Identification and characterization of B"-subunits of protein phosphatase 2 A in Xenopus laevis oocytes and adult tissues.

Protein phosphatase 2A is a phosphoserine/threonine phosphatase implicated in many cellular processes. The core enzyme comprises a catalytic and a PR65/A-subunit. The substrate specificity and subcellular localization are determined by a third regulatory B-subunit (PR55/B, PR61/B' and PR72/130/B"). To identify the proteins of the B" family in Xenopus laevis oocytes, a prophase Xenopus oocyte cDNA library was screened using human PR130 cDNA as a probe. Three different classes of cDNAs were isolated. One class is very similar to human PR130 and is probably the Xenopus orthologue of PR130 (XPR130). A second class of clones (XN73) is identical to the N-terminal part of XPR130 but ends a few amino acids downstream of the putative splicing site of PR130. To investigate how this occurs, the genomic structure of the human PR130 gene was determined. This novel protein does not act as a PP2A subunit but might compete with the function of PR130. The third set of clones (XPR70) is very similar to human PR48 but has an N-terminal extension. Further analysis of the human EST-database and the human PR48 gene structure, revealed that the human PR48 clone published is incomplete. The Xenopus orthologue of PR48 encodes a protein of 70 kDa which like the XPR130, interacts with the A-subunit in GST pull-down assays. XPR70 is ubiquitously expressed in adult tissues and oocytes whereas expression of XPR130 is very low in brain and oocytes. Expression of XN73 mainly parallels XPR130 with the exception of the brain.     

Nonsyndromic X-linked mental retardation: where are the missing mutations?

Analysis of linkage intervals from 125 unrelated families with nonsyndromic X-linked mental retardation (NS-XLMR) has revealed that the respective gene defects are conspicuously clustered in defined regions of the human X-chromosome, with approximately 30% of all mutations being located on the proximal Xp. In 83% of these families, underlying gene defects are not yet known. Our observations should speed up the search for mutations that are still missing and pave the way for the molecular diagnosis of this common disorder.     

Y14 and hUpf3b form an NMD-activating complex

Messenger RNAs with premature translation termination codons (PTCs) are degraded by nonsense-mediated mRNA decay (NMD). In mammals, PTCs are discriminated from physiological stop codons by a process thought to involve the splicing-dependent deposition of an exon junction complex (EJC), EJC-mediated recruitment of Upf3, and Upf2 binding to the N terminus of Upf3. Here, we identify a conserved domain of hUpf3b that mediates an interaction with the EJC protein Y14. Tethered function analysis shows that the Y14/hUpf3b interaction is essential for NMD, while surprisingly the interaction between hUpf3b and hUpf2 is not. Nonetheless, hUpf2 is necessary for NMD mediated by tethered Y14. RNAi-induced knockdown and Y14 repletion of siRNA-treated cells implicates Y14 in the degradation of beta-globin NS39 mRNA and demonstrates that Y14 is required for NMD induced by tethered hUpf3b. These results uncover a direct role of Y14 in NMD and suggest an unexpected hierarchy in the assembly of NMD complexes.     

Impaired c-Fos and Polo-Like Kinase 2 Induction in the Limbic System of Fear-conditioned α-Synuclein Transgenic Mice

α-Synuclein (αSYN) is genetically and neuropathologically linked to a spectrum of neurodegenerative diseases including Parkinson’s disease, dementia with Lewy bodies, and related disorders. Cognitive impairment is recapitulated in several αSYN transgenic mouse lines. However, the mechanisms of dysfunction in affected neurons are largely unknown. Here we measured neuronal activity induced gene products in the limbic system of αSYN transgenic mice upon fear conditioning (FC). Induction of the synaptic plasticity marker c-Fos was significantly reduced in the amygdala and hippocampus of (Thy1)-h[A30P]αSYN transgenic mice in an age-dependent manner. Similarly, the neuronal activity inducible polo-like kinase 2 (Plk2) that can phosphorylate αSYN at the pathological site serine-129 was up-regulated in both brain regions upon FC. Plk2 inductions were also significantly impaired in aged (Thy1)-h[A30P]αSYN transgenic mice, both in the amygdala and hippocampus. Plk2 inductions in the amygdala after FC were paralleled by a small but significant increase in the number of neuronal cell bodies immunopositive for serine-129 phosphorylated αSYN in young but not aged (Thy1)-h[A30P]αSYN transgenic mice. In addition, we observed in the aged hippocampus a distinct type of apparently unmodified transgenic αSYN profiles resembling synaptic accumulations of αSYN. Thus, the cognitive decline observed in aged αSYN transgenic mice might be due to impairment of neurotransmission and synaptic plasticity in the limbic system by distinct αSYN species.     

Heme Oxygenase-1 Regulates the Progression of K/BxN Serum Transfer Arthritis

Background

Heme oxygenase-1 (HO-1) is induced in many cell types as a defense mechanism against stress. We have investigated the possible role of endogenous HO-1 in the effector phase of arthritis using the K/BxN serum transfer model of arthritis in HO-1 heterozygous and homozygous knock-out mice.

Methodology/Principal Findings

Arthritis was induced in C57/Black-6 xFVB (HO-1^+/+, HO-1^+/− and HO-1^−/−) mice by intraperitoneal injection of 150 µl serum from arthritic K/BxN mice at days 0 and 2. Blood was collected and animals were sacrificed at day 10. Histological analysis was performed in ankle sections. The levels of inflammatory mediators were measured in serum and paw homogenates by enzyme-linked immunosorbent assay or Multiplex technology. The incidence of arthritis was higher in HO-1^+/− and HO-1^−/− groups compared with HO-1^+/+. The inflammatory response was aggravated in HO-1^+/− mice as shown by arthritic score and the migration of inflammatory cells that could be related to the enhancement of CXCL-1 production. In addition, the HO-1^+/− group showed proteoglycan depletion significantly higher than HO-1^+/+ mice. Serum levels of matrix metalloproteinase-3, monocyte chemotactic protein-1, plasminogen activator inhibitor-1, E-selectin and intercellular adhesion molecule-1 were increased in arthritic HO-1^−/− mice, whereas vascular endothelial growth factor and some cytokines such as interferon-γ showed a reduction compared to HO-1^+/+ or HO-1^+/− mice. In addition, down-regulated gene expression of ferritin, glutathione S-reductase A1 and superoxide dismutase-2 was observed in the livers of arthritic HO-1^+/− animals.

Conclusion/Significance

Endogenous HO-1 regulates the production of systemic and local inflammatory mediators and plays a protective role in K/BxN serum transfer arthritis.     

Attachment in integrative neuroscientific perspective

Attachment theory is a very influential general concept of human social and emotional development, which emphasizes the role of early mother-infant interactions for infant's adaptive behavioural and stress copying strategies, personality organization and mental health. Individuals with disrupted development of secure attachment to mother/primary caregiver are at higher risk of developing mental disorders. This theory consists of the complex developmental psycho-neurobiological model of attachment and emerges from principles of psychoanalysis, evolutionary biology, cognitive-developmental psychology, ethology, physiology and control systems theory. The progress of modern neuroscience enables interpretation of neurobiological aspects of the theory as multi-level neural interactions and functional development of important neural structures, effects of neuromediattors, hormones and essential neurobiological processes including emotional, cognitive, social interactions and the special key role of mentalizing. It has multiple neurobiological, neuroendocrine, neurophysiological, ethological, genetic, developmental, psychological, psychotherapeutic and neuropsychiatric consequences and is a prototype of complex neuroscientific concept as interpretation of modern integrated neuroscience.     

An Effective Combination of Two Different Methods of Postconditioning

Ischemic tolerance based on the synthesis of protective proteins acquires its full strength by repeated exposure to stress, and "the end effector of tolerance" may paradoxically be activated by the second or lethal stress, particularly in the case of preconditioning. That happens when an additional nonspecific stressor is applied either before (preconditioning) or after (postconditioning) the period of lethal ischemia. A combination of antioxidants with pre or postconditioning prevents the acquisition of tolerance, and in the case of more severe attacks repeated stress can lead to accumulation of damage. Our attempt to weaken ischemic injury to hippocampal CA1 with antioxidants applied after lethal stress, i.e. before delayed postconditioning, was ineffective. We then tried using rapid postconditioning consisting of 30-s reperfusion alternating with 15-s ischemia repeated three times and applied immediately at the end of lethal ischemia as a tool decreasing post-ischemic production of reactive oxygen species, and combining that with delayed postconditioning consisting of an i.p. injection of Bradykinin 2?days after lethal ischemia. This approach once more confirmed the efficacy of both rapid as well as delayed postconditioning but, more importantly, it demonstrated the possibility of effectively combining these two procedures. Our findings further confirm that in cases of delayed neuronal death, which is practically pathologically-induced apoptosis, there exists a 2-day-wide therapeutic window that can be effectively exploited.