Identification and quantitative mRNA analysis of a novel splice variant of GPIHBP1 in dairy cattle

Background： Identification of functional genes affecting milk production traits is very crucial for improving breeding efficiency in dairy cattle. Many potential candidate genes have been identified through our previous genome wide association study （GWAS）. Of these, GPIHBP1 is an important novel candidate gene for milk production traits. However, the mRNA structure of the bovine GPIHBP1 gene is not fully determined up to now. Results： In this study, we identified a novel alternatively splice transcript variant （XS） which leads to a 3] bp insertion in exon 3 and also confirmed the other four existed transcripts （X1, X2, X3 and X4） of the bovine GPIHBP1 gene. We showed that transcript X5 with a 31 bp insertion and transcript X1 with an 8 bp deletion might have tremendous effect on the protein function and structure of GPIHBP1, respectively. With semi-quantitative PCR and quantitative real-time RT-PCR, we found that the mRNA expression of GPIHBPI, GPIHBP1-X1 and GPIHBP1-X5 in mammary gland of lactating cows were much higher than that in other tissues. Conclusions： Our study reports a novel alternative splicing of GPIHBP1 in bovine for the first time and provide useful information for the further functional analyses of GPIHBP1 in dairy cattle.

Expression of multiple glutamate transporter splice variants in the rodent testis

Glutamate is a regulated molecule in the mammalian testis. Extracellular regulation of glutamate in the body is determined largely by the expression of plasmalemmal glutamate transporters. We have examined by PCR, western blotting and immunocytochemistry the expression of a panel of sodium-dependent plasmalemmal glutamate transporters in the rat testis. Proteins examined included： glutamate aspartate transporter （GLAST）, glutamate transporter 1 （GLT1）, excitatory amino acid carrier 1 （EAAC1）, excitatory amino acid transporter 4 （EAAT4） and EAAT5. We demonstrate that many of the glutamate transporters in the testis are alternately spliced. GLAST is present as exon-3- and exon-9-skipping forms. GLT1 was similarly present as the alternately spliced forms GLT1 b and GLTlc, whereas the abundant brain form （GLTla） was detectable only at the mRNA level. EAAT5 was also strongly expressed, whereas EAAC1 and EAAT4 were absent. These patterns of expression were compared with the patterns of endogenous glutamate localization and with patterns of D-aspartate accumulation, as assessed by immunocytochemistry. The presence of multiple glutamate transporters in the testis, including unusually spliced forms, suggests that glutamate homeostasis may be critical in this organ. The apparent presence of many of these transporters in the testis and sperm may indicate a need for glutamate transport by such cells.

Expression of Cyclooxygenase-2 mRNA and Identification of Its Splice Variant in Human Myometrium Obtained from Women in Labor

In order to investigate the expression of cyclooxygenase-2 (COX-2) in human lower segments of myometrium obtained from women in labor and those not in labor and identify the splicing variant of COX-2, reverse transcriptase-polymerase chain reaction (RT-PCR) was used to detect the expression of COX-2. The primers were designed and synthesized according to the sequence of rat COX-2 splice variant which was discovered firstly by us. Then the splicing variant of COX-2 in human myometrium from woman in labor was identified, cloned into vector and sequenced. The results showed that the expression of COX-2 mRNA was lower in human myometrium obtained from women who were not in labor than that in labor women and a new band of COX-2 was obtained in myometrium from labor woman. The fragment included an unspliced intron, which pitched between exons 7 and 8. It was suggested that COX-2 gene was not only expressed highly in human myometrium from woman in labor, but also produced splicing variant by alternative splicing.

Expression of Survivin and Its Splice Variants in Gastric Cancer

Survivin variants specific real time quantitative RT-PCR was developed to analyze their expression in 53 paired cancer and para-cancerous tissues, and the expression of the wild-type survivin protein was detected by immunohistochemistry. The results showed that survivin mRNA and protein were expressed in gastric cancer and para-cancerous tissues, The survivin-2B was dominantly expressed in para-cancerous tissues, whereas the survivin-△Ex3 was more frequently detected in cancer tissues. The positive rate of survivin-2a was 100% in both cancer and para-cancerous tissues, but its relative transcript expression level was not significantly increased in cancer tissues in comparison with para-cancerous tissues. The correlation analysis revealed that the expression of survivin-2a mRNA was significantly associated with that of total survivin （rs=0.4178, P=0.0018）, whereas inversely to that of survivin-△EX3 （rs=-0.4506, P=0.0007）. It was suggested that survivin-2a may act as an antagonist of survivin-△EX3. The balance between antiapoptotic survivin iso-forms and nonantiapoptotic ones may play an important role in tumorigenesis and tumor progression, Promising value is hinted to analyze survivin and its variants in tumor early diagnosis and distinguishing malignant tumors from benign ones.

Role of androgen receptor splice variants in prostate cancer metastasis

Prostate cancer(PCa)is one of the most lethal cancers in western countries.Androgen receptor(AR)signaling pathway plays a key role in PCa progression.Despite the initial effectiveness of androgen deprivation therapy(ADT)for treatment of patients with advanced PCa,most of them will develop resistance to ADT and progress to metastatic castration resistant prostate cancer(mCRPC).Constitutively transcriptional activated AR splice variants(AR-Vs)have emerged as critical players in the development and progression of mCRPC.Among AR-Vs identified to date,AR-V7(a.k.a.AR3)is one of the most abundant and frequently found in both PCa cell lines and in human prostate tissues.Most of functional studies have been focused on AR-V7/AR3 and revealed its role in regulation of survival,growth,differentiation and migration in prostate cells.In this review,we will summarize our current understanding of regulation of expression and activity of AR-Vs in mCRPC.

Differential expression of glial cell line-derived neurotrophic factor splice variants in the mouse brain

Glial cell line-derived neurotrophic factor(GDNF) plays a critical role in neuronal survival and function. GDNF has two major splice variants in the brain,α-pro-GDNF and β-pro-GDNF, and both isoforms have strong neuroprotective effects on dopamine neurons. However, the expression of the GDNF splice variants in dopaminergic neurons in the brain remains unclear. Therefore, in this study, we investigated the mRNA and protein expression of α-and β-pro-GDNF in the mouse brain by real-time quantitative polymerase chain reaction, using splice variant-specific primers, and western blot analysis. At the mRNA level,β-pro-GDNF expression was significantly greater than that of α-pro-GDNF in the mouse brain. In contrast, at the protein level,α-pro-GDNF expression was markedly greater than that of β-pro-GDNF. To clarify the mechanism underlying this inverse relationship in mRNA and protein expression levels of the GDNF splice variants, we analyzed the expression of sorting protein-related receptor with A-type repeats(SorLA) by real-time quantitative polymerase chain reaction. At the mRNA level, SorLA was positively associated with β-pro-GDNF expression, but not with α-pro-GDNF expression. This suggests that the differential expression of α-and β-pro-GDNF in the mouse brain is related to SorLA expression. As a sorting protein, SorLA could contribute to the inverse relationship among the mRNA and protein levels of the GDNF isoforms. This study was approved by the Animal Ethics Committee of Xuzhou Medical University, China on July 14, 2016.

Frequency of Bcr-Abl Fusion Oncogene Splice Variants Associated with Chronic Myeloid Leukemia (CML)

BCR-ABL fusion oncogene originates from the reciprocal translocation of chromosome 9 and 22 t(9;22) (q34;q11). It translates a chimeric protein, p210, characterized by constitutive activation of its tyrosine kinase, which triggers leukemogenic pathways resulting in onset of chronic myeloid leukemia (CML). In CML, the classic fusion is b2a2 or b3a2 fusing exon 13 (b2) or exon 14 (b3) of BCR to exon 2 (a2) of ABL. The type of bcr/abl transcripts may be associated with different prognosis and hence useful in therapeutic plan. This study was conducted to calculate the frequency of these splice variants as the frequencies of different fusion oncogenes associated with leukaemia can vary in different geographical regions due to interplay of genetic variation in different ethnic populations, diverse environmental factors and living style. A very sensitive nested RT-PCR was established to detect BCR-ABL splice variants in CML. Sensitivity of RT-PCR assay was of the order of 10–6. Thirty CML patients were subjected to BCR-ABL analysis. Out of 30 Pakistani patients, 19 (64%) expressed b3a2 while 11 (36%) expressed b2a2 transcript. This shows that BCR-ABL splice variants differ in their frequencies which may have an effect on biology and implications for prognosis and management of BCR-ABL positive Leukemias.

Mechanism underlying the retarded nuclear translocation of androgen receptor splice variants

As shown in our previous study, two alternatively spliced androgen receptor(AR) variants, which are exclusively expressed in the granulosa cells of patients with polycystic ovary syndrome, exhibit retarded nuclear translocation compared with wild-type AR. However, researchers have not yet determined whether these abnormalities correlate with heat shock protein 90(HSP90)and importin α(the former is a generally accepted co-chaperone of AR, and the latter is a component of classical nuclear import complexes). Here, these two variants were mainly retained in cytoplasm with HSP90 and importin α in the presence of dihydrotestosterone(DHT), and their levels in nucleus were significantly reduced, according to the immunofluorescence staining. The binding affinity of two AR variants for importin α was consistently decreased, while it was increased in WT-AR following DHT stimulation, leading to reduced nuclear import, particularly for the insertion-AR(Ins-AR). However, the binding affinities of two AR variants for HSP90 were increased in the absence of DHT compared with WT-AR, which functioned to maintain spatial structural stability, particularly for the deletion-AR(Del-AR). Therefore, the retarded nuclear translocation of two AR variants is associated with HSP90 and importin α, and the abnormal binding affinities for them play critical roles in this process.

A BRCA1 Splice Site Variant Responsible for Familial Ovarian Cancer in a Han-Chinese Family

Objective Ovarian cancer(OC)is one of the most common and most lethal gynecological malignancies.OC has an age-dependent incidence and occurs more commonly in females older than 50 years old.Most OC patients are diagnosed at an advanced stage and have a poor prognosis.Germline mutations in the BRCA1 DNA repair associated gene(BRCA1)and the BRCA2 DNA repair associated gene(BRCA2)account for 20%–25%of epithelial ovarian cancer(EOC).BRCA1 germline mutations are more common in Chinese EOC patients.Methods This study reported a three-generation Han-Chinese family containing four EOC patients and a rectal adenocarcinoma patient.Whole-exome sequencing was performed on two EOC patients and an unaffected individual.Variant validation was also performed in all available members by Sanger sequencing.Results A heterozygous splice site variant,c.4358-2A>G in the BRCA1 gene,was identified.Bioinformatic analysis showed that the variant may change the splicing machinery.Conclusion The BRCA1 splice site variant,c.4358-2A>G was identified as the likely genetic cause for EOC,and may also be associated with the increased risk of rectal adenocarcinoma in the family.The findings were beneficial for genetic counseling,helpful for cancer prevention in other family members,and may facilitate therapy decision-making in the future to reduce cancer lethality.

An alternative splice variant of human thioredoxin

An alternative splice variant of human thioredoxin (hTRX) has been identified by using reverse transcription_polymerase chain reaction, cloning and expressing of hTRX_encoding gene, and DNA sequencing. This variant contains hTRX exons 1, 2, 4 and 5. The entire protein encoding region of this variant, named hTRXδ3, is identical to hTRX except for the omission of exon 3. Human TRX and TRXδ3 cDNA has been expressed in \%E.coli\%. The catalytic activity of rhTRXδ3 on DTT_dependent insulin reduction is lower than that of rhTRX, although hTRXδ3 still contains the active site.

PMCA1-4及其A端和C端剪接变异体在成年大鼠前庭组织中的表达

目的研究质膜钙ATP酶异构体1-4(plasma membrane Ca^(2+)-ATPase 1-4,PMCA1-4)在成年大鼠前庭组织的分布部位,及其A端和C端剪接变异体的表达类型。方法选择8周龄健康SD大鼠,解剖出内耳器官行前庭切片,同时取前庭椭圆囊斑和球囊斑提取总RNA。通过免疫荧光方法检测PMCA1-4在成年大鼠内耳前庭组织的表达部位,通过逆转录聚合酶链反应(RT-PCR)法检测PMCA1-4的A端和C端剪接变异体在成年大鼠前庭组织的表达类型。结果球囊和椭圆囊荧光染色切片中,于毛细胞和支持细胞的胞体外侧膜可见PMCA1表达,毛细胞纤毛中可见PMCA2强表达,毛细胞和支持细胞的胞体外侧膜可见PMCA3弱表达,PMCA4几乎不表达。4种PMCA亚型在球囊表达的剪接体分别为PMCA1x/b、PMCA2w/b、PMCA3z/(a,b)和PMCA4x/b,它们在椭圆囊的表达类型与球囊相同。结论PMCA1-4在成年大鼠前庭器官的表达部位存在差异,这4种PMCA亚型的剪接体类型也各不相同。这种差异性可能是为了满足前庭组织和亚细胞结构域对Ca2+调节的特殊需求。

miR-141-3p、KLF9异常表达对前列腺癌细胞株药物敏感性和雄激素受体表达的影响及靶向关系

目的观察miR-141-3p、Krüppel样因子9(KLF9)对前列腺癌细胞株药物敏感性、雄激素受体(AR)表达的影响,验证miR-141-3p、KLF9之间的靶向关系,以探讨miR-141-3p、KLF9对PCa药物敏感性的调控作用及机制。方法选择雄激素敏感且表达AR的LNCaP细胞株。将细胞分为miR-141-3p低表达组、miR-141-3p正常组、KLF9过表达组、KLF9正常组,采用脂质体转染法分别转染miR-141-3p-inhibitor、inhibitor阴性对照物(inhibitor-NC)、KLF9过表达质粒、空白质粒。上述各组细胞加入不同浓度(0、10、25、50、75、100µmol/L)比卡鲁胺或(0.5、1.0、2.5、5.0 nmol/L)多西他赛后培养48 h,检测各组细胞OD值,计算细胞增殖率(反映药物敏感性)。采用qRT-PCR和Western blotting法检测各组细胞中AR及AR-V7。采用TargetScan数据库预测miR-141-3p与KLF9是否存在结合位点,然后采用荧光素酶报告基因实验验证miR-141-3p与KLF9的靶向调控关系[将LNCaP细胞株分别分为A、B、C、D组,A组先后转染野生型KLF9荧光素酶报告基因质粒(KLF9-WT)、inhibitor-NC,B组先后转染KLF9-WT、miR-141-3p-inhibitor,C组先后转染突变型KLF9荧光素酶报告基因质粒(KLF9-Mut)、inhibitor-NC,D组先后转染KLF9-Mut、miR-141-3p-inhibitor,转染24 h后检测各组荧光素酶活性]。通过细胞功能回复实验进一步验证miR-141-3p通过靶向调控KLF9抑制前列腺癌细胞药物敏感性[将LNCaP细胞株分别分为a、b、c、d组,a组先后转染si-KLF9阴性对照(si-Ctrl)、inhibitor-NC,b组先后转染si-Ctrl、miR-141-3p-inhibitor,c组先后转染si-KLF9、inhibitor-NC,d组先后转染si-KLF9、miR-141-3p-inhibitor,转染24 h后分别使用75µmol/L比卡鲁胺或2.5 nmol/L多西他赛处理细胞48 h,使用CCK-8法检测细胞OD值,并计算细胞增殖率]。结果LNCaP细胞培养48 h,在无药物加入时,miR-141-3p低表达组细胞增殖率低于miR-141-3p正常组(P均<0.05),KLF9过表达组细胞增殖率低于KLF9正常组(P均<0.05);随着药物浓度升高,各组细胞增殖率呈下降趋势(P均<0.05);在同等药物浓度情况下,miR-141-3p低表达组细胞增殖率低于miR-141-3p正常组(P均<0.05),KLF9过表达组细胞增殖率低于KLF9正常组(P均<0.05)。LNCaP细胞培养48 h,与不加入药物的miR-141-3p正常组相比,加入75、100µmol/L比卡鲁胺的miR-141-3p正常组AR相对表达量升高(P均<0.05),加入50、75、100µmol/L比卡鲁胺的miR-141-3p正常组AR-V7相对表达量升高(P均<0.05);加入0.5、1.0、2.5、5.0 nmol/L多西他赛的miR-141-3p正常组AR及AR-V7相对表达量升高(P均<0.05)。miR-141-3p低表达组的AR及AR-V7相对表达量低于加入同药物浓度的miR-141-3p正常组(P均<0.05),KLF9过表达组的AR及AR-V7相对表达量低于加入同药物浓度的KLF9正常组(P均<0.05)。TargetScan数据库预测miR-141-3p与KLF9存在结合位点,双荧光素酶报告实验显示,B组的相对荧光活性高于A组、C组及D组(P均<0.05)。功能回复实验结果显示,d组的细胞增殖率高于b组(P均<0.05),低于c组(P均<0.05),但与a组差异无统计学意义(P>0.05)。结论miR-141-3p低表达、KLF9过表达均可增强LNCaP细胞株的药物敏感性,并可抑制LNCaP细胞株AR和AR-V7的表达,miR-141-3p和KLF9存在靶向关系,miR-141-3p可靶向KLF9抑制LNCaP细胞药物敏感性,可能是通过促进AR-V7的表达实现的。

应用Minigene剪接变异体分析技术诊断PMM2基因非经典剪接位点新变异的致病性

目的:研究Minigene剪接变异体分析技术在诊断磷酸甘露糖变位酶2(PMM2)相关先天性糖基化障碍(PMM2-CDG)中的价值,探讨磷酸甘露糖变位酶2(PMM2)基因剪接位点新变异对其转录产物的影响。方法:通过对1例PMM2-CDG患儿进行高通量测序查找可能的遗传学病因,利用Minigene剪接变异体分析技术,研究PMM2基因新剪接位点变异的致病性。根据美国医学遗传学与基因组学学会(ACMG)指南,判断新变异的致病性。结果:遗传学分析发现患儿系PMM2基因母源性c.691G>A(p.Val231Met)变异和父源性c.447+5G>A变异复合杂合子。Minigene剪接变异体分析发现:变异c.447+5G>A导致PMM2基因转录产物形成r.348_447del转录本,为致病性PMM2基因变异。患儿的临床特征为皮肤巩膜黄染,血清总胆红素、非结合胆红素和总胆汁酸明显升高,白蛋白明显降低,甲胎蛋白、铁蛋白和促甲状腺素等升高,对症支持治疗效果欠佳。结论:Minigene剪接变异体分析可为PMM2-CDG确诊和家系遗传咨询提供新的分子标记物,扩展了PMM2基因变异谱,为该病的临床诊治提供新的参考依据。

中华蜜蜂工蜂幼虫肠道细胞自噬与凋亡相关基因及其剪接本鉴定

【目的】通过鉴定和解析中华蜜蜂(Apis cerana cerana)工蜂幼虫肠道细胞自噬与凋亡相关基因及其剪接本,为进一步的功能研究提供依据。【方法】使用Blast工具将中华蜜蜂剪接本与Nr数据库进行比对,以鉴定自噬与凋亡相关基因及其剪接本。采用Astalavista软件挖掘相关基因的可变剪接(alternative splicing,AS)事件。通过RT-PCR验证AS事件的真实性。利用TAPIS pipeline软件预测相关基因的可变多聚腺苷酸化(alternative polyadenylation,APA)位点。使用TBtools软件预测APA位点上游的基序(motif)。【结果】鉴定出中华蜜蜂工蜂幼虫肠道中与自噬相关的49个基因及其170种剪接本,以及与凋亡相关的76个基因及其347种剪接本。鉴定出细胞自噬相关的8个基因的88次AS事件及凋亡相关的15个基因的339次AS事件。PCR扩增结果符合预期,证实了随机选择的3种类型AS事件(3'端可变剪接、外显子跳跃、内含子保留)的真实性。预测结果表明,自噬相关的36个基因含有1个或多个APA位点,但在这些APA位点的上游未鉴定到任何motif;而凋亡相关的55个基因含有1个或多个APA位点,并在其上游识别出多个motif,具有一致性序列:NNNDNDNNDNDNDNNDNDNDNNDNDNNNNDDHNNN,NNNNNVNNDNNNNNDHNNHNNNNVNNNH。【结论】中华蜜蜂工蜂幼虫肠道细胞自噬与凋亡相关基因可通过AS和APA形成数量丰富的剪接本,自噬和凋亡相关基因中最丰富的AS类型分别是3'端可变剪接和外显子跳跃,含1个APA位点的基因数目最多。

心肌病相关基因剪接变异预测软件的评估与临床应用

目的:发生在非经典剪接区域的基因突变是遗传性心肌病的重要致病因素。目前研究者已经开发了多种软件来预测变异对可变剪接的影响。然而,这些预测软件在遗传性心肌病基因诊断中的应用尚不明确。因此,本研究拟评估相关软件的预测性能,并探讨这些预测软件在肥厚型心肌病(HCM)患者中的临床应用。方法:对1 212名散发性肥厚型心肌病患者进行全外显子组测序(WES),并从公开发表研究中收集引起HCM相关基因可变剪接的突变位点。基于剪接区域特异性的策略来评估剪接变异预测软件的性能,找到针对各个区域的最优预测软件来筛选候选剪接变异,最后在体外HEK293细胞中通过Minigene实验来验证这些变异的剪接结果。结果:性能评估表明,各个剪接区域的最佳预测软件分别是Pangolin(深外显子、核心供体和扩展供体区)、MLCsplice(扩展供体、核心受体和扩展受体区)、MMSplice和SpliceAI(扩展供体区)。本研究在4.5%(54/1 212)的散发性肥厚型心肌病病例中预测得到43个“优先变异”,其中有23个变异经实验证实会导致异常剪接。结论:基于剪接区域特异性预测方法可以有效识别剪接变异,从而提高遗传性心肌病基因检测的诊断率。

生长阻滞特异性转录因子5剪接变异体GAS5_O1增强慢性髓系白血病细胞对伊马替尼的敏感性

在多种肿瘤中,生长阻滞特异性转录因子5(growth-arrest specific transcript 5,GAS5)高表达与患者的良好生存期相关。GAS5存在多种剪接变异体,本研究探讨GAS5部分剪接变异体在髓系白血病细胞系中的表达模式。并基于对凋亡诱导敏感的慢性髓系白血病(chronic myeloid leukemia,CML)细胞系K562,研究GAS5部分剪接变异体对K562细胞自身增殖、凋亡以及对靶向药物伊马替尼(imatinib,IM)的敏感性的影响。反转录PCR结果显示,GAS5剪接模式在髓系白血病细胞系HL-60、K562、NB4和KASUMI-1之间未见明显差异。相较于指数增长期,GAS5_AE表达水平在细胞密度引起的生长停滞期有一定程度的累积。通过核转染,将GAS5剪接变异体(pcDNA3-GAS5_1B、-GAS5_2B、-GAS5_3A、-GAS5_4A、-GAS5_O1或-GAS5_AE)转入K562细胞的单克隆株中。通过台盼蓝染色、吖啶橙染色后进行细胞计数,克隆形成实验检测细胞集落形成能力。结果与对照组相比,瞬时转染GAS5剪接变异体并无抑制细胞的基础增殖或增强细胞对药物的敏感性。建立GAS5_O1的稳定转染株,延长培养时程并计算倍增时间,发现GAS5_O1的表达水平和倍增时间成正比(R^(2)=0.5692)。在稳转株O1-C8中观察到GAS5_O1可促进IM引起的细胞生长抑制(56.94%±2.84%vs.36.07%±2.32%,P<0.05)和凋亡(29.33%±1.30%vs.52.00%±2.52%,P<0.05)。上述结果表明,GAS5_O1的上调可能增加CML细胞的倍增时间,并使CML细胞对IM处理敏感。

Heat Stress Upregulates the Expression of TLR4 and Its Alternative Splicing Variant in Bama Miniature Pigs

Alternative splicing is a cellular mechanism in eukaryotes that results in considerable diversity ofgene products. It plays an important role in several diseases and cellular signal regulation. Heat stress is a major factor that induces immunosuppression in pigs. Little is known about the correlation between alternative splicing and heat stress in pigs. Therefore, this study aimed to clone, sequence and quantify the alternative splicing variant of toll-like receptor 4 （TLR4） in Bama miniature pigs （Sus scrofa domestica） following exposure to heat stress. The results showed that the second exon of TLR4 was spliced and 167 bp shorter in the alternative splicing variant, and the protein was putatively identified as a type of truncated membrane protein consisting of extramembrane, transmembrane and intramembrane regions lacking a signal peptide. Further, it was not a non- classical secretory protein. Five potential reference genes were screened for their potential as reliable standards to quantify the expression of TLR4 alternative spliced variants by real-time quantitative reverse-transcriptase polymerase chain reaction （qRT-PCR）. The stability of these reference genes was ranked using the geNorm and NormFinder programs, and ribosomal protein L4 （RPL4） and TATA box-binding protein （TBP） were found to be the two genes showing the most stable expression in the in vitro cultured peripheral blood mononuclear ceils （PBMCs） during heat shock. The mRNA level of the TLR4 gene （both classical and spliced） in stressed pigs increased significantly （P〈0.05）. Further, the expression levels of the alternative spliced variant of TLR4 （TLR4-ASV） showed a 2-3 folds increase in heat-stressed PBMCs as compared to control pigs. The results of the present study suggested that heat shock might modulate the host immune response by regulating the expressions of TLR4 and its alternative splicing variant.

Hepatitis B virus pre-S/S variants in liver diseases

Chronic hepatitis B is a global health problem. The clinical outcomes of chronic hepatitis B infection include asymptomatic carrier state, chronic hepatitis(CH), liver cirrhosis(LC), and hepatocellular carcinoma(HCC). Because of the spontaneous error rate inherent to viral reverse transcriptase, the hepatitis B virus(HBV) genome evolves during the course of infection under the antiviral pressure of host immunity. The clinical significance of pre-S/S variants has become increasingly recognized in patients with chronic HBV infection. Pre-S/S variants are often identified in hepatitis B carriers with CH, LC, and HCC, which suggests that these naturally occurring pre-S/S variants may contribute to the development of progressive liver damage and hepatocarcinogenesis. This paper reviews the function of the pre-S/S region along with recent findings related to the role of pre-S/S variants in liver diseases. According to the mutation type, five pre-S/S variants have been identified: pre-S deletion, pre-S point mutation, pre-S1 splice variant, C-terminus S point mutation, and pre-S/S nonsense mutation. Their associations with HBV genotype and the possible pathogenesis of pre-S/S variants are discussed. Different pre-S/S variants cause liver diseases through different mechanisms. Most cause the intracellular retention of HBV envelope proteins and induction of endoplasmic reticulum stress, which results in liver diseases. Pre-S/S variants should be routinely determined in HBV carriers to help identify individuals who may be at a high risk of less favorable liver disease progression. Additional investigations are required to explore the molecular mechanisms of the pre-S/S variants involved in the pathogenesis of each stage of liver disease.

Heterologous Expression of Rat Testis GABA_A Receptor β3t Splicing Variant in CHO Cells

Objective To characterize a possible retention function of unique sequence in the 5＇end of rat testis GABAA receptor β3t splicing variant Methods Rat testis GABAA receptor β3t splicing variant cDNA was cloned and two eukaryotic expression recombinant plasmids of pEGFP-N1 and pEGFP-C1 were constructed respectively by fusing green fluorescent protein to the N or C-terminus of β3t isoform. The recombinant plasmids were transfected into CHO cells by calcium phosphate co-precipitation method Fluorescence microscope and laser confocal microscope were used to analyze localization of β3t in the transfected cells. ConA-Texas-Red was used to label cell ER and the localization of rat testis β3t splicing variant in CHO cells was determined. Results When rat testis β3t splicing variant was expressed in CHO cells, two expression patterns were delineated, the distributions of uniform and mainly discrete intracellular compartments respectively, The chimera product failed to be translocated into the cell surface when expressed in ClIO cells; whereas the β3 subunit of rat brain was incorporated into the plasma membrane. Conclusion The inability of β3t to target into the ER may be a consequence of the unique 25 specific amino acid segments in the N terminus.

中国人群中RHAG变异对mRNA剪接影响的体外研究

目的通过mRNA异常剪接体外验证实验,即体外微基因剪接系统(minigene splicing assay,MSA),研究中国人群中发现的RHAG突变对于RHAG基因mRNA剪接的影响。方法通过对KMxD数据库中RHAG基因数据的分析,选择10种中国人群中分布频率相对较高的位于RHAG基因剪接位点附近的突变或编码区域的同义突变,构建相应的RHAG外显子野生型及突变型pSplicePOLR2G微基因表达质粒。转染HEK-293T细胞,48 h后收集细胞提取总RNA,反转录后进行PCR扩增,然后进行琼脂糖凝胶电泳检测和毛细管电泳检测,根据实验结果判断RHAG基因突变是否会影响相应外显子的正常剪接。结果2种RHAG基因剪接位点附近突变(c.158-5delT,c.807+3A>C)轻微减弱了原剪接位点的剪接效率,其余8种突变(c.312G>A,c.341+3G>A,c.609C>T,c.681G>A,c.861G>A,c.957T>A,c.984T>C和c.1139-7G>A)均不影响RHAG基因mRNA的剪接。结论RHAG基因在剪接方面比较保守,剪接位点附近突变及编码区同义突变较少会引起RHAG基因异常剪接。