1
|
Morris R, Butler L, Perkins A, Kershaw NJ, Babon JJ. The Role of LNK (SH2B3) in the Regulation of JAK-STAT Signalling in Haematopoiesis. Pharmaceuticals (Basel) 2021; 15:ph15010024. [PMID: 35056081 PMCID: PMC8781068 DOI: 10.3390/ph15010024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Revised: 12/17/2021] [Accepted: 12/21/2021] [Indexed: 01/05/2023] Open
Abstract
LNK is a member of the SH2B family of adaptor proteins and is a non-redundant regulator of cytokine signalling. Cytokines are secreted intercellular messengers that bind to specific receptors on the surface of target cells to activate the Janus Kinase-Signal Transducer and Activator of Transcription (JAK-STAT) signalling pathway. Activation of the JAK-STAT pathway leads to proliferative and often inflammatory effects, and so the amplitude and duration of signalling are tightly controlled. LNK binds phosphotyrosine residues to signalling proteins downstream of cytokines and constrains JAK-STAT signalling. Mutations in LNK have been identified in a range of haematological and inflammatory diseases due to increased signalling following the loss of LNK function. Here, we review the regulation of JAK-STAT signalling via the adaptor protein LNK and discuss the role of LNK in haematological diseases.
Collapse
Affiliation(s)
- Rhiannon Morris
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; (R.M.); (N.J.K.)
- Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - Liesl Butler
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC 3001, Australia; (L.B.); (A.P.)
- Alfred Health, Melbourne, VIC 3001, Australia
| | - Andrew Perkins
- Australian Centre for Blood Diseases, Monash University, Melbourne, VIC 3001, Australia; (L.B.); (A.P.)
- Alfred Health, Melbourne, VIC 3001, Australia
| | - Nadia J. Kershaw
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; (R.M.); (N.J.K.)
- Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
| | - Jeffrey J. Babon
- Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; (R.M.); (N.J.K.)
- Department of Medical Biology, The University of Melbourne, Parkville, VIC 3052, Australia
- Correspondence: ; Tel.: +61-3-9345-2960; Fax: +61-3-9347-0852
| |
Collapse
|
2
|
Morris R, Zhang Y, Ellyard JI, Vinuesa CG, Murphy JM, Laktyushin A, Kershaw NJ, Babon JJ. Structural and functional analysis of target recognition by the lymphocyte adaptor protein LNK. Nat Commun 2021; 12:6110. [PMID: 34671038 PMCID: PMC8528861 DOI: 10.1038/s41467-021-26394-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 09/30/2021] [Indexed: 01/17/2023] Open
Abstract
The SH2B family of adaptor proteins, SH2-B, APS, and LNK are key modulators of cellular signalling pathways. Whilst SH2-B and APS have been partially structurally and biochemically characterised, to date there has been no such characterisation of LNK. Here we present two crystal structures of the LNK substrate recognition domain, the SH2 domain, bound to phosphorylated motifs from JAK2 and EPOR, and biochemically define the basis for target recognition. The LNK SH2 domain adopts a canonical SH2 domain fold with an additional N-terminal helix. Targeted analysis of binding to phosphosites in signalling pathways indicated that specificity is conferred by amino acids one- and three-residues downstream of the phosphotyrosine. Several mutations in LNK showed impaired target binding in vitro and a reduced ability to inhibit signalling, allowing an understanding of the molecular basis of LNK dysfunction in variants identified in patients with myeloproliferative disease.
Collapse
Affiliation(s)
- Rhiannon Morris
- grid.1042.7Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052 Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, The University of Melbourne, Royal Parade, Parkville, VIC 3052 Australia
| | - Yaoyuan Zhang
- grid.1001.00000 0001 2180 7477Australia Department of Immunology and Infectious Diseases, Australian National University, Canberra, ACT Australia ,grid.1001.00000 0001 2180 7477Australia Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, Canberra, ACT Australia
| | - Julia I. Ellyard
- grid.1001.00000 0001 2180 7477Australia Department of Immunology and Infectious Diseases, Australian National University, Canberra, ACT Australia ,grid.1001.00000 0001 2180 7477Australia Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, Canberra, ACT Australia
| | - Carola G. Vinuesa
- grid.1001.00000 0001 2180 7477Australia Department of Immunology and Infectious Diseases, Australian National University, Canberra, ACT Australia ,grid.1001.00000 0001 2180 7477Australia Centre for Personalised Immunology, John Curtin School of Medical Research, Australian National University, Canberra, ACT Australia
| | - James M. Murphy
- grid.1042.7Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052 Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, The University of Melbourne, Royal Parade, Parkville, VIC 3052 Australia
| | - Artem Laktyushin
- grid.1042.7Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052 Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, The University of Melbourne, Royal Parade, Parkville, VIC 3052 Australia
| | - Nadia J. Kershaw
- grid.1042.7Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052 Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, The University of Melbourne, Royal Parade, Parkville, VIC 3052 Australia
| | - Jeffrey J. Babon
- grid.1042.7Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, VIC 3052 Australia ,grid.1008.90000 0001 2179 088XDepartment of Medical Biology, The University of Melbourne, Royal Parade, Parkville, VIC 3052 Australia
| |
Collapse
|
3
|
SRC-like adaptor protein 2 (SLAP2) is a negative regulator of KIT-D816V-mediated oncogenic transformation. Sci Rep 2018; 8:6405. [PMID: 29686302 PMCID: PMC5913247 DOI: 10.1038/s41598-018-24743-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2017] [Accepted: 04/04/2018] [Indexed: 12/03/2022] Open
Abstract
KIT is a receptor tyrosine kinase (RTK) involved in several cellular processes such as regulation of proliferation, survival and differentiation of early hematopoietic cells, germ cells and melanocytes. Activation of KIT results in phosphorylation of tyrosine residues in the receptor, and recruitment of proteins that mediate downstream signaling and also modulate receptor signaling. Here we show that the SRC-like adaptor protein 2 (SLAP2) binds to wild-type KIT in a ligand-dependent manner and is furthermore found constitutively associated with the oncogenic mutant KIT-D816V. Peptide fishing analysis mapped pY568 and pY570 as potential SLAP2 association sites in KIT, which overlaps with the SRC binding sites in KIT. Expression of SLAP2 in cells expressing the transforming mutant KIT-D816V led to reduced cell viability and reduced colony formation. SLAP2 also partially blocked phosphorylation of several signal transduction molecules downstream of KIT such as AKT, ERK, p38 and STAT3. Finally, SLAP2 expression enhanced ubiquitination of KIT and its subsequent degradation. Taken together, our data demonstrate that SLAP2 negatively modulates KIT-D816V-mediated transformation by enhancing degradation of the receptor.
Collapse
|
4
|
Naudin C, Chevalier C, Roche S. The role of small adaptor proteins in the control of oncogenic signalingr driven by tyrosine kinases in human cancer. Oncotarget 2017; 7:11033-55. [PMID: 26788993 PMCID: PMC4905456 DOI: 10.18632/oncotarget.6929] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 01/01/2016] [Indexed: 12/15/2022] Open
Abstract
Protein phosphorylation on tyrosine (Tyr) residues has evolved as an important mechanism to coordinate cell communication in multicellular organisms. The importance of this process has been revealed by the discovery of the prominent oncogenic properties of tyrosine kinases (TK) upon deregulation of their physiological activities, often due to protein overexpression and/or somatic mutation. Recent reports suggest that TK oncogenic signaling is also under the control of small adaptor proteins. These cytosolic proteins lack intrinsic catalytic activity and signal by linking two functional members of a catalytic pathway. While most adaptors display positive regulatory functions, a small group of this family exerts negative regulatory functions by targeting several components of the TK signaling cascade. Here, we review how these less studied adaptor proteins negatively control TK activities and how their loss of function induces abnormal TK signaling, promoting tumor formation. We also discuss the therapeutic consequences of this novel regulatory mechanism in human oncology.
Collapse
Affiliation(s)
- Cécile Naudin
- CNRS UMR5237, University Montpellier, CRBM, Montpellier, France.,Present address: INSERM U1016, CNRS UMR8104, Institut Cochin, Paris, France
| | - Clément Chevalier
- CNRS UMR5237, University Montpellier, CRBM, Montpellier, France.,Present address: SFR Biosit (UMS CNRS 3480/US INSERM 018), MRic Photonics Platform, University Rennes, Rennes, France
| | - Serge Roche
- CNRS UMR5237, University Montpellier, CRBM, Montpellier, France.,Equipe Labellisée LIGUE 2014, Ligue Contre le Cancer, Paris, France
| |
Collapse
|
5
|
Yano M, Imamura T, Asai D, Deguchi T, Hashii Y, Endo M, Sato A, Kawasaki H, Kosaka Y, Kato K, Hori H, Yumura-Yagi K, Hara J, Oda M, Horibe K. Clinical significance of SH2B3 (LNK) expression in paediatric B-cell precursor acute lymphoblastic leukaemia. Br J Haematol 2017; 183:327-330. [PMID: 29082511 DOI: 10.1111/bjh.14981] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mio Yano
- Department of Paediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Department of Paediatrics, Kyoto City Hospital, Kyoto, Japan.,Clinical Research Centre, National Hospital Organization Nagoya Medical Centre, Nagoya, Japan
| | - Toshihiko Imamura
- Department of Paediatrics, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, Japan.,Clinical Research Centre, National Hospital Organization Nagoya Medical Centre, Nagoya, Japan
| | - Daisuke Asai
- Department of Paediatrics, Japanese Red Cross Kyoto Daini Hospital, Kyoto, Japan
| | - Takao Deguchi
- Department of Paediatrics, Mie University, Tsu, Japan
| | - Yoshiko Hashii
- Department of Paediatrics, Osaka University, Osaka, Japan
| | - Mikiya Endo
- Department of Paediatrics, Iwate Medical University, Iwate, Japan
| | - Atsushi Sato
- Department of Haematology and Oncology, Miyagi Children's Hospital, Sendai, Japan
| | - Hirohide Kawasaki
- Department of Paediatrics, Kansai Medical University, Hirakata, Japan
| | - Yoshiyuki Kosaka
- Department of Haematology and Oncology, Hyogo Prefectural Children's Hospital, Kobe, Japan
| | - Koji Kato
- Department of Haematology Oncology, Children's Medical Centre, Japanese Red Cross Nagoya First Hospital, Nagoya, Japan
| | - Hiroki Hori
- Department of Paediatrics, Mie University, Tsu, Japan
| | | | - Junichi Hara
- Department of Paediatric Haematology/Oncology, Osaka City General Hospital, Osaka, Japan
| | - Megumi Oda
- Department of Paediatrics, Okayama University, Okayama, Japan
| | - Keizo Horibe
- Clinical Research Centre, National Hospital Organization Nagoya Medical Centre, Nagoya, Japan
| |
Collapse
|
6
|
Hao M, Yuan F, Jin C, Zhou Z, Cao Q, Xu L, Wang G, Huang H, Yang D, Xie M, Zhao X. Overexpression of Lnk in the Ovaries Is Involved in Insulin Resistance in Women With Polycystic Ovary Syndrome. Endocrinology 2016; 157:3709-3718. [PMID: 27459314 PMCID: PMC5045500 DOI: 10.1210/en.2016-1234] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Polycystic ovary syndrome (PCOS) progression involves abnormal insulin signaling. SH2 domain-containing adaptor protein (Lnk) may be an important regulator of the insulin signaling pathway. We investigated whether Lnk was involved in insulin resistance (IR). Thirty-seven women due to receive laparoscopic surgery from June 2011 to February 2012 were included from the gynecologic department of the Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University. Samples of polycystic and normal ovary tissues were examined by immunohistochemistry. Ovarian cell lines underwent insulin stimulation and Lnk overexpression. Expressed Lnk underwent coimmunoprecipitation tests with green fluorescent protein-labeled insulin receptor and His-tagged insulin receptor substrate 1 (IRS1), and their colocalization in HEK293T cells was examined. Ovarian tissues from PCOS patients with IR exhibited higher expression of Lnk than ovaries from normal control subjects and PCOS patients without IR; mainly in follicular granulosa cells, the follicular fluid and plasma of oocytes in secondary follicles, and atretic follicles. Lnk was coimmunoprecipitated with insulin receptor and IRS1. Lnk and insulin receptor/IRS1 locations overlapped around the nucleus. IR, protein kinase B (Akt), and ERK1/2 activities were inhibited by Lnk overexpression and inhibited further after insulin stimulation, whereas IRS1 serine activity was increased. Insulin receptor (Tyr1150/1151), Akt (Thr308), and ERK1/2 (Thr202/Tyr204) phosphorylation was decreased, whereas IRS1 (Ser307) phosphorylation was increased with Lnk overexpression. In conclusion, Lnk inhibits the phosphatidylinositol 3 kinase-AKT and MAPK-ERK signaling response to insulin. Higher expression of Lnk in PCOS suggests that Lnk probably plays a role in the development of IR.
Collapse
Affiliation(s)
- Meihua Hao
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Feng Yuan
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Chenchen Jin
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Zehong Zhou
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Qi Cao
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Ling Xu
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Guanlei Wang
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Hui Huang
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Dongzi Yang
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Meiqing Xie
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| | - Xiaomiao Zhao
- Department of Obstetrics and Gynecology (M.H., H.H., D.Y., M.X., X.Z.), Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Pharmacology (F.Y., C.J., G.W.), Cardiac and Cerebral Vascular Research Center, Zhongshan School of Medicine, Sun Yat-Sen University, Guangzhou, 510120 China; Department of Obstetrics and Gynecology (Z.Z.), Reproductive Medical Center, Peking University Third Hospital, Haidian District, Beijing, China; Division of Hematology/Oncology (Q.C.), Cedar-Sinai Medical Center, University of California, Los Angeles School of Medicine, Los Angeles, California; and Cedar-Sinai Medical Center (L.X.), University of California, Los Angeles School of Medicine, Los Angeles, California
| |
Collapse
|
7
|
Lee SH, Lee KB, Lee JH, Kang S, Kim HG, Asahara T, Kwon SM. Selective Interference Targeting of Lnk in Umbilical Cord-Derived Late Endothelial Progenitor Cells Improves Vascular Repair, Following Hind Limb Ischemic Injury, via Regulation of JAK2/STAT3 Signaling. Stem Cells 2015; 33:1490-500. [DOI: 10.1002/stem.1938] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 11/28/2014] [Indexed: 12/27/2022]
Affiliation(s)
- Sang Hun Lee
- Medical Science Research Institute, Soonchunhyang University Seoul Hospital; Seoul South Korea
- Department of Biochemistry; School of Medicine, Soonchunhyang University; Cheonan South Korea
- Laboratory for Vascular Medicine and Stem Cell Biology; Department of Physiology; School of Medicine; Pusan National University; Medical Research Institute, School of Medicine, Pusan National University; Yangsan Gyeongnam South Korea
| | - Kyeung Bin Lee
- Laboratory for Vascular Medicine and Stem Cell Biology; Department of Physiology; School of Medicine; Pusan National University; Medical Research Institute, School of Medicine, Pusan National University; Yangsan Gyeongnam South Korea
| | - Jun Hee Lee
- Laboratory for Vascular Medicine and Stem Cell Biology; Department of Physiology; School of Medicine; Pusan National University; Medical Research Institute, School of Medicine, Pusan National University; Yangsan Gyeongnam South Korea
- Convergence Stem Cell Research Center, Immunoregulatory Therapeutics Group in Brain Busan 21 Project; Pusan National University, Yangsan Gyeongnam South Korea
| | - Songhwa Kang
- Laboratory for Vascular Medicine and Stem Cell Biology; Department of Physiology; School of Medicine; Pusan National University; Medical Research Institute, School of Medicine, Pusan National University; Yangsan Gyeongnam South Korea
- Convergence Stem Cell Research Center, Immunoregulatory Therapeutics Group in Brain Busan 21 Project; Pusan National University, Yangsan Gyeongnam South Korea
| | - Hwi Gon Kim
- Department of Obstetrics and Gynecology; Pusan National University, School of Medicine; Busan South Korea
| | - Takayuki Asahara
- Department of Regenerative Medicine Science; Tokai University School of Medicine; Shimokasuya Isehara Kanagawa Japan
| | - Sang Mo Kwon
- Laboratory for Vascular Medicine and Stem Cell Biology; Department of Physiology; School of Medicine; Pusan National University; Medical Research Institute, School of Medicine, Pusan National University; Yangsan Gyeongnam South Korea
- Convergence Stem Cell Research Center, Immunoregulatory Therapeutics Group in Brain Busan 21 Project; Pusan National University, Yangsan Gyeongnam South Korea
| |
Collapse
|
8
|
Abstract
LNK (SH2B3) is an adaptor protein studied extensively in normal and malignant hematopoietic cells. In these cells, it downregulates activated tyrosine kinases at the cell surface resulting in an antiproliferative effect. To date, no studies have examined activities of LNK in solid tumors. In this study, we found by in silico analysis and staining tissue arrays that the levels of LNK expression were elevated in high-grade ovarian cancer. To test the functional importance of this observation, LNK was either overexpressed or silenced in several ovarian cancer cell lines. Remarkably, overexpression of LNK rendered the cells resistant to death induced by either serum starvation or nutrient deprivation, and generated larger tumors using a murine xenograft model. In contrast, silencing of LNK decreased ovarian cancer cell growth in vitro and in vivo. Western blot studies indicated that overexpression of LNK upregulated and extended the transduction of the mitogenic signal, whereas silencing of LNK produced the opposite effects. Furthermore, forced expression of LNK reduced cell size, inhibited cell migration and markedly enhanced cell adhesion. Liquid chromatography-mass spectroscopy identified 14-3-3 as one of the LNK-binding partners. Our results suggest that in contrast to the findings in hematologic malignancies, the adaptor protein LNK acts as a positive signal transduction modulator in ovarian cancers.
Collapse
|
9
|
Varricchio L, Mancini A, Migliaccio AR. Pathological interactions between hematopoietic stem cells and their niche revealed by mouse models of primary myelofibrosis. Expert Rev Hematol 2014; 2:315-334. [PMID: 20352017 DOI: 10.1586/ehm.09.17] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Primary myelofibrosis (PMF) belongs to the Philadelphia-negative myeloproliferative neoplasms and is a hematological disorder caused by abnormal function of the hematopoietic stem cells. The disease manifests itself with a plethora of alterations, including anemia, splenomegaly and extramedullary hematopoiesis. Its hallmarks are progressive marrow fibrosis and atypical megakaryocytic hyperplasia, two distinctive features used to clinically monitor disease progression. In an attempt to investigate the role of abnormal megakaryocytopoiesis in the pathogenesis of PMF, several transgenic mouse models have been generated. These models are based either on mutations that interfere with the extrinsic (thrombopoietin and its receptor, MPL) and intrinsic (the GATA1 transcription factor) control of normal megakaryocytopoiesis, or on known genetic lesions associated with the human disease. Here we provide an up-to-date review on the insights into the pathobiology of human PMF achieved by studying these animal models, with particular emphasis on results obtained with Gata1(low) mice.
Collapse
Affiliation(s)
- Lilian Varricchio
- Department of Medicine, Division of Hematology/Oncology, Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1079, New York, NY 10029, USA Tel.: +1 212 241 6974
| | | | | |
Collapse
|
10
|
Koren-Michowitz M, Gery S, Tabayashi T, Lin D, Alvarez R, Nagler A, Koeffler HP. SH2B3 (LNK) mutations from myeloproliferative neoplasms patients have mild loss of function against wild type JAK2 and JAK2 V617F. Br J Haematol 2013; 161:811-20. [PMID: 23590807 PMCID: PMC3672250 DOI: 10.1111/bjh.12327] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2012] [Accepted: 02/26/2013] [Indexed: 12/17/2022]
Abstract
Somatic point mutations in the PH domain of SH2B3 (LNK), an adaptor protein that is highly expressed in haematopoietic cells, were recently described in patients with myeloproliferative neoplasms. We studied the effect of these mutations on the JAK2 signalling pathway in cells expressing either wild type JAK2 or the JAK2 V617F mutation. Compared to wild type SH2B3, PH domain mutants have mild loss of function, with no evidence for a dominant-negative effect. Mutants retain binding capacity for JAK2, an established SH2B3 target, as well as for the adaptor proteins 14-3-3 and CBL. Our data suggest that the loss of SH2B3 inhibitory function conferred by the PH domain mutations is mild and may collaborate with JAK2 V617F and CBL mutations in order to promote either the development or the progression of myeloproliferative neoplasms.
Collapse
Affiliation(s)
- Maya Koren-Michowitz
- Hematology/Oncology, Cedars-Sinai Medical Center, UCLA School of Medicine, Los Angeles, CA 90048, USA.
| | | | | | | | | | | | | |
Collapse
|
11
|
Gery S, Koeffler HP. Role of the adaptor protein LNK in normal and malignant hematopoiesis. Oncogene 2012; 32:3111-8. [DOI: 10.1038/onc.2012.435] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
12
|
Velazquez L. The Lnk adaptor protein: a key regulator of normal and pathological hematopoiesis. Arch Immunol Ther Exp (Warsz) 2012; 60:415-29. [PMID: 22990499 DOI: 10.1007/s00005-012-0194-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 08/06/2012] [Indexed: 01/24/2023]
Abstract
The development and function of blood cells are regulated by specific growth factors/cytokines and their receptors' signaling pathways. In this way, these factors influence cell survival, proliferation and differentiation of hematopoietic cells. Central to this positive and/or negative control are the adaptor proteins. Since their identification 10 years ago, members of the Lnk adaptor protein family have proved to be important activators and/or inhibitors in the hematopoietic, immune and vascular system. In particular, the generation of animal and cellular models for the Lnk and APS proteins has helped establish the physiological role of these molecules through the identification of their specific signaling pathways and the characterization of their binding partners. Moreover, the recent identification of mutations in the LNK gene in myeloproliferative disorders, as well as the correlation of a single nucleotide polymorphism on LNK with hematological, immune and vascular diseases have suggested its involvement in the pathophysiology of these malignancies. The latter findings have thus raised the possibility of addressing Lnk signaling for the treatment of certain human diseases. This review therefore describes the pathophysiological role of this adaptor protein in hematological malignancies and the potential benefits of Lnk therapeutic targeting.
Collapse
Affiliation(s)
- Laura Velazquez
- UMR U978 Inserm/Université Paris 13, UFR SMBH, Bobigny, France.
| |
Collapse
|
13
|
Abstract
Fms-like tyrosine kinase 3 (FLT3) is a receptor tyrosine kinase with important roles in hematopoietic progenitor cell survival and proliferation. It is mutated in approximately one-third of AML patients, mostly by internal tandem duplications (ITDs). Adaptor protein Lnk is a negative regulator of hematopoietic cytokine signaling. In the present study, we show that Lnk interacts physically with both wild-type FLT3 (FLT3-WT) and FLT3-ITD through the SH2 domains. We have identified the tyrosine residues 572, 591, and 919 of FLT3 as phosphorylation sites involved in direct binding to Lnk. Lnk itself was tyrosine phosphorylated by both FLT3 ligand (FL)-activated FLT3-WT and constitutively activated FLT3-ITD. Both shRNA-mediated depletion and forced overexpression of Lnk demonstrated that activation signals emanating from both forms of FLT3 are under negative regulation by Lnk. Moreover, Lnk inhibited 32D cell proliferation driven by different FLT3 variants. Analysis of primary BM cells from Lnk-knockout mice showed that Lnk suppresses the expansion of FL-stimulated hematopoietic progenitors, including lymphoid-primed multipotent progenitors. The results of the present study show that through direct binding to FLT3, Lnk suppresses FLT3-WT/ITD-dependent signaling pathways involved in the proliferation of hematopoietic cells. Therefore, modulation of Lnk expression levels may provide a unique therapeutic approach for FLT3-ITD-associated hematopoietic disease.
Collapse
|
14
|
Octa-arginine mediated delivery of wild-type Lnk protein inhibits TPO-induced M-MOK megakaryoblastic leukemic cell growth by promoting apoptosis. PLoS One 2011; 6:e23640. [PMID: 21853157 PMCID: PMC3154509 DOI: 10.1371/journal.pone.0023640] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 07/22/2011] [Indexed: 11/19/2022] Open
Abstract
Background Lnk plays a non-redundant role by negatively regulating cytokine signaling of TPO, SCF or EPO. Retroviral expression of Lnk has been shown to suppress hematopoietic leukemic cell proliferation indicating its therapeutic value in cancer therapy. However, retroviral gene delivery carries risks of insertional mutagenesis. To circumvent this undesired consequence, we fused a cell permeable peptide octa-arginine to Lnk and evaluated the efficacy of inhibition of leukemic cell proliferation in vitro. Methodology/Principal Findings In this study, proliferation assays, flow cytometry, Western Blot analyses were performed on wild-type (WT), mutant Lnk R8 or BSA treated M-MOK cells. We found that delivered WT, but not mutant Lnk R8 blocked TPO-induced M-MOK megakaryoblastic leukemic cell proliferation. In contrast, WT Lnk R8 showed no growth inhibitive effect on non-hematopoietic HELA or COS-7 cell. Moreover, we demonstrated that TPO-induced M-MOK cell growth inhibition by WT Lnk R8 was dose-dependent. Penetrated WT Lnk R8 induced cell cycle arrest and apoptosis. Immunoprecipitation and Western blots data indicated WT Lnk R8 interacted with endogeneous Jak2 and downregulated Jak-Stat and MAPK phosphorylation level in M-MOK cells after TPO stimulation. Treatment with specific inhibitors (TG101348 and PD98059) indicated Jak-Stat and MAPK pathways were crucial for TPO-induced proliferation of M-MOK cells. Further analyses using TF-1 and HEL leukemic cell-lines showed that WT Lnk R8 inhibited Jak2-dependent cell proliferation. Using cord blood-derived CD34+ stem cells, we found that delivered WT Lnk R8 blocked TPO-induced megakaryopoiesis in vitro. Conclusions/Significance Intracellular delivery of WT Lnk R8 fusion protein efficiently inhibited TPO-induced M-MOK leukemic cell growth by promoting apoptosis. WT Lnk R8 protein delivery may provide a safer and more practical approach to inhibit leukemic cell growth worthy of further development.
Collapse
|
15
|
Gueller S, Hehn S, Nowak V, Gery S, Serve H, Brandts CH, Koeffler HP. Adaptor protein Lnk binds to PDGF receptor and inhibits PDGF-dependent signaling. Exp Hematol 2011; 39:591-600. [PMID: 21310211 DOI: 10.1016/j.exphem.2011.02.001] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2009] [Revised: 01/11/2011] [Accepted: 01/27/2011] [Indexed: 12/19/2022]
Abstract
OBJECTIVE Platelet-derived growth factor receptors α and β (PDGFRA, PDGFRB) are frequently expressed on hematopoietic cells and regulate cellular responses such as proliferation, differentiation, survival, and transformation. Stimulation by autocrine loops or activation by chromosomal translocation makes them important factors in development of hematopoietic disorders. Interaction with the ligand PDGF results in activation of the tyrosine kinase domain and phosphorylation of tyrosine residues, thereby creating binding sites for molecules containing Src homology 2 domains. We hypothesized that one such protein may be Lnk, a negative regulator of cytokine receptors, including Mpl, EpoR, c-Kit, and c-Fms. MATERIALS AND METHODS Interaction of Lnk with PDGFRA, PDGFRB, or leukemogenic FIP1L1-PDGFRA or TEL-PDGFRB was studied in cotransfected 293T cells. Effects of Lnk on PDGFR signaling were shown in 293T and NIH3T3 cells, whereas its influence on either PDGF-dependent or factor-independent growth was investigated using Ba/F3 or 32D cells expressing wild-type PDGFR, FIP1L1-PDGFRA, or TEL-PDGFRB. RESULTS We show that Lnk binds to PDGFR after exposure of cells to PDGF. Furthermore, Lnk can bind the FIP1L1-PDGFRA fusion protein. Mutation or deletion of the Lnk Src homology 2 domain completely abolished binding of Lnk to FIP1L1-PDGFRA, but just partly prevented binding to PDGFRA or PDGFRB. Expression of Lnk inhibited proliferation of PDGF-dependent Ba/F3 cells and diminished phosphorylation of Erk in PDGF-treated NIH3T3. 32D cells transformed by either FIP1L1-PDGFRA or TEL-PDGFRB stopped growing when Lnk was expressed. CONCLUSIONS Lnk is a negative regulator of PDGFR signaling. Development of Lnk mimetic drugs might provide a novel therapeutic strategy for myeloproliferative disorders.
Collapse
Affiliation(s)
- Saskia Gueller
- Department of Medicine, Hematology/Oncology, Johann Wolfgang Goethe University, Theodor-Stern-Kai 7, Frankfurt, Germany.
| | | | | | | | | | | | | |
Collapse
|
16
|
Gueller S, Goodridge HS, Niebuhr B, Xing H, Koren-Michowitz M, Serve H, Underhill DM, Brandts CH, Koeffler HP. Adaptor protein Lnk inhibits c-Fms-mediated macrophage function. J Leukoc Biol 2010; 88:699-706. [PMID: 20571037 DOI: 10.1189/jlb.0309185] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The M-CSFR (c-Fms) participates in proliferation, differentiation, and survival of macrophages and is involved in the regulation of distinct macrophage functions. Interaction with the ligand M-CSF results in phosphorylation of tyrosine residues on c-Fms, thereby creating binding sites for molecules containing SH2 domains. Lnk is a SH2 domain adaptor protein that negatively regulates hematopoietic cytokine receptors. Here, we show that Lnk binds to c-Fms. Biological and functional effects of this interaction were examined in macrophages from Lnk-deficient (KO) and WT mice. Clonogenic assays demonstrated an elevated number of M-CFUs in the bone marrow of Lnk KO mice. Furthermore, the M-CSF-induced phosphorylation of Akt in Lnk KO macrophages was increased and prolonged, whereas phosphorylation of Erk was diminished. Zymosan-stimulated production of ROS was increased dramatically in a M-CSF-dependent manner in Lnk KO macrophages. Lastly, Lnk inhibited M-CSF-induced migration of macrophages. In summary, we show that Lnk binds to c-Fms and can blunt M-CSF stimulation. Modulation of levels of Lnk in macrophages may provide a unique therapeutic approach to increase innate host defenses.
Collapse
Affiliation(s)
- Saskia Gueller
- Department of Hematology and Oncology, Johann Wolfgang Goethe University, Frankfurt, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Han L, Schuringa JJ, Mulder A, Vellenga E. Dasatinib impairs long-term expansion of leukemic progenitors in a subset of acute myeloid leukemia cases. Ann Hematol 2010; 89:861-71. [PMID: 20387067 PMCID: PMC2908401 DOI: 10.1007/s00277-010-0948-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 03/17/2010] [Indexed: 11/25/2022]
Abstract
A number of signaling pathways might be frequently disrupted in acute myeloid leukemia (AML). We questioned whether the dual SRC/ABL kinase inhibitor dasatinib can affect AML cells and whether differences can be observed with normal CD34(+) cells. First, we demonstrated that normal cord blood (CB) CD34(+) cells were unaffected by dasatinib at a low concentration (0.5 nM) in the long-term culture on MS5 stromal cells. No changes were observed in proliferation, differentiation, and colony formation. In a subset of AML cases (3/15), a distinct reduction in cell proliferation was observed, ranging from 48% to 91% inhibition at 0.5 nM of dasatinib, in particular, those characterized by BCR-ABL or KIT mutations. Moreover, the inhibitory effects of dasatinib were cytokine specific. Stem cell factor-mediated proliferation was significantly impaired, associated with a reduced phosphorylation of ERK1/2 and STAT5, whereas no effect was observed on interleukin-3 and thrombopoietin-mediated signaling despite SRC activation. In conclusion, this study demonstrates that dasatinib is a potential inhibitor in a subgroup of AML, especially those that express BCR-ABL or KIT mutations.
Collapse
Affiliation(s)
- Lina Han
- Department of Hematology, University of Groningen and University Medical Center Groningen, P.O. Box 30001, 9700 RB Groningen, the Netherlands
- Department of Hematology, The First Clinical College of Harbin Medical University, Harbin, China
| | - Jan Jacob Schuringa
- Department of Hematology, University of Groningen and University Medical Center Groningen, P.O. Box 30001, 9700 RB Groningen, the Netherlands
| | - André Mulder
- Department of Clinical Chemistry, University of Groningen and University Medical Center Groningen, Groningen, the Netherlands
| | - Edo Vellenga
- Department of Hematology, University of Groningen and University Medical Center Groningen, P.O. Box 30001, 9700 RB Groningen, the Netherlands
| |
Collapse
|
18
|
DiNitto JP, Deshmukh GD, Zhang Y, Jacques SL, Coli R, Worrall JW, Diehl W, English JM, Wu JC. Function of activation loop tyrosine phosphorylation in the mechanism of c-Kit auto-activation and its implication in sunitinib resistance. J Biochem 2010; 147:601-9. [PMID: 20147452 DOI: 10.1093/jb/mvq015] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The activation of receptor tyrosine kinases (RTKs) is tightly regulated through a variety of mechanisms. Kinetic studies show that activation of c-Kit RTK occurs through an inter-molecular autophosphorylation. Phosphopeptide mapping of c-Kit reveals that 14-22 phosphates are added to each mol of wild-type (WT) c-Kit during the activation. Phosphorylation sites are found on the JM, kinase insert (KID), c-terminal domains and the activation loop (A-loop), but only the sites on the JM domain contribute to the kinase activation. The A-loop tyrosine (Y(823)) is not phosphorylated until very late in the activation (>90% completion), indicating that the A-loop phosphorylation is not required for c-Kit activation. A sunitinib-resistant mutant D816H that accelerates auto-activation by 184-fold shows no phosphorylation on the A-loop tyrosine after full activation. A loss-of-phosphorylation mutation Y823F remains fully competent in auto-activation. Similar to WT and D816H, the unactivated Y823F mutant binds sunitinib and imatinib with high affinity (K(D) = 5.9 nM). But unlike the WT and D816H where the activated enzymes lose the ability to bind the two drugs, activated Y823F binds the two inhibitors effectively. These observations suggest that the A-loop of activated Y823F remains flexible and can readily adopt unactivated conformations to accommodate DFG-out binders.
Collapse
Affiliation(s)
- Jonathan P DiNitto
- Pfizer Research Technology Center, 620 Memorial Drive, Cambridge, MA 02139, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
19
|
Masson K, Rönnstrand L. Oncogenic signaling from the hematopoietic growth factor receptors c-Kit and Flt3. Cell Signal 2009; 21:1717-26. [PMID: 19540337 DOI: 10.1016/j.cellsig.2009.06.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 06/04/2009] [Accepted: 06/09/2009] [Indexed: 01/01/2023]
Abstract
Signal transduction in response to growth factors is a strictly controlled process with networks of feedback systems, highly selective interactions and finely tuned on-and-off switches. In the context of cancer, detailed signaling studies have resulted in the development of some of the most frequently used means of therapy, with several well established examples such as the small molecule inhibitors imatinib and dasatinib in the treatment of chronic myeloid leukemia. Impaired function of receptor tyrosine kinases is implicated in various types of tumors, and much effort is put into mapping the many interactions and downstream pathways. Here we discuss the hematopoietic growth factor receptors c-Kit and Flt3 and their downstream signaling in normal as well as malignant cells. Both receptors are members of the same family of tyrosine kinases and crucial mediators of stem-and progenitor-cell proliferation and survival in response to ligand stimuli from the surrounding microenvironment. Gain-of-function mutations/alterations render the receptors constitutively and ligand-independently activated, resulting in aberrant signaling which is a crucial driving force in tumorigenesis. Frequently found mutations in c-Kit and Flt3 are point mutations of aspartic acid 816 and 835 respectively, in the activation loop of the kinase domains. Several other point mutations have been identified, but in the case of Flt3, the most common alterations are internal tandem duplications (ITDs) in the juxtamembrane region, reported in approximately 30% of patients with acute myeloid leukemia (AML). During the last couple of years, the increasing understanding of c-Kit and Flt3 signaling has also revealed the complexity of these receptor systems. The impact of gain-of-function mutations of c-Kit and Flt3 in different malignancies is well established and shown to be of clinical relevance in both prognosis and therapy. Many inhibitors of both c-Kit or Flt3 or of their downstream substrates are in clinical trials with encouraging results, and targeted therapy using a combination of such inhibitors is considered a promising approach for future treatments.
Collapse
Affiliation(s)
- Kristina Masson
- Experimental Clinical Chemistry, Wallenberg Laboratory, Department of Laboratory Medicine, Malmö University Hospital, Lund University, 20502 Malmö, Sweden
| | | |
Collapse
|
20
|
Takaki S. [Sh2b3/Lnk family adaptor proteins in the regulation of lymphohematopoiesis]. NIHON RINSHO MEN'EKI GAKKAI KAISHI = JAPANESE JOURNAL OF CLINICAL IMMUNOLOGY 2009; 31:440-7. [PMID: 19122374 DOI: 10.2177/jsci.31.440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Sh2b3/Lnk consisting of an N-terminal proline-rich region, PH-, SH2-domains and a tyrosine phosphorylation site, forms an intracellular adaptor protein family conserved from drosophila to mammals, together with Sh2b1/SH2-B and Sh2b2/APS (adaptor protein with PH and SH2 domains). Lnk negatively regulates lymphopoiesis and early hematopoiesis. The lnk-deficiency results in enhanced production of B cells, and expansion as well as enhanced function of hematopoietic stem cells (HSCs), demonstrating negative regulatory functions of Sh2b3/Lnk in cytokine signaling. Our recent studies also revealed that Sh2b3/Lnk functions in responses controlled by cell adhesion and in crosstalk between integrin- and cytokine-mediated signaling. Importantly, recent genome-wide association studies of the autoimmune type 1 diabetes or celiac disease identified risk variants in the SH2B3/LNK region, indicating possible unrevealed functions mediated by this adaptor molecule. This review summarizes roles of Sh2b3/Lnk in the regulation of B-lymphopoiesis and HSCs expansion and function, and briefly introduces our approach for modulating HSCs function by targeting Sh2b3/Lnk-mediated pathways.
Collapse
Affiliation(s)
- Satoshi Takaki
- Research Institute, International Medical Center of Japan
| |
Collapse
|