Effect of insulin receptor expressing T cell infiltration in islets on beta cell functionality

T cells have a major role in the progression of type 1 diabetes (T1D) in human and the non-obese diabetic (NOD) mouse model. Activated T cells have increased insulin receptor (IR) expression on their surface. When T cells with high density of IR from NOD mice were transferred into young irradiated non-diabetic NOD mice, recipient mice developed insulitis and diabetes. Irradiated non-diabetic NOD mice that received T cells with low to negative density of IR had neither insulitis nor diabetes. In order to understand the effect of IR expressing T cells in T1D development, our lab has developed a novel transgenic mouse model, C57BL/6-CD3FLAGmIR/mfm, genetically modified to express FLAG tagged mouse insulin receptor (mIR) on T cells.

It was observed that FLAG-mIR expressing T cells can chemotax to the islet leading to insulitis. However, C57BL/6-CD3FLAGmIR/mfm mice were not hyperglycemic at any age. Metabolic studies were performed to evaluate if FLAG-mIR expressing T cell infiltration in the transgenic mice has effect on beta cell functionality. Impaired in vitro islet insulin secretion on treatment with non-glucose beta cells secretagogue and abnormal glucose tolerance in the transgenic mice resemble the pathological changes during prediabetes in human and NOD mice. Islet and Metabolic changes were also found in immunocompromised RAG mice that received transgenic mice splenocytes confirming that the transgenic phenotype can be passaged to immunocompromised RAG mice in a short time frame. This study provides a new perspective to understand the pathology of T1D and design a novel therapeutic approach targeting IR overexpressing T cells.

Apoptotic activities in closely related styryllactone stereoisomers toward human tumor cell lines: Investigation of synergism of styryllactone-induced apoptosis with TRAIL

A related series of styryllactones with small functional and stereochemical variations were compiled for a comparative study of their apoptotic activities toward two tumorigenic and one non-tumorigenic control cell line. While a substantial range of intrinsic activity was observed, the relative order of activity of the different compounds toward the cell types varied somewhat as did the relative ratios of apoptosis and necrosis observed in conjunction with the loss of cell viability. While some of the styryllactones showed substantial activity, a small but significant apoptosis-induced synergism was demonstrated with (-)-altholactone and TRAIL (tumor necrosis factor-related apoptosis-inducing ligand).

Dissociative symptoms are positively related to stress in borderline personality disorder

OBJECTIVE

According to DSM-IV criteria, dissociative symptoms in borderline personality disorder (BPD) occur in response to stress. Empirical evidence is, however, lacking.

METHOD

Using ambulatory monitoring, we assessed dissociative symptoms and subjective ratings of stress every 60 min for 48 h on a palmtop computer in BPD-patients (n = 51), clinical controls (CC; major depression n = 25; panic disorder n = 26), and healthy controls (HC; n = 40). Data analyses were primarily based on hierarchical linear models.

RESULTS

In all groups, states of increased stress were paralleled by increased scores of dissociation, thus confirming the hypothesized association between stress and dissociation. The increase in dissociation was more pronounced in BPD-patients when compared with CC and HC. Additionally, BPD-patients reported heightened dissociative experience compared with CC and HC, even after controlling for stress.

CONCLUSION

Our data suggest that BPD-patients might be prone to dissociation when experiencing stress and are characterized by a generally heightened level of dissociation.

In vitro and in vivo characterization of a novel nonsteroidal, species-specific progesterone receptor modulator, PRA-910

The progesterone receptor (PR) is an important regulator of female reproduction. Consequently, PR modulators have found numerous pharmaceutical utilities in women's reproductive health. In the process of identifying more receptor-specific and tissue-selective PR modulators, we discovered a novel nonsteroidal, 6-aryl benzoxazinone compound, PRA-910, that displays unique in vitro and in vivo activities. In a PR/PRE reporter assay in COS-7 cells, PRA-910 shows potent PR antagonist activity with an IC50 value of approximately 20 nM. In the alkaline phosphatase assay in the human breast cancer cell line T47D, PRA-910 is a partial progesterone antagonist at low concentrations and is also an effective PR agonist at higher concentrations (EC50 value of approximately 700 nM). PRA-910 binds to the human PR with high affinity (Kd = 4 nM) and was previously shown to exhibit greater than 100-fold selectivity for the PR versus other steroid receptors. In the adult ovariectomized rat, PRA-910 is a potent PR antagonist. It inhibits progesterone-induced uterine decidual response with an ED50 value of 0.4 mg/kg, p.o., and reverses progesterone suppression of estradiol-induced complement C3 expression with potency similar to RU-486. In the nonhuman primate, however, PRA-910 is a PR agonist. The effect on endometrial histology strongly resembles that of progesterone. This unique compound also suppresses estradiol-induced epithelial cell proliferation and both estrogen and progesterone receptor expression in the uterine endometrium as a PR agonist would. In summary, PRA-910 is a structurally and biologically novel selective PR modulator with either PR agonist or antagonist activity, depending on context, concentration, and species.

Lon protease functions as a negative regulator of type III protein secretion in Pseudomonas syringae

The central conserved region of the Pseudomonas syringae hrp pathogenicity island encodes a type III protein secretion system (TTSS) that is required for pathogenicity in plants. Expression of the hrp TTSS is controlled by the alternative sigma factor, HrpL, whose expression, in turn, is positively controlled by two truncated enhancer binding proteins, HrpR and HrpS. Although a number of environmental conditions are known to modulate hrp TTSS expression, such as stringent conditions and pathogenesis, the mechanism by which the activities of these transcriptional factors are modulated had not been established. In this study, HrpR and HrpS were found to be constitutively expressed under conditions in which the hrpL promoter was inactive. To identify a postulated negative regulator of hrpL expression, transposome (Tz) mutagenesis was used to isolate hrp constitutive mutants. P. syringae Pss61 and DC3000 hrp constitutive mutants were identified that carried lon::Tz insertions and exhibited increased cell length and UV sensitivity typical of Delta lon mutants. The P. syringae Lon protease retained structural features of its homologues found in other bacteria and was capable of complementing an Escherichia coli Delta lon mutant. P. syringae lon::Tz mutants exhibited enhanced expression of the hrpL promoter, suggesting an effect on HrpR and/or HrpS. HrpR was observed to be unstable in wild-type P. syringae strains grown in non-inductive media. However, the apparent half-life increased more than 10-fold in the P. syringae lon::Tz mutants or upon transfer to an inductive medium. The P. syringae lon mutants elicited rapidly developing plant responses and were shown to hypersecrete effector proteins, such as AvrPto. These results indicate that expression of the hrp regulon and type III secretion are negatively regulated by Lon-mediated degradation of HrpR.

Enhancer-binding proteins HrpR and HrpS interact to regulate hrp-encoded type III protein secretion in Pseudomonas syringae strains

In Pseudomonas syringae strains, the hrp-hrc pathogenicity island consists of an HrpL-dependent regulon that encodes a type III protein translocation complex and translocated effector proteins required for pathogenesis. HrpR and HrpS function as positive regulatory factors for the hrpL promoter, but their mechanism of action has not been established. Both HrpR and HrpS are structurally related to enhancer-binding proteins, but they lack receiver domains and do not appear to require a cognate protein kinase for activity. hrpR and hrpS were shown to be expressed as an operon: a promoter was identified 5' to hrpR, and reverse transcriptase PCR detected the presence of an hrpRS transcript. The hrpR promoter and coding sequence were conserved among P. syringae strains. The coding sequences for hrpR and hrpS were cloned into compatible expression vectors, and their activities were monitored in Escherichia coli transformants carrying an hrpL'-lacZ fusion. HrpS could function as a weak activator of the hrpL promoter, but the activity was only 2.5% of the activity detected when both HrpR and HrpS were expressed in the reporter strain. This finding is consistent with a requirement for both HrpR and HrpS in the activation of the hrpL promoter. By using a yeast two-hybrid assay, an interaction between HrpR and HrpS was detected, suggestive of the formation of a heteromeric complex. Physical interaction of HrpR and HrpS was confirmed by column-binding experiments. The results show that HrpR and HrpS physically interact to regulate the sigma(54)-dependent hrpL promoter in P. syringae strains.

Thyroid cell apoptosis. A new understanding of thyroid autoimmunity

Apoptosis is a highly regulated mechanism of cell death involved in normal development, immune regulation, and homeostasis. Abnormal apoptotic activity has been implicated in a variety of diseases including cancer, autoimmunity, and degenerative disorders. In the thyroid, altered cell death may play a role in the pathogenesis of autoimmune disorders such as Hashimoto's thyroiditis and Graves' disease. Apoptosis-signaling pathways can be initiated through activation of death receptors or in response to cellular damage, such as in gamma irradiation. It has been demonstrated that Fas, tumor necrosis factor, and tumor necrosis factor-related apoptosis-inducing ligand pathways are present and functional in the thyroid, although the expression of these molecules and their roles in thyroid autoimmunity have been debated. Thyroid apoptosis is regulated at multiple levels, including receptor and ligand expression, and the expression of antiapoptotic proteins, such as FAP-1 and Bcl-2. These factors may provide potential mechanisms for modifying the pathogenesis of autoimmune thyroid disease.