DJ-1 was recently identified as a gene product responsible for a subset of familial Parkinson's disease (PD). The mechanisms by which mutations in DJ-1 alter its function and account for PD-related ...pathology remained largely unknown. We show that DJ-1 is processed by caspase-6 and that the caspase-6-derived C-terminal fragment of DJ-1 fully accounts for associated p53-dependent cell death. In line with the above data, we show that a recently described early-onset PD-associated mutation (D149A) renders DJ-1 resistant to caspase-6 proteolysis and abolishes its protective phenotype. Unlike the D149A mutation, the L166P mutation that prevents DJ-1 dimerization does not impair its proteolysis by caspase-6 although it also abolishes DJ-1 antiapoptotic function. Therefore, we show here that DJ-1 loss of function could be due to impaired caspase-6 proteolysis and we document the fact that various DJ-1 mutations could lead to PD pathology through distinct molecular mechanisms.
From a systematic screening of animal venoms, we isolated a new toxin (APETx2) from the sea anemone Anthopleura elegantissima, which inhibits ASIC3 homomeric channels and ASIC3‐containing heteromeric ...channels both in heterologous expression systems and in primary cultures of rat sensory neurons. APETx2 is a 42 amino‐acid peptide crosslinked by three disulfide bridges, with a structural organization similar to that of other sea anemone toxins that inhibit voltage‐sensitive Na+ and K+ channels. APETx2 reversibly inhibits rat ASIC3 (IC50=63 nM), without any effect on ASIC1a, ASIC1b, and ASIC2a. APETx2 directly inhibits the ASIC3 channel by acting at its external side, and it does not modify the channel unitary conductance. APETx2 also inhibits heteromeric ASIC2b+3 current (IC50=117 nM), while it has less affinity for ASIC1b+3 (IC50=0.9 μM), ASIC1a+3 (IC50=2 μM), and no effect on the ASIC2a+3 current. The ASIC3‐like current in primary cultured sensory neurons is partly and reversibly inhibited by APETx2 with an IC50 of 216 nM, probably due to the mixed inhibitions of various co‐expressed ASIC3‐containing channels.
Genetic and biochemical evidence have led to the suggestion that presenilins could be the long-searched-for γ-secretase, the proteolytic activity that generates the carboxy terminus of amyloid ...β-peptides. This activity is also thought to be responsible for the release of the Notch intracellular domain (NICD) from Notch. Here, we report the production of endogenous secreted and intracellular 40- and 42-amino-acid Aβ peptides in mouse fibroblasts deficient in presenilin 1, presenilin 2 or both. We show that the endogenous production of Aβ40 and Aβ42 was not altered by presenilin deficiency. By contrast, inactivating presenilin genes fully abolished NICD production. These data indicate that Aβ and NICD production are distinct catabolic events. Also, even though NICD formation is indeed presenilin dependent, endogenous secreted and intracellular β-amyloid peptides are still generated in absence of presenilins, indicating that there is a γ-secretase activity distinct from presenilins, at least in murine fibroblasts.
La protéine prion cellulaire (PrPc) est impliquée dans le développement des Encéphalopathies Spongiformes Transmissibles (EST). Sa maturation physiologique produit un fragment N-terminal soluble, N1 ...et sa contrepartie C-terminale C1, ancrée à la membrane. Lors du développement des EST, une coupure alternative a lieu plus en amont : il en résulte un fragment N-terminal plus court, N2 et sa contrepartie C2. Les fonctions respectives des fragments sécrétés N1 et N2 demeurent méconnues. Nous avons produit des fragments N1 et N2 recombinants afin d’étudier leurs effets sur l’apoptose. In vitro, l’apoptose est induite par un traitement à la Staurosporine ou par privation de glucose et d’oxygène (OGD). In vivo, nous avons utilisé, chez le rat, un modèle d’ischémie rétinienne par hyperpression de l’œil. Au cours de nos expériences in vitro, un traitement avec le fragment N1 induit une diminution du nombre de cellules positives au marquage TUNEL ainsi qu’une baisse de l’activation de la caspase 3. Cette protection contre l’apoptose est liée à une régulation de la transcription et de l’activité transcriptionnelle de p53. De plus, les mêmes effets sont retrouvés en stimulant la production endogène de N1. Cette fonction neuroprotectrice est confirmée in vivo lors d’expériences d’ischémie rétinienne. Elle se caractérise au niveau cellulaire par une réduction du nombre de cellules ganglionnaires positives lors d’un marquage TUNEL et une diminution de l’immunoréactivité p53. De plus, aux niveaux tissulaire et fonctionnel, la protection se traduit par un maintien de la structure de la rétine et une récupération partielle de l’activité mesurée par électrorétinogramme. Le fragment N2 est inerte dans ces paradigmes. Nos travaux sont la première démonstration de la fonction neuroprotectrice d’un fragment sécrété issu de la protéolyse de la PrPc. Ils montrent in vitro et in vivo que les différents produits dérivés des clivages N-terminaux de la PrPc portent des activités biologiques distinctes. D’autre part, le fragment sAPPα produit de la maturation non amyloidogénique de la βAPP, porte également
une fonction neuroprotectrice renforçant l’hypothèse d’un dialogue fonctionnel entre la Prpc et la βAPP déjà mise en évidence au laboratoire.
The present study analyses, by two-dimensional polyacrylamide gel electrophoresis, the protease SP220K isolated from renal cell carcinoma. The pure molecule is separated using either immobilized pH ...gradient or isoelectric focusing in conventional carrier ampholyte in the first dimension. Some interactions with the acrylamide matrix in isoelectric focusing are discussed. The results demonstrate that two-dimensional gel electrophoresis performed with enriched media such as basolateral membranes, allows the detection of the protease. In addition, the non detection of the molecule up to now by this methodology can be explained by the high tendency of oligomerization of SP220K. Effectively the high molecular weight form of the molecule of 220 kDa is favoured in two-dimensional gel electrophoresis over monomeric forms which are better detected in SDS PAGE. This was confirmed by immunostaining performed with an antiserum to SP220K produced by nitrocellulose-bound antigen.
The literature has long recognized that parental emotional competence, that is, the ability to express, understand, and regulate emotions, plays a key role in children’s development from early ...childhood. Nevertheless, the effect of parental alexithymia, which can be understood as a deficit in emotional competence, has not been thoroughly studied. In particular, the association between paternal alexithymia and behavioral problems in young children is still a neglected area of research. This study aims to investigate the association between paternal alexithymia and children’s internalizing and externalizing problems during the first three years of life, including whether overreactive parenting practices mediate the effect of alexithymia on children’s behavioral problems. A sample of 203 fathers of children aged 18–36 months were administered the TAS-20, the Overreactivity subscale of the Parenting Scale, and the Child Behavior Checklist (CBCL)/1½-5. The data indicate that paternal alexithymia is a predictor of children’s internalizing and externalizing behavioral problems and that paternal overreactivity mediates the effect of alexithymia. These results highlight the importance of preventing parental alexithymia and involving fathers in parenting support programs aimed at ensuring children’s mental health and adjustment.
Interferons (IFNs) are a family of pleiotropic cytokines that typically exhibit antiviral, antiproliferative, antitumor, and immunomodulatory properties. While their complex mechanisms of action ...remain unclear, IFNs are used clinically in the treatment of viral infections, such as hepatitis B and hepatitis C, and remain the primary treatment for a limited number of malignancies, such as melanoma, hairy cell leukemia, and non-Hodgkins lymphoma and in autoimmune diseases such as multiple sclerosis. IFNs not only regulate somatic cell growth and division but also influence cell survival through the modulation of apoptosis. Paradoxically, IFNs are described to be both pro- and anti-apoptotic in nature. The biological effects of IFNs are primarily mediated via activation of the JAK/STAT pathway, formation of the ISGF3 and STAT1:STAT1 protein complexes, and the subsequent induction of IFN-stimulated genes. However, the activation of JAK/STAT-independent signal transduction pathways also contribute to IFN-mediated responses. To further demonstrate the complexity of the downstream events following stimulation, oligonucleotide microarray studies have shown that in excess of 300 genes are induced following treatment with IFN, some of which are crucial to the induction of apoptosis and cell growth control. In this review we describe the recent advances made in elucidating the various signaling pathways that are activated by IFNs and how these diverse signals contribute to the regulation of cell growth and apoptosis and inhibition of viral replication. Furthermore, we highlight the role of specific signaling molecules and the function(s) of particular IFN-stimulated genes that have been implicated in determining cell fate in response to IFN, as well as the clinical experience of IFN immunotherapy.
Oncological treatments are responsible for many of the physical changes (aesthetic and functional) associated with cancer. Because of this, cancer patients are at high risk of developing mental ...health problems. The aim of this study is to propose an innovative Virtual Reality (VR) training that uses a somatic technique (i.e., embodiment) to create a bridge with the bodily dimension of cancer. After undergoing a psycho-educational procedure, a combination of exposure, out-of-body experience, and body swapping will gradually train the patient to cope with cancer-related difficulties, increasing stress tolerance, and patient empowerment. The most engaging step of this advanced form of Stress Inoculation Training is the body swapping experience, which will guide the patient in embodying a resilient cancer patient who is facing similar difficulties. Through the VR ability to simulate the human brain functioning, and the potential of embodiment to hook to the somatic dimension of illness, we expect that once the concepts endured through the patient’s experience of resilience are triggered, the patient will be more prone to implement functional coping strategies in real life, reaching empowerment and adjusting to the post-treatment difficulties. When the scenarios are built and the training tested, our intervention could be used to support patients with different oncological diseases and who are treated in different cancer hospitals, as well as patients with other non-oncological problems (e.g., social anxiety). Future research should focus on using our paradigm for other clinical populations, and supporting cancer patients in coping with different distressing situations.
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