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Zhu S, Sun R, Guo X, Bao Y, Zhang D. Regulation, targets and functions of CHK. Front Cell Dev Biol 2022; 10:1068952. [PMID: 36568988 PMCID: PMC9780368 DOI: 10.3389/fcell.2022.1068952] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 11/22/2022] [Indexed: 12/13/2022] Open
Abstract
Src family kinases (SFKs) play pivotal roles in multiple signaling pathways (Yeatman, 2004). SFK activity is inhibited by phosphorylation at its C-terminal tyrosine, by CSK (C-terminal Src kinase) and CHK (CSK-homologous kinase). CHK expression is restricted to normal hematopoietic cells, brain, and colon tissues. Downregulation of CHK in brain and colon tumors contributes to tumorigenicity in these tissues. CHK does not phosphorylate Src efficiently, however, in contrast to CSK, CHK inhibits Src kinase activity allosterically. Although the functions of CHK are still largely unknown, potential substrates of CHK including β-synuclein, α-tubulin, α-spectrin, 14-3-3, and Hsp90 have been identified. CHK is regulated epigenetically via promoter methylation. As the unknown roles of CHK are beginning to be revealed, current knowledge of regulation, molecular targets and functions of CHK is summarized, and important topics for future CHK research are discussed.
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Affiliation(s)
- Shudong Zhu
- School of Medicine, Nantong University, Nantong, China,Argus Pharmaceuticals, Changsha, China,*Correspondence: Shudong Zhu,
| | - Rong Sun
- School of Medicine, Nantong University, Nantong, China
| | | | | | - Dianzheng Zhang
- Department of Bio-medical Sciences, Philadelphia College of Osteopathic Medicine, Philadelphia, PA, United States
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Interplay between the tyrosine kinases Chk and Csk and phosphatase PTPRJ is critical for regulating platelets in mice. Blood 2020; 135:1574-1587. [PMID: 32016283 DOI: 10.1182/blood.2019002848] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 01/06/2020] [Indexed: 12/17/2022] Open
Abstract
The Src family kinases (SFKs) Src, Lyn, and Fyn are essential for platelet activation and also involved in megakaryocyte (MK) development and platelet production. Platelet SFKs are inhibited by C-terminal Src kinase (Csk), which phosphorylates a conserved tyrosine in their C-terminal tail, and are activated by the receptor-type tyrosine phosphatase PTPRJ (CD148, DEP-1), which dephosphorylates the same residue. Deletion of Csk and PTPRJ in the MK lineage in mice results in increased SFK activity, but paradoxically hypoactive platelets resulting from negative feedback mechanisms, including upregulation of Csk homologous kinase (Chk) expression. Here, we investigate the role of Chk in platelets, functional redundancy with Csk, and the physiological consequences of ablating Chk, Csk, and PTPRJ in mice. Platelet count was normal in Chk knockout (KO) mice, reduced by 92% in Chk;Csk double KO (DKO) mice, and partially rescued in Chk;Csk;Ptprj triple KO (TKO) mice. Megakaryocyte numbers were significantly increased in both DKO and TKO mice. Phosphorylation of the inhibitory tyrosine of SFKs was almost completely abolished in DKO platelets, which was partially rescued in Src and Fyn in TKO platelets. This residual phosphorylation was abolished by Src inhibitors, revealing an unexpected mechanism in which SFKs autoinhibit their activity by phosphorylating their C-terminal tyrosine residues. We demonstrate that reduced inhibitory phosphorylation of SFKs leads to thrombocytopenia, with Csk being the dominant inhibitor in platelets and Chk having an auxiliary role. PTPRJ deletion in addition to Chk and Csk ameliorates the extent of thrombocytopenia, suggesting targeting it may have therapeutic benefits in such conditions.
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Advani G, Lim YC, Catimel B, Lio DSS, Ng NLY, Chüeh AC, Tran M, Anasir MI, Verkade H, Zhu HJ, Turk BE, Smithgall TE, Ang CS, Griffin M, Cheng HC. Csk-homologous kinase (Chk) is an efficient inhibitor of Src-family kinases but a poor catalyst of phosphorylation of their C-terminal regulatory tyrosine. Cell Commun Signal 2017; 15:29. [PMID: 28784162 PMCID: PMC5547543 DOI: 10.1186/s12964-017-0186-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 07/28/2017] [Indexed: 11/10/2022] Open
Abstract
Background C-terminal Src kinase (Csk) and Csk-homologous kinase (Chk) are the major endogenous inhibitors of Src-family kinases (SFKs). They employ two mechanisms to inhibit SFKs. First, they phosphorylate the C-terminal tail tyrosine which stabilizes SFKs in a closed inactive conformation by engaging the SH2 domain in cis. Second, they employ a non-catalytic inhibitory mechanism involving direct binding of Csk and Chk to the active forms of SFKs that is independent of phosphorylation of their C-terminal tail. Csk and Chk are co-expressed in many cell types. Contributions of the two mechanisms towards the inhibitory activity of Csk and Chk are not fully clear. Furthermore, the determinants in Csk and Chk governing their inhibition of SFKs by the non-catalytic inhibitory mechanism are yet to be defined. Methods We determined the contributions of the two mechanisms towards the inhibitory activity of Csk and Chk both in vitro and in transduced colorectal cancer cells. Specifically, we assayed the catalytic activities of Csk and Chk in phosphorylating a specific peptide substrate and a recombinant SFK member Src. We employed surface plasmon resonance spectroscopy to measure the kinetic parameters of binding of Csk, Chk and their mutants to a constitutively active mutant of the SFK member Hck. Finally, we determined the effects of expression of recombinant Chk on anchorage-independent growth and SFK catalytic activity in Chk-deficient colorectal cancer cells. Results Our results revealed Csk as a robust enzyme catalysing phosphorylation of the C-terminal tail tyrosine of SFKs but a weak non-catalytic inhibitor of SFKs. In contrast, Chk is a poor catalyst of SFK tail phosphorylation but binds SFKs with high affinity, enabling it to efficiently inhibit SFKs with the non-catalytic inhibitory mechanism both in vitro and in transduced colorectal cancer cells. Further analyses mapped some of the determinants governing this non-catalytic inhibitory mechanism of Chk to its kinase domain. Conclusions SFKs are activated by different upstream signals to adopt multiple active conformations in cells. SFKs adopting these conformations can effectively be constrained by the two complementary inhibitory mechanisms of Csk and Chk. Furthermore, the lack of this non-catalytic inhibitory mechanism accounts for SFK overactivation in the Chk-deficient colorectal cancer cells. Electronic supplementary material The online version of this article (doi:10.1186/s12964-017-0186-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Gahana Advani
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia.,Cell Signalling Research Laboratories, School of Biomedical Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Ya Chee Lim
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,PAP Rashidah Sa'adatul Bolkiah Institute of Health Sciences, Universiti Brunei Darussalam, Gadong, Brunei Darussalam
| | - Bruno Catimel
- Walter and Eliza Hall Institute for Medical Research and Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Daisy Sio Seng Lio
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia.,Cell Signalling Research Laboratories, School of Biomedical Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Nadia L Y Ng
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia.,Cell Signalling Research Laboratories, School of Biomedical Sciences, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Anderly C Chüeh
- Walter and Eliza Hall Institute for Medical Research and Department of Medical Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Mai Tran
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Mohd Ishtiaq Anasir
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Heather Verkade
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Hong-Jian Zhu
- Department of Surgery, University of Melbourne, Royal Melbourne Hospital, Parkville, VIC, 3052, Australia
| | - Benjamin E Turk
- Department of Pharmacology, Yale University School of Medicine, New Haven, CT, USA
| | - Thomas E Smithgall
- Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Ching-Seng Ang
- Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Michael Griffin
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia.,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia
| | - Heung-Chin Cheng
- Department of Biochemistry & Molecular Biology, University of Melbourne, Parkville, VIC, 3010, Australia. .,Bio21 Biotechnology and Molecular Science Institute, University of Melbourne, Parkville, VIC, 3010, Australia. .,Cell Signalling Research Laboratories, School of Biomedical Sciences, University of Melbourne, Parkville, VIC, 3010, Australia.
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Abstract
Since the discovery of the v-src and c-src genes and their products, much progress has been made in the elucidation of the structure, regulation, localization, and function of the Src protein. Src is a non-receptor protein tyrosine kinase that transduces signals that are involved in the control of a variety of cellular processes such as proliferation, differentiation, motility, and adhesion. Src is normally maintained in an inactive state, but can be activated transiently during cellular events such as mitosis, or constitutively by abnormal events such as mutation (i.e. v-Src and some human cancers). Activation of Src occurs as a result of disruption of the negative regulatory processes that normally suppress Src activity, and understanding the various mechanisms behind Src activation has been a target of intense study. Src associates with cellular membranes, in particular the plasma membrane, and endosomal membranes. Studies indicate that the different subcellular localizations of Src could be important for the regulation of specific cellular processes such as mitogenesis, cytoskeletal organization, and/or membrane trafficking. This review will discuss the history behind the discovery and initial characterization of Src and the regulatory mechanisms of Src activation, in particular, regulation by modification of the carboxy-terminal regulatory tyrosine by phosphatases and kinases. Its focus will then turn to the different subcellular localizations of Src and the possible roles of nuclear and perinuclear targets of Src. Finally, a brief section will review some of our present knowledge regarding Src involvement in human cancers.
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Affiliation(s)
- J D Bjorge
- Cancer Biology Research Group, Department of Biochemistry and Molecular Biology, University of Calgary Medical Center, 3330 Hospital Dr. N.W., Calgary, Alberta T2N 4N1, Canada
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Luo H, Chaudhuri A, Zbrzezna V, He Y, Pogo AO. Deletion of the murine Duffy gene (Dfy) reveals that the Duffy receptor is functionally redundant. Mol Cell Biol 2000; 20:3097-101. [PMID: 10757794 PMCID: PMC85604 DOI: 10.1128/mcb.20.9.3097-3101.2000] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
All of the antigenic determinants of the Duffy blood group system are in a glycoprotein (gp-Fy), which is encoded by a single-copy gene (FY) located on chromosome 1. gp-Fy is also produced in several cell types, including endothelial cells of capillary and postcapillary venules, the epithelial cell of kidney collecting ducts, lung alveoli, and the Purkinje cells of the cerebellum. This protein, which spans the cell membrane seven times, is a member of the superfamily of chemokine receptors and a malarial parasite receptor. The mouse Duffy gene (Dfy) homolog of human FY is also a single-copy gene, which maps in a region of conserved synteny with FY and produces a glycoprotein with 60% homology to the human protein. The mouse Duffy-like protein also binds chemokines. To study the biological role of gp-Fy, we generated a mouse strain in which Dfy was deleted. These homozygous Dfy(-/-) mice were indistinguishable in size, development, and health from wild-type and heterozygous littermates. We also examined components of the immune system and found no differences in lymph nodes or peripheral blood leukocyte levels between knockout and wild-type mice. The gross and histological anatomy of the thymus, spleen, lung, and brain showed no significant differences between mutants and wild-type mice. There was no indication of an overall difference between the knockout and wild-type mice in systematic neurological examinations. The only significant difference between Dfy(-/-) and Dfy(+/+) mice that we found was in neutrophil migration in peritoneal inflammations induced by lipopolysaccharide and thioglycolate. In mice homozygous for the deletion, there was less neutrophil recruitment into the peritoneal cavity and neutrophil influx in the intestines and lungs than in wild-type mice. Despite this, the susceptibility to Staphylococcus aureus infection was the same in the absence and in the presence of gp-Fy. Our results indicate that gp-Fy is functionally a redundant protein that may participate in the neutrophil migratory process.
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Affiliation(s)
- H Luo
- Laboratory of Cell Biology, Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, USA
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