Cappai Laboratory
| Contact: | Roberto Cappai |
|---|---|
| Phone: | +61 3 8344 5868 |
| Fax: | +61 3 8344 4004 |
| Email: | r.cappai@unimelb.edu.au |
The Cappai laboratory studies the molecular, cellular and structural interactions that result in Alzheimer's disease, prion disease and Parkinson's disease. The group has expertise in a diversity of molecular, biophysical and cell biology techniques, thus allowing different approaches to be applied to a given problem. The laborartory is located in the Bio21 Institute, 30 Flemington Rd, Parkville. www.bio21.org
Key research areas are:
Alzheimer's disease (AD)
The key pathological hallmarks of AD are the extracellular amyloid plaques and the intracellular tangles. The principle component of plaques is the amyloid beta peptide (Aβ). The Aβ peptide is derived from the proteolytic cleavage of the amyloid precursor protein (APP). The Aβ peptide is believed to provide the neurotoxic insult that causes the neurodegeneration that leads to AD.
Functional studies of the APP-family.
The normal function of APP and the amyloid precursor-like proteins (APLP1 and APLP2) is unknown. The current data suggests they have a role in modulating cellular viability, since reducing the redundancy of the APP-gene family in APP-family double and triple knockout mice can lead to a lethal phenotype. Current studies are using APP-family knockout mice for in vitro cell based assays and in vivo whole animal studies to determine how APP-family expression affects cellular function. A major effort involves studying the N-terminal Cu-binding domain (CuBD) which has a role in modulating Cu homeostasis and Cu-mediated toxicity. A molecular target for the APP:Cu complex is the proteoglycan molecule called glypican-1. The SorLA protein has been identified as a key regulator of APP. We are delineating the key residues that mediate this interaction. These studies will provide a clearer insight into the normal function of APP.
Mechanisms of amyloid toxicity.
The cellular and molecular factors mediating Aβ neurotoxicity remain poorly defined. Cell culture models are being used to identify the cellular and subcellular changes that occur following exposure to toxic Aβ. The proteins and cellular factors that modulate Aβ toxicity are being investigated including lipids and tau. These studies will identify the neurotoxic Aβ species, markers for Aβ toxicity and targets that can be inhibited to prevent neurotoxicity.
Structural biology of the amyloid precursor protein (APP).
The aim of this project is to understand the three dimensional structure of the APP molecule either alone or in co-complex with APP-binding proteins. Knowing the structure of APP will provide insights into APP function and the structures will also identify targets upon which to develop drugs to modulate APP processing and therefore prevent Aβ generation.
Parkinson's disease (PD)
PD is a movement disorder caused by the loss of neurons from the substantia nigra. The key pathological hallmark of PD is the intracellular inclusions called Lewy bodies which are composed mainly of the α-synuclein protein. In addition to α-synuclein a number of other genes have been identified using genetic studies to directly cause PD in either an autosomal dominant or recessive manner.
Structural properties of α-synuclein.
The α-synuclein protein is a cytoplasmic protein that undergoes a structural transition from an unfolded state into an α-helical containing conformation. We have been studying the factors that modulate this structural change and shown that dopamine and membranes can alter the biophysical properties of α-synuclein. Our goal is to relate these in vitro studies to cell based assays and in vivo models of PD.
Prion disease
The prion diseases which include Creutzfeldt-Jakob Disease (CJD) and mad cow disease are a group of transmissible neurodegenerative diseases. The infectious agent is believed to be composed solely of a protein called the prion protein and devoid of nucleic acid.
The structural and biophysical properties of the prion molecule.
Our work uses a synthetic peptide of the PrP molecule corresponding to residues 106-126 as a model for neurotoxic PrP to study the cellular and subcellular factors responsible for PrP106-126 toxicity and to correlate this to its biophysical properties. We are seeking to extend these studies into the full-length forms of PrP and its behaviour in vitro and in cell culture
Objectives
- To develop therapeutics and imaging agents by identifying the key molecular interactions and cellular pathways that are critical for neurotoxicity and pathology.
- Determining the normal function of the proteins involved in AD, PD and prion disease.
- Solving the structures of the proteins involved in AD, PD and prion disease.
Major Achievements
- Identifying APP as a modulator of metal homeostasis.
- Identifying dopamine as a modulator of α-synuclein aggregation
- Identifying glypican-1 as a target for the APP:Cu complex.
- Solving the structure of the N-terminal growth factor and copper binding domains of APP.
- Identifying SorLA as a key modulator of APP processing.
Techniques
- Molecular biology
- Cell biology
- Protein expression and purification
- Structural biology
- Neurochemistry
Collaborations
Departmental:
Drs Kevin Barnham, Steven Collins, Janetta Culvenor, Cyril Curtain, Genevieve Evin, Qiao-Xin Li and Tony White
University:
Assoc Prof James Camakaris (Genetics), Dr Andrew Hill (Biochemistry)
External:
National Collaborators
- Prof Colin Masters, Ashley Bush and Dr Robert Cherny.
International Collaborators
- Prof Gerd Multhaup, Free University, Berlin, Germany
- Prof Lars-Åke Fransson, Dr Katrin Mani, Lund University, Lund, Sweden
- Dr Olav Andersen, University of Aarhus, Denmark
- Prof Maheswari, University of Madras, Chennai, India
- Prof K.P Mohanakumar, Indian Institute of Chemical Biology, Kolkata, India
- Dr Frédéric Mascarelli, INSERM, Centre de Recherche des Cordeliers, Paris, France
- Dr Sasanka Chakrabarti, Institute of Post-Graduate Medical Education & Research, Kolkata India
- Dr Fabio Falsone, Institute of Chemistry, University of Graz, Austria
Funding
- NHMRC Program Grant
- NHMRC Senior Research Fellowship
- NHMRC Project Grant
Recent Publications
- Barnham K.J., Kenche V.B., Ciccotosto G.D., Smith D.P., Tew D.J., Liu X., Perez K., Cranston G.A., Johanssen T.J., Volitakis I., Bush A.I., Masters C.L., White A.R.,, Smith J.P., Cherny R.A and Cappai R. Platinum based inhibitors of amyloid-β as therapeutic agents for Alzheimer’s disease. Proceeding of the National Academy of Sciences (USA) (2008) 105: 6813– 6818
- Needham B.E., Wlodek M.E., Ciccotosto G.D., Fam B.C., Masters C.L., Proietto J, Andrikopoulos S. and Cappai R. Identification of the Alzheimer's disease amyloid precursor protein (APP) and its homolog APLP2 as essential modulators of glucose and insulin homeostasis and growth. Journal of Pathology (2008) 215: 155-163
- Smith D.P., Tew D.J., Hill A.F., Bottomley S.P., Masters C.L., Barnham K.J. and Cappai R. Formation of a high affinity lipid-binding intermediate during the early aggregation phase of α-synuclein. Biochemistry (2008) 47: 1425-1434
- Cappai R., Leck S-L., Tew D.J., Williamson N.A., Smith D.P., Galatis D., Sharples R.A., Curtain C.C., Ali F., Cherny R.A., Culvenor J.G., Bottomley S.P., Masters C.L., Barnham K.J. and Hill A.F. Dopamine promotes a-synuclein aggregation into SDS-resistant soluble oligomers via a distinct folding pathway. FASEB Journal (2005) 19: 1377-1379.
- Cappai R., Cheng F., Ciccotosto G.D., Needham B.E., Masters C.L., Multhaup G., Fransson L-A and Mani K. The Amyloid Precursor Protein (APP) of Alzheimer disease and its paralog APLP2 modulate the Cu/Zn-NO catalyzed degradation of glypican-1 heparan sulfate in vivo. Journal of Biological Chemistry (2005) 280: 13913–13920
- Barnham K.J, Haeffner F., Ciccotosto G.D., Curtain C.C., Tew D., Mavros C., Beyreuther K., Carrington D., Masters C.L., Cherny R.A., Cappai R. and Bush A.I. Tyrosine gated electron transfer is key to the toxic mechanism of Alzheimer’s disease b-amyloid. FASEB Journal (2004) 18: 1427-1429
- Barnham K.J, Ciccotosto G.D., Tickler A.K., Ali F.E., Smith D.G., Williamson N.A., Lam Y-H., Carrington D., Tew D., Kocak G., Volitakis I., Separovic F., Barrow C.J., Wade J.D., Masters C.L., Cherny R.A., Curtain C.C., Bush A.I.,. and Cappai R. Neurotoxic, redox-competent Alzheimer’s b-amyloid is released from lipid membrane by methionine oxidation. Journal of Biological Chemistry (2003) 278: 42959–42965.
- Barnham K.J, McKinstry W.J., Multhaup G., Galatis D., Morton C.J., Curtain C.C., Williamson N.A., White A.R., Hinds M.G., Norton R.S., Beyreuther K., Masters C.L., Parker M.W. and Cappai R. Structure of the Alzheimer’s disease amyloid precursor protein copper binding domain: a regulator of neuronal copper homeostasis. Journal of Biological Chemistry (2003) 278:17401-17407
- Jobling M.F., Huang X., Stewart L.R., Barnham K.J., Curtain C., Volitakis I., Perugini M., White A.R., Cherny R., Masters C.L., Barrow C.J., Collins S.J., Bush A.I., and Cappai R. Copper and zinc binding modulates the aggregation and neurotoxic properties of the prion peptide PrP106-126. Biochemistry (2001) 40, 8073-8084