Molecular Medicine

Introduction

The Division of Molecular Medicine is comprised of several groups and laboratories that pursue fundamental research into cellular, molecular and genetic processes of relevance to medicine. Common medical problems investigated by members of the Division include cancer, diabetes, autoimmune disease and mental illness. Several of the groups with overlapping interests have formed collaborative research programs within and between the separate Divisions. These programs focus on specific areas and generate synergies that could not be achieved independently. For example, the Integrative Genetics Program is pooling the expertise of several groups in order to address fundamental questions regarding the biological and clinical significance of genetic diversity. These studies have implications for understanding of the genotype / environmental interactions that appear to have a role in many disorders such as common forms of mental illness that are characterized by anxiety and depression, Parkinson's disease and different forms of cancer.

Another major program in the Division is focused on the development and regulation of the immune system and the molecular and physiological analysis of autoimmunity and its contribution to the pathogenesis of diseases such as diabetes and multiple sclerosis.

The research carried out within the Division and its associated programs has been enhanced recently by the establishment of the Medical Genome Centre. The mutant mice generated in the Centre will provide a range of animal models for the detailed study of the many biological processes under investigation within the Division.

The groups within the Division continuously review their research findings to identify those aspects with potential clinical applications. Many of the groups have well established collaborations with hospital based researchers to facilitate the transfer, to the clinic, of advances made in fundamental research.

The establishment of the Centre for Bioinformational Science in a joint venture with the School of Mathematical Sciences has been an exciting development within the Division. The Centre will foster cross campus developments in the application of bioinformatics to medical research.

Professor Philip Board
Head of Division

Essays

Molecular Genetics Group
Professor Philip Board

Because human beings are constantly exposed to a variety of environmentally derived chemicals that effect the normal function of our cells, tissues and organs, we have evolved a complex group of enzymes that detoxify these compounds and provide an important layer of protection against their deleterious effects. It is now very clear that an individual's genetically determined compliment of detoxication enzymes has a significant influence on their response to a variety of therapeutic drugs and environmentally derived toxins. The work of the Molecular Genetics Group is aimed at gaining a fundamental understanding of the molecular and biochemical mechanisms that underlie individual responses to such compounds. One of the major research interests of the Molecular Genetics Group is the role played by the glutathione linked enzymes such as the glutathione transferases (GSTs) in the metabolism and detoxification of therapeutic drugs and environmentally derived carcinogens and toxins.

The GSTs are a large family of enzymes and previous studies have shown that they can be subdivided into a number of different classes that have characteristic structural variations, substrate preferences and sites of expression. The GSTs function by conjugating glutathione to the target chemical thereby making it more water soluble and making it recognisable by an export pump that expels glutathione conjugates from cells.

Genetically determined deficiency in the expression of some GSTs can be a risk factor for lung, stomach and skin cancer. In contrast, over expression of GSTs has been associated with resistance to cancer chemotherapy. Genetic variations that cause subtle changes in GST function can be clinically important. For example, we found that a variant form of glutathione transferase GSTP1 that works with different substrates was associated with the occurrence of Parkinson's disease in patients who had been exposed to pesticides.

To gain a comprehensive understanding of the genetic diversity in response to environmental toxins and therapeutic drugs it will be necessary to identify all the enzymes involved in detoxication processes and to identify the common genetic variants of these enzymes that contribute to functional differences. The recent expansion of the Expressed Sequence Tag database (EST) to include more than a million DNA sequences encoding copies of most active human genes has provided a remarkable resource for the identification of new genes and polymorphisms. We have developed novel screening strategies that have successfully identified several new glutathione transferase gene families and a number of novel polymorphisms. The new enzymes discovered by this data mining approach have been shown to catalyse unique detoxification reactions and to participate in metabolic pathways not previously attributed to the action of glutathione transferases. For example we recently discovered that a GST we have termed Omega can inhibit ryanodine receptor calcium release channels in the heart.

The strategies we have developed for screening the EST database can be readily applied to other genes and gene families and will be of great value in the identification of new genes and polymorphic variants of pharmacogenetic interest.

Developmental Physiology Group
Peter McCullagh

The principal project underway in the Developmental Physiology Group during 2000, has been directed to elucidating details of migratory and microenvironmental conditions regulating development of the immune system in the fetal lamb. Both B- and T- cell development may be interpreted as a sequence of migration of increasingly mature cells between the successive microenviroments required for the following stage.

Our approach has been twofold, on one hand to detect migrational streams by selective interruption of migration and, on the other, to attempt to simulate specific fetal microenvironmens in vitro where they will more accessible to study. It has been found that interruption of migration of immature B cells from spleen to Peyer's patches requires the removal not only of the spleen itself but also of the prescapular lymph nodes. In the absence of the latter excision, these nodes effectively assume splenic functions. Whether the normal migratory process entails a stages migration from spleen to nodes and then to the Peyer's patches has not yet been determined

We have replicated in tissue culture the B lymphocyte-epithelial cell interactions that define the microenvironment of the ileal Peyer's patch, the primary B lymphocyte organ of the fetal lamb. Mixed suspensions of ileal epithelial cells, lymphocytes and fibroblasts from fetuses of 63-103 days gestation organized into macroscopically visible agglomerates within 72 hours of initiating culture. Agglomerates contained translucent spherical cavities, were enclosed within a marginal cell layer and surrounded by an expanding corona of emigrating cells. The lining of the cavities and marginal layer consisted of well differentiated, polarized columnar ileal epithelial cells. B lymphocytes differentiated into two discrete populations reproducing the characteristics of intact fetal ileal Peyer's patches. B cells opposed to follicle-associated epithelium (FAE) within agglomerates underwent apoptosis, a characteristic of negative selection of autoreactive cells. Emigrant B cells proliferated and expressed a differentiation marker characteristic of positive selection. Differentiation of ileal epithelial cells into FAE typical of Peyer's patches was markedly accelerated. The mutually inductive influences of intestinal epithelial cells and B lymphocytes in these agglomerates replicates normal mid-gestational fetal development of the mucosal immune system and affords new opportunities for its investigation

In contrast to B cell maturation, which requires migration between discrete tissues, all stages of T cell development occur within one organ, the thymus, albeit with intra-thymic migration between discrete microenvironments. We have actively sought to determine whether other lymphoid tissues can undertake what are generally assumed to be exclusively thymic functions. Our preliminary studies indicate a highly reproducible re-location of at least some thymic functions to the prescapular lymph nodes after early thymectomy of the fetal lamb..

Autoimmunity / Genetic Manipulation Laboratory
Dr Brett Charlton

Autoimmunity and mechanisms of disease development in insulin dependent diabetes mellitus and multiple sclerosis

Our lab is studying the processes of autoimmune disease with a focus on type I diabetes and multiple sclerosis. To analyze the immunological and pathological process we use animal models of the disease, including transgenic and knockout mice, to isolate particular processes.We aim to understand what is abnormal in autoimmunity and determine new means of counteracting these abnormalities. Particular areas of study include the role of nitric oxide in autoimmunity, the role of Fas and fas ligand in diabetes and the role of the MHC in diabetes susceptibility.

Transplantation Immunobiology Laboratory
Dr C Simeonovic

Studies in the laboratory have focussed on the immunobiology of pancreatic islet xenotransplantation and allotransplantation in mice.

1. Role of activated macrophages in the rejection and survival of pig islet xenografts in mice

The rejection of fetal pig proislet xenografts in mice is a CD4 T cell-dependent process in which macrophages play an important role. To assess the potential for activated macrophages to act as effector cells in xenograft destruction, we have examined the relationship between proislet xenograft rejection, two principal markers of macrophage activation, transcription of iNOS and production of NO, and their temporal relationship to intragraft cytokine gene expression. Xenograft rejection in CBA/H mice correlated with early induction of intragraft host iNOS, IFN-gamma, IL-1b and TNF mRNA expression, marked intragraft production of NO (RNI) but not with elevated systemic levels of RNI. Activated macrophages may therefore contribute to xenograft destruction via local NO-mediated toxicity at the graft site. Nevertheless, pig proislet xenografts were rejected with normal kinetics in iNOS-/- mice; intragraft NO production was not detected despite porcine iNOS gene expression.

In contrast, QFA-induced high systemic RNI levels correlated with prolonged xenograft survival at 7 days post-transplant. Splenocytes from QFA-treated but not control mice at 7 and 22 days post-transplant, exhibited inhibition of secondary xenogeneic mouse anti-porcine MLR that was reversed by culture with 2mM NMA. Xenograft protection was temporary with complete rejection by day 22. Failure of activated macrophages to achieve indefinite xenograft survival suggests that other factors are also required. Macrophage potential to effect either destructive or protective roles after pig proislet xenotransplantation, suggests that such functions may depend on the site and magnitude of macrophage activation. Together these findings clearly demonstrate that high NO levels in the periphery are not damaging to xenogeneic islet tissue, neither host nor donor NO production is essential for islet xenograft rejection and consequently elevated plasma RNI levels do not represent a marker for rejection.

Charmaine J. Simeonovic, Damien V. Cordery, Barbara Van Leeuwen, Sarah K. Popp, Michelle J. Townsend, Michelle F. Paule, J. Dennis Wilson and William B. Cowden

2. No transmission of porcine C-type endogenous retrovirus (PERV) following pig proislet xenotransplantation in foetal lambs

In vitro evidence for transmission of endogenous porcine retroviruses from pig cell lines to cultured human cells has raised major concerns about retroviral transmission following the xenotransplantation of pig tissues. We set out to ascertain whether PERV transmission can occur in vivo following xenotransplantation of foetal pig proislets to recipient foetal lambs (in utero). This model provides optimal conditions for retroviral infection i.e. rapidly dividing host cells and no immunosuppression. Foetal lambs in utero at 56 days of gestation were thymectomised and pig proislets embedded in sheep plasma were grafted to the thymic space. At 5 to 84 days post- transplant (i.e. just before birth), the transplanted lambs were euthanased and various tissues (liver, spleen, lung, pancreas, heart, brain and kidney) were harvested and frozen in liquid nitrogen for DNA and RNA extraction. The pre-transplant recipient foetal lamb thymus, adult sheep liver, tissues harvested from untransplanted co-twin lambs, pig proislets, other fetal pig tissues and the PK15 cell line served as controls. PCR and RT-PCR using PERV A-specific, PERV B-specific, PERV C-specific or PERV ABC-common primers were used to identify PERV nucleotide sequences in extracted DNA (i.e. integrated into host genome) and RNA (viral genomes). PERV sequences were detected in DNA samples of pig proislets but not of liver, pancreas, heart, lung, kidney and brain samples from transplanted and control untransplanted foetal lambs. None of the cDNA samples yielded PERV-specific PCR products. These findings indicate that pig proislets carry endogenous PERV but lack active virus (PERV RNA). Following xenotransplantation of pig proislets to foetal lambs, there is no evidence for the transmission of PERV to host foetal lamb tissues and no evidence of integration of PERV DNA into the genome of transplanted lamb tissues.

David Mann, Adrian Gibbs, Peter McCullagh, J. Dennis Wilson and Charmaine Simeonovic

3. The role of chemokines in the rejection of murine proislet allografts

Chemokines are a large family of low molecular weight proteins which recruit immune cells to sites of infection and disease. Chemokines may therefore play a role in the recruitment of inflammatory cells to allograft sites, thereby facilitating graft rejection. Fetal CBA/H (H-2^k) or BALB/c (H-2^d) mouse proislets (12 donor equiv.) were transplanted beneath the kidney capsule of CBA/H mice. Mice were treated with phosphate-buffered saline (PBS:300ml/dose) or GK1.5 (anti-CD4) mAb (0.45mg Ig/100ml/dose) and 49-11.1 (anti-CD8) mAb (1.12mg Ig /200ml /dose) i.p. on days -1, 1, 3, 7 and 10. Grafts were harvested at 3-14 days post-transplant. Part of each graft was frozen in liquid freon for histology; the remainder was frozen in liquid nitrogen for RNA extraction and RT-PCR analysis of murine a-chemokines (IP-10, KC, and MIP-2), and b-chemokines (JE, TCA-4, RANTES, MIP-1 a, MIP-1b, and Eotaxin). Additional control allografts were transplanted to chemokine receptor knockout mice: CCR2-/-, CCR5-/- and their wildtype strain CCR+/+ (129/Ola x C57BL/6J). Grafts were harvested at days 3, 5 and 7 post-transplant for histological and immunohistochemical analyses. Rejecting allografts displayed enhanced intragraft expression of mRNA for the b- chemokines RANTES, MIP-1a and MIP-1 b as well as the a -chemokine IP-10 on days 5, 6, 10 and14. Allografts harvested from CCR5-/- (receptor for RANTES, MIP-1a and MIP-1b) mice at day 7 post-transplant showed delayed rejection; allografts in CCR2-/- and CCR+/+ mice were completely rejected. These findings suggest a role for RANTES, MIP-1a and MIP-1b in recruiting T cells into the graft site and in promoting the onset of allograft destruction. The early intragraft expression of chemokine mRNA may play a role in facilitating proislet allograft rejection; chemokine receptors may therefore represent a potential target for anti-rejection therapy.

Michelle Paule, William Kuziel and Charmaine Simeonovic

Ubiquitin Laboratory
Dr Rohan Baker

Dr Rohan Baker. Photo Karen Edwardss
The Ubiquitin Laboratory investigates the small protein ubiquitin; its role in the destruction of other proteins (proteolysis) in the cell; and in the consequences of aberrant proteolysis due to defects in the ubiquitin system.

Dr Rohan Baker

Complex processes such as cell growth, development, and gene expression, are controlled by proteins that are only required transiently and must be rapidly destroyed to control their activity. This is accomplished by attaching multiple ubiquitin proteins to the target, which "marks" it for destruction by a large proteolytic complex called the proteasome. Most of our research focuses on a family of enzymes called ubiquitin-specific proteases (USPs), that have the ability to cleave ubiquitin from such marked proteins, and thus slow or prevent their destruction. In this context, some USPs can be considered "proof-reading" components of the system, safeguarding a target from inappropriate ubiquitination (and thus destruction), and imposing a further level of regulation on the pathway.

We study USP enzymes using yeast as a model system, both because it is very amenable to genetic and biochemical studies, and also because the ubiquitin system is so highly conserved between yeast and humans, that insights we gain in yeast can be applied to our studies on mouse and human enzymes. Current work centres on Ubp15, one of a family of 16 USPs in yeast. Ubp15 binds directly to yeast multi-drug resistance (mdr) proteins, and Ubp15 can regulate drug sensitivity of cells, presumably by affecting function and/or degradation of mdr proteins. We are extending this work to the study of drug resistance in mouse and human cells.

We also use mice as a model organism to study human disease. We have previously identified a USP that functions as an oncogene in mice; that is, it causes cancer when overproduced. Others have linked the human version of this USP with certain types of lung cancer. We and our collaborators have shown that this USP interacts with the Retinoblastoma protein, which functions to prevent cell growth by keeping transcription factors (proteins that control gene expression) in check. The human genome project has revealed at least 28 USPs in humans; one of these is a very close relative of this oncogenic USP in both mouse and human cells, and it is also predicted to interact with the Retinoblastoma protein. Our current efforts are aimed at determining the functional significance of these interactions; whether these USPs traffic to the nucleus; and if the closely-related USP is also an oncogene. We are also studying novel USPs identified by the genome project.

Our results show that USPs can play important roles in regulating the ubiquitin pathway, and through this, processes such as cell growth. Aberrations in the function of these USPs may lead to cancer and disease.

Human Genetics Group
Professor Simon Easteal

Research in the Human Genetics Group is aimed at understanding the nature of genetic variation as it relates to disease. We take a broad view, recognising the importance of the evolutionary forces that have shaped the structure of the human genome and the nature of human genetic diversity. Our investigations can be divided into two areas: Mechanisms of gene and genome evolution, and the nature of human genetic and genomic variation.

Gene and genome evolution

In mammals genetic novelty arises through genetic and evolutionary processes, such as mutation, gene duplication, gene conversion, genetic drift and natural selection, occurring in large and structurally complex genomes. Information relating to genome and protein function, the processes by which functional novelty has arisen and patterns of species evolution are contained within DNA and protein sequences.

Susan Tan

Susan Tan. Photo Karen Edwards

We use a comparative approach to the interpretation of this information, investigating differences in genomes, genes and the proteins they encode, among related species, particularly humans and other primates.

Human genetic and genomic variation

Medical genetics has largely been focussed on understanding single gene defects. Less attention has been given to genetic disorders that have a polygenic basis, such as mental illness, cardiovascular disease and diabetes. Although these are more important from a public health point of view, they are technically more difficult to investigate. This situation is changing largely through the technological advances of the human genome project. Associated with this change is an increased recognition of the importance of the normal range of human genetic variation, and its importance in relation to disease prevention. Understanding the relationship between molecular genotypes and disease phenotypes becomes more dependent on population-based rather than family-based investigations. Our research is directed at understanding the basis of a number of genetic disorders, and of the patterns of normal genetic variation in human populations.

One particular focus is the genetic basis of personality variation, which is associated with a predisposition to common forms of mental illness involving depression and anxiety. This work is done in collaboration with the NH&MRC Centre for Mental Health Research.

Medical Genome Centre
Professor Chris Goodnow

Many of the health problems we face today - cancer, autoimmune diseases, allergy, cardiovascular disease, osteoporosis, - stem from a discordance between genetics and environment. Our genetic code was selected to survive for a shorter period of time in a very different world, and it is inevitably out of step with the lifestyles we lead today. In some cases we know what to do to fix this imbalance, like putting on a hat and sunscreen to offset genetic susceptibility to the sun. For many cancers and numerous other diseases such as rheumatoid arthritis, diabetes, osteoporosis or obesity, the solutions are not so straightforward.

Rapid advances in gene technology are bringing us to the point of visualizing the imbalance between our genetic code and lifestyle/environment. A worldwide effort has already given us a map and a "dictionary" of many of our genes - collectively referred to as our genome. The epic challenge for the next decade is to decipher what these gene words mean. How are they combined into the genetic language that guides the cells in our body and determines how well we cope with different environmental stresses? Which gene products are good targets for new drugs to prevent or cure common diseases? Differences in the spelling of those gene words underlie differences in susceptibility to modern diseases, and in response to particular therapies, and it is likely that technology will soon allow a list of spelling differences to be rapidly compiled from each person's unique genetic dictionary.

The Medical Genome Centre was officially opened in 1997 to promote research into the function of genes that underpin human health. To decipher the functional meaning of genes and their contextual interactions, laboratory mice represent a crucial Rosetta stone. Almost all of the genes in mice match a human counterpart with only small changes in their spelling. While surprising given the large differences in external appearance, the mouse and human genetic languages are in fact no more different than Chaucer's english and modern english. This underlying similarity makes it possible to define the function of human health genes in the mouse in a way that is impossible in humans.

The strategy being followed is genome-wide mutagenesis in the mouse at an unparalleled scale. In the last year, the Medical Genome Centre has successfully analysed a large panel of new mutant strains. These strains were derived from the first of a series of libraries of laboratory mice in which single letters in the spelling of many of the genes in the mouse genetic dictionary have been changed by random chemical mutagenesis. The ENU1 library comprised 185 pedigrees of ENU mutagenised C57BL/6 mice, bred 3 generations to yield at least 25 potentially recessive homozyogous offspring in each pedigree. Collectively, we estimate that this library scans 15,000 loss of function mutations. By visual inspection and high-throughput screening of blood, this library has yielded many new mutant mouse models to discover and understand genes controlling obesity and diabetes, cardiovascular disease, kidney disease, limb and spine abnormalities, eye function, melanocyte function, coordination, seizures, dermatitis, colitis, and disorders of lymphocyte development such as autoimmunity, immunodeficiency, and leukemia/lymphoma. Collaborative screening projects are underway with several other groups: with the Garvan Institute in Sydney using the library to discover genes affecting bone density and breast cancer; with the Walter and Eliza Hall Institute to discover genes controlling platelet and neutrophil function; with the University of California San Francisco to illuminate genes controlling lymphocyte migration; and with the Novartis Institute of Functional Genomics in San Diego to illuminate genes controlling brain functions.

State-of-the-art facilities for transgenic mouse production, sperm freezing, and database tracking of genetic and phenotypic data have been developed to support this resource and provide a service to researchers. The chromosomal location of the defective in each of the mutant strains has been or is currently being determined, employing an efficient strategy for gene mapping many mutant strains in parallel. Emerging information on the mouse and human genome will be used to identify the defective gene in each strain through resequencing of mRNA. In parallel, we have defined the precise cellular abnomalities brought about by each mutation by cell and biochemical analysis. The feasibility of proceeding quickly from mutant to gene and cellular process has been established using a strain that develops T cell leukemia (see ACRF Genetics Lab report).

Australian Cancer Research Foundation Genetics Laboratory

A one million dollar grant from the Australian Cancer Research Foundation in 1997 made possible the establishment of the ACRF Genetics Laboratory in the Medical Genome Centre. The laboratory's focus is on developing genome-wide mutagenesis resources for studying candidate human cancer genes and novel laboratory mouse models to accelerate cancer research at both the basic and clinical ends of the spectrum.

Four new mouse strains to illuminate cancer genes have been obtained from the ENU1 forward genetics library. One of these strains carries a single dominant gene defect that results in acute T cell lymphoblastic leukemia. Mr Peter Papathanasiou has mapped and identified the mutation in this strain, which creates a single change in a protein that appears to be frequently defective in human T cell lymphoblastic leukemia. The protein normally regulates expression of many other genes. Ms Adele Loy has mapped the mutation in another cancer-prone strain, which carries a gene defect that results in leukemia, lymphoma, osteosarcoma, chondrosarcoma and teratocarcinoma. At least ten new mouse strains that have recessive gene defects in lymphocyte development and growth regulation have also been obtained, and it is likely that these represent important leads on new targets for cancer vaccination and anti-lymphoma drugs.

A separate discovery project has begun, aimed at illuminating genes regulating solid tumours of the skin and cervix. This project involves a consortium with Dr Douglas Hanahan at the University of California in San Francisco, who has developed a sensitized mouse strain for skin and cervical cancer research, and Dr Simon Foote at the Walter and Eliza Hall Institute. The project is mapping cancer inhibitory genes between two inbred mouse strains, C57BL/6 and FVB, and conducting genome-wide mutagenesis to illuminate dominant and recessive skin cancer inhibitory genes.

Genes and functions discovered by these efforts will be available to the research community to help in three key areas: 1. primary prevention, where illuminating patterns of inherited susceptibility will help to resolve environmental risk factors and target preventive measures; 2. early diagnosis, where alterations in gene spelling and expression pattern will help to distinguish cancer cells early and predict the best course for treatment; 3. therapy and prevention of secondary tumours, where the genes identified will provide new targets for drugs and new avenues for chemotherapeutic or immunological intervention.

Goodnow Laboratory
Professor Chris Goodnow

Our research aims to understand how immune cells make a fundamental decision: either to fight or to disarm. The process of deciding which immune cells should fight and which should disarm is key to our ability to resist infection and parasitism. Mistakes in this process result in autoimmune diseases, allergy, lymphoma, and leukemia. Moreover, drugs and other ways to alter fight or disarm decisions are sorely needed to improve the success of organ transplantation and treatment of autoimmune diseases and metastatic cancer.

The immune system is made up of billions of immune cells called lymphocytes. By a remarkable gene shuffling process akin to a poker machine, each lymphocyte carries a unique receptor, enabling every lymphocyte to detect a different set of molecules termed antigens. Some lymphocytes have receptors for foreign antigens that are unique parts of the molecular makeup of different infectious organisms. When these rare lymphocytes bind a foreign antigen during an infection, they receive a signal to fight. The lymphocyte first multiplies to make many clones of itself, and then the cells elaborate destructive compounds that neutralize the infectious antigen.

By chance, other lymphocytes carry receptors for self antigens, ie. parts of our own normal tissues and body fluids. When a lymphocyte binds a self antigen it normally receives a signal to disarm. Instead of multiplying and producing destructive compounds, the lymphocyte either commits cell suicide by apoptosis or the cell disarms itself by becoming functionally tolerant, ie. less responsive to antigens and less able to multiply or produce destructive compounds.

For a long time it was not possible to see how self-reactive lymphocytes disarm themselves. Our laboratory has developed ways to visualize this process in genetically modified laboratory mice called transgenic mice. By studying cells in the transgenic mice, we have discovered that each immune cell must run through a complex series of fight or disarm checkpoints before it can be fully launched into an immune response. In some ways, the process resembles the sequence of fight/disarm decisions in a military missile launch, which serve a similar purpose of preventing friendly fire.

Members of the laboratory are deciphering different fight/disarm checkpoint processes, using a combination of biochemistry, cellular immunology, genetic analysis, and transgenesis. At each of these checkpoints, we are focussing much of our work on elucidating how it is that antigen receptors on lymphocytes can trigger several different cell fates ranging from cell proliferation to cell death. Two examples of our work are summarized below.

T cell tolerance and destruction of pancreatic islets.

The cellular and molecular processes regulating CD4 T cell responses to self antigens that are restricted to specific organs (organ-specific tolerance and autoimmunity) are being investigated through an NIH and JDRF-funded project involving a unique transgenic mouse model. The core of this model is a "TCR-transgenic" mouse where most CD4 T cells react with a model antigen, and where the model antigen is made by pancreatic islet b cells. The islet-reactive T cells are normally regulated so that they can cause inflammation of the pancreatic islets, but this inflammation does not progress to diabetes or autoantibody production. This regulation is broken by one or more genes from the NOD strain, an excellent animal model for spontaneous Type 1 diabetes in humans. A combination of non-MHC susceptibility genes from the NOD strain allows the T cells to reorganize the invading cells within the islets to promote antibody formation, islet destruction and diabetes. In the last year, Dr Sylvie Lesage has discovered that one of the main actions of the diabetes susceptibility genes is to dramatically reduce the efficiency of islet-reactive T cell deletion in the thymus and the the state of anergy in these cells in the periphery. In parallel, Dr Simon Prasad has shown that the diabetes-susceptible NOD genes also cause a profound imbalance in the production of different subsets of dendritic cells, which are key cells for regulating T cell tolerance and autoimmunity. The combination of these two cellular defects may explain susceptibility of particular individuals to Type 1 diabetes and other organs-specific autoimmune diseases. This experimental model provides a unique opportunity to define the molecular pathways regulating these diseases.

Memory receptor tail.

Our ability to resist infection stems from a cardinal property of the immune system, namely an ability to mobilise a much higher and faster antibody response when the antigens that make up a virus or bacteria are seen a second time. This phenomenon of immunological memory lasts for years after infection or immunisation, but its cellular and molecular basis is still poorly understood. In the last year, Mr Stephen Martin has defined a key role for the "BCR Tail sequence" in promoting memory-level antibody responses. It has been known for many years that B cells switch portions of the antibodies they produce from IgM to IgG as part of the memory process. Among the many changes that result from switching to IgG, one intriguing change is in the sequence and length of the antibody segment that serves as a receptor for antigen- the transmembrane and cytoplasmic tail. Through a sophisticated combination of transgenic mice and in vivo immunological analyses, Steve has shown that the memory-type IgG tail dramatically increases the number of progeny cells that are formed by proliferation of initially rare B cells that react to antigen. This finding explains the memory phenomenon by a localizing it to a precise sequence of amino acids and a specific process- augmenting the clonal burst. This finding has wide implications for vaccination, allergy and autoimmunity, where B cells bearing the memory tail are formed.

Staff - Division of Molecular Medicine

Professor and Head:
PG Board BSc (Hons), PhD (UNE)

School Technical Support Officer: (from June)
CE Woodhams, BAppSc (CCAE), GradDipInfSyst (Canb) (from June)
Divisional Administrator:
M Goodisson
Administrative Assistants:
G Noble, M Tankosic (until March)
Visiting Fellows:
M L Bassett, MB ChB (Otago), MD (Qld), FRACP
WM Burch, MSc (Melb), PhD (Lond), MIE (Aust)
J Cavanaugh, BSc, MS (North Carolina State University, PhD
A Killian, MSc (Silesian University)PhD(Silesian Uni)
F Lomas, MB, BS (Hons) (Syd), FRACP, DDU, FRACR
JE Dahlstrom, MB BS(Hons) (Syd), PhD, FRCPA
DP Dhall, MB ChB (Manchester), PhD (Aberdeen), MIBiol, MRCS, LRCP, FRACS
SG Nogrady, MB BS (Syd), FRACP

Developmental Physiology Group
Senior Fellow and Leader:
PJ McCullagh, MD BS (Melb), DPhil (Oxon), MRCP
School Visitors:
W Whitten, BVSc DSc (Syd), FAA
M Peek, MB, BS BSc (Med) (Hons) PhD, FRACOG, MRCOG
HA McKenzie, MSc PhD (Syd) FRACI
Technical Officers:
B Barancewicz, BRTC, AIST
K King, BAppSc, MedLabSci (Canberra) (until March)

Autoimmunity/Genetic Manipulation Laboratory
Fellow:
B Charlton, MB BS, PhD (UNSW)
Laboratory Technician:
J Kofler, DipApp AnimalSc (until June)

Transplantation Immunology Laboratory
Fellow:
CJ Simeonovic, BSc (Hons), PhD
Visiting Fellow:
JD Wilson, BSc (Hons), MB BCh, BAO (Hons), MD (Queens, Belfast), MRCP (U.K.), FRACP
A Gibbs, BSc (Hons), OhD (London)
M Gibbs, BSc, GradDip, P.Phil (Oxon)
School Associate
J Armstrong
Senior Technical Officers:
D Mann, BSc (Hons)
MJ Townsend, Ass Dip App Path. (Bruce TAFE)
Laboratory Technicians:
K Debono,
P Hamilton (Part-time from June)
S Popp, BSc, AssDipApSciBiol (CIT)
JC Zarb
R McMurray, (Part-time) (until June)

Human Genetics Group
Professor and Leader:
S Easteal, BSc (St Andrews), PhD (Griffith) (from July)
Senior Fellow:
S Easteal, BSc (St Andrews), PhD (Griffith) (until June)
Research Fellows:
G Chelvanayagam, BSc (UWA), PhD (UWA/EMBL) (until April)
Research Fellow:
G Huttley, BSc (Hons) (Macquarie); PhD (Univ California, Riverside, USA) (from October)
Postdoctoral Fellows:
G Huttley, BSc (Hons) (Macquarie); PhD (Univ California, Riverside, USA) (until October)
C Wise, BSc (Hons) (Monash); PhD (until October)
Visiting Fellows:
LS Jermiin, Cand. Scient. (Århus), PhD (LaTrobe)
N Saha, BSc (Calcutta), MBBS (Calcutta), MD (Punjab), PhD (Med) (Calcutta)
Senior Technical Officer:
X Tan, BSc, (Shandong University, Jinan), MSc (China Pharmaceutical Univ, Nanjing)
Technical Officers:
B Whittle, BSc (Hons) (until October)
Y Zhang, MSc (Xinjing, China)
A Mettenmeyer, BSc (Hons) (until Febuary)

Molecular Genetics Group
Professor and Leader:
PG Board, B.Sc (Hons), PhD (UNE)
Research Fellows:
G Chelvanayagam, BSc (UWA), PhD (UWA/EMBL) (from April until July)
Visiting Fellows:
D Liu, PhD (Syd) (until December
M Webb, MB BS, FRACP (UWA), FRCPA
D Le Couteur, MB BS (Hons) (Syd), FRACP, PhD (UQLD)
A Clarke, BSc, PhD (Victoria Uni, NZ)

Senior Technical Officer:
MA Coggan, BSc (Hons)
Laboratory Technicians:
L Langton, Ass Dip Sci (Pathology) (CIT) (until October)
Y Karunasekara, MD (USSR) (from May)

Ubiquitin Laboratory
Fellow (RFT) and Leader
RT Baker, BSc (Hons) (UNSW), PhD
Post Doctoral Fellow:
G McGurk, BSc (Hons), PhD (Edinburgh)
C Angelats, Maitrise/DE, (University of the Méditerranée, Marseille, France), PhD (Institut de Biologie du Développement de Marseille, France) (from July)
Visiting Fellow:
Professor R John Mayer, Queens Medical School, University of Nottingham, UK (July-Aug)
Technical Officer:
XW Wang, BSc (Fudan, Shanghai, China), MSc (Melb)

Medical Genome Centre

Professor and Leader:
CC Goodnow, BVSc (Hons) Syd, BScVet (Hons) Syd, PhD (Syd)
Facility Manager
A McKenzie,BSc (Hons) Monash
Coordinator/Animal Technician
K Sullivan, Assoc DipAppSci (Animal Science), Adv CertVetNursing
Animal Technicians
J Carter, City & Guilds 244 Marine Craft Fitter (BCA, UK)
S Chaudhry, Assoc DipAppSci (Animal Science)
L De Wit, Animal Care Certificate Course, (CIT) (until Nov)
S Ewing, Biological Research Techicians's Certificate, (CIT)
J Hardy, BSc (Biomed) (UTS)
M Jukes,DipAppSci (Animal Tech & Biology) to be completed June 2001
E Kucharska, BSc (Warsaw, Poland) MSc (Warsaw, Poland)
I Whiting, BSc
J Wilson, Assoc.DipAppSci (Animal Science) (CIT)
Material Support Technicians
J Borrett
R Blundell
D Hebda (from Oct)
W King (until July)
M Marien (until July)
J Webster
D Smith

Goodnow Laboratory
Professor and Leader:
CC Goodnow, BVSc (Hons) Syd, BScVet (Hons) Syd, PhD (Syd)
Research Fellow
K Nelms (PhD (Minnesota) (from April)
Database Developer
G Quinn, BSc, Grad Dip Computer Studies
Postdoctoral Fellows (externally funded):
J Blasioli, BSc (Hons) (Melb), PhD (Melb)
M Blery, PhD (Aix-Marseille)
A Fahrer, BSc (Hons) (Melb), PhD (Melb)
S Lesage, PhD (McGill)
Visiting Fellow
C De Vinuesa, LMS (MBBS) DRCOG, MSc, PhD (from Oct)
Laboratory Technicians:
S McCarthy, (BSc) (until Dec)
A Murtagh, Dipl Biol Science (CIT)
S Ward (from Dec)
B Whittle, BSc (Hons)
L Wilson, Dipl Biol Science (CIT)