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Background: Glucokinase is a key player in carbohydrate metabolism, but how this enzyme is regulated by post-translational modifications is largely unknown. Results: Glucokinase is SUMO-modified in vitro and in pancreatic ␤-cells, increasing its activity and stability. Conclusion: SUMOylation of glucokinase is a novel form of modification, regulating its cellular stability and activity. Significance: SUMO conjugation of glucokinase may have an important regulatory function in pancreatic ␤-cells.

How the T cell receptor (TcR)/CD3 complex mediates not only the induction of T cell activation but also suppressive effects like T cell anergy or apoptosis is not well understood. Here we describe a series of preincubation and restimulation experiments which demonstrate that primary stimulation of resting, unseparated human T cells with mitogenic doses of immobilized anti-CD3 antibodies induces hyporesponsiveness upon restimulation of the cells. Various costimuli can prevent this type of anergy to a variable degree if present during the preincubation period, phorbol 12-myristate 13-acetate (PMA) being the most and anti-CD4 antibody the least effective. If employed together with anti-CD3 antibody during the restimulation phase of the assay, interleukin (IL)-2, IL-4 and anti-CD28 antibody break anergy almost completely. Proliferation induced by a submitogenic dose of anti-CD3 antibody supplemented by costimulatory signals (anti-CD2, anti-CD4, anti-CD28, IL-2, IL-4 or PMA) does not result in hyporesponsiveness. Taken together, these results support a modified view of the two-signal model for T cell activation according to which anergy induction in resting T cells occurs if primary proliferation is induced by high density triggering of the TcR/CD3 complex in the absence of accessory signals. We discuss possible implications of these findings for the induction of peripheral tolerance.

Mouse models show that experimental stress mimicking prolonged life-stress exposure enhances neurogenic inflammation, induces adaptive immunity cytokine-imbalance characterized by a shift to Type 1 T-helper cell cytokines and increases apoptosis of epithelial cells. This affects hair growth in otherwise healthy animals. In this study, we investigate whether a prolonged naturalistic life-stress exposure affects cytokine balance and hair parameters in healthy humans. 33 (18 exam, 15 comparison) female medical students with comparable sociobiological status were analyzed during a stressful final examination period, at three points in time (T) 12 weeks apart. T1 was before start of the learning period, T2 between the three-day written exam and an oral examination, and T3 after a 12 week rest and recovery from the stress of the examination period. Assessments included: self-reported distress and coping strategies (Perceived Stress Questionnaire [PSQ], Trier Inventory for the Assessment of Chronic Stress [TICS]), COPE), cytokines in supernatants of stimulated peripheral blood mononucleocytes (PBMCs), and trichogram (hair cycle and pigmentation analysis). Comparison between students participating in the final medical exam at T2 and non-exam students, revealed significantly higher stress perception in exam students. Time-wise comparison revealed that stress level, TH1/TH2 cytokine balance and hair parameters changed significantly from T1 to T2 in the exam group, but not the control. However, no group differences were found for cytokine balance or hair parameters at T2. The study concludes that in humans, naturalistic stress, as perceived during participation in a major medical exam, has the potential to shift the immune response to TH1 and transiently hamper hair growth, but these changes stay within a physiological range. Findings are instructive for patients suffering from hair loss in times of high stress. Replication in larger and more diverse sample populations is required, to assess suitability of trichogram analysis as biological outcome for stress studies.