Modulation of lncRNA H19 enhances resveratrol‐inhibited cancer cell proliferation and migration by regulating endoplasmic reticulum stress

The phytoalexin resveratrol exhibits anti‐tumour activity in many types of cancer. In this study, we showed that resveratrol suppressed the survival of gastric tumour cells both in vivo and in vitro. Resveratrol promoted apoptosis, autophagy and endoplasmic reticulum (ER) stress in a dose‐dependent manner. RNA‐seq analysis showed that multiple cell death signalling pathways were activated after resveratrol treatment, while the use of ER stress activators (tunicamycin and thapsigargin) in combinatorial with resveratrol led to further inhibition of cancer cell survival. Results also showed that resveratrol altered the expression of several long non‐coding RNAs (lncRNAs), including MEG3, PTTG3P, GAS5, BISPR, MALAT1 and H19. Knockdown of H19 in resveratrol‐treated cells further enhanced the effects of resveratrol on apoptosis, ER stress and cell cycle S‐phase arrest. Furthermore, the migratory ability of resveratrol‐treated cells was dramatically decreased after H19 knockdown. In conclusion, resveratrol inhibited cancer cell survival, while knockdown of lncRNA H19 resulted in increased sensitivity to resveratrol therapy.     

Site-specific regulation of the GEF Cdc24p by the scaffold protein Far1p during yeast mating

Receptor-mediated cell polarization via heterotrimeric G-proteins induces cytoskeletal rearrangements in a variety of organisms. In yeast, Far1p is required for orienting cell growth towards the mating partner by linking activated Gbetagamma to the guanine-nucleotide exchange factor (GEF) Cdc24p, which activates the Rho-type GTPase Cdc42p. Here we investigated the role of Far1p in the regulation of Cdc24p in vivo. Using time-lapse microscopy of mating cells and artificial membrane targeting of Far1p, we show that Far1p is necessary and sufficient to recruit Cdc24p to the plasma membrane. Wild-type Far1p contains a PH-like domain, which is required for its membrane localization in vivo. Interestingly, expression of membrane-targeted Far1p causes toxicity, most likely by activating Cdc42p uniformly at the cell cortex. The ability of full-length Far1p to function as an activator of Cdc24p in vivo requires its interaction with Cdc24p and Gbetagamma. Our results imply that Gbetagamma not only targets Far1p to the correct site but may also trigger a conformational change in Far1p that is required for its ability to activate Cdc24p in vivo.     

慢性间歇性低氧降低急性缺氧对大鼠肺动脉平滑肌细胞膜上电压门控性钾通道的抑制

为了从离子通道水平上探讨机体低氧适应的离子机制,本实验将雄性 SD 大鼠随机分为常氧对照组和慢性间歇性低氧组[氧浓度(10 ± 0.5) %, 间断缺氧每天 8 h]。用酶解法急性分离单个大鼠肺内动脉平滑肌细胞(pulmonary artery smoothmuscle cells, PASMCs),以全细胞膜片钳技术记录 PASMCs 膜上的电压门控性钾通道 (voltage-gated potassium channel, KV) 电流,观察急性缺氧对慢性间歇性低氧大鼠 PASMCs 的 KV 的影响, 为机体适应低氧能力提供实验依据。结果显示:⑴常氧对照组在电流钳下,急性缺氧可使膜电位明显去极化(由-47.2 ±2.6 mV 去极到 -26.7 ±1.2 mV ); 在电压钳下, 急性缺氧可显著抑制 KV电流( 60 mV 时, KV电流密度从 153.4 ± 9.5 pA/pF降到 70.1 ± 10.6 pA/pF), 峰电流的抑制率为(57.6 ± 3.3) %, 电流-电压关系曲线向右下移。⑵慢性间歇性低氧组KV电流密度随低氧时间延长而逐渐减少(慢性低氧10 d后就有显著性意义),电流- 电压关系曲线逐渐右下移。⑶急性缺氧对慢性间歇性低氧大鼠PASMCs KV电流的抑制作用随慢性间歇性低氧时间延长而逐渐减弱。上述观察结果提示慢性间歇性低氧减弱急性缺氧对 KV 的抑制, 这可能是机体低氧适应的一种重要机制。     

NHE3 inhibition activates duodenal bicarbonate secretion in the rat

We examined the effect of inhibition of Na+/H+ exchange (NHE) on duodenal bicarbonate secretion (DBS) in rats to further understand DBS regulation. DBS was measured by using the pH-stat method and by using CO2-sensitive electrodes. 5-(N,N-dimethyl)-amiloride (50 microM; DMA), a concentration that selectively inhibits the NHE isoforms NHE1 and NHE2, but not NHE3, did not affect DBS. Nevertheless, 3 mM DMA, a higher concentration that inhibits NHE1, NHE2, and NHE3, significantly increased DBS. Moreover, S1611 and S3226, both specific inhibitors of NHE3 only, or perfusion with Na+-free solutions, dose dependently increased DBS, as measured by pH-stat and CO2-sensitive electrode, without affecting intracellular pH. Coperfusion with 0.1 microM indomethacin, 0.5 mM DIDS, or 1 mM methazolamide did not affect S3226-induced DBS. Nevertheless, coperfusion with 0.1 and 0.3 mM 5-nitro-2-(3-phenylpropylamino) benzoic acid, which inhibits the cystic fibrosis transmembrane conductor regulator (CFTR), dose dependently inhibited S3226-induced DBS. In conclusion, only specific apical NHE3 inhibition increased DBS, whereas prostaglandin synthesis, Na+-HCO3- cotransporter activation, or intracellular HCO3- formation by carbonic anhydrase was not involved. Because NHE3 inhibition-increased DBS was inhibited by an anion channel inhibitor and because reciprocal CFTR regulation has been previously shown between NHE3 and apical membrane anion transporters, we speculate that NHE3 inhibition increased DBS by altering anion transporter function.     

A comparative binding study of modified bovine immunodeficiency virus TAR RNA against its TAT peptide

Besides generating novel binding peptides or small molecules to their RNA target, successful design of chemically modified RNA constructs capable of tighter binding with their binding peptides is also of significant importance. Herein, the synthesis and binding studies of a series of both wt and mutant bovine immunodeficiency virus (BIV) TAR RNA constructs against its Tat peptide are reported. Understanding the requirements that enable RNA construct binding properties, especially at the hairpin loop or internal bulge, would afford potential therapeutic approaches to control the BIV life cycle.