Calpain activation mediates microgravity-induced myocardial abnormalities in mice via p38 and ERK1/2 MAPK pathways

The human cardiovascular system has adapted to function optimally in Earth''s 1G gravity, and microgravity conditions cause myocardial abnormalities, including atrophy and dysfunction. However, the underlying mechanisms linking microgravity and cardiac anomalies are incompletely understood. In this study, we investigated whether and how calpain activation promotes myocardial abnormalities under simulated microgravity conditions. Simulated microgravity was induced by tail suspension in mice with cardiomyocyte-specific deletion of Capns1, which disrupts activity and stability of calpain-1 and calpain-2, and their WT littermates. Tail suspension time-dependently reduced cardiomyocyte size, heart weight, and myocardial function in WT mice, and these changes were accompanied by calpain activation, NADPH oxidase activation, and oxidative stress in heart tissues. The effects of tail suspension were attenuated by deletion of Capns1. Notably, the protective effects of Capns1 deletion were associated with the prevention of phosphorylation of Ser-345 on p47^phox and attenuation of ERK1/2 and p38 activation in hearts of tail-suspended mice. Using a rotary cell culture system, we simulated microgravity in cultured neonatal mouse cardiomyocytes and observed decreased total protein/DNA ratio and induced calpain activation, phosphorylation of Ser-345 on p47^phox, and activation of ERK1/2 and p38, all of which were prevented by calpain inhibitor-III. Furthermore, inhibition of ERK1/2 or p38 attenuated phosphorylation of Ser-345 on p47^phox in cardiomyocytes under simulated microgravity. This study demonstrates for the first time that calpain promotes NADPH oxidase activation and myocardial abnormalities under microgravity by facilitating p47^phox phosphorylation via ERK1/2 and p38 pathways. Thus, calpain inhibition may be an effective therapeutic approach to reduce microgravity-induced myocardial abnormalities.     

From signaling to function: how strigolactones regulate plant development

Science China Life Sciences -     

Low temperature alters plasma membrane lipid composition and ATPase activity of pineapple fruit during blackheart development

Plasma membrane (PM) plays central role in triggering primary responses to chilling injury and sustaining cellular homeostasis. Characterising response of membrane lipids to low temperature can provide important information for identifying early causal factors contributing to chilling injury. To this end, PM lipid composition and ATPase activity were assessed in pineapple fruit (Ananas comosus) in relation to the effect of low temperature on the development of blackheart, a form of chilling injury. Chilling temperature at 10 °C induced blackheart development in concurrence with increase in electrolyte leakage. PM ATPase activity was decreased after 1 week at low temperature, followed by a further decrease after 2 weeks. The enzyme activity was not changed during 25 °C storage. Loss of total PM phospholipids was found during postharvest senescence, but more reduction was shown from storage at 10 °C. Phosphatidylcholine and phosphatidylethanolamine were the predominant PM phospholipid species. Low temperature increased the level of phosphatidic acid but decreased the level of phosphatidylinositol. Both phospholipid species were not changed during storage at 25 °C. Postharvest storage at both temperatures decreased the levels of C18:3 and C16:1, and increased level of C18:1. Low temperature decreased the level of C18:2 and increased the level of C14:0. Exogenous application of phosphatidic acid was found to inhibit the PM ATPase activity of pineapple fruit in vitro. Modification of membrane lipid composition and its effect on the functional property of plasma membrane at low temperature were discussed in correlation with their roles in blackheart development of pineapple fruit.     

Glycosaminoglycan-dependent restriction of FGF diffusion is necessary for lacrimal gland development

Glycosaminoglycans (GAGs) play a central role in embryonic development by regulating the movement and signaling of morphogens. We have previously demonstrated that GAGs are the co-receptors for Fgf10 signaling in the lacrimal gland epithelium, but their function in the Fgf10-producing periocular mesenchyme is still poorly understood. In this study, we have generated a mesenchymal ablation of UDP-glucose dehydrogenase (Ugdh), an essential biosynthetic enzyme for GAGs. Although Fgf10 RNA is expressed normally in the periocular mesenchyme, Ugdh mutation leads to excessive dispersion of Fgf10 protein, which fails to elicit an FGF signaling response or budding morphogenesis in the presumptive lacrimal gland epithelium. This is supported by genetic rescue experiments in which the Ugdh lacrimal gland defect is ameliorated by constitutive Ras activation in the epithelium but not in the mesenchyme. We further show that lacrimal gland development requires the mesenchymal expression of the heparan sulfate N-sulfation genes Ndst1 and Ndst2 but not the 6-O and 2-O-sulfation genes Hs6st1, Hs6st2 and Hs2st. Taken together, these results demonstrate that mesenchymal GAG controls lacrimal gland induction by restricting the diffusion of Fgf10.     

骨骼肌M蛋白抗血清的制备及正常人骨骼肌M蛋白的免疫电镜定位

分别制备了兔抗人Ｍ蛋白（Ｂ成分）抗血清和兔抗人Ｃ成分［１］抗血清。用蛋白Ａ－胶体金作标记物,对经ＬｏｗｉｃｒｙｌＫ４Ｍ低温包埋的人骨骼肌超薄切片中Ｍ蛋白和分子量１４００００的Ｃ成分进行免疫电镜定位。发现Ｍ蛋白分布于整个Ｍ线,而Ｃ成分虽然也集中于Ｍ线以内,但主要分布于Ｍ线内的边缘区域。     

A nano-Ni based ultrasensitive nonenzymatic electrochemical sensor for glucose: Enhancing sensitivity through a nanowire array strategy

Highly ordered Ni nanowire arrays (NiNWAs) were synthesized for the first time using a template-directed electropolymerization strategy with a nanopore polycarbonate (PC) membrane template, and their morphological characterization were examined by scanning electron microscopy (SEM) and transmission electron microscope (TEM). A NiNWAs based electrode shows very high electrochemical activity for electrocatalytic oxidation of glucose in alkaline medium, which has been utilized as the basis of the fabrication of a nonenzymatic biosensor for electrochemical detection of glucose. The biosensor can be applied to the quantification of glucose with a linear range covering from 5.0 × 10⁻⁷ to 7.0 × 10⁻³ M, a high sensitivity of 1043 μA mM⁻¹ cm⁻², and a low detection limit of 1 × 10⁻⁷ M. The experiment results also showed that the sensor exhibits good reproducibility and long-term stability, as well as high selectivity with no interference from other oxidable species.     

LncRNA RP11-89 facilitates tumorigenesis and ferroptosis resistance through PROM2-activated iron export by sponging miR-129-5p in bladder cancer

Long non-coding RNAs (lncRNAs) act as important regulators of tumorigenesis and development in bladder cancer. However, the underlying molecular mechanisms remain elusive. We previously identified a novel lncRNA signature related to immunity and progression in bladder cancer. Here we further explored the function of RP11-89, a lncRNA discovered in the previous signature. Loss- and gain-of function experiments were performed using CCK-8 assay, flow cytometry, Transwell assays, scratch tests and subcutaneous nude mouse models. High-throughput RNA sequencing was conducted to identify dysregulated genes in bladder cancer cells with RP11-89 knockdown or overexpression. Regulation of RP11-89 on miR-129-5p and PROM2 was explored through luciferase reporter assay, RIP assay and RNA pull-down assay. RP11-89 promoted cell proliferation, migration and tumorigenesis and inhibited cell cycle arrest via the miR-129-5p/PROM2 axis. We found that RP11-89 “sponges” miR-129-5p and upregulates PROM2. Elevated PROM2 in cells was associated with attenuated ferroptosis through iron export, formation of multivesicular bodies and less mitochondrial abnormalities. We demonstrated that RP11-89 is a novel tumorigenic regulator that inhibits ferroptosis via PROM2-activated iron export. RP11-89 may serve as a potential biomarker for targeted therapy in bladder cancer.Subject terms: Tumour biomarkers, Tumour biomarkers     

The Shelterin TIN2 Subunit Mediates Recruitment of Telomerase to Telomeres

Dyskeratosis Congenita (DC) is a heritable multi-system disorder caused by abnormally short telomeres. Clinically diagnosed by the mucocutaneous symptoms, DC patients are at high risk for bone marrow failure, pulmonary fibrosis, and multiple types of cancers. We have recapitulated the most common DC-causing mutation in the shelterin component TIN2 by introducing a TIN2-R282H mutation into cultured telomerase-positive human cells via a knock-in approach. The resulting heterozygous TIN2-R282H mutation does not perturb occupancy of other shelterin components on telomeres, result in activation of telomeric DNA damage signaling or exhibit other characteristics indicative of a telomere deprotection defect. Using a novel assay that monitors the frequency and extension rate of telomerase activity at individual telomeres, we show instead that telomerase elongates telomeres at a reduced frequency in TIN2-R282H heterozygous cells; this recruitment defect is further corroborated by examining the effect of this mutation on telomerase-telomere co-localization. These observations suggest a direct role for TIN2 in mediating telomere length through telomerase, separable from its role in telomere protection.     

Studies on the interaction mechanism between hexakis(imidazole) manganese(II) terephthalate and DNA and preparation of DNA electrochemical sensor

The interaction between hexakis(imidazole) manganese(II) terephthalate ([Mn(Im)(6)](teph).4H(2)O) and salmon sperm DNA in 0.2M pH 2.30 Britton-Robinson buffer solution was studied by fluorescence spectroscopy and cyclic voltammetry. Increasing fluorescence was observed for [Mn(Im)(6)](2+) with DNA addition, while quenching fluorescence phenomenon appeared for EB-DNA system when [Mn(Im)(6)](2+) was added. There were a couple quasi-reversible redox peaks of [Mn(Im)(6)](2+) from the cyclic voltammogram on the glassy carbon electrode. The peak current of [Mn(Im)(6)](2+) decreased with positive shift of the formal potential in the presence of DNA compared with that in the absence of DNA. All the experimental results indicate that [Mn(Im)(6)](2+) can bind to DNA mainly by intercalative binding mode. The binding ratio of the DNA-[Mn(Im)(6)](2+) association complex is calculated to be 1:1 and the binding constant is 4.44x10(3) M(-1). By using [Mn(Im)(6)](teph).4H(2)O as the electrochemical hybridization indicator, the DNA electrochemical sensor was prepared by covalent interaction and the selectivity of ssDNA modified electrode were described. The results demonstrate the use of electrochemical DNA biosensor in the determination of complementary ssDNA.