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Kazami M, Sakamoto T, Suzuki T, Inoue H, Kato H, Kobayashi KI, Tadokoro T, Yamamoto Y. Ca2+/Calmodulin induces translocation of membrane-associated TSC2 to the nucleus where it suppresses CYP24A1 expression. Biosci Biotechnol Biochem 2022; 87:45-53. [PMID: 36331254 DOI: 10.1093/bbb/zbac174] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/31/2022] [Indexed: 11/06/2022]
Abstract
Tuberous sclerosis complex 2 (TSC2) is a tumor-suppressor protein. A loss of TSC2 function induces hyperactivation of mechanistic target of rapamycin (mTOR). The C-terminal region of TSC2 contains a calmodulin (CaM) binding region and the CaM-TSC2 interaction contributes to proper mTOR activity. However, other downstream signaling pathways/effectors activated by the CaM-TSC2 complex have not been fully elucidated. In this study, we found that activation of Ca2+/CaM signaling resulted in the translocation of membrane-associated TSC2 to the nucleus and suppressed the transcriptional activity of the vitamin D receptor (VDR). TSC2 was released from the membrane in an activated CaM-dependent state in rat brain and HeLa cells. It subsequently formed a transcriptional complex to partially suppress the transcription of CYP24A1, a well-known VDR target gene. These data suggest, in part, that TSC2 attenuates VDR-associated transcriptional regulation via Ca2+/CaM signaling.
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Affiliation(s)
- Machiko Kazami
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Tomoya Sakamoto
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Tsukasa Suzuki
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Hirofumi Inoue
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Hayato Kato
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Ken-Ichi Kobayashi
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Tadahiro Tadokoro
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
| | - Yuji Yamamoto
- Department of Agricultural Chemistry, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo, Japan
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Geraniin inhibits proliferation and induces apoptosis through inhibition of phosphatidylinositol 3-kinase/Akt pathway in human colorectal cancer in vitro and in vivo. Anticancer Drugs 2021; 31:575-582. [PMID: 32427739 DOI: 10.1097/cad.0000000000000929] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Geraniin, a polyphenolic component isolated from Phyllanthus amarus, has been reported to possess diverse biological activities, including antitumor, antiinflammatory, antihyperglycemic, antihypertensive, and antioxidant. However, the role and underlying mechanisms of geraniin in colorectal cancer still remain unclear. In the present study, we found that geraniin notably inhibited cell proliferation and clonogenic formation of colorectal cancer cell SW480 and HT-29 in a dose-dependent manner by Cell Counting Kit 8, EdU, and colony formation assays, respectively. Additionally, geraniin remarkably induced apoptosis of SW480 and HT-29 cells in a dose-dependent way by Hoechst 33342 staining, flow cytometric analysis, and TdT-mediated dUTP nick-end labeling assays and increased the expressions of Bax, caspase-3, and caspase-9, while decreased the level of Bcl-2. Besides, wound healing, transwell migration, and invasion assays demonstrated that geraniin obviously inhibited the migration and invasion of SW480 and HT-29 cells. Moreover, it also inhibited the levels of phospho (p)-phosphatidylinositol 3-kinase and p-Akt. Furthermore, in-vivo animal study revealed that geraniin had the significant inhibitory effects on tumor growth and promoted cancer cell apoptosis remarkably, which further confirmed the antitumor effect of geraniin. Taken together, the present study exhibited the positive role of geraniin in inhibiting proliferation and inducing apoptosis through suppression of phosphatidylinositol 3-kinase/Akt pathway in colorectal cancer cells in vitro and in vivo, which might provide new insights in searching for new drug candidates of anticolorectal cancer.
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Natarajan N, Thiruvenkatam V. An Insight of Scientific Developments in TSC for Better Therapeutic Strategy. Curr Top Med Chem 2020; 20:2080-2093. [PMID: 32842942 DOI: 10.2174/1568026620666200825170355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/15/2020] [Accepted: 07/20/2020] [Indexed: 11/22/2022]
Abstract
Tuberous sclerosis complex (TSC) is a rare genetic disease, which is characterized by noncancerous tumors in multi-organ systems in the body. Mutations in the TSC1 or TSC2 genes are known to cause the disease. The resultant mutant proteins TSC1 (hamartin) and TSC2 (tuberin) complex evade its normal tumor suppressor function, which leads to abnormal cell growth and proliferation. Both TSC1 and TSC2 are involved in several protein-protein interactions, which play a significant role in maintaining cellular homeostasis. The recent biochemical, genetic, structural biology, clinical and drug discovery advancements on TSC give a useful insight into the disease as well as the molecular aspects of TSC1 and TSC2. The complex nature of TSC disease, a wide range of manifestations, mosaicism and several other factors limits the treatment choices. This review is a compilation of the course of TSC, starting from its discovery to the current findings that would take us a step ahead in finding a cure for TSC.
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Affiliation(s)
- Nalini Natarajan
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
| | - Vijay Thiruvenkatam
- Discipline of Biological Engineering, Indian Institute of Technology Gandhinagar, Gujarat-382355, India
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4
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Natarajan N, Shaik A, Thiruvenkatam V. Recombinant Tumor Suppressor TSC1 Differentially Interacts with Escherichia coli DnaK and Human HSP70. ACS OMEGA 2020; 5:19131-19139. [PMID: 32775915 PMCID: PMC7408181 DOI: 10.1021/acsomega.0c02480] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2020] [Accepted: 07/14/2020] [Indexed: 06/11/2023]
Abstract
Tuberous sclerosis complex (TSC) is a neurological syndrome manifested by non-cancerous tumors in several organs. Mutations in either TSC1 or TSC2 tumor suppressor gene cause the disease. In the cell, TSC1 is known to form a heterodimer with TSC2 because of which an active complex is formed that negatively regulates the mTORC1 activity during cellular stress. Hence, mutation in TSC1 or TSC2 is manifested by excess proliferation of the cells leading to the development of numerous benign tumors. The TSC1 and TSC2 complex is known to interact with several protein-binding partners. One such significant interaction of this complex is with the molecular chaperone HSP70. The role of TSC1 in that interaction is still elusive. Here, we have expressed and purified TSC1 (302-420 residues) in a bacterial expression system and have shown that this region directly interacts with HSP70. We have shown that TSC1 increases the ATPase activity of Escherichia coli DnaK, a HSP70 homologue. On the contrary, TSC1 was found to show inhibitory activity toward human HSP70. Our result suggests that TSC1 (302-420 aa) shows differential interaction between the HSP70 homologues. This points toward the evolutionary significance of chaperoning system and the importance of eukaryotic tetratricopeptide repeat domain interaction motif -EEVD. Our study shows the evidence that TSC1 interacts with HSP70 and has a role to play in the chaperoning activity to maintain cellular homeostasis.
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Affiliation(s)
- Nalini Natarajan
- Discipline
of Biological Engineering, Indian Institute
of Technology Gandhinagar, Simkheda, Palaj, Gandhinagar, 382355 Gujarat, India
| | - Althaf Shaik
- Discipline
of Chemistry, Indian Institute of Technology
Gandhinagar, Simkheda, Palaj, Gandhinagar, 382355 Gujarat, India
| | - Vijay Thiruvenkatam
- Discipline
of Biological Engineering, Indian Institute
of Technology Gandhinagar, Simkheda, Palaj, Gandhinagar, 382355 Gujarat, India
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5
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Aizawa Y, Shirai T, Kobayashi T, Hino O, Tsujii Y, Inoue H, Kazami M, Tadokoro T, Suzuki T, Kobayashi KI, Yamamoto Y. The tuberous sclerosis complex model Eker (TSC2+/-) rat exhibits hyperglycemia and hyperketonemia due to decreased glycolysis in the liver. Arch Biochem Biophys 2015; 590:48-55. [PMID: 26550928 DOI: 10.1016/j.abb.2015.10.019] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 10/29/2015] [Accepted: 10/29/2015] [Indexed: 12/17/2022]
Abstract
Tuberous sclerosis complex (TSC) presents as benign tumors that affect the brain, kidneys, lungs and skin. The inactivation of TSC2 gene, through loss of heterozygosity is responsible for tumor development in TSC. Since TSC patients are carriers of heterozygous a TSC2; mutation, to reveal the risk factors which these patients carry prior to tumor development is important. In this experiment, Eker rat which carry a mutation in this TSC2 gene were analyzed for their metabolic changes. Wild-type (TSC2+/+) and heterozygous mutant TSC2 (TSC2+/-) Eker rats were raised for 100 days. As a result, the Eker rats were found to exhibit hyperglycemia and hyperketonemia. However the high ketone body production in the liver was observed without accompanying increased levels of plasma free fatty acids or insulin. Further, production of the ketone body β-hydroxybutyrate was inhibited due to the low NADH/NAD(+) ratio resulting from the restraint on glycolysis, which was followed by inhibition of the malate-aspartate shuttle and TCA cycle. Therefore, we conclude that glycolysis is restrained in the livers of TSC2 heterozygous mutant rats, and these defects lead to abnormal production of acetoacetate.
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Affiliation(s)
- Yumi Aizawa
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Tomomi Shirai
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Toshiyuki Kobayashi
- Department of Pathology and Oncology Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Okio Hino
- Department of Pathology and Oncology Juntendo University Faculty of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan
| | - Yoshimasa Tsujii
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Hirofumi Inoue
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Machiko Kazami
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Tadahiro Tadokoro
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Tsukasa Suzuki
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Ken-Ichi Kobayashi
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan
| | - Yuji Yamamoto
- Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya, Tokyo 156-8502, Japan.
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6
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Abstract
Studies of epilepsy have mainly focused on the membrane proteins that control neuronal excitability. Recently, attention has been shifting to intracellular proteins and their interactions, signaling cascades and feedback regulation as they relate to epilepsy. The mTOR (mammalian target of rapamycin) signal transduction pathway, especially, has been suggested to play an important role in this regard. These pathways are involved in major physiological processes as well as in numerous pathological conditions. Here, involvement of the mTOR pathway in epilepsy will be reviewed by presenting; an overview of the pathway, a brief description of key signaling molecules, a summary of independent reports and possible implications of abnormalities of those molecules in epilepsy, a discussion of the lack of experimental data, and questions raised for the understanding its epileptogenic mechanism.
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Affiliation(s)
- Chang Hoon Cho
- Epilepsy Research Laboratory Department of Pediatrics Children's Hospital of Philadelphia, Pennsylvania 19104, USA.
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Inoue H, Uyama T, Hayashi J, Watanabe A, Kobayashi KI, Tadokoro T, Yamamoto Y. N-Formyl-3,4-methylenedioxy-benzylidene-gamma-butyrolaetam, KNK437 induces caspase-3 activation through inhibition of mTORC1 activity in Cos-1 cells. Biochem Biophys Res Commun 2010; 395:56-60. [PMID: 20350529 DOI: 10.1016/j.bbrc.2010.03.134] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Accepted: 03/20/2010] [Indexed: 01/12/2023]
Abstract
The mammalian target of rapamycin complex 1 (mTORC1: mTOR-raptor interaction) and heat shock protein 70 (Hsp70) regulate various cellular processes and are crucial for the progression of many cancers and metabolic diseases. In the recent study, we reported that interaction of Hsp70 with tuberous sclerosis complex 1 (TSC1) regulated apoptosis. This study was designed to elucidate the underlying mechanism in Cos-1 cells. Here, we show that N-formyl-3,4-methylenedioxy-benzylidene-gamma-butyrolaetam (KNK437), which inhibits the expression level of Hsp70, abrogated phosphorylation of mTOR and S6K in response to insulin, and inhibited mTORC1 activity via disruption of an interaction between mTOR and raptor. In addition, KNK437 did not alter TSC1/2 complex formation. Furthermore, KNK437 inhibited the mTOR-raptor interaction on the outer membrane of the mitochondria and triggered caspase-3 activation. A reduction in the level of Hsp70 could result in the inhibition of the mTORC1 signaling pathway, thereby inducing apoptosis.
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Affiliation(s)
- Hirofumi Inoue
- Department of Applied Biology and Chemistry, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan
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Phosphorylated hamartin–Hsp70 complex regulates apoptosis via mitochondrial localization. Biochem Biophys Res Commun 2010; 391:1148-53. [DOI: 10.1016/j.bbrc.2009.12.054] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2009] [Accepted: 12/09/2009] [Indexed: 11/20/2022]
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