The role of cytochrome c in caspase activation in Drosophila melanogaster cells

The release of cytochrome c from mitochondria is necessary for the formation of the Apaf-1 apoptosome and subsequent activation of caspase-9 in mammalian cells. However, the role of cytochrome c in caspase activation in Drosophila cells is not well understood. We demonstrate here that cytochrome c remains associated with mitochondria during apoptosis of Drosophila cells and that the initiator caspase DRONC and effector caspase DRICE are activated after various death stimuli without any significant release of cytochrome c in the cytosol. Ectopic expression of the proapoptotic Bcl-2 protein, DEBCL, also fails to show any cytochrome c release from mitochondria. A significant proportion of cellular DRONC and DRICE appears to localize near mitochondria, suggesting that an apoptosome may form in the vicinity of mitochondria in the absence of cytochrome c release. In vitro, DRONC was recruited to a >700-kD complex, similar to the mammalian apoptosome in cell extracts supplemented with cytochrome c and dATP. These results suggest that caspase activation in insects follows a more primitive mechanism that may be the precursor to the caspase activation pathways in mammals

The two cytochrome c species, DC3 and DC4, are not required for caspase activation and apoptosis in Drosophila cells

In Drosophila, activation of the apical caspase DRONC requires the apoptotic protease-activating factor homologue, DARK. However, unlike caspase activation in mammals, DRONC activation is not accompanied by the release of cytochrome c from mitochondria. Drosophila encodes two cytochrome c proteins, Cytc-p (DC4) the predominantly expressed species, and Cytc-d (DC3), which is implicated in caspase activation during spermatogenesis. Here, we report that silencing expression of either or both DC3 and DC4 had no effect on apoptosis or activation of DRONC and DRICE in Drosophila cells. We find that loss of function mutations in dc3 and dc4, do not affect caspase activation during Drosophila development and that ectopic expression of DC3 or DC4 in Drosophila cells does not induce caspase activation. In cell-free studies, recombinant DC3 or DC4 failed to activate caspases in Drosophila cell lysates, but remarkably induced caspase activation in extracts from human cells. Overall, our results argue that DARK-mediated DRONC activation occurs independently of cytochrome c

Online Resource to Promote Vocational Interests Among Job Seekers With Multiple Sclerosis: A Randomized Controlled Trial in Australia

© 2017 American Congress of Rehabilitation Medicine Objective: To provide a preliminary evaluation of the effectiveness of an online resource for job seekers with multiple sclerosis (MS). Design: Randomized controlled design. Setting: Community-dwelling cohort. Participants: Adults (N = 95) with relapsing-remitting or progressive MS were randomly assigned to one of two groups. Forty-five accessed an email delivered, 7 module resource, Work and MS, over a 4 week period. Waitlist control participants (n=50) were offered the opportunity to access Work and MS 4 weeks postenrollment. Main Outcome Measures: Primary outcomes focused on vocational interests (My Vocational Situation Scale) and self-efficacy in job-seeking activities (Job-Procurement Self Efficacy Scale). Secondary outcomes focused on perceived workplace difficulties (Multiple Sclerosis Work Difficulties Questionnaire [MSWDQ]), optimism (Life Orientation Test – Revised), and mood (Patient Health Questionnaire-9). Results: Intention-to-treat analyses revealed pre-post gains: participants who accessed Work and MS reported improved confidence in their career goals (My Vocational Situation Scale g=.55; 95% confidence interval [CI],.14–.96; P=.008) and positively reappraised potential workplace difficulties (MSWDQ g range,.42–.47; P range,.023–.042). The effect on job self-efficacy was not significant, but changed in the expected direction (g=.17; 95% CI, –.23 to.57; P=.409). Completer data revealed larger, significant effect estimates (g range,.52–.64; P range,.009–.035). Conclusions: Findings provide preliminary support for the utility of a job information resource, Work and MS, to augment existing employment services. The results also suggest the need to test employment-ready interventions in a larger study population. This might include the addition of online peer support to increase intervention compliance

Impaired haematopoietic stem cell differentiation and enhanced skewing towards myeloid progenitors in aged caspase-2-deficient mice

The apoptotic cysteine protease caspase-2 has been shown to suppress tumourigenesis in mice and its reduced expression correlates with poor prognosis in some human malignancies. Caspase-2-deficient mice develop normally but show ageing-related traits and, when challenged by oncogenic stimuli or certain stress, show enhanced tumour development, often accompanied by extensive aneuploidy. As stem cells are susceptible to acquiring age-related functional defects because of their self-renewal and proliferative capacity, we examined whether loss of caspase-2 promotes such defects with age. Using young and aged Casp2−/− mice, we demonstrate that deficiency of caspase-2 results in enhanced aneuploidy and DNA damage in bone marrow (BM) cells with ageing. Furthermore, we demonstrate for the first time that caspase-2 loss results in significant increase in immunophenotypically defined short-term haematopoietic stem cells (HSCs) and multipotent progenitors fractions in BM with a skewed differentiation towards myeloid progenitors with ageing. Caspase-2 deficiency leads to enhanced granulocyte macrophage and erythroid progenitors in aged mice. Colony-forming assays and long-term culture-initiating assay further recapitulated these results. Our results provide the first evidence of caspase-2 in regulating HSC and progenitor differentiation, as well as aneuploidy, in vivo.Swati Dawar, Nur Hezrin Shahrin, Nikolina Sladojevic, Richard J D, Andrea, Loretta Dorstyn, Devendra K Hiwase and Sharad Kuma

The p53-caspase-2 axis in the cell cycle and DNA damage response

Caspase-2 was discovered almost three decades ago. It was one of the first two mammalian homologs of CED-3, the other being interleukin 1β-converting enzyme (ICE/caspase-1). Despite high similarity with CED-3 and its fly and mammalian counterparts (DRONC and caspase-9, respectively), the function of caspase-2 in apoptosis has remained enigmatic. A number of recent studies suggest that caspase-2 plays an important role in the regulation of p53 in response to cellular stress and DNA damage to prevent the proliferation and accumulation of damaged or aberrant cells. Here, we review these recent observations and their implications in caspase-2-mediated cellular death, senescence, and tumor suppression.Yoon Lim, Loretta Dorstyn and Sharad Kuma

Debcl, a Proapoptotic Bcl-2 Homologue, Is a Component of the Drosophila melanogaster Cell Death Machinery

Bcl-2 family of proteins are key regulators of apoptosis. Both proapoptotic and antiapoptotic members of this family are found in mammalian cells, but no such proteins have been described in insects. Here, we report the identification and characterization of Debcl, the first Bcl-2 homologue in Drosophila melanogaster. Structurally, Debcl is similar to Bax-like proapoptotic Bcl-2 family members. Ectopic expression of Debcl in cultured cells and in transgenic flies causes apoptosis, which is inhibited by coexpression of the baculovirus caspase inhibitor P35, indicating that Debcl is a proapoptotic protein that functions in a caspase-dependent manner. debcl expression correlates with developmental cell death in specific Drosophila tissues. We also show that debcl genetically interacts with diap1 and dark, and that debcl-mediated apoptosis is not affected by gene dosage of rpr, hid, and grim. Biochemically, Debcl can interact with several mammalian and viral prosurvival Bcl-2 family members, but not with the proapoptotic members, suggesting that it may regulate apoptosis by antagonizing prosurvival Bcl-2 proteins. RNA interference studies indicate that Debcl is required for developmental apoptosis in Drosophila embryos. These results suggest that the main components of the mammalian apoptosis machinery are conserved in insects

Belonging in the Online World: Older Adults' Use of Internet for Community

Objective: To explore older Australians’ experiences of using computermediated communication (CMC) to engage with their social networks and communities. Background: Use of CMC among older adults has been associated with favourable social outcomes. How older adults engage with others to foster these outcomes is less well known. Understanding this may be useful when developing programs to encourage older adults’ use of CMC for social purposes. Methods: In-depth semi-structured interviews with 12 adults (five women, seven men; aged 69 to 81) were conducted. Interview questions focused on individuals’ use of CMC to engage with online communities. Data were transcribed and thematically analysed. Results: Two overarching themes relating to a sense of Belonging and Support emerged. Belonging was most heavily emphasised, and included subthemes on how participants experienced their close social networks online, as well as their broader engagement with building interests and identity. Support arose to a lesser extent, and included subthemes relating to how CMC was used not only for the provision and receipt of such, but also to signal availability or need for support. Throughout, participants consistently weighed the benefits of CMC against the disadvantages. Conclusion: The findings highlight the importance of social networks and online communities for older adults and, in particular, how CMC facilitates feelings of belongingness and provides opportunities for reciprocal instrumental, emotional, and informational support. Future research needs to consider the importance of having a sense of belonging when describing the social functioning of digitally literate older adults.Belinda Grace Fuss, Diana Dorstyn, Lynn War

Caspase-2 deficiency enhances whole-body carbohydrate utilisation and prevents high-fat diet-induced obesity

Published online 26 October 2017Caspase-2 has been shown to be involved in metabolic homeostasis. Here, we show that caspase-2 deficiency alters basal energy metabolism by shifting the balance in fuel choice from fatty acid to carbohydrate usage. At 4 weeks of age, whole-body carbohydrate utilisation was increased in Casp2-/- mice and was maintained into adulthood. By 17 weeks of age, Casp2-/- mice had reduced white adipose mass, smaller white adipocytes decreased fasting blood glucose and plasma triglycerides but maintained normal insulin levels. When placed on a 12-week high-fat diet (HFD), Casp2-/- mice resisted the development of obesity, fatty liver, hyperinsulinemia and insulin resistance. In addition, HFD-fed Casp2-/- mice had reduced white adipocyte hypertrophy, apoptosis and expansion of both subcutaneous and visceral adipose depots. Increased expression of UCP1 and the maintenance of adiponectin levels in white adipose tissue of HFD-fed Casp2-/- mice indicated increased browning and adipocyte hyperplasia. We found that while the preference for whole-body carbohydrate utilisation was maintained, HFD-fed Casp2-/- mice were not impaired in their ability to switch to utilising fats as a fuel source. Our findings suggest that caspase-2 impacts basal energy metabolism by regulating adipocyte biology and fat expansion, most likely via a non-apoptotic function. Furthermore, we show that caspase-2 deficiency shifts the balance in fuel choice towards increased carbohydrate utilisation and propose that this is due to mild energy stress. As a consequence, Casp2-/- mice show an adaptive remodelling of adipose tissue that protects from HFD-induced obesity and improves glucose homeostasis while paradoxically increasing their susceptibility to oxidative stress induced damage and premature ageing.Claire H Wilson, Andrej Nikolic, Stephen J Kentish, Marianne Keller, George Hatzinikolas, Loretta Dorstyn, Amanda J Page and Sharad Kuma

Mindfulness Therapies for Improving Mental Health in Parents of Children with a Developmental Disability: a Systematic Review

© 2020, Springer Science+Business Media, LLC, part of Springer Nature. Mindfulness offers promise as a therapy approach for parents of children with developmental disabilities (DD), however its effectiveness in managing mental health symptoms remains unclear. This review quantitatively examines the comparative effectiveness of mindfulness-based and informed interventions, drawing on the evidence base from randomised controlled trials (RCTs). Eight RCTs were identified from the Embase, PsycINFO, PubMed and Scopus databases. Risk of bias was assessed using the Cochrane Collaboration tool and Hedges’ g effect sizes, with associated 95% confidence intervals and p values calculated. Parents who completed Mindful Parenting or Mindfulness-Based Stress Reduction programs reported immediate and large to very large reductions in psychological distress (gw range:.39–1.94), with some improvements maintained up to 6 months post-treatment. A single study reported short-term benefits with Acceptance and Commitment Therapy. Evidence for the mental health benefits of mindfulness for parents of children with DD is still at an early stage. Controlled trials are needed to determine the differential effects of specific mindfulness techniques and how to best adapt this approach to best meet the unique needs of a vulnerable caregiver population

p53 accumulation following cytokinesis failure in the absence of caspase-2

Abstract not availableYoon Lim, Dylan De Bellis, Loretta Dorstyn, Sharad Kuma