Compartment‐specific aggregases direct distinct nuclear and cytoplasmic aggregate deposition

Disruption of the functional protein balance in living cells activates protective quality control systems to repair damaged proteins or sequester potentially cytotoxic misfolded proteins into aggregates. The established model based on Saccharomyces cerevisiae indicates that aggregating proteins in the cytosol of eukaryotic cells partition between cytosolic juxtanuclear (JUNQ) and peripheral deposits. Substrate ubiquitination acts as the sorting principle determining JUNQ deposition and subsequent degradation. Here, we show that JUNQ unexpectedly resides inside the nucleus, defining a new intranuclear quality control compartment, INQ, for the deposition of both nuclear and cytosolic misfolded proteins, irrespective of ubiquitination. Deposition of misfolded cytosolic proteins at INQ involves chaperone‐assisted nuclear import via nuclear pores. The compartment‐specific aggregases, Btn2 (nuclear) and Hsp42 (cytosolic), direct protein deposition to nuclear INQ and cytosolic (CytoQ) sites, respectively. Intriguingly, Btn2 is transiently induced by both protein folding stress and DNA replication stress, with DNA surveillance proteins accumulating at INQ. Our data therefore reveal a bipartite, inter‐compartmental protein quality control system linked to DNA surveillance via INQ and Btn2.     

Differential effects of cyclophosphamide and mycophenolate mofetil on cellular and serological parameters in patients with systemic lupus erythematosus

IntroductionDisease activity and therapy show an impact on cellular and serological parameters in patients with systemic lupus erythematosus (SLE). This study was performed to compare the influence of mycophenolate mofetil (MMF) and cyclophosphamide (CYC) therapy on these parameters in patients with flaring, organ-threatening disease.MethodsSLE patients currently receiving CYC (n = 20), MMF (n = 25) or no immunosuppressive drugs (n = 22) were compared using a cross-sectional design. Median disease activity and daily corticosteroid dose were similar in these treatment groups. Concurrent medication, organ manifestations, and disease activity were recorded, and cellular and serological parameters were determined by routine diagnostic tests or flow cytometric analysis. In addition follow-up data were obtained from different sets of patients (CYC n = 24; MMF n = 23).ResultsAlthough both drugs showed a significant effect on disease activity and circulating B cell subsets, only MMF reduced circulating plasmablasts and plasma cells as well as circulating free light chains within three months of induction therapy. Neither MMF nor CYC were able to reduce circulating memory B cells. MMF lowered IgA levels more markedly than CYC. We did not observe a significant difference in the reduction of IgG levels or anti-dsDNA antibodies comparing patients receiving MMF or CYC. In contrast to MMF, induction therapy with CYC was associated with a significant increase of circulating CD8+ effector T cells and plasmacytoid dendritic cells (PDCs) after three months.ConclusionsThe results indicate differences between MMF and CYC with regard to the mechanism of action. MMF, but not CYC, treatment leads to a fast and enduring reduction of surrogate markers of B cell activation, such as circulating plasmablasts, plasma cells and free light chains but a comparable rate of hypogammaglobulinemia.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0603-8) contains supplementary material, which is available to authorized users.     

ATP synthase repression in tobacco restricts photosynthetic electron transport, CO2 assimilation, and plant growth by overacidification of the thylakoid lumen

Tobacco (Nicotiana tabacum) plants strictly adjust the contents of both ATP synthase and cytochrome b(6)f complex to the metabolic demand for ATP and NADPH. While the cytochrome b(6)f complex catalyzes the rate-limiting step of photosynthetic electron flux and thereby controls assimilation, the functional significance of the ATP synthase adjustment is unknown. Here, we reduced ATP synthase accumulation by an antisense approach directed against the essential nuclear-encoded γ-subunit (AtpC) and by the introduction of point mutations into the translation initiation codon of the plastid-encoded atpB gene (encoding the essential β-subunit) via chloroplast transformation. Both strategies yielded transformants with ATP synthase contents ranging from 100 to <10% of wild-type levels. While the accumulation of the components of the linear electron transport chain was largely unaltered, linear electron flux was strongly inhibited due to decreased rates of plastoquinol reoxidation at the cytochrome b(6)f complex (photosynthetic control). Also, nonphotochemical quenching was triggered at very low light intensities, strongly reducing the quantum efficiency of CO(2) fixation. We show evidence that this is due to an increased steady state proton motive force, resulting in strong lumen overacidification, which in turn represses photosynthesis due to photosynthetic control and dissipation of excitation energy in the antenna bed.     

Quantitative and dynamic expression profile of premature and active forms of the regional ADAM proteins during chicken brain development

The ADAM (A Disintegrin and Metalloprotease) family of transmembrane proteins plays important roles in embryogenesis and tissue formation based on their multiple functional domains. In the present study, for the first time, the expression patterns of the premature and the active forms of six members of the ADAM proteins — ADAM9, ADAM10, ADAM12, ADAM17, ADAM22 and ADAM23 — in distinct parts of the developing chicken brain were investigated by quantitative Western blot analysis from embryonic incubation day (E) 10 to E20. The results show that the premature and the active forms of various ADAM proteins are spatiotemporally regulated in different parts of the brain during development, suggesting that the ADAMs play a very important role during embryonic development.     

Multicenter phase 2 trial of sirolimus for tuberous sclerosis: kidney angiomyolipomas and other tumors regress and VEGF- D levels decrease

Background

Tuberous sclerosis (TSC) related tumors are characterized by constitutively activated mTOR signaling due to mutations in TSC1 or TSC2.

Methods

We completed a phase 2 multicenter trial to evaluate the efficacy and tolerability of the mTOR inhibitor, sirolimus, for the treatment of kidney angiomyolipomas.

Results

36 adults with TSC or TSC/LAM were enrolled and started on daily sirolimus. The overall response rate was 44.4% (95% confidence intervals [CI] 28 to 61); 16/36 had a partial response. The remainder had stable disease (47.2%, 17/36), or were unevaluable (8.3%, 3/36). The mean decrease in kidney tumor size (sum of the longest diameters [sum LD]) was 29.9% (95% CI, 22 to 37; n = 28 at week 52). Drug related grade 1–2 toxicities that occurred with a frequency of >20% included: stomatitis, hypertriglyceridemia, hypercholesterolemia, bone marrow suppression (anemia, mild neutropenia, leucopenia), proteinuria, and joint pain. There were three drug related grade 3 events: lymphopenia, headache, weight gain. Kidney angiomyolipomas regrew when sirolimus was discontinued but responses tended to persist if treatment was continued after week 52. We observed regression of brain tumors (SEGAs) in 7/11 cases (26% mean decrease in diameter), regression of liver angiomyolipomas in 4/5 cases (32.1% mean decrease in longest diameter), subjective improvement in facial angiofibromas in 57%, and stable lung function in women with TSC/LAM (n = 15). A correlative biomarker study showed that serum VEGF-D levels are elevated at baseline, decrease with sirolimus treatment, and correlate with kidney angiomyolipoma size (Spearman correlation coefficient 0.54, p = 0.001, at baseline).

Conclusions

Sirolimus treatment for 52 weeks induced regression of kidney angiomyolipomas, SEGAs, and liver angiomyolipomas. Serum VEGF-D may be a useful biomarker for monitoring kidney angiomyolipoma size. Future studies are needed to determine benefits and risks of longer duration treatment in adults and children with TSC.

Trial Registration

Clinicaltrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00126672","term_id":"NCT00126672"}}NCT00126672     

Effects of dam breed and dietary source of n-3 polyunsaturated fatty acids on the growth and carcass characteristics of lambs sourced from hill sheep flocks

The objectives of this study were to investigate the effect of dietary lipid source on the growth and carcass characteristics of lambs sourced from a range of crossbred hill ewes. Over a 2-year period, 466 lambs representing the progeny of Scottish Blackface (BF × BF), Swaledale (SW) × BF, North Country Cheviot (CH) × BF, Lleyn (LL) × BF and Texel (T) × BF ewes were sourced from six commercial hill flocks and finished on one of four diets: grass pellets (GP), cereal-based concentrate (CC), CC enriched with oilseed rape (CR) and CC enriched with fish oil (CF). Dry matter intake (DMI) was highest (P < 0.001) in lambs offered GP; however, carcass weight gain (CWG) and feed conversion efficiency were higher (P < 0.001) in lambs fed concentrate-based diets. For lambs offered concentrate-based diets, DMI and live weight gain were lower (P < 0.001) for CF than CC or CR. Lambs with T × BF dams achieved a higher (P < 0.05) daily CWG and CWG/kg DMI than BF × BF, SW × BF or LL × BF dams. When lambs were slaughtered at fat score 3, CH × BF, LL × BF and T × BF dams increased carcass weight by 0.8 to 1.4 kg (P < 0.001) and conformation score (CS) by 0.2 to 0.4 units (P < 0.001) compared with BF × BF or SW × BF dams. However, breed effects on carcass conformation were reduced by 50% when lambs were slaughtered at a constant carcass weight. Diets CC and CR increased carcass weight by 0.8 to 1.6 kg (P < 0.001) and CS by 0.1 to 0.3 units (P < 0.001) compared with GP and CF. Both, dam breed and dietary effects on carcass conformation were associated with an increase (P < 0.001) in shoulder width of the lambs. Lambs fed CF and slaughtered at a constant carcass weight had more subcutaneous fat over the Longissumus dorsi (P < 0.05), Iliocostalis thoracis (P < 0.001) and Obliquus internus abdominis (P < 0.001) compared with those fed CC. However, these effects were removed when lambs were slaughtered at a constant fat score. At both endpoints, lambs from T × BF dams contained less (P < 0.05) perinephric and retroperitoneal fat than SW × BF or LL × BF dams fed GP or CC, respectively. The results from this study show that using crossbred ewes sired by CH, LL or T sires will increase carcass weight and improve carcass conformation of lambs sourced from hill flocks. Inclusion of oilseed rape in lamb finishing diets had only minor effects on performance compared with a standard CC but feeding fish oil or GP impacted negatively on lamb growth and carcass quality.