PDX-1及其对胰岛β细胞的调控作用

胰腺十二指肠同源盒(PDX-1)具有促进胰岛β细胞增殖以及抑制其凋亡的作用。PDX-1通过调控胰岛素及胰岛素相关基因如葡萄糖激酶(GK)、葡萄糖转运蛋白(GLUT2)等的表达,促进胰岛素分泌,维持胰岛β细胞的正常功能。提高胰岛β细胞PDX-1蛋白表达量,可对抗因“糖毒性”所致的胰岛β细胞功能损伤,促进胰岛素基因表达。PDX-1还可以将非胰岛素分泌细胞如肝细胞等转化为胰岛素分泌细胞。     

槟榔碱对2型糖尿病大鼠胰腺β细胞PDX-1 mRNA表达的影响

目的：探讨槟榔碱对2型糖尿病大鼠β细胞分泌功能及胰腺十二指肠同源盒因子 1（pancreas duodenum homeobox 1,PDX 1）mRNA表达的影响。方法：采用高果糖饲料饲养Wistar大鼠12周制备2型糖尿病大鼠模型,40只实验动物随机分为5组：对照组、模型组、模型+1 mg/kg槟榔碱组、模型+5 mg/kg槟榔碱组、模型+10 mg/kg槟榔碱组。药物注射4周后股动脉取血检测空腹血糖、三酰甘油、总胆固醇、高密度脂蛋白、低密度脂蛋白、血清胰岛素,处死大鼠取胰腺组织,石蜡切片HE染色观察组织形态学变化,RT PCR检测β细胞内PDX 1及胰岛素mRNA的表达水平。 结果：（1）高糖作用引起Wistar大鼠胰腺β细胞PDX 1 及胰岛素mRNA 的表达水平显著下降（P＜0.01）;（2）1 mg/kg和5 mg/kg槟榔碱处理能显著上调高糖喂养Wistar大鼠胰腺β细胞PDX 1与胰岛素mRNA表达水平（P＜0.05,P＜0.01）。结论：槟榔碱可以通过上调PDX 1和胰岛素基因表达,改善高糖环境下的β细胞胰岛素合成和分泌功能的损伤。     

缺氧诱导因子-1转录活性的调控

缺氧诱导因子-1(hypoxia-inducible tactor 1,HIF-1)是缺氧活化的转录因子,在调节氧稳态、氧输送及肿瘤细胞的缺氧适应方面具有重要作用。HIF-1是由HIF-1α和HIF-1β组成的异源二聚体,HIF-1α为调节亚基。HIF-α的调节主要发生在转录后的蛋白修饰,包括羟化、乙酰化和磷酸化。另外,PI-3K/AKT信号通路也参与HIF-1转录活性的调节。研究HIF-1转录活性的调控对于深入了解肿瘤细胞耐受缺氧的分子机制具有重要意义。     

人胚胎胰腺发育中微血管密度的变化

胚胎胰腺的发育经历了原始胰管的形成、胰岛原基的形成、胰腺外分泌部各级导管及腺泡的形成3个阶段,与血管的发育和分布密切相关。选用CD34标记血管内皮细胞,检测和量化组织中的微血管密度(Microvessel density,MVD),多用于推测实体肿瘤预后的指标。检测MVD来了解胚胎器官的发育很少见报道。本实验应用CD34抗体标记胚胎胰腺中的血管内皮细胞并计数,旨在探讨MVD与胚胎胰腺发育的关系。     

粒细胞巨噬细胞集落刺激因子调控树突状细胞发育和功能的研究进展

树突状细胞(DC)是重要的抗原提呈细胞,专门负责抗原捕获、加工并提呈给下游T淋巴细胞从而诱导免疫应答或者免疫耐受。维持DC亚群在体内的动态平衡是保证机体免疫系统正常运转的基础。无论机体处于炎症或静息状态,粒细胞巨噬细胞集落刺激因子(GM-CSF)对DC亚群发育、分布、功能及维持DC亚群动态平衡均具有重要的调控作用。本文主要综述了GM-CSF对DC亚群发育与功能的调控作用。阐明DC发育与功能的调控机制,有助于开发新的基于DC的免疫治疗方案。     

脐血干细胞对1型糖尿病大鼠血糖及PDX-1、MafA表达水平的影响

背景：1型糖尿病是一种自身免疫性疾病,以胰腺β细胞选择性破坏,导致患者体内胰岛素分泌绝对不足为特征。脐血干细胞具有多分化潜能,在体内外均可以诱导分化为胰岛细胞,发挥出一定的降糖作用。目的：探讨脐血干细胞对1型糖尿病大鼠血糖水平及胰腺组织PDX-1、MafA表达的影响。方法：30只SD大鼠随机分为3组,每组10只,治疗组和模型组大鼠建立1型糖尿病模型,造模成功后,治疗组尾静脉一次性注射脐血干细胞,正常组给予相同体积的生理盐水,模型组给予相同体积的脐血干细胞缓冲液。采用口服葡萄糖耐量试验评价大鼠胰岛功能,苏木精-伊红染色观察大鼠胰腺形态,Western blot 和PCR 检测胰腺组织PDX-1、MafA蛋白和mRNA表达。结果与结论：①模型组和治疗组大鼠0,30,60,90 min的血糖值均显著高于正常组,差异均有显著性意义(P < 0.05);120 min时间点模型组血糖值显著高于正常组(P < 0.05);治疗组则与正常组之间差异无显著性意义(P > 0.05)。②模型组胰岛数量出现下降,边界模糊不清,呈不规则形态,治疗组胰岛数量出现一定的减少,但尚维持清晰的结构。③治疗组PDX-1及MafA表达水平与正常组比较差异无显著性意义(P > 0.05),但显著高于模型组(P < 0.05)。以上结果表明,脐血干细胞可以显著降低1型糖尿病大鼠的血糖水平,改善胰岛功能及胰腺组织形态,并具有上调PDX-1、MafA表达的作用。中国组织工程研究杂志出版内容重点：干细胞;骨髓干细胞;造血干细胞;脂肪干细胞;肿瘤干细胞;胚胎干细胞;脐带脐血干细胞;干细胞诱导;干细胞分化;组织工程     

神经嵴细胞和胰岛因子-1阳性细胞与小鼠胚胎心动脉端的发育

目的:探讨神经嵴细胞和胰岛因子-1(ISL-1)阳性细胞与小鼠胚胎心动脉端发育的关系.方法:胚龄8～12 d小鼠胚胎心连续石蜡切片,进行免疫组织化学检测.结果:α-平滑肌肌动蛋白(α-SMA)、心肌肌球蛋白重链(MHC)、转录因子ISL-1、激活蛋白-2α(AP-2α)的表达胚龄8d,AP-2α阳性神经嵴细胞主要表达于神经褶外胚层.胚龄9～11 d,AP-2α阳性神经嵴细胞在前肠两侧沿弓动脉逐渐迁移至流出道头端心内膜垫,并形成主肺动脉隔雏形.胚龄8～10 d,ISL-1阳性细胞分布于前肠及神经沟两侧中胚层,构成第2生心区,向流出道添加心肌细胞.胚龄10～11 d,ISL-1阳性细胞在前肠腹侧正中间充质中聚集、与AP-2α阳性细胞共同参与主肺动脉隔形成.心包腔背侧脏壁中胚层及鳃弓核心间充质的ISL-1阳性细胞与流出道α-SMA或MHC阳性心肌相延续.胚龄12d,主肺动脉隔及流出道心内膜垫失去AP-2α及ISL-1阳性表达,转变为α-SMA阳性表达结构.结论:AP-2α阳性心神经嵴细胞和第2生心区来源的ISL-1阳性心前体细胞共同参与了小鼠心动脉端的形态发生.胚龄8～10 d,ISL-1阳性细胞分化为流出道心肌细胞.胚龄10～12 d,ISL-1阳性心前体细胞与AP-2α阳性细胞共同参与了主肺动脉隔的形成和流出道的分隔.     

Pdx1基因修饰的人脐带间充质干细胞体外诱导分化为胰岛β样细胞

本研究探讨胰十二指肠同源框因子-1(Pdx1)基因修饰的人脐带间充质干细胞(MSCs)体外分化为胰岛β样细胞。采用携带Pdx1基因的重组腺病毒感染MSCs 7d,联合细胞因子分阶段诱导分化。RT-PCR及Westernblot、免疫细胞化学法检测诱导后细胞胰岛素相关基因表达变化;化学发光法检测诱导后细胞培养液上清中胰岛素和C肽的分泌水平。用流式细胞术检测胰岛素阳性细胞百分率。结果显示:诱导转入Pdx1基因的人脐带MSCs后,梭形细胞聚集形成胰岛样细胞团,双硫腙染色胞浆呈亮红色;诱导后的细胞表达Pdx1、胰岛素、C肽和葡萄糖转运体2基因;诱导细胞分泌胰岛素和C肽,并且在高糖作用后,胰岛素和C肽分泌增加;诱导后胰岛素阳性细胞百分率为(11.61±4.83)%。结果表明,Pdx1修饰人脐带MSCs在体外能够诱导分化为胰岛β样细胞。     

新生昆明小鼠胰腺干细胞体外分离、培养及自然分化的潜能**

背景：关于胰腺干细胞在胰腺组织中的分布情况,以及如何有效的将其分离、体外优化培养,目前仍有一定的困难。 目的：从新生昆明小鼠胰腺组织中分离出胰腺干细胞,在体外条件下培养观察其形态学和生物学特征,并进行初步鉴定。 方法：取新生SPF级昆明小鼠的胰腺组织,使用Ⅴ型胶原酶消化,采用Percoll不连续密度梯度离心,使胰腺组织内、外分泌部细胞分离,分布在3个不同的密度界面;收集各界面的细胞,以无血清、添加碱性成纤维细胞生长因子和表皮细胞生长因子的DMEM培养基培养。 结果与结论：通过细胞形态学和细胞生长特性的观察,结合双硫腙染色证实：采用Percoll不连续密度梯度离心,第一、二密度界面的细胞来源于胰腺内分泌部;第三密度界面细胞来源于胰腺外分泌部。分别从胰腺内、外分泌部获取胰腺组织细胞,在体外培养观察发现均存在一类大、圆、单个核的细胞,呈集落样附壁生长,具有较活跃的分裂增殖能力,碱性磷酸酶染色阳性,表达胰腺干细胞的特异性标志巢蛋白,即为胰腺干细胞;随着体外培养时间的延长,分别表达PDX-1和CK-19,呈现向胰腺内分泌部细胞和外分泌部细胞分化的趋势。     

低氧诱导肺动脉内皮细胞间质细胞衍生因子-1的表达及其调控机制

肺血管重塑（PVR）是低氧性肺动脉高压持续且难以逆转的主要原因,其主要病变表现为肺动脉壁细胞增多,但其来源和机制仍不清楚。研究表明骨髓和外周血中存在血管壁细胞的祖细胞,并且参与了PVR的形成。间质细胞衍生因子-1（SDF-1）是特异性介导干细胞归巢至骨髓,介导祖细胞归巢至损伤或缺血组织的关键因子。SDF-1表达在这些部位的血管内皮细胞,而低氧是这些部位的微环境特征,也是诱导SDF-1表达的主要原因。低氧诱导因子-1α（HIF-1α）是特异性介导细胞低氧反应的关键因子,直接调控脐静脉内皮细胞SDF-1基因的表达㈨。我们旨在探讨低氧对肺动脉内皮细胞SDF-1表达的影响及HIF-1α对其表达的调控作用。     

Absence of a PDX-1 mutation and normal gastroduodenal immunohistology in a child with pancreatic agenesis

Pancreatic agenesis is a rare condition, of which only a limited number of cases have been described. One recent paper reported a homozygous mutation in the pancreatic duodenal homeobox gene 1 (PDX-1) in a child with pancreatic agenesis. We report a 6-year-old boy with pancreatic agenesis, treated medically, without abnormalities in the PDX-1 gene coding sequence and with normal gastroduodenal endocrine cell distribution. Genes other than PDX-1 also appear to be involved in human pancreatic agenesis.     

Beta-catenin is a promising key factor in the SDF-1/CXCR4 axis on metastasis of pancreatic cancer

Metastasis is recently the most fearsome of cancer. Pancreatic cancer is the fourth leading cause of cancer death. Morbidity and mortality from pancreatic cancer is conspicuously associated with metastasis. However, the mechanism of metastasis is not well described. Early studies mostly focus on the "soil and seed" hypothesis. Recently, the chemotaxis hypothesis has been paid more attention. Cancer cell with high expression of chemokine receptor will spread to the specific sites where the ligand is highly secreted. It has been demonstrated that SDF-1/CXCR4 signaling, one of the most important chemokine receptor-ligand complexes, was considered to play a critical role in pancreatic cancer organ-specific metastasis through some possible pathways. However, studies do not clarify the mechanism of SDF-1/CXCR4 signaling on pancreatic cancer progression. Beta-catenin, an important factor in canonical Wnt signaling pathway, also makes great contributions on cancer invasion and metastasis. It seems that Wnt/beta-catenin has a significant role in pancreatic cancer progression through interactions with different protein complexes. In the previous study of neural development, the relationship between SDF-1/CXCR4 signaling and beta-catenin has been described. It gave a clue to describe the correlation between SDF-1/CXCR4 signaling and Wnt/beta-catenin pathway. According to this, we postulate that beta-catenin is a promising key factor of SDF-1/CXCR4 signaling to regulate the metastasis of pancreatic cancer. With the stimulation of SDF-1 on highly metastatic pancreatic cancer cells, beta-catenin will separate from different complexes, translocate into the nucleus, trigger the expression of target genes and finally promote the migration of pancreatic cancer cells to specific sites. Through the observation of this crosstalk, it is possible to understand more clearly about the pancreatic cancer specific metastasis and to make some contributions on gene therapy of pancreatic cancer.     

The zinc-finger factor Insm1 (IA-1) is essential for the development of pancreatic beta cells and intestinal endocrine cells

The pancreatic and intestinal primordia contain epithelial progenitor cells that generate many cell types. During development, specific programs of gene expression restrict the developmental potential of such progenitors and promote their differentiation. The Insm1 (insulinoma-associated 1, IA-1) gene encodes a Zinc-finger factor that was discovered in an insulinoma cDNA library. We show that pancreatic and intestinal endocrine cells express Insm1 and require Insm1 for their development. In the pancreas of Insm1 mutant mice, endocrine precursors are formed, but only few insulin-positive beta cells are generated. Instead, endocrine precursor cells accumulate that express none of the pancreatic hormones. A similar change is observed in the development of intestine, where endocrine precursor cells are formed but do not differentiate correctly. A hallmark of endocrine cell differentiation is the accumulation of proteins that participate in secretion and vesicle transport, and we find many of the corresponding genes to be down-regulated in Insm1 mutant mice. Insm1 thus controls a gene expression program that comprises hormones and proteins of the secretory machinery. Our genetic analysis has revealed a key role of Insm1 in differentiation of pancreatic and intestinal endocrine cells.     

ff1b, the SF1 ortholog, is important for pancreatic islet cell development in zebrafish

The adrenal cortex and pancreatic islets have endocrine functions, producing steroid-based hormones and insulin, respectively. Cells of the adrenal cortex originate in the mesoderm while the cells of pancreatic islets originate in the endoderm. The zebrafish is a powerful model for understanding organ development due to its ease of genetic and molecular manipulation, transparent embryos, and large number of progeny for statistically powerful experiments. Like humans, the zebrafish pancreas has both exocrine and endocrine functions; unlike humans, there is only one endocrine islet cell group, instead of multiple islets. Using an eGFP-transgenic line of zebrafish, we have observed that the steroidogenic factor 1 (SF1) ortholog, ff1b, which is critical for adrenal cortex development and function in the zebrafish, is also implicated in zebrafish pancreatic islet development. We show that interruption of ff1b expression using an ff1b-morpholino (MO) disrupts development of insulin expressing cells. We conclude that ff1b-MO alters pancreatic islet development in zebrafish, demonstrating the utility of the zebrafish as a model for studying pancreatic development. This work is consistent with previous studies in mouse and human that have suggested SF1 participates in the vascular and ductal development of the pancreas, and disruption of SF1 function leads to abnormal development of the pancreatic islets due to poor vascularization.     

Spatio-temporally regulated expression of receptor tyrosine kinases, mRor1, mRor2, during mouse development: implications in development and function of the nervous system

BACKGROUNDS: Drosophila neurospecific receptor tyrosine kinases (RTKs), Dror and Dnrk, as well as Ror1 and Ror2 RTKs, isolated from human neuroblastoma, have been identified as a structurally related novel family of RTKs (Ror-family RTKs). Thus far, little is known about the expression and function of mammalian Ror-family RTKs. RESULTS: We have identified murine Ror-family RTKs, mRor1 and mRor2. Both mRor1 and mRor2 genes are induced upon neuronal differentiation of P19EC cells. During neuronal differentiation in vitro, the expression of mRor2 is transiently induced, although that of mRor1 increases continuously. During embryogenesis, the mRor1 gene is expressed in the developing nervous system within restricted regions and in the developing lens epithelium. The expression of mRor1 is sustained in the nervous system and is also detected in non-neuronal tissues after birth. In contrast, the expression of mRor2 is detected mainly in the developing nervous system within broader regions and declines after birth. Possible relationships of mRor1 and mRor2 genes with previously identified mutants have also been examined. CONCLUSIONS: The developmental expressions of mRor1 and mRor2, in particular in the nervous system, are differentially regulated, reflecting their expression patterns in vitro. mRor1 and mRor2 may thus play differential roles during the development of the nervous system.