-containing protein. Biochem Biophys Res Commun 2003; 300:862-7. [PMID: 12559952 DOI: 10.1016/s0006-291x(02)02945-5] [Citation(s) in RCA: 127] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
In a yeast two hybrid screen with the human isoform of Dendrin (KIAA0749), a putative modulator of the postsynaptic cytoskeleton, we isolated a cDNA coding for a novel protein, KIBRA, possessing two amino-terminal WW domains, an internal C2-like domain and a carboxy-terminal glutamic acid-rich stretch. Northern blot analysis revealed that the expression of KIBRA mRNA was predominately found in kidney and brain. In vitro interaction studies revealed that the first KIBRA WW domain binds specifically to PPxY motifs. Transient transfection of monkey kidney cells with constructs encoding Myc-tagged KIBRA displayed a cytoplasmic localization and a perinuclear enrichment of the protein.
Collapse
Affiliation(s)
- Joachim Kremerskothen
- Department for Experimental Tumorbiology, University Muenster, Badestrasse 9, D-48149 Muenster, Germany.
| | | | | | | | | | | | | | | |
Collapse
|
20
|
Kango-Singh M, Nolo R, Tao C, Verstreken P, Hiesinger PR, Bellen HJ, Halder G. Shar-pei mediates cell proliferation arrest during imaginal disc growth in Drosophila. Development 2002; 129:5719-30. [PMID: 12421711 DOI: 10.1242/dev.00168] [Citation(s) in RCA: 276] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
During animal development, organ size is determined primarily by the amount of cell proliferation, which must be tightly regulated to ensure the generation of properly proportioned organs. However, little is known about the molecular pathways that direct cells to stop proliferating when an organ has attained its proper size. We have identified mutations in a novel gene, shar-pei, that is required for proper termination of cell proliferation during Drosophila imaginal disc development. Clones of shar-pei mutant cells in imaginal discs produce enlarged tissues containing more cells of normal size. We show that this phenotype is the result of both increased cell proliferation and reduced apoptosis. Hence, shar-pei restricts cell proliferation and promotes apoptosis. By contrast, shar-pei is not required for cell differentiation and pattern formation of adult tissue. Shar-pei is also not required for cell cycle exit during terminal differentiation, indicating that the mechanisms directing cell proliferation arrest during organ growth are distinct from those directing cell cycle exit during terminal differentiation. shar-pei encodes a WW-domain-containing protein that has homologs in worms, mice and humans, suggesting that mechanisms of organ growth control are evolutionarily conserved.
Collapse
Affiliation(s)
- Madhuri Kango-Singh
- Department of Biochemistry and Molecular Biology, M. D. Anderson Cancer Center, Houston, TX 77030, USA
| | | | | | | | | | | | | |
Collapse
|
21
|
Rothenberg ME, Jan YN. salvador--The persistence of proliferation. Cancer Cell 2002; 2:171-3. [PMID: 12242148 DOI: 10.1016/s1535-6108(02)00131-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Despite years of extensive studies on genes that regulate proliferation and cell death, two processes that must be tightly coordinated throughout development to regulate cell number, remarkably few genes have been shown to affect both processes. Using an elegant genetic screen in the fly eye, have identified a gene, salvador, which is especially significant, because it not only regulates and coordinates both exit from the cell cycle and apoptosis, but also has a human homolog that may play a key role in tumorigenesis.
Collapse
Affiliation(s)
- Michael E Rothenberg
- Howard Hughes Medical Institute, Departments of Physiology and Biochemistry, University of California, San Francisco, 533 Parnassus Avenue, 94143, San Francisco, CA, USA
| | | |
Collapse
|
22
|
Tapon N, Harvey KF, Bell DW, Wahrer DCR, Schiripo TA, Haber DA, Hariharan IK. salvador Promotes both cell cycle exit and apoptosis in Drosophila and is mutated in human cancer cell lines. Cell 2002; 110:467-78. [PMID: 12202036 DOI: 10.1016/s0092-8674(02)00824-3] [Citation(s) in RCA: 673] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The number of cells in an organism is determined by regulating both cell proliferation and cell death. Relatively few mechanisms have been identified that can modulate both of these processes. In a screen for Drosophila mutations that result in tissue overgrowth, we identified salvador (sav), a gene that promotes both cell cycle exit and cell death. Elevated Cyclin E and DIAP1 levels are found in mutant cells, resulting in delayed cell cycle exit and impaired apoptosis. Salvador contains two WW domains and binds to the Warts (or LATS) protein kinase. The human ortholog of salvador (hWW45) is mutated in three cancer cell lines. Thus, salvador restricts cell numbers in vivo by functioning as a dual regulator of cell proliferation and apoptosis.
Collapse
Affiliation(s)
- Nicolas Tapon
- Massachusetts General Hospital Cancer Center, Building 149, 13th Street, Charlestown 02129, USA
| | | | | | | | | | | | | |
Collapse
|