Publications by authors named "Steve Callaghan"

Parkinson's disease (PD) is a debilitating neurodegenerative disease characterized by the loss of midbrain dopaminergic neurons (DaNs) and the abnormal accumulation of α-Synuclein (α-Syn) protein. Currently, no treatment can slow nor halt the progression of PD. Multiplications and mutations of the α-Syn gene (SNCA) cause PD-associated syndromes and animal models that overexpress α-Syn replicate several features of PD.

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Parkinson's disease (PD) is the second most common neurodegenerative disease worldwide and presents pathologically with Lewy pathology and dopaminergic neurodegeneration. Lewy pathology contains aggregated α-synuclein (αSyn), a protein encoded by the SNCA gene which is also mutated or duplicated in a subset of familial PD cases. Due to its predominant presynaptic localization, immunostaining for the protein results in a diffuse reactivity pattern, providing little insight into the types of cells expressing αSyn.

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SUMOylation is an evolutionarily conserved eukaryotic posttranslational protein modification with broad biological relevance. Differentiating between the major small ubiquitin-like modifier (SUMO) paralogs and uncovering paralog-specific functions has long been very difficult. To overcome this problem, we generated His-HA-Sumo2 and HA-Sumo2 knockin mouse lines, expanding upon our existing His-HA-Sumo1 mouse line, to establish a "toolbox" for Sumo1-Sumo2 comparisons Leveraging the specificity of the HA epitope, we performed whole-brain imaging and uncovered regional differences between Sumo1 and Sumo2 expression.

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Background: Activated Cdk5 regulates a number of processes during nervous system formation, including neuronal differentiation, growth cone stabilization, and axonal growth. Cdk5 phosphorylates its downstream substrates located in axonal growth cones, where the highly expressed c-Jun N-terminal kinase (JNK)-interacting protein1 (JIP1) has been implicated as another important regulator of axonal growth. In addition, stringent control of the level of intracellular domain of Notch1 (Notch1-IC) plays a regulatory role in axonal outgrowth during neuronal differentiation.

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A growing body of evidence suggests that nuclear alpha-synuclein (αSyn) plays a role in the pathogenesis of Parkinson's disease (PD). However, this question has been difficult to address as controlling the localization of αSyn in experimental systems often requires protein overexpression, which affects its aggregation propensity. To overcome this, we engineered SncaNLS mice, which localize endogenous αSyn to the nucleus.

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Objectives: To explore the different factors of resilience for people living with dementia and unpaid carers, in response to sudden changes in care and lifestyle during the COVID-19 pandemic.

Methods: Unpaid carers and people living with dementia were offered telephone interviews in April 2020 to discuss their experiences since the COVID-19 pandemic. Participants were asked about the benefits and challenges of accessing dementia support, as well as coping, symptoms, strategies and impacts.

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Objectives: Little is known about how community services and institutional care settings have adapted to providing support since the COVID-19 pandemic. The aim was to explore how these care services have adapted during the pandemic in the UK and are providing care to people living with dementia (PLWD) and carers.

Method: Semi-structured telephone interviews were conducted in June and July 2020 with 16 purposefully sampled unpaid dementia carers.

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Background: Sudden public health restrictions can be difficult to comprehend for people with cognitive deficits. However, these are even more important for them to adhere to due to their increased levels of vulnerability, particularly to COVID-19. With a lack of previous evidence, we explored the understanding and changes in adherence to COVID-19 public health restrictions over time in people living with dementia (PLWD).

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Background: Social support services such as day care centres are important in post-diagnostic dementia care to enable people living with dementia stay at home for longer. Little research has addressed potential inequalities in access, with no research on variations before and since COVID-19. The aim of this study was to explore inequalities in social support service usage before and since the pandemic.

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Article Synopsis
  • The study investigates how parkin, a protein, protects the brain from Parkinson's disease, particularly focusing on its cysteine residues that undergo redox reactions and posttranslational modifications.* -
  • Research findings reveal that aging leads to parkin becoming largely insoluble due to oxidation, particularly at specific cysteine residues, and this results in increased levels of harmful hydrogen peroxide (HO) in both mice and parkin-deficient human brains.* -
  • The protective effects of wild-type parkin against dopamine toxicity are emphasized, as it reduces HO levels and neutralizes reactive dopamine metabolites, while disease-linked parkin mutants do not exhibit these protective characteristics.*
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Background: To date, there appears to be no evidence on the longer-term impacts caused by COVID-19 and its related public health restrictions on some of the most vulnerable in our societies. The aim of this research was to explore the change in impact of COVID-19 public health measures on the mental wellbeing of people living with dementia (PLWD) and unpaid carers.

Method: Semi-structured, follow-up telephone interviews were conducted with PLWD and unpaid carers between June and July 2020.

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Background: The COVID-19 pandemic has had a major impact on delivery of social support services. This might be expected to particularly affect older adults and people living with dementia (PLWD), and to reduce their well-being.

Aims: To explore how social support service use by older adults, carers and PLWD, and their mental well-being changed over the first 3 months since the pandemic outbreak.

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Objectives: Accessing social care and social support services is key to support the well-being of people living with dementia (PLWD) and unpaid carers. COVID-19 has caused sudden closures or radical modifications of these services, and is resulting in prolonged self-isolation. The aim of this study was to explore the effects of COVID-19 related social care and support service changes and closures on the lives of PLWD and unpaid carers.

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Objectives: The aim of this national survey was to explore the impact of COVID-19 public health measures on access to social support services and the effects of closures of services on the mental well-being of older people and those affected by dementia.

Methods: A UK-wide online and telephone survey was conducted with older adults, people with dementia, and carers between April and May 2020. The survey captured demographic and postcode data, social support service usage before and after COVID-19 public health measures, current quality of life, depression, and anxiety.

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Background: The lockdown imposed in the UK on the 23rd of March and associated public health measures of social distancing are likely to have had a great impact on care provision. The aim of this study was to explore the decision-making processes of continued paid home care support for dementia in the time of COVID-19.

Methods: Unpaid carers caring for a person living with dementia (PLWD) who were accessing paid home care before COVID-19 and residing in the UK were eligible to take part.

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We previously reported that the cell cycle-related cyclin-dependent kinase 4-retinoblastoma (RB) transcriptional corepressor pathway is essential for stroke-induced cell death both and However, how this signaling pathway induces cell death is unclear. Previously, we found that the cyclin-dependent kinase 4 pathway activates the pro-apoptotic transcriptional co-regulator Cited2 after DNA damage. In the present study, we report that Cited2 protein expression is also dramatically increased following stroke/ischemic insult.

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The unfolded protein response (UPR) triggered by endoplasmic reticulum (ER) stress is a feature of many neurodegenerative diseases including Alzheimer's disease, Huntington's disease and Parkinson's disease (PD). Although the vast majority of PD is sporadic, mutations in a number of genes including PARK7 which encodes the protein DJ-1 have been linked to early-onset, familial PD. In this regard, both PD of sporadic and genetic origins exhibit markers of ER stress-induced UPR.

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Loss of function mutations in the PTEN-induced putative kinase 1 (Pink1) gene have been linked with an autosomal recessive familial form of early onset Parkinson's disease (PD). However, the underlying mechanism(s) responsible for degeneration remains elusive. Presently, using co-immunoprecipitation in HEK (Human embryonic kidney) 293 cells, we show that Pink1 endogenously interacts with FK506-binding protein 51 (FKBP51 or FKBP5), FKBP5 and directly phosphorylates FKBP5 at Serine in an in vitro kinase assay.

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Leucine-rich repeat kinase 2 () has been implicated in both familial and sporadic Parkinson's disease (PD), yet its pathogenic role remains unclear. A previous screen in identified Scar/WAVE (Wiskott-Aldrich syndrome protein-family verproline) proteins as potential genetic interactors of Here, we provide evidence that LRRK2 modulates the phagocytic response of myeloid cells via specific modulation of the actin-cytoskeletal regulator, WAVE2. We demonstrate that macrophages and microglia from PD patients and mice display a WAVE2-mediated increase in phagocytic response, respectively.

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Dysregulation of cell cycle machinery is implicated in a number of neuronal death contexts, including stroke. Increasing evidence suggests that cyclin-dependent kinases (Cdks) are inappropriately activated in mature neurons under ischemic stress conditions. We previously demonstrated a functional role for the cyclin D1/Cdk4/pRb (retinoblastoma tumor suppressor protein) pathway in delayed neuronal death induced by ischemia.

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Emerging evidence has demonstrated a growing genetic component in Parkinson disease (PD). For instance, loss-of-function mutations in PINK1 or PARKIN can cause autosomal recessive PD. Recently, PINK1 and PARKIN have been implicated in the same signaling pathway to regulate mitochondrial clearance through recruitment of PARKIN by stabilization of PINK1 on the outer membrane of depolarized mitochondria.

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Loss-of-function mutations in DJ-1 (PARK7) gene account for about 1% of all familial Parkinson's disease (PD). While its physiological function(s) are not completely clear, DJ-1 protects neurons against oxidative stress in both in vitro and in vivo models of PD. The molecular mechanism(s) through which DJ-1 alleviates oxidative stress-mediated damage remains elusive.

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DJ-1 (PARK7) is a gene linked to autosomal recessive Parkinson disease (PD). We showed previously that DJ-1 loss sensitizes neurons in models of PD and stroke. However, the biochemical mechanisms underlying this protective role are not completely clear.

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Inappropriate activation of cell cycle proteins, in particular cyclin D/Cdk4, is implicated in neuronal death induced by various pathologic stresses, including DNA damage and ischemia. Key targets of Cdk4 in proliferating cells include members of the E2F transcription factors, which mediate the expression of cell cycle proteins as well as death-inducing genes. However, the presence of multiple E2F family members complicates our understanding of their role in death.

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We have earlier reported the critical nature of calpain-CDK5-MEF2 signaling in governing dopaminergic neuronal loss in vivo. CDK5 mediates phosphorylation of the neuronal survival factor myocyte enhancer factor 2 (MEF2) leading to its inactivation and loss. However, the downstream factors that mediate MEF2-regulated survival are unknown.

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