Thapsigargin down-regulates protein levels of GRP78/BiP in INS-1E cells

Pancreatic β-cells have a well-developed endoplasmic reticulum (ER) and express large amounts of chaperones and protein disulfide isomerases (PDI) to meet the high demand for synthesis of proteins. We have observed an unexpected decrease in chaperone protein level in the β-cell model INS-1E after exposure to the ER stress inducing agent thapsigargin. As these cells are a commonly used model for primary β-cells and has been shown to be vulnerable to ER stress, we hypothesize these cells are incapable of mounting a chaperone defense upon activation of ER stress. To investigate the chaperone expression during an ER stress response, induced by thapsigargin in INS-1E cells, we used quantitative mass spectrometry based proteomics. The results displayed a decrease of GRP78/BiP, PDIA3 and PDIA6. Decrease of GRP78/BiP was verified by Western blot and occurred in parallel with enhanced levels of p-eIF2α and CHOP. In contrast to INS-1E cells, GRP78/BiP was not decreased in MIN6 cell or rat and mouse islets after thapsigargin exposure. Investigation of the decreased protein levels of GRP78/BiP indicates that this is not a consequence of reduced mRNA expression. Rather the reduction results from the combined effect of reduced protein synthesis and enhanced proteosomal degradation and possibly also degradation via autophagy. Induction of ER stress with thapsigargin leads to lower protein levels of GRP78/BiP, PDIA3 and PDIA6 in INS-1E cells which may contribute to the susceptibility of ER stress in this β-cell model.     

THE BEHAVIOR OF THE NUCLEIC ACIDS DURING THE EARLY DEVELOPMENT OF THE SEA URCHIN EGG (ARBACIA)

The authors wish to correct an error in the paper "The behavior of the nucleic acids during the early development of the sea urchin egg (Arbacia)" (J. Gen. Physiol., 1947–48, 31, 203). Owing to an oversight, the figures for the amounts of various P fractions in a single Arbacia egg have been erroneously expressed in γ x 10^–3 units (Tables I and II, page 205; the last two lines of page 206). The figures should have been expressed in γ x 10^–5 units. Thus, the fertilized Arbacia egg contains an average of 20 γ x 10^–5 ribonucleic acid P and 0.7 to 1 γ x 10^–5 desoxyribonucleic acid P.     

Interleukin-1 regulates keratinocyte expression of T cell targeting chemokines through interleukin-1 receptor associated kinase-1 (IRAK1) dependent and independent pathways

IL-1 is a potent pro-inflammatory cytokine that activates intracellular signaling cascades some of which may involve IL-1 receptor associated kinase-1 (IRAK1). Psoriasis is a T cell dependent chronic inflammatory condition of the skin of unknown cause. IL-1 has been implicated in psoriasis pathology, but the mechanism has not been elucidated. Interestingly, expression of IRAK1 is elevated in psoriatic skin. To identify a potential link between IL-1, keratinocytes and T cells in skin inflammation we employed pathway-focused microarrays to evaluate IL-1 dependent gene expression in keratinocytes. Several candidate mRNAs encoding known T cell chemoattractants were identified in primary keratinocytes and the stable keratinocyte cell line HaCaT. CCL5 and CCL20 mRNA and protein levels were confirmed up-regulated by IL-1 in concentration and time-dependent manners. Furthermore IL-1 synergized with IFN-γ and TNF-α. Expression of CXCL9, CXCL10 and CXCL11 mRNAs was also increased in response to IL-1, but protein could only be detected in medium from cells treated with IFN-γ alone or in combination with IL-1. Over-expression of IRAK1 led to increased constitutive and cytokine induced production of CCL5 and CCL20. Inhibition of IRAK1 activity through RNAi or expression of a dominant negative mutant blocked production of CCL5 and CCL20 but had no effect upon the IL-1 enhancement of IFN-γ induced CXCL9, CXCL10 and CXCL11 production. In conclusion IL-1 regulates T cell targeting chemokine production in keratinocytes through IRAK1 dependent and independent pathways. These pathways may contribute to acute and chronic skin inflammation.     

Chemical and pharmacological investigations of Metaxya rostrata

In a bioassay-guided approach the chemical composition of rhizomes of Metaxya rostrata (Kunth C. Presl) was studied for the first time. Investigations of the cytotoxicity of extracts and fractions on SW480 colorectal carcinoma cells resulted in the isolation of two polyphenols--cinnamtannin B-1 and aesculitannin B. The structures of the compounds were elucidated by different NMR experiments. Additionally, sugars, common sterols, such as sitosterol, stigmasterol and campesterol, as well as chlorogenic acid and caffeic acid were identified in Metaxya rostrata.     

Obesity and Sarcopenia after Menopause Are Reversed by Sex Hormone Replacement Therapy

Objective: Menopause is linked to an increase in fat mass and a decrease in lean mass exceeding age‐related changes, possibly related to reduced output of ovarian steroids. In this study we examined the effect of combined postmenopausal hormone replacement therapy (HRT) on the total and regional distribution of fat and lean body mass. Research Methods and Procedures: Sixteen healthy postmenopausal women (age: 55 ± 3 years) were studied in a placebo‐controlled, crossover study and were randomized to 17β estradiol plus cyclic norethisterone acetate (HRT) or placebo in two 12‐week periods separated by a 3‐month washout. Total and regional body composition was measured by DXA at baseline and in the 10th treatment week in both periods. Changes were compared by a paired Student's t test. Results: The change in body weight during HRT was equal to the change during placebo (?24.6 g vs. ?164 g, p = 0.42), but relative fat mass was significantly reduced (?0.5% vs. +1.24%, p < 0.01). During HRT, compared with during placebo, lean body mass increased (+347 g vs. ?996 g, p < 0.01) and total fat mass decreased (?400 g vs. +836 g, p = 0.06). Total bone mineral content increased (+28.9 g vs. ?4.4 g, p = 0.04) and abdominal fat decreased (?185 g vs. +253 g, p = 0.04) during HRT compared with placebo. Discussion: HRT is linked to the reversal of both menopause‐related obesity and loss of lean mass, without overall change in body weight. The increase in lean body mass during HRT is likely explained by muscle anabolism, which in turn, prevents disease in the elderly.     

Conservation genetics of harbour porpoises, Phocoena phocoena, in eastern and central North Atlantic

We examined polymorphism at 12 microsatelliteloci in 807 harbour porpoises , Phocoenaphocoena, collected from throughout thecentral and eastern North Atlantic to theBaltic Sea. Multilocus tests for allelefrequency differences, assignment tests,population structure estimates (F_ST) andgenetic distance measures (D_LR andD_C) all indicate six geneticallydifferentiated populations/sub-populationsafter pooling sub-samples within regions.Harbour porpoises from West Greenland, theNorwegian Westcoast, Ireland, the British NorthSea, the Danish North Sea and the inland watersof Denmark (IDW) are all geneticallydistinguishable from each other. A sample ofharbour porpoises collected off the Dutch coast(mainly during winter) was geneticallyheterogeneous and likely comprised a mixture ofindividuals of diverse origin. A mixed stockanalysis indicated that most of the individualsin this sample (77%) were likely migrantsfrom the British and Danish North Sea.