Platelet-derived growth factor triggers PKA-mediated signalling by a redox-dependent mechanism in rat renal mesangial cells

Inflammatory glomerular kidney diseases are often accompanied with a massive production of reactive oxygen species (ROS) that affect the function of the glomerular filtration barrier and contribute to mesangiolysis via the induction of cell death in mesangial cells. Intriguingly, ROS also trigger fine-tuned signalling processes that affect gene expression and cell proliferation or migration. To define such redox-driven signalling devices, a proteomics approach was performed to identify the formation of protein complexes induced by ROS. To this end, protein lysates of human podocytes were treated with or without hydrogen peroxide (250 μM). Thereafter cell lysates were subjected to diagonal 2D gel electrophoresis and putative redox-affected proteins were analysed by MS/MS analysis. Among others, the regulatory subunit of protein kinase A (PKA) could be identified that forms homodimers under oxidative conditions. To evaluate whether ROS dependent dimerization of PKA also occurs in a more physiological setting, rat mesangial cells were treated with platelet-derived growth factor-BB (PDGF-BB) to induce ROS formation. This regimen resulted in a redox dependent dimerization of the R-subunits of PKA. To demonstrate whether PDGF-BB induced ROS formation affects PKA dependent pathways, the effects of PDGF-BB on phosphorylation of serine 157 of vasodilator stimulated protein (VASP) a classical target of PKA were analysed. Interestingly PDGF-BB induced VASP phosphorylation in a ROS dependent manner but independent of changes in cAMP levels. Taken together, we demonstrate a redox-mediated activation of PKA by PDGF-BB thus highlighting a physiological role of ROS as regulator of PKA activity in rat mesangial cells.     

Fehlleistungen als Empathie-Chance – die Gegenläufigkeit von „Projekten“ der Patientin und der Therapeutin

A patient in a session of behavior therapy commits a Freudian parapraxis relevant for what follows in the session. This is taken as a starting point for a single case conversation analysis (CA). CA is a well known tool in psychotherapy process research. The role of theory as “sensitizing concept” is discussed as relevant for what we see how the therapist responds to the parapraxis. As psychoanalytic authors we got support in our view by Eva-Lotta Brakemeier, full professor for cognitive behavioral therapy at Psychologische Hochschule (PHB), Berlin. Questions of professional integration vs. difference between behavioral therapy and psychoanalysis can be discussed more fertile along such concrete examples.     

Folding and ligand recognition of the TPP riboswitch aptamer at single-molecule resolution

Thiamine pyrophosphate (TPP)-sensitive mRNA domains are the most prevalent riboswitches known. Despite intensive investigation, the complex ligand recognition and concomitant folding processes in the TPP riboswitch that culminate in the regulation of gene expression remain elusive. Here, we used single-molecule fluorescence resonance energy transfer imaging to probe the folding landscape of the TPP aptamer domain in the absence and presence of magnesium and TPP. To do so, distinct labeling patterns were used to sense the dynamics of the switch helix (P1) and the two sensor arms (P2/P3 and P4/P5) of the aptamer domain. The latter structural elements make interdomain tertiary contacts (L5/P3) that span a region immediately adjacent to the ligand-binding site. In each instance, conformational dynamics of the TPP riboswitch were influenced by ligand binding. The P1 switch helix, formed by the 5′ and 3′ ends of the aptamer domain, adopts a predominantly folded structure in the presence of Mg²⁺ alone. However, even at saturating concentrations of Mg²⁺ and TPP, the P1 helix, as well as distal regions surrounding the TPP-binding site, exhibit an unexpected degree of residual dynamics and disperse kinetic behaviors. Such plasticity results in a persistent exchange of the P3/P5 forearms between open and closed configurations that is likely to facilitate entry and exit of the TPP ligand. Correspondingly, we posit that such features of the TPP aptamer domain contribute directly to the mechanism of riboswitch-mediated translational regulation.     

Altered functional connectivity of basal ganglia circuitry in dental phobia

Recent symptom provocation studies that compared patients suffering from dental phobia with healthy controls identified hyperactivation of basal ganglia structures, but none have assessed striatal functional connectivity. We reanalyzed data from a previous functional magnetic resonance imaging study on dental phobia. Patients (20 men, 25 women) and healthy controls (18 men, 23 women) had been exposed to pictures showing dental treatment, and neutral contents. We conducted connectivity analyses via psychophysiological interactions (PPIs). Relative to non-phobic controls, the patients showed decreased connectivity between prefrontal and basal ganglia regions. Moreover, the clinical group was characterized by increased internal basal ganglia connectivity, which was more pronounced in female compared with male patients. This study provides first evidence for an altered information flow within a fronto-striatal network in dentophobic individuals during visual symptom provocation, which can be considered a neuromarker of this disorder.     

A Test of Adolescent Internalizing and Externalizing Symptoms as Prospective Predictors of Type of Trauma Exposure and Posttraumatic Stress Disorder

The present study utilized longitudinal data from a high‐risk community sample (N = 377; 166 trauma‐exposed; 202 males; 175 females; 73% non‐Hispanic Caucasian) to test pretrauma measures of adolescent internalizing and externalizing symptoms as unique prospective predictors of type of trauma exposure and PTSD over and above the influence of correlated family adversity (a composite of family conflict, stress, and parental psychopathology). Data were analyzed with logistic and multinomial logistic regressions. Results indicated that females, but not males, with higher levels of internalizing (OR = 2.91) and externalizing (OR = 2.37) symptoms during adolescence were significantly more likely to be exposed to assaultive violence (over and above family adversity). In fact, males with higher levels of internalizing symptoms were significantly less likely to be exposed to assaultive violence (OR = 0.54). Neither internalizing nor externalizing symptoms uniquely predicted exposure to traumatic events that did not involve assaultive violence. Among trauma‐exposed participants, the unique association between internalizing symptoms and later PTSD yielded an odds ratio of 1.79 (p = .07) over and above the influences of family adversity, type of trauma exposure, and gender. Assaultive violence exposure fully mediated the association between females’ externalizing symptoms and future PTSD. Findings may help inform the prevention of both assaultive violence exposure and PTSD.