Ataxin-2 associates with rough endoplasmic reticulum

Ataxin-2 is a novel protein, normally with a domain of 22 consecutive glutamine (Q) residues, which may expand beyond a threshold of (Q)₃₂, causing a neurodegenerative disease named Spinocerebellar ataxia type 2 (SCA2). To obtain clues about the functions of ataxin-2, we used fluorescence microscopy and centrifugation fractionation analyses. Immunocytochemical detection in non-neuronal and neuronal cells showed endogenous and transfected ataxin-2 distributed throughout the cytoplasm, with perinuclear preference and a granular appearance. Triple-labelling and confocal microscopy demonstrated co-localisation with the endoplasmic reticulum (ER) markers calreticulin, calnexin and CFP-ER. The pathogenic form of ataxin-2 with an expanded polyQ domain showed the same distribution pattern. Subcellular fractionation of mouse brain homogenates showed endogenous ataxin-2 associated with rough ER (rER) membranes, in a manner dependent on RNA, salt and phosphorylation. Our data are in agreement with recent findings that ataxin-2 directly interacts with poly(A)-binding protein (PABP), thus associating with polyribosomes under normal conditions and being recruited to stress granules under environmental stress. These data, in conjunction with the presence of Lsm domains within ataxin-2, suggest that ataxin-2 is involved in the processing of mRNA and/or the regulation of translation.     

Equol is more active than soy isoflavone itself to compete for binding to thromboxane A(2) receptor in human platelets

Introduction

Several dietary intervention studies examining the health effect of soy isoflavones allude to the importance of equol in establishing the cardiovascular response to soy protein. Although, the specific mechanism by which this action occurs has not been established. The aim of this study was to investigate the inhibitory effect of soy-isoflavones and the metabolite of daidzein, equol, on agonist-induced platelet responses dependent on thromboxane A₂ (TxA₂) receptor.

Material and methods

Competitive radioligand binding assay was used to screen for affinity of these compounds to the TxA₂ receptor. The effect of equol on platelet activation, evaluate through of release of the ATP, by analogs of TxA₂ was analyzed. The effect of equol on platelet aggregation was investigated with ADP, U46619 (a TxA₂ mimic) and the calcium ionophore A23187.

Results

The data showed that aglycone isoflavones and equol bind to TxA₂ receptor in the µmol/L range, whereas their glucoside derivates had very low binding activity for this receptor. Under equilibrium conditions, the following order of the relative affinity in inhibiting [³H]-SQ29585 binding was: equol > genistein > daidzein > glycitein ? genistin, daidzin, glycitin. Equol interaction was reversible and competitive for labeled-SQ29548 with not apparent decrease in the number of TxA₂ binding sites. In addition, from platelet activation studies, equol effectively inhibited ATP secretion elicited by the TxA₂ analog U46619. On the other hand, equol inhibited the platelet aggregation induced by U46619 and A23187, while it failed to inhibit that induced by ADP.

Conclusions

The aglycone isoflavones from soy, and particularly equol, have been found to have biological effects attributable to thromboxane A₂ receptor antagonism. These findings may help elucidate how dietary isoflavone modulate platelet function and explain why soy-rich foods are claimed to have beneficial effects in the prevention of thrombotic events.     

卵巢癌细胞IL-6、IL-8分泌与其他莫西芬敏感性及ER亚型及p160共激活因子表达关系的初步探讨

目的分析比较4种常见的人上皮性卵巢癌细胞系(A2780、CAOV-3、SKOV-3和ES-2)IL-6、IL-8分泌与其他莫西芬(Tamoxifen,TAM)敏感性及雌激素受体(estrogen receptor,ER)亚型及p160共激活因子表达的关系,为今后研究IL-6、IL-8诱导卵巢癌细胞对内分泌治疗产生耐药的机制奠定基础。方法 IL-6、IL-8的表达采用RT-PCR及ELISA法进行检测,卵巢癌细胞对TAM的敏感性采用MTT试验进行分析,ERα、ERβ及p160共激活因子的表达采用免疫印迹和RT-PCR技术进行检测。结果 4种卵巢癌细胞除A2780细胞外均组成性分泌IL-6和IL-8;4种细胞对TAM的敏感性不同,其中A2780细胞最敏感,CAOV-3、SKOV-3和ES-2细胞则有不同程度的耐药性(耐药倍数分别为4.98、3.75和2.66);这些细胞均不同程度地表达ERα,其中A2780细胞较低,CAOV-3和SKOV-3细胞较高,ES-2细胞居中;ERβ的表达情况则与ERα恰好相反;3种p160共激活因子mRNA的表达水平均以A2780细胞为最低,而ES-2、SKOV-3和CAOV-3细胞则依次升高。结论卵巢癌细胞IL-6、IL-8的自分泌水平与其对TAM的敏感性呈负相关,与其ERβ(而非ERα)及3种p160共激活因子的表达水平相一致。     

Association of estrogen receptor alpha (ERα) gene polymorphisms with endometrial thickness and lipid profile in women with breast cancer treated with aromatase inhibitors

Aromatase inhibitors (AIs) provide an alternative to tamoxifen as an adjuvant therapy for post-menopausal, hormone-receptor positive breast cancer patients. The aim of the present study was to evaluate the effect of PvuII and XbaI polymorphisms of the ERα gene at ΑΙs treatment’s adverse effects in post-menopausal women with breast cancer. The study included 87 post-menopausal women with ER-positive breast cancer treated with AIs and 80 healthy controls. The overall presence of ERα polymorphisms in all women with breast cancer was not different from the healthy controls. Endometrial thickness under AIs treatment was reduced from (mean value ± SD) 6,404 ± 2,901 mm to 3,666 ± 1,4656 mm. Moreover, the AA XbaI genotype was associated with greater reduction in endometrial thickness during therapy with AIs (p = 0.005). The presence of the CC PvuII and the AA XbaI genotypes were associated with elevated LDL levels and elevated triglycerides. In conclusion, the results of the present study showed that the genotype of women with breast cancer under AIs treatment might influence treatment’s adverse effects, as, the presence of the CC PvuII and the AA XbaI genotypes of the ERα were associated with elevated LDL and triglycerides serum levels, while the AA XbaI genotype was associated with a greater reduction in endometrial thickness.     

Factors associated with the increasing trend of contralateral prophylactic mastectomy among patients with ductal carcinoma in situ: Analysis of Surveillance,Epidemiology, and End Results data

PurposeOur study aimed to investigate the factors influencing trends of contralateral prophylactic mastectomy (CPM) among patients with unilateral ductal carcinoma in situ (DCIS).Patients and MethodsWe used the Surveillance, Epidemiology, and End Results (SEER) data to identify patients with unilateral DCIS diagnosed from 1998 to 2013. Patients were categorized as breast-conserving surgery (BCS), Unilateral Mastectomy and CPM group. Univariate and multivariate logistic regressions were applied to assess the factors associated with undergoing CPM among mastectomy patients. The trends of CPM among mastectomy patients through year were presented by different subgroups of sociodemographic and pathological characteristics.ResultsOf those, 105326 patients with DCIS were identified, and 6370 patients underwent CPM. The proportion of CPM was 6.05% for all surgically-treated patients and 21.09% for mastectomy patients, and it increased more than six-fold between 1998 and 2013 (from 1.74% to 10.89% for all surgically-treated patients and from 5.44% to 37.47% for mastectomy patients). Younger age, white race, married status, smaller tumor size, positive ER and PR status were significantly associated with higher CPM proportion among mastectomy patients. The proportion of CPM was increasing through year, and the increasing trends were obvious in the subgroups of younger, white, married, metropolitan, with higher bachelor degree and higher median family income patients, while there were no apparent differences in the trends between subgroups of pathological characteristics.ConclusionThe trends of CPM among mastectomy patients were increasing through years and influenced by patients’ sociodemographic characteristics, but not pathological characteristics.     

Altered platelet calsequestrin abundance,Na/Ca exchange and Ca signaling responses with the progression of diabetes mellitus

Introduction

Downregulation of calsequestrin (CSQ), a major Ca^2 + storage protein, may contribute significantly to the hyperactivity of internal Ca^2 + ([Ca^2 +]_i) in diabetic platelets. Here, we investigated changes in CSQ-1 abundance, Ca^2 + signaling and aggregation responses to stimulation with the progression of diabetes, especially the mechanism(s) underlying the exaggerated Ca^2 + influx in diabetic platelets.

Materials and methods

Type 1 diabetes was induced by streptozotocin in rats. Platelet [Ca^2 +]_i and aggregation responses upon ADP stimulation were assessed by fluorescence spectrophotometry and aggregometry, respectively. CSQ-1 expression was evaluated using western blotting.

Results

During the 12-week course of diabetes, the abundance of CSQ-1, basal [Ca^2 +]_i and ADP-induced Ca^2 + release were progressively altered in diabetic platelets, while the elevated Ca^2 + influx and platelet aggregation were not correlated with diabetes development. 2-Aminoethoxydiphenyl borate, the store-operated Ca^2 + channel blocker, almost completely abolished ADP-induced Ca^2 + influx in normal and diabetic platelets, whereas nifedipine, an inhibitor of the nicotinic acid adenine dinucleotide phosphate receptor, showed no effect. Additionally, inhibition of Na⁺/Ca^2 + exchange induced much slower Ca^2 + extrusion and more Ca^2 + influx in normal platelets than in diabetic platelets. Furthermore, under the condition of Ca^2 +-ATPase inhibition, ionomycin caused greater Ca^2 + mobilization and Ca^2 + influx in diabetic platelets than in normal platelets.

Conclusions

These data demonstrate that platelet hyperactivity in diabetes is caused by several integrated factors. Besides the downregulation of CSQ-1 that mainly disrupts basal Ca^2 + homeostasis, insufficient Na⁺/Ca^2 + exchange also contributes, at least in part, to the hyperactive Ca^2 + response to stimulation in diabetic platelets.     

Sex differences in circadian timing systems: Implications for disease

Virtually every eukaryotic cell has an endogenous circadian clock and a biological sex. These cell-based clocks have been conceptualized as oscillators whose phase can be reset by internal signals such as hormones, and external cues such as light. The present review highlights the inter-relationship between circadian clocks and sex differences. In mammals, the suprachiasmatic nucleus (SCN) serves as a master clock synchronizing the phase of clocks throughout the body. Gonadal steroid receptors are expressed in almost every site that receives direct SCN input. Here we review sex differences in the circadian timing system in the hypothalamic–pituitary–gonadal axis (HPG), the hypothalamic–adrenal–pituitary (HPA) axis, and sleep–arousal systems. We also point to ways in which disruption of circadian rhythms within these systems differs in the sexes and is associated with dysfunction and disease. Understanding sex differentiated circadian timing systems can lead to improved treatment strategies for these conditions.