Publications by authors named "Matilda A Haas"

11 Publications

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'CTRL': an online, Dynamic Consent and participant engagement platform working towards solving the complexities of consent in genomic research.

Eur J Hum Genet 2021 Jan 6. Epub 2021 Jan 6.

Australian Genomics Health Alliance, Parkville, VIC, Australia.

The complexities of the informed consent process for participating in research in genomic medicine are well-documented. Inspired by the potential for Dynamic Consent to increase participant choice and autonomy in decision-making, as well as the opportunities for ongoing participant engagement it affords, we wanted to trial Dynamic Consent and to do so developed our own web-based application (web app) called CTRL (control). This paper documents the design and development of CTRL, for use in the Australian Genomics study: a health services research project building evidence to inform the integration of genomic medicine into mainstream healthcare. Australian Genomics brought together a multi-disciplinary team to develop CTRL. The design and development process considered user experience; security and privacy; the application of international standards in data sharing; IT, operational and ethical issues. The CTRL tool is now being offered to participants in the study, who can use CTRL to keep personal and contact details up to date; make consent choices (including indicate preferences for return of results and future research use of biological samples, genomic and health data); follow their progress through the study; complete surveys, contact the researchers and access study news and information. While there are remaining challenges to implementing Dynamic Consent in genomic research, this study demonstrates the feasibility of building such a tool, and its ongoing use will provide evidence about the value of Dynamic Consent in large-scale genomic research programs.
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http://dx.doi.org/10.1038/s41431-020-00782-wDOI Listing
January 2021

The ethics approval process for multisite research studies in Australia: changes sought by the Australian Genomics initiative.

Med J Aust 2019 11;211(10):440-444.e1

Australian Genomics Health Alliance, Melbourne, VIC.

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http://dx.doi.org/10.5694/mja2.50397DOI Listing
November 2019

De Novo Mutations in DENR Disrupt Neuronal Development and Link Congenital Neurological Disorders to Faulty mRNA Translation Re-initiation.

Cell Rep 2016 06 26;15(10):2251-2265. Epub 2016 May 26.

EMBL Australia, The Australian Regenerative Medicine Institute, Monash University, Clayton, VIC 3800, Australia; The Harry Perkins Institute of Medical Research, QEII Medical Centre and Centre for Medical Research, the University of Western Australia, Nedlands, WA 6009, Australia. Electronic address:

Disruptions to neuronal mRNA translation are hypothesized to underlie human neurodevelopmental syndromes. Notably, the mRNA translation re-initiation factor DENR is a regulator of eukaryotic translation and cell growth, but its mammalian functions are unknown. Here, we report that Denr influences the migration of murine cerebral cortical neurons in vivo with its binding partner Mcts1, whereas perturbations to Denr impair the long-term positioning, dendritic arborization, and dendritic spine characteristics of postnatal projection neurons. We characterized de novo missense mutations in DENR (p.C37Y and p.P121L) detected in two unrelated human subjects diagnosed with brain developmental disorder to find that each variant impairs the function of DENR in mRNA translation re-initiation and disrupts the migration and terminal branching of cortical neurons in different ways. Thus, our findings link human brain disorders to impaired mRNA translation re-initiation through perturbations in DENR (OMIM: 604550) function in neurons.
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http://dx.doi.org/10.1016/j.celrep.2016.04.090DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4906373PMC
June 2016

MicroRNAs: Not "Fine-Tuners" but Key Regulators of Neuronal Development and Function.

Front Neurol 2015 24;6:245. Epub 2015 Nov 24.

Development and Stem Cells Program, Monash Biomedicine Discovery Institute, Department of Anatomy and Developmental Biology, Monash University , Melbourne, VIC , Australia.

MicroRNAs (miRNAs) are a class of short non-coding RNAs that operate as prominent post-transcriptional regulators of eukaryotic gene expression. miRNAs are abundantly expressed in the brain of most animals and exert diverse roles. The anatomical and functional complexity of the brain requires the precise coordination of multilayered gene regulatory networks. The flexibility, speed, and reversibility of miRNA function provide precise temporal and spatial gene regulatory capabilities that are crucial for the correct functioning of the brain. Studies have shown that the underlying molecular mechanisms controlled by miRNAs in the nervous systems of invertebrate and vertebrate models are remarkably conserved in humans. We endeavor to provide insight into the roles of miRNAs in the nervous systems of these model organisms and discuss how such information may be used to inform regarding diseases of the human brain.
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http://dx.doi.org/10.3389/fneur.2015.00245DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4656843PMC
December 2015

Alterations to dendritic spine morphology, but not dendrite patterning, of cortical projection neurons in Tc1 and Ts1Rhr mouse models of Down syndrome.

PLoS One 2013 30;8(10):e78561. Epub 2013 Oct 30.

Division of Molecular Neurobiology, Medical Research Council National Institute for Medical Research, London, United Kingdom.

Down Syndrome (DS) is a highly prevalent developmental disorder, affecting 1/700 births. Intellectual disability, which affects learning and memory, is present in all cases and is reflected by below average IQ. We sought to determine whether defective morphology and connectivity in neurons of the cerebral cortex may underlie the cognitive deficits that have been described in two mouse models of DS, the Tc1 and Ts1Rhr mouse lines. We utilised in utero electroporation to label a cohort of future upper layer projection neurons in the cerebral cortex of developing mouse embryos with GFP, and then examined neuronal positioning and morphology in early adulthood, which revealed no alterations in cortical layer position or morphology in either Tc1 or Ts1Rhr mouse cortex. The number of dendrites, as well as dendrite length and branching was normal in both DS models, compared with wildtype controls. The sites of projection neuron synaptic inputs, dendritic spines, were analysed in Tc1 and Ts1Rhr cortex at three weeks and three months after birth, and significant changes in spine morphology were observed in both mouse lines. Ts1Rhr mice had significantly fewer thin spines at three weeks of age. At three months of age Tc1 mice had significantly fewer mushroom spines--the morphology associated with established synaptic inputs and learning and memory. The decrease in mushroom spines was accompanied by a significant increase in the number of stubby spines. This data suggests that dendritic spine abnormalities may be a more important contributor to cognitive deficits in DS models, rather than overall neuronal architecture defects.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0078561PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3813676PMC
August 2014

Visualization and genetic manipulation of dendrites and spines in the mouse cerebral cortex and hippocampus using in utero electroporation.

J Vis Exp 2012 Jul 26(65). Epub 2012 Jul 26.

Division of Molecular Neurobiology, MRC National Institute for Medical Research.

In utero electroporation (IUE) has become a powerful technique to study the development of different regions of the embryonic nervous system (1-5). To date this tool has been widely used to study the regulation of cellular proliferation, differentiation and neuronal migration especially in the developing cerebral cortex (6-8). Here we detail our protocol to electroporate in utero the cerebral cortex and the hippocampus and provide evidence that this approach can be used to study dendrites and spines in these two cerebral regions. Visualization and manipulation of neurons in primary cultures have contributed to a better understanding of the processes involved in dendrite, spine and synapse development. However neurons growing in vitro are not exposed to all the physiological cues that can affect dendrite and/or spine formation and maintenance during normal development. Our knowledge of dendrite and spine structures in vivo in wild-type or mutant mice comes mostly from observations using the Golgi-Cox method( 9). However, Golgi staining is considered to be unpredictable. Indeed, groups of nerve cells and fiber tracts are labeled randomly, with particular areas often appearing completely stained while adjacent areas are devoid of staining. Recent studies have shown that IUE of fluorescent constructs represents an attractive alternative method to study dendrites, spines as well as synapses in mutant / wild-type mice (10-11) (Figure 1A). Moreover in comparison to the generation of mouse knockouts, IUE represents a rapid approach to perform gain and loss of function studies in specific population of cells during a specific time window. In addition, IUE has been successfully used with inducible gene expression or inducible RNAi approaches to refine the temporal control over the expression of a gene or shRNA (12). These advantages of IUE have thus opened new dimensions to study the effect of gene expression/suppression on dendrites and spines not only in specific cerebral structures (Figure 1B) but also at a specific time point of development (Figure 1C). Finally, IUE provides a useful tool to identify functional interactions between genes involved in dendrite, spine and/or synapse development. Indeed, in contrast to other gene transfer methods such as virus, it is straightforward to combine multiple RNAi or transgenes in the same population of cells. In summary, IUE is a powerful method that has already contributed to the characterization of molecular mechanisms underlying brain function and disease and it should also be useful in the study of dendrites and spines.
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http://dx.doi.org/10.3791/4163DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3476406PMC
July 2012

Behavioral and other phenotypes in a cytoplasmic Dynein light intermediate chain 1 mutant mouse.

J Neurosci 2011 Apr;31(14):5483-94

Department of Neurodegenerative Disease, Medical Research Council Centre for Neuromuscular Diseases, University College London Institute of Neurology, London WC1N 3BG, United Kingdom.

The cytoplasmic dynein complex is fundamentally important to all eukaryotic cells for transporting a variety of essential cargoes along microtubules within the cell. This complex also plays more specialized roles in neurons. The complex consists of 11 types of protein that interact with each other and with external adaptors, regulators and cargoes. Despite the importance of the cytoplasmic dynein complex, we know comparatively little of the roles of each component protein, and in mammals few mutants exist that allow us to explore the effects of defects in dynein-controlled processes in the context of the whole organism. Here we have taken a genotype-driven approach in mouse (Mus musculus) to analyze the role of one subunit, the dynein light intermediate chain 1 (Dync1li1). We find that, surprisingly, an N235Y point mutation in this protein results in altered neuronal development, as shown from in vivo studies in the developing cortex, and analyses of electrophysiological function. Moreover, mutant mice display increased anxiety, thus linking dynein functions to a behavioral phenotype in mammals for the first time. These results demonstrate the important role that dynein-controlled processes play in the correct development and function of the mammalian nervous system.
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http://dx.doi.org/10.1523/JNEUROSCI.5244-10.2011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3096546PMC
April 2011

Axonal shearing in mature cortical neurons induces attempted regeneration and the reestablishment of neurite polarity.

Brain Res 2009 Dec 26;1300:24-36. Epub 2009 Aug 26.

Wicking Dementia Research and Education Centre and NeuroRepair Group, Menzies Research Institute, University of Tasmania, Private Bag 29, Hobart, Tasmania, Australia 7000.

While functional recovery after injury is limited, it has become evident that the mature central nervous system does retain some ability to regenerate. This study investigated the intrinsic capacity of relatively mature cortical neurons (21 days in vitro) to respond to axonal loss. Neurons, growing as clusters on poly-L-lysine, were completely sheared of axons through chemical and mechanical disruption and transferred to either an intact astrocyte monolayer or a substrate of poly-L-lysine. Injured neurons exhibited a regenerative sprouting response that was independent of neuronal cell division or neural progenitors, as demonstrated by negative bromodeoxyuridine (BrdU) and the neuronal precursor intermediate filament nestin, labeling. At 24 h after injury, neurons had extended appropriately polarized neurites, demonstrated by compartmentalized microtubule-associated proteins MAP2 and tau immunolabeling. Newly sprouting axons were tipped by growth cones; however, growth cones on the tips of sprouting axons (mean area, 26.32 +/- 2.20 microm) were significantly (p<0.05) smaller than their developmental counterparts (mean area, 48.64 +/- 5.9 microm), independent of substrate. Furthermore, live imaging indicated that regenerating neurons exhibited distinct axonal dynamics, with a significant (p<0.05) reduction (70%) in pausing, considered vital for interstitial branching and pathfinding, relative to developmental growth cones. This study indicates that mature cultured cortical pyramidal and interneurons have the intrinsic potential to survive, extend processes, and reestablish neurite polarity following significant physical damage. These results may aid in defining the cellular basis of neuronal structural plasticity and defining the role of astrocyte reactivity in the response to trauma.
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http://dx.doi.org/10.1016/j.brainres.2009.08.059DOI Listing
December 2009

Identification and characterization of a population of motile neurons in long-term cortical culture.

Cell Motil Cytoskeleton 2007 Apr;64(4):274-87

NeuroRepair Group, University of Tasmania, Hobart, Tasmania, Australia.

The specific phenotypes and progression to maturity of primary cortical neurons in long-term culture correlate well with neurons in vivo. Utilizing a model of neuronal injury in long-term cultures at 21 days in vitro (DIV), we have identified a distinct population of neurons that translocate into the injury site. 5-bromo-2'-deoxyUridine (BrdU) incorporation studies demonstrated that neurons with the capacity to translocate were 21 days old. However, this motile ability is not consistent with the traditional view of the maturation and structural stability of neurons in long-term culture. Therefore, we examined the neurons' cytoskeletal profile using immunocytochemistry, to establish relative stage of maturation and phenotype. Expression of marker proteins including beta-III-tubulin, alpha-internexin, NF-L and NF-M, tau and L1 indicated the neurons were differentiated, and in some cases polarized. The neurons did not immunolabel with NF-H or MAP2, which might suggest they had not reached the level of maturity of other neurons in culture. They did not express the microtubule-associated migration marker doublecortin (DCX). Cytoskeletal disrupting agents were used to further investigate the role of the microtubule cytoskeleton in translocation, and microtubule destabilization significantly enhanced aspects of their motility. Finally, molecular guidance cues affected their motility in a similar manner to that reported for both axon guidance and early neuron migration. Therefore, this study has identified and characterized a population of motile neurons in vitro that have the capacity to migrate into a site of injury. These studies provide new information on the structurally dynamic features of subsets of neurons.
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http://dx.doi.org/10.1002/cm.20182DOI Listing
April 2007

Rho kinase activates ezrin-radixin-moesin (ERM) proteins and mediates their function in cortical neuron growth, morphology and motility in vitro.

J Neurosci Res 2007 Jan;85(1):34-46

NeuroRepair Group, University of Tasmania, Hobart, Australia.

The ezrin-radixin-moesin (ERM) family of proteins contribute to cytoskeletal processes underlying many vital cellular functions. Their previously elucidated roles in non-neuronal cells are an indication of their potential importance in CNS neurons. The specific mechanisms of their activation are unknown, but are likely to depend on factors such as the cell type and biological context. For ERM proteins to become active they must be phosphorylated at a specific C-terminal threonine residue. In non-neuronal cells, several kinases, including the Rho GTPase family member Rho kinase, have been identified as capable of phosphorylating the C-terminal threonine. In these experiments we have investigated specifically the potential role of Rho kinase mediated ERM activation in cortical neurons, utilizing a new pharmacologic inhibitor of Rho kinase and quantitative analysis of aspects of neuronal functions potentially mediated by ERM proteins. Rho kinase inhibition significantly suppressed aspects of neuronal development including neurite initiation and outgrowth, as well as growth cone morphology, with a concomitant loss of phosphorylated ERM immunolabeling in areas associated with neuronal growth. The ability of the Rho kinase inhibitor to decrease the amount of pERM protein was shown by immunoblotting. Post-injury responses were negatively affected by Rho kinase inhibition, namely by a significant decrease in the number of regenerative neurites. We investigated a novel role for ERM proteins in neuron migration using a post-injury motility assay, where Rho kinase inhibition resulted in significant and drastic reduction in neuron motility and phosphorylated ERM immunolabeling. Thus, Rho kinase is an important activator of ERMs in mediating specific neuronal functions.
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http://dx.doi.org/10.1002/jnr.21102DOI Listing
January 2007

Binding partners L1 cell adhesion molecule and the ezrin-radixin-moesin (ERM) proteins are involved in development and the regenerative response to injury of hippocampal and cortical neurons.

Eur J Neurosci 2004 Sep;20(6):1436-44

NeuroRepair Group, University of Tasmania, 43 Collins Street, Hobart, Tasmania, 7000, Australia.

Regeneration of the adult central nervous system may require recapitulation of developmental events and therefore involve the re-expression of developmentally significant proteins. We have investigated whether the L1 cell adhesion molecule, and its binding partner, the ezrin-radixin-moesin (ERM) proteins are involved in the neuronal regenerative response to injury. Hippocampal and cortical neurons were cultured in vitro on either an L1 substrate or poly-L-lysine, and ERM and other neuronal proteins were localized immunocytochemically both developmentally and following neurite transection of neurons maintained in long-term culture. Activated ERM was localized to growth cones up to 7 days in vitro but relatively mature cultures (21 days in vitro) were devoid of active ERM proteins. However, ERM proteins were localized to the growth cones of sprouting neuronal processes that formed several hours after neurite transection. In addition, the L1 substrate, relative to poly-L-lysine, resulted in significantly longer regenerative neurites, as well as larger growth cones with more filopodia. Furthermore, neurons derived from the cortex formed significantly longer post-injury neurite sprouts at 6 h post-injury than hippocampal derived neurons grown on both substrates. We have demonstrated that L1 and the ERM proteins are involved in the neuronal response to injury, and that neurons derived from the hippocampus and cortex may have different post-injury regenerative neurite sprouting abilities.
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http://dx.doi.org/10.1111/j.1460-9568.2004.03620.xDOI Listing
September 2004