Proliferation and Fibrosis
Dr Zhonglin Chai
Head, Proliferation and Fibrosis
Laboratory Research Overview
Research in the Proliferation and Fibrosis Laboratory focuses on:
(1) The biological function of Cell Division Autoantigen 1 (CDA1) and the pathological role it plays in diabetic complications;
(2) Ttranslational studies to validate CDA1 as a molecular target and to develop potential novel strategies to prevent and treat diabetic complications such as diabetic nephropathy and diabetes-accelerated atherosclerosis.
CDA1 was identified and cloned several years ago by our group. CDA1 was named to reflect our initial specific finding that CDA1 arrested growth of HeLa cells when overexpressed (JBC, 2001). This anti-proliferative effect of CDA1 was subsequently found to be mediated by the cyclin-dependent kinase inhibitor protein, p21Waf1/Cip1 (p21) (JBC, 2007). Furthermore, CDA1 was found to be able to induce p53 and to activate ERK MAPK signalling pathway, which are required for CDA1-induced upregulation of p21 gene (JBC, 2007). p21 is also upregulated by Transforming Growth Factor beta (TGF-ß), requiring activation of the ERK MAPK pathway and involvement of p53 or p53 family members such as p63 and p73.
TGF-ß, with its pro-fibrotic effect, has been known to be a critical growth factor for diabetic nephropathy and diabetes-accelerated atherosclerosis associated with tissue fibrosis or scarring, a condition with excess accumulation of extracellular matrix proteins such as various types of collagen and fibronectin. TGF-ß action is enhanced in diabetic nephropathy and diabetes-accelerated atherosclerosis. Diabetic nephropathy has clearly been shown to be at least partly TGF-ß dependent and attenuated by anti-TGF-ß strategies. ACE inhibitor and/or angiotensin II receptor blockers targeting the profibrotic role of angiotensin II via TGF-ß-dependent and -independent TGF-ß signaling pathways significantly improves cardiovascular outcomes, presumably partially as a result of attenuating atherosclerosis.
Recently, we have demonstrated that CDA1 has a synergistic action with TGF-ß in stimulating production of extracellular matrix proteins in the vasculature and in kidney. This is due to the ability of CDA1 to amplify the TGF-ß signalling via modulating the TGF-ß type I receptor (TßRI). Indeed, CDA1 expression levels are elevated in kidneys of diabetic subjects with nephropathy as well as in human atherosclerotic plaques. CDA1 expression levels are also elevated in the experimental diabetic nephropathy models in spontaneous hypertensive rats (SHRs) and in ApoE knockout mice, as well as in atherosclerosis in diabetic ApoE knockout mice (KI, 2010; Diabetologia, 2010).
Targeting CDA1, using retroviral or adenoviral delivered expression of siRNA, effectively block the activity of TGF-ß in stimulating gene expression of collagen, with TGF-ß signalling significantly attenuated, in cultured human renal cells and mouse vascular cells (KI, 2010; Diabetologia, 2010), indicating a likely efficacy of targeting CDA1 for preventing and treating tissue fibrosis.
In order to develop a strategy to target CDA1's profibrotic effect, we have identified a novel protein interacting with CDA1, which we have named CDA1 binding protein 1 (CDA1BP1). We have shown that this CDA1/CDA1BP1 interaction is required for CDA1's profibrotic action. Our pilot study shows that interruption of this interaction seems to be effective to inhibit gene expression of collagen I and III in human renal cells. We are currently collaborating with experts from Monash, ANU and WEHI to further develop a drug-like agent to target CDA1.
Research Focus
- Biological role for CDA1 in regulating cell division and production of extracellular matrix proteins
- Molecular basis for CDA1 to modulate intracellular signalling pathways
- Pathological role of CDA1 in diseases
- Regulation of CDA1 expression in physiology and pathology
- Structural studies of the CDA1/CDA1BP1 interaction
- Drug development to target CDA1
Research Projects
Role for CDA1 in diabetic nephropathy
Group Leader: Dr Zhonglin Chai
Aim: To establish the pathological role of Cell Division Autoantigen 1 (CDA1) in diabetic nephropathy and to demonstrate the efficacy of targeting CDA1 in attenuating the profibrotic effect of Transforming growth factor beta (TGF-ß).
Background: TGF-ß is a major player in diabetic nephropathy due to its profibrotic effect. CDA1 is a molecule we recently identified. We have demonstrated that CDA1 influences pathways known to be regulated by TGF-ß. Therefore, we hypothesize that CDA1 may play a role in TGF-ß mediated extracellular matrix (ECM) accumulation in diabetic nephropathy. Targeting CDA1 may attenuate TGF-ß stimulated production of ECMs. Genetic knockout in mouse may prevent or attenuate the development of nephropathy caused by diabetes in vivo.
Methods: Diabetes will be induced in mice by streptozotocin injection. Wild type and CDA1 gene knockout mice will be used. Kidney function and structure will be examined. Expression of CDA1, profibrotic molecules and ECM will be examined in kidneys from diabetic and non-diabetic rodents including wild type mice, ApoE KO mice, CDA1 KO mice and ApoE/CDA1 double knockout (dKO) mice. The role of CDA1 in TGF-ß-mediated signaling and ECM production will be examined by using retrovirus and adenovirus constructs to silence or overexpress CDA1 in a human renal cell line, HK-2, and/or in renal cells isolated from wild type and CDA1 KO mice, in the presence and absence of TGF-ß. Newly developed agent to target CDA1 will be tested in cultured cells and in animals for its efficacy to reduce ECM production, fibrosis and nephrapathy.
Lab Head Profile
Dr Zhonglin Chai has trained as a veterinarian, with a Bachelor's degree in Veterinary Medicine (1978 - 1982) and a Master's degree in the field of Immunology and Microbiology (1983 - 1986) in China. He did his PhD at CSIRO and Deakin University in Australia (1991 -1995). He joined Professor Ban-Hock Toh's research team in the Department of Immunology, Faculty of Medicine, Monash University as a postdoctoral research fellow (1995 - 2000), where he identified and cloned the molecule, Cell Division Autoantigen 1 (CDA1).
Dr Chai joined Baker IDI in the Molecular Hypertension Laboratory led by A/Prof Zygmunt Krozowski in 2001, where he initiated collaboration with Dr Zemin Cao and Prof Mark Cooper to investigate the role of CDA1 in diabetic complications and subsequently joined the Diabetes and Metabolism Division led by Prof Cooper as a Laboratory Head. Dr Chai leads a research team with Postdoctoral Fellows, Senior Research Assistant and Visiting Scholars/Doctors. Dr Chai has been supervising Honours, Master and PhD students with a position of Honorary/Adjunct Lecturer in the Department of Immunolgy, Monash University since 2004.
Achievements/Awards
- Overseas Postgraduate Research Scholarship, Australian Federal Government (1991-1994)
- PhD scholarship, Deakin University (1991-1994)
- International Patents:
PCT/AU01/01418 (lapsed);
PCT/AU2004/000873 (national phase);
PCT/AU2010/000073
Publication Highlights
- Chai Z, Sarcevic B, Mawson A, Toh B-H. SET-related Cell Division Autoantigen-1 (CDA1) Arrests Cell Growth. J Biol Chem 2001;276:33665-33674.
- Tu Y, Wu W, Wu T, Cao Z, Wilkins R, Toh B-H, Cooper ME, Chai Z. Antiproliferative autoantigen CDA1 transcriptionally upregulates p21Wafl/Cip1 by activating p53 and MEK/ERK1/2 MAPK pathways. J Biol Chem 2007;282(16):11722-11731.
- Pham Y, Tu Y, Wu T, Allen TJ, Calkin AC, Watson AM, Li J, Jandeleit-Dahm KA, Toh B-H, Cao Z, Cooper ME, Chai Z. Cell division autoantigen 1 plays a profibrotic role by modulating downstream signalling of TGF-beta in a murine diabetic model of atherosclerosis. Diabetologia 2010;53:170-179.
- Tu Y, Wu T, Dai A, Pham Y, Chew P, de Haan JB, Wang Y, Toh B-H, Zhu H, Cao Z, Cooper ME, Chai Z. Cell division Autoantigen 1 enhances signaling and the profibrotic effects of transforming growth factor-ß in diabetic nephropathy. Kidney International 2010 Oct 20;in press.
- Toh B-H, Tu Y, Cao Z, Cooper ME, Chai Z. Role of Cell Division Autoantigen-1 (CDA1) in Cell Proliferation and Fibrosis. Genes 2010;1(3):335-348.
Key Staff
| Scientific Staff: | Dr Zemin Cao |
| Dr Yugang Tu | |
| Dr Tieqiao Wu | |
| Ms Aozhi Dai | |
| Students: | Jiaze Li |
| Yen Pham | |
