Autoimmunity-Associated LYP-W620 Does Not Impair Thymic Negative Selection of Autoreactive T Cells.

A C1858T (R620W) variation in the PTPN22 gene encoding the tyrosine phosphatase LYP is a major risk factor for human autoimmunity. LYP is a known negative regulator of signaling through the T cell receptor (TCR), and murine Ptpn22 plays a role in thymic selection. However, the mechanism of action of the R620W variant in autoimmunity remains unclear. One model holds that LYP-W620 is a gain-of-function phosphatase that causes alterations in thymic negative selection and/or thymic output of regulatory T cells (Treg) through inhibition of thymic TCR signaling. To test this model, we generated mice in which the human LYP-W620 variant or its phosphatase-inactive mutant are expressed in developing thymocytes under control of the proximal Lck promoter. We found that LYP-W620 expression results in diminished thymocyte TCR signaling, thus modeling a "gain-of-function" of LYP at the signaling level. However, LYP-W620 transgenic mice display no alterations of thymic negative selection and no anomalies in thymic output of CD4(+)Foxp3(+) Treg were detected in these mice. Lck promoter-directed expression of the human transgene also causes no alteration in thymic repertoire or increase in disease severity in a model of rheumatoid arthritis, which depends on skewed thymic selection of CD4(+) T cells. Our data suggest that a gain-of-function of LYP is unlikely to increase risk of autoimmunity through alterations of thymic selection and that LYP likely acts in the periphery perhaps selectively in regulatory T cells or in another cell type to increase risk of autoimmunity

New genetic loci link adipose and insulin biology to body fat distribution.

Body fat distribution is a heritable trait and a well-established predictor of adverse metabolic outcomes, independent of overall adiposity. To increase our understanding of the genetic basis of body fat distribution and its molecular links to cardiometabolic traits, here we conduct genome-wide association meta-analyses of traits related to waist and hip circumferences in up to 224,459 individuals. We identify 49 loci (33 new) associated with waist-to-hip ratio adjusted for body mass index (BMI), and an additional 19 loci newly associated with related waist and hip circumference measures (P < 5 × 10(-8)). In total, 20 of the 49 waist-to-hip ratio adjusted for BMI loci show significant sexual dimorphism, 19 of which display a stronger effect in women. The identified loci were enriched for genes expressed in adipose tissue and for putative regulatory elements in adipocytes. Pathway analyses implicated adipogenesis, angiogenesis, transcriptional regulation and insulin resistance as processes affecting fat distribution, providing insight into potential pathophysiological mechanisms

A Conformational Change in the Adeno-Associated Virus Type 2 Capsid Leads to the Exposure of Hidden VP1 N Termini

The complex infection process of parvoviruses is not well understood so far. An important role has been attributed to a phospholipase A(2) domain which is located within the unique N terminus of the capsid protein VP1. Based on the structural difference between adeno-associated virus type 2 wild-type capsids and capsids lacking VP1 or VP2, we show via electron cryomicroscopy that the N termini of VP1 and VP2 are involved in forming globules inside the capsids of empty and full particles. Upon limited heat shock, VP1 and possibly VP2 become exposed on the outsides of full but not empty capsids, which is correlated with the disappearance of the globules in the inner surfaces of the capsids. Using molecular modeling, we discuss the constraints on the release of the globularly organized VP1-unique N termini through the channels at the fivefold symmetry axes outside of the capsid

Electron cryo-microscopy and image reconstruction of adeno-associated virus type 2 empty capsids

Adeno-associated virus type 2 empty capsids are composed of three proteins, VP1, VP2 and VP3, which have relative molecular masses of 87, 72 and 62 kDa, respectively, and differ in their N-terminal amino acid sequences. They have a likely molar ratio of 1:1:8 and occupy symmetrical equivalent positions in an icosahedrally arranged protein shell. We have investigated empty capsids of adeno-associated virus type 2 by electron cryo-microscopy and icosahedral image reconstruction. The three-dimensional map at 1.05 nm resolution showed sets of three elongated spikes surrounding the three-fold symmetry axes and narrow empty channels at the five-fold axes. The inside of the capsid superimposed with the previously determined structure of the canine parvovirus (Q. Xie and M.S. Chapman, 1996, J. Mol. Biol., 264, 497–520), whereas the outer surface showed clear discrepancies. Globular structures at the inner surface of the capsid at the two-fold symmetry axes were identified as possible positions for the N-terminal extensions of VP1 and VP2

Mortality and Incidence of Renal Replacement Therapy in People With Type 1 Diabetes Mellitus–A Three Decade Long Prospective Observational Study in the Lainz T1DM Cohort

CONTEXT AND OBJECTIVE: We investigated long term mortality, requirement for renal replacement therapy (RRT), and incidence of other late diabetic complications in an observational cohort study of 641 people with type 1 diabetes (T1DM).DESIGN: Prospective observational cohort study.SETTING: The study was conducted at a Tertiary Diabetes Centre in Vienna, Austria.PATIENTS: A cohort with all people with T1DM (n = 641, 47% females, 30 ± 11 years) attending their annual diabetes review was created in 1983-1984. Biomedical data were collected.MAIN OUTCOME MEASURES: In 2013 we investigated mortality rates and incidence rates of RRT by record linkage with national registries and incidence of other major diabetes complications by questionnaire.RESULTS: 156 (24%) patients died [mortality rate: 922 (95%CI: 778-1066) per 100 000 person years]. Fifty-five (8.6%) received RRT [incidence rate: 335 (95%CI: 246-423) per 100 000 person years]. The 380 questionnaires (78% return rate) recorded cardiac events, strokes, limb amputations, and/or blindness, affecting 21.8% of survivors. Mortality and incidence of RRT increased in each quartile of baseline HbA1c, with the lowest rates in the quartile with HbA1c ≤ 6.5% (48 mmol/mol) (P &lt; .05).CONCLUSIONS: In people with established type 1 diabetes who were observed for almost three decades, the overall mortality was 24% and the incidence of renal replacement therapy was 8.6%, with a 21.8% combined incidence rate of the other hard endpoints in the surviving people. A clear linear relationship between early glycemic control and the later development of end stage renal disease and mortality has been found.</p

Cell distribution in thymus of TgLYPW and TgLYPW^C227S.

<p>Table shows the basic statistics (average±SD) of cell counts in transgenic animals and non transgenic littermates.</p