The intracellular quality control system down-regulates the secretion of amyloidogenic apolipoprotein A-I variants: A possible impact on the natural history of the disease

Hereditary systemic amyloidosis caused by apolipoprotein A-I variants is a dominantly inherited disease characterised by fibrillar deposits mainly localized in the kidneys, liver, testis and heart. We have previously shown that the apolipoprotein A-I variant circulates in plasma at lower levels than the wild-type form (Mangione et al., 2001; Obici et al., 2004) thus raising the possibility that the amyloid deposits could sequester the circulating amyloidogenic chain or that the intracellular quality control can catch and capture the misfolded amyloidogenic chain before the secretion. In this study we have measured plasma levels of the wild-type and the variant Leu75Pro apolipoprotein A-I in two young heterozygous carriers in which tissue amyloid deposition was still absent. In both cases, the mutant was present at significantly lower levels than the wild-type form, thus indicating that the low plasma concentration of the apolipoprotein A-I variant is not a consequence of the protein entrapment in the amyloid deposits. In order to explore the cell secretion of amyloidogenic apolipoprotein A-I variants, we have studied COS-7 cells expressing either wild-type apolipoprotein A-I or two amyloidogenic mutants: Leu75Pro and Leu174Ser. Quantification of intracellular and extracellular apolipoprotein A-I alongside the intra-cytoplasmatic localization indicates that, unlike the wild-type protein, both variants are retained within the cells and mainly accumulate in the endoplasmic reticulum. The low plasma concentration of amyloidogenic apolipoprotein A-I may therefore be ascribed to the activity of the intracellular quality control that represents a first line of defence against the secretion of pathogenic variants.     

Neuropeptide exocytosis involving synaptotagmin-4 and oxytocin in hypothalamic programming of body weight and energy balance

Hypothalamic neuropeptides play essential roles in regulating energy and body weight balance. Energy imbalance and obesity have been linked to hypothalamic signaling defects in regulating neuropeptide genes; however, it is unknown whether dysregulation of neuropeptide exocytosis could be critically involved. This study discovered that synaptotagmin-4, an atypical modulator of synaptic exocytosis, is expressed most abundantly in oxytocin neurons of the hypothalamus. Synaptotagmin-4 negatively regulates oxytocin exocytosis, and dietary obesity is associated with increased vesicle binding of synaptotagmin-4 and thus enhanced negative regulation of oxytocin release. Overexpressing synaptotagmin-4 in hypothalamic oxytocin neurons and centrally antagonizing oxytocin in mice are similarly obesogenic. Synaptotagmin-4 inhibition prevents against dietary obesity by normalizing oxytocin release and energy balance under chronic nutritional excess. In conclusion, the negative regulation of synaptotagmin-4 on oxytocin release represents a hypothalamic basis of neuropeptide exocytosis in controlling obesity and related diseases.     

Peroxisome proliferator-activated receptor β/δ agonism protects the kidney against ischemia/reperfusion injury in diabetic rats

Diabetes is an important risk factor for ischemic acute kidney injury, whose pharmacological treatment remains an unmet medical need. The peroxisome proliferator-activated receptor (PPAR) β/δ is highly expressed in the kidney, although its role has not yet been elucidated. Here, we used an in vivo model of renal ischemia/reperfusion (I/R) in streptozotocin-induced diabetic rats (i) to evaluate whether diabetes increases kidney susceptibility to I/R injury and (ii) to investigate the effects of PPARβ/δ activation. The degree of renal injury (1h ischemia/6h reperfusion) was significantly increased in diabetic rats compared with nondiabetic littermates. PPARβ/δ expression was increased after I/R, with the highest levels in diabetic rats. Administration of the selective PPARβ/δ agonist GW0742 attenuated the renal dysfunction, leukocyte infiltration, and formation of interleukin-6 and tumor necrosis factor-α. These effects were accompanied by an increased expression of the suppressor of cytokine signaling (SOCS)-3, which plays a critical role in the cytokine-activated signaling pathway. The beneficial effects of GW0742 were attenuated by the selective PPARβ/δ antagonist GSK0660. Thus, we report herein that PPARβ/δ activation protects the diabetic kidney against I/R injury by a mechanism that may involve changes in renal expression of SOCS-3 resulting in a reduced local inflammatory response.     

Long-term cultures of stem/progenitor cells from lobular and ductal breast carcinomas under non-adherent conditions

A small subpopulation of stem/progenitor cells can give rise to the diversity of differentiated cells that comprise the bulk of the tumor. Are proliferating cells, within the bulk of tumor, few cells with uncommon features? The cell biological approach provides a limitless model for studying the hierarchical organization of progenitor subpopulation and identifying potential therapeutic targets. Aim of the study was to expand patients’ breast cancer cells for evaluating functional cell properties, and to characterize the protein expression profile of selected cells to be compared with that of primary tumors. Breast cancer cells from estrogen receptor (ERα) positive, HER2 negative lobular (LoBS cells) and ductal (DuBS cells) histotype were cultured under non-adherent conditions to form mammospheres. Sorting of the cells by their surface expression of CD24 and CD44 gave rise to subpopulations which were propagated, enriched and characterized for the expression of epithelial and stromal markers. We found that non-adherent culture conditions generate mammospheres of slowly proliferating cells; single cells, dissociated from mammospheres, grow in soft agar; long-term cultured LoBS and DuBS cells, CD44+/CD24low, express cytokeratin 5 (CK5), α-smooth muscle actin (α-sma) and vimentin, known as markers of basal/myoepithelial cells; and ERα (only DuBS cells), HER1 (EGF-Receptor), activated HER2, and cyclinD1 as markers of luminal epithelial cell. Isolates of cells from breast cancer patients may be a tool for a marker-driven testing of targeted therapies.     

Active process mediates species-specific tuning of Drosophila ears

The courtship behavior of Drosophilid flies has served as a long-standing model for studying the bases of animal communication. During courtship, male flies flap their wings to send a complex pattern of airborne vibrations to the antennal ears of the females. These "courtship songs" differ in their spectrotemporal composition across species and are considered a crucial component of the flies' premating barrier. However, whether the species-specific differences in song structure are also reflected in the receivers of this communication system, i.e., the flies' antennal ears, has remained unexplored. Here we show for seven members of the melanogaster species group that (1) their ears are mechanically tuned to different best frequencies, (2) the ears' best frequencies correlate with high-frequency pulses of the conspecific courtship songs, and (3) the species-specific tuning relies on amplificatory mechanical feedback from the flies' auditory neurons. As a result of its level-dependent nature, the active mechanical feedback amplification is particularly useful for the detection of small stimuli, such as conspecific song pulses, and becomes negligible for sensing larger stimuli, such as the flies' own wingbeat during flight.     

Sex allocation in haplodiploids is mediated by egg size: evidence in the spider mite Tetranychus urticae Koch

Haplodiploid species display extraordinary sex ratios. However, a differential investment in male and female offspring might also be achieved by a differential provisioning of eggs, as observed in birds and lizards. We investigated this hypothesis in the haplodiploid spider mite Tetranychus urticae, which displays highly female-biased sex ratios. We show that egg size significantly determines not only larval size, juvenile survival and adult size, but also fertilization probability, as in marine invertebrates with external fertilization, so that female (fertilized) eggs are significantly larger than male (unfertilized) eggs. Moreover, females with on average larger eggs before fertilization produce a more female-biased sex ratio afterwards. Egg size thus mediates sex-specific egg provisioning, sex and offspring sex ratio. Finally, sex-specific egg provisioning has another major consequence: male eggs produced by mated mothers are smaller than male eggs produced by virgins, and this size difference persists in adults. Virgin females might thus have a (male) fitness advantage over mated females.     

Design and synthesis of long acting inhaled corticosteroids for the treatment of asthma

In this Letter we present data for a novel series of ICS for the treatment of asthma. 'Inhalation by design' principles have been applied to a series of highly potent steroidal GR agonists, with a focus on optimising the potential therapeutic index in human. Pharmacokinetic properties were tuned with high intrinsic clearance and low oral bioavailability in mind, to minimise systemic exposure and reduce systemically driven adverse events. High CYP mediated clearance as well as glucuronidation were targeted to achieve high intrinsic clearance coupled with multiple routes of clearance to minimise drug-drug interactions. Furthermore, pharmaceutical properties such as stability, crystallinity and solubility were considered to ensure compatibility with a dry powder inhaler. This work culminated in the identification of the clinical candidate 15, which demonstrates preclinically the desired efficacy and safety profiles confirming its potential as an inhaled agent for the treatment of asthma.     

Association of polymorphisms in glutamate-cysteine ligase catalytic subunit and microsomal triglyceride transfer protein genes with nonalcoholic fatty liver disease

Genetic and environmental factors are important for the development of nonalcoholic fatty liver disease (NAFLD). The aim of the present study was to examine the single nucleotide polymorphism (SNP) -129C/T (rs17883901) in glutamate-cysteine ligase catalytic subunit (GCLC) and SNPs I128T (rs3816873) and Q95H (rs61733139) in microsomal triglyceride transfer protein (MTTP) in NAFLD. Eighty-three patients with a diagnosis of NAFLD and 93 healthy subjects were included in the study. Tetra amplification refractory mutation system-polymerase chain reaction was designed to detect the SNPs. There were no significant differences in the polymorphism of -129C/T (rs17883901) of the GCLC gene among NAFLD and control groups (p?>?0.05). A significant difference was observed between NAFLD and control group regarding the SNP I128T (rs3816873) in the coding region of the MTTP gene (p?相似文献