The extreme N-terminal region of human apolipoprotein A-I has a strong propensity to form amyloid fibrils

The N-terminal 1–83 residues of apolipoprotein A-I (apoA-I) have a strong propensity to form amyloid fibrils, in which the 46–59 segment was reported to aggregate to form amyloid-like fibrils. In this study, we demonstrated that a fragment peptide comprising the extreme N-terminal 1–43 residues strongly forms amyloid fibrils with a transition to β-sheet-rich structure, and that the G26R point mutation enhances the fibril formation of this segment. Our results suggest that in addition to the 46–59 segment, the extreme N-terminal region plays a crucial role in the development of amyloid fibrils by the N-terminal fragment of amyloidogenic apoA-I variants.     

cPPB‐aE is discovered from photosynthetic benthic dinoflagellates

Although chlorophyll degradation pathways in higher plants have been well studied, little is known about the mechanisms of chlorophyll degradation in microalgae. In this article, we report the occurrence of a chlorophyll a derivative that has never been discovered in photosynthetic organisms. This chlorophyll derivative emits no fluorescence and has a peculiar absorbance peak at 425, 451, 625, and 685 nm. From these features, it was identified as 13²,17³‐cyclopheophorbide a enol (cPPB‐aE), reported as a degradation product of chlorophyll a derived from prey algal cells in heterotrophic protists. We discovered cPPB‐aE in six benthic photosynthetic dinoflagellates that are phylogenetically separated into four clades based on SSU rDNA molecular phylogeny. This is the first report of this chlorophyll derivative in photosynthetic organisms and we suggest that the derivative is used to quench excess light energy.     

Effects of Krill-derived phospholipid-enriched n − 3 fatty acids on Ca regulation system in cerebral arteries from ovariectomized rats

Aims

To investigate the effects of n − 3 polyunsaturated fatty acids on cerebral circulation, ovariectomized (OVX) rats were administered with phospholipids in krill oil (KPL) or triglycerides in fish oil (FTG); effects on the Ca^2 + regulating system in their basilar artery (BA) were then analyzed.

Main methods

The rats were divided into 4 groups: control, OVX, OVX given KPL (OVXP), and OVX given FTG (OVXT) orally, daily for 2 weeks. Time dependent relaxation (TDR) of contractile response to 5HT in BA was determined myographically, Na⁺/Ca^2 + exchanger (NCX) 1 mRNA expression was determined by real time PCR, and nucleotides were analyzed by HPLC.

Key findings

The level of TDR in OVX that was significantly lower in the control was inhibited by l-NAME and indomethacin; TEA inhibited TDR totally in the control but only partly in OVXP and OVXT. Relaxation induced by the addition of 5 mM KCl to the BA pre-contracted with 5-HT was inhibited by TEA in the controls, OVXP and OVXT, but not in OVX. Overexpression of NCX1 mRNA in the BA from OVX was significantly inhibited by FTG. The ratio of ADP/ATP in cerebral arteries from OVX was significantly inhibited by KPL and FTG. Levels of triglyceride and arachidonic acid in the plasma of OVX increased, but were significantly inhibited by KPL and FTG.

Significance

Ovarian dysfunction affects Ca^2 + activated-, ATP-sensitive-K⁺ channels and NCX1, which play crucial roles in the autoregulation of cerebral blood flow. Also, KPL may become as good a supplement as FTG for postmenopausal women.     

Phosphorylation of Arabidopsis Ubiquitin Ligase ATL31 Is Critical for Plant Carbon/Nitrogen Nutrient Balance Response and Controls the Stability of 14-3-3 Proteins

Ubiquitin ligase plays a fundamental role in regulating multiple cellular events in eukaryotes by fine-tuning the stability and activity of specific target proteins. We have previously shown that ubiquitin ligase ATL31 regulates plant growth in response to nutrient balance between carbon and nitrogen (C/N) in Arabidopsis. Subsequent study demonstrated that ATL31 targets 14-3-3 proteins for ubiquitination and modulates the protein abundance in response to C/N-nutrient status. However, the underlying mechanism for the targeting of ATL31 to 14-3-3 proteins remains unclear. Here, we show that ATL31 interacts with 14-3-3 proteins in a phosphorylation-dependent manner. We identified Thr²⁰⁹, Ser²⁴⁷, Ser²⁷⁰, and Ser³⁰³ as putative 14-3-3 binding sites on ATL31 by motif analysis. Mutation of these Ser/Thr residues to Ala in ATL31 inhibited the interaction with 14-3-3 proteins, as demonstrated by yeast two-hybrid and co-immunoprecipitation analyses. Additionally, we identified in vivo phosphorylation of Thr²⁰⁹ and Ser²⁴⁷ on ATL31 by MS analysis. A peptide competition assay showed that the application of synthetic phospho-Thr²⁰⁹ peptide, but not the corresponding unphosphorylated peptide, suppresses the interaction between ATL31 and 14-3-3 proteins. Moreover, Arabidopsis plants overexpressing mutated ATL31, which could not bind to 14-3-3 proteins, showed accumulation of 14-3-3 proteins and growth arrest in disrupted C/N-nutrient conditions similar to wild-type plants, although overexpression of intact ATL31 resulted in repression of 14-3-3 accumulation and tolerance to the conditions. Together, these results demonstrate that the physiological role of phosphorylation at 14-3-3 binding sites on ATL31 is to modulate the binding ability and stability of 14-3-3 proteins to control plant C/N-nutrient response.     

Defective Craniofacial Development and Brain Function in a Mouse Model for Depletion of Intracellular Inositol Synthesis

myo-Inositol is an essential biomolecule that is synthesized by myo-inositol monophosphatase (IMPase) from inositol monophosphate species. The enzymatic activity of IMPase is inhibited by lithium, a drug used for the treatment of mood swings seen in bipolar disorder. Therefore, myo-inositol is thought to have an important role in the mechanism of bipolar disorder, although the details remain elusive. We screened an ethyl nitrosourea mutant mouse library for IMPase gene (Impa) mutations and identified an Impa1 T95K missense mutation. The mutant protein possessed undetectable enzymatic activity. Homozygotes died perinatally, and E18.5 embryos exhibited striking developmental defects, including hypoplasia of the mandible and asymmetric fusion of ribs to the sternum. Perinatal lethality and morphological defects in homozygotes were rescued by dietary myo-inositol. Rescued homozygotes raised on normal drinking water after weaning exhibited a hyper-locomotive trait and prolonged circadian periods, as reported in rodents treated with lithium. Our mice should be advantageous, compared with those generated by the conventional gene knock-out strategy, because they carry minimal genomic damage, e.g. a point mutation. In conclusion, our results reveal critical roles for intracellular myo-inositol synthesis in craniofacial development and the maintenance of proper brain function. Furthermore, this mouse model for cellular inositol depletion could be beneficial for understanding the molecular mechanisms underlying the clinical effect of lithium and myo-inositol-mediated skeletal development.     

Genetic modulation of the SERCA activity does not affect the Ca leak from the cardiac sarcoplasmic reticulum

The Ca²⁺ content in the sarcoplasmic reticulum (SR) determines the amount of Ca²⁺ released, thereby regulating the magnitude of Ca²⁺ transient and contraction in cardiac muscle. The Ca²⁺ content in the SR is known to be regulated by two factors: the activity of the Ca²⁺ pump (SERCA) and Ca²⁺ leak through the ryanodine receptor (RyR). However, the direct relationship between the SERCA activity and Ca²⁺ leak has not been fully investigated in the heart. In the present study, we evaluated the role of the SERCA activity in Ca²⁺ leak from the SR using a novel saponin-skinned method combined with transgenic mouse models in which the SERCA activity was genetically modulated. In the SERCA overexpression mice, the Ca²⁺ uptake in the SR was significantly increased and the Ca²⁺ transient was markedly increased. However, Ca²⁺ leak from the SR did not change significantly. In mice with overexpression of a negative regulator of SERCA, sarcolipin, the Ca²⁺ uptake by the SR was significantly decreased and the Ca²⁺ transient was markedly decreased. Again, Ca²⁺ leak from the SR did not change significantly. In conclusion, the selective modulation of the SERCA activity modulates Ca²⁺ uptake, although it does not change Ca²⁺ leak from the SR.     

Unintentional Flow of Alloying Elements in Steel during Recycling of End‐of‐Life Vehicles

Alloying elements in steel add a wide range of valuable properties to steel materials that are indispensable for the global economy. However, they are likely to be effectively irretrievably blended into the steel when recycled because of (among other issues) the lack of information about the composition of the scrap. This results in the alloying elements dissipating in slag during steelmaking and/or becoming contaminants in secondary steel. We used the waste input‐output material flow analysis model to quantify the unintentional flows of alloying elements (i.e., chromium, nickel, and molybdenum) that occur in steel materials and that result from mixing during end‐of‐life (EOL) processes. The model can be used to predict in detail the flows of ferrous materials in various phases, including the recycling phase by extending steel, alloying element source, and iron and steel scrap sectors. Application of the model to Japanese data indicates the critical importance of the recycling of EOL vehicles (ELVs) in Japan because passenger cars are the final destination of the largest share of these alloying elements. However, the contents of alloying elements are rarely considered in current ELV recycling. Consequently, the present study demonstrates that considerable amounts of alloying elements, which correspond to 7% to 8% of the annual consumption in electric arc furnace (EAF) steelmaking, are unintentionally introduced into EAFs. This result suggests the importance of quality‐based scrap recycling for efficient management of alloying elements.     

Butyric acid-induced rat jugular blood cytosolic oxidative stress is associated with SIRT1 decrease

Butyric acid (BA) induces jugular blood mitochondrial oxidative stress, whereas heme-induced oxidative stress was previously reported to inhibit SIRT1 in vitro. This would imply that BA-induced oxidative stress may similarly affect SIRT1. Here, we elucidated the BA effects on jugular blood cytosolic oxidative stress and SIRT1. Jugular blood cytosol was collected 0, 60, and 180 min after BA injection into rat gingival tissues and used throughout the study. Blood cytosolic oxidative stress induction, heme accumulation, NADPH oxidase (NOX) activation, nicotinamide adenine dinucleotide (NAD⁺) and NADP pool levels, NAD kinase (NADK), and SIRT1 amounts were determined. We found that BA retention in the gingival tissue induces blood cytosolic oxidative stress and heme accumulation which we correlated to both NOX activation and NADP pool increase. Moreover, we showed that BA-related NADP pool build-up is associated with NADK increase which we suspect decreased NAD⁺ levels and consequentially lowered SIRT1 amounts in the rat blood cytosol.     

Clinical course after corticosteroid therapy in IgG4-related aortitis/periaortitis and periarteritis: a retrospective multicenter study

Introduction

Immunoglobulin G4 (IgG4)–related aortitis/periaortitis and periarteritis are vascular manifestations of IgG4-related disease. In this disease, the affected aneurysmal lesion has been suspected to be at risk of rupture. In this study, we aimed to clarify the clinical course after corticosteroid therapy in IgG4-related aortitis/periaortitis and periarteritis.

Methods

We retrospectively evaluated clinical features, including laboratory data, imaging findings and the course after corticosteroid therapy, in 40 patients diagnosed with IgG4-related aortitis/periaortitis and periarteritis on the basis of periaortic/periarterial radiological findings, satisfaction of the comprehensive diagnostic criteria or each organ-specific diagnostic criteria, and exclusion of other diseases.

Results

The patients were mainly elderly, with an average age of 66.4 years and with a marked male predominance and extensive other organ involvement. Subjective symptoms were scanty, and only a small proportion had elevated serum C-reactive protein levels. The affected aorta/artery were the abdominal aortas or the iliac arteries in most cases. Thirty-six patients were treated with prednisolone, and the periaortic/periarterial lesions improved in most of them during the follow-up period. Two (50.0%) of four patients with luminal dilatation of the affected lesions before corticosteroid therapy had exacerbations of luminal dilatation after therapy, whereas none of the twenty-six patients without it had a new appearance of luminal dilatation after therapy.

Conclusions

The results of this retrospective multicenter study highlight three important points: (1) the possibility of latent existence and progression of periaortic/periarterial lesions, (2) the efficacy of corticosteroid therapy in preventing new aneurysm formation in patients without luminal dilatation of periaortic/periarterial lesions and (3) the possibility that a small proportion of patients may actually develop luminal dilatation of periaortic/periarterial lesions in IgG4-related aortitis/periaortitis and periarteritis. A larger-scale prospective study is required to confirm the efficacy and safety of corticosteroid therapy in patients with versus those without luminal dilatation and to devise a more useful and safe treatment strategy, including administration of other immunosuppressants.