NuMA 的分布和功能

核有丝分裂器蛋白(Nuclear Mitotic Apparatus Protein,NuMA)是一种在间期细胞核内有大量表达的大分子蛋白。NuMA是微管聚合因子,能使微管锚定于纺锤体极。在细胞有丝分裂,减数分裂过程中对纺锤体的形成和形态的维持发挥重要作用。     

四膜虫大核基质中含有NuMA类似蛋白

NuMA (Nuclear mitotic apparatus protein)是细胞核基质中的一种高分子量蛋白质,具有一个特殊的细胞周期依赖性(cell cycle- dependent distribution)。在多细胞动物中有关NuMA的研究已经很深入,但是目前尚未见原生动物中NuMA蛋白的报道。四膜虫(Tetrahymena)是一种单细胞真核生物,属原生动物(Protozoa)纤毛虫纲(Ciliata),具有较特殊的分类地位和分子生物学研究背景。本实验结果表明,四膜虫大核基质中含有NuMA类似蛋白,不仅进一步验证了NuMA蛋白存在的普遍性,而且是对四膜虫中大核基质成分研究的补充。     

植物细胞中NuMA类似蛋白的分布及其在细胞周期中的变化

免疫荧光染色结果说明植物细胞核内含有与抗动物ＮｕＭＡ多抗呈阳性交叉反应的多肽。选择性抽提并结合免疫荧光染色结果说明这种多肽位于核基质纤维蛋白网络上。免疫印迹反应显示胡萝卜（ＤａｕｃｕｓｃａｒｏｔａＬ．）悬浮培养细胞核基质蛋白与抗动物ＮｕＭＡ蛋白多抗的阳性反应条带为７４ｋＤ和７６ｋＤ。有丝分裂各期免疫荧光染色的结果表明植物细胞中的ＮｕＭＡ类似蛋白在有丝分裂过程中呈现有规律的变化。结合选择性抽提的有丝分裂各期的免疫荧光染色的结果表明核基质在此过程中也发生明显变化。应用选择性抽提并结合ＤＧＤ包埋去包埋电镜技术对植物细胞间期及有丝分裂期核基质的形态结构进行了观察。结果显示胡萝卜悬浮培养细胞间期核内存在一个非染色质性的纤维蛋白网络体系,而在正处于分裂的细胞中则未观察到。以上结果说明ＮｕＭＡ类似蛋白是核基质的组分之一并与有丝分裂密切相关。     

植物细胞核基质（Nuclear Matrix）的形态结构及其NuMA蛋白成份的…

应用细胞选择性抽提并结合ＤＧＤ包埋去包埋剂电技术对植物细胞核基质的形态结构进行了观察。结果显示胡萝卜悬浮培养细胞、银杏花粉细胞和精子细胞的细胞核内存在一个非染色质性的纤维蛋白网络体系。     

植物细胞核基质(Nuclear Matrix)的形态结构及其NuMA蛋白成分的研究

应用细胞选择性抽提并结合DGD包埋去包埋剂电镜技术对植物细胞核基质的形态结构进行了观察。结果显示胡萝卜悬浮培养细胞、银杏花粉细胞和精子细胞的细胞核内存在一个非染色质性的纤维蛋白网络体系。免疫荧光染色结果说明植物细胞核基质中含有与动物NuMA多抗交叉反应的多肽。免疫印迹反应显示胡萝卜悬浮培养细胞核基质蛋白与NuMA蛋白多抗的阳性反应条带为74KD和76 KD;银杏花粉细胞只有78 KD一条阳性带。以动物核基质NuMA蛋白保守杆状区的cDNA片段作为探针,与白菜子叶总DNA进行Southern杂交的结果表明植物细胞基因组中含有动物NuMA蛋白cDNA的同源序列。     

5—羟色胺受体的分型,分布和功能

5-HT受体分为5-HT_1、5-HT_2和5-HT_3受体三种亚型。5-HT_1受体又可划分为5-HT_(1A)、5-HT_(1B)、5-HT_(1C)、5-HT_(1D)受体亚亚型;5-HT_3又划分为5-HT_(3S)、5-HT_)3P)、5-HT_(3A)受体亚亚型。5-HT_1受体可能还有新的亚亚型。5-HT受体的上述分型,为解释5-HT的复杂生理、病理生理作用及其某些拮抗效应提供了依据。     

热休克蛋白的产生,分布及功能

生物体在各种应激条件下,诸如高温、缺氧、机体损伤、接触某些重金属离子和其它化学物质时,都可能引起的一种生理效应,称之为“热休克反应”(heat shock response)。在热休克反应过程中,细胞内正常蛋白质合成关闭,热休克基因(heat shock gene)的转录被激活,并诱导产生一组特殊蛋白质——热休克蛋白(heat shock proteins,HSP)。     

昆虫体内章鱼胺的分布、功能及其研究进展

章鱼胺是无脊椎动物神经系统中普遍存在的多种微量生物胺之一。章鱼胺的分布及含量变化对于昆虫的生长、取食、代谢等多种生理、生物效应具有重要的作用。文章对昆虫体内章鱼胺的功能性、昆虫体内章鱼胺的分布及其主要功能、章鱼胺痕量测定方法、生存环境的改变及化学药剂的作用对章鱼胺含量的影响以及外界刺激对章鱼胺含量影响的生理及生物化学机理研究进行了综述。     

长江口底栖动物功能群分布格局及其变化

用功能群方法对长江口南岸潮滩底栖动物与河口环境梯度和生境变化的关系进行了研究。根据底栖动物的取食类型,运动能力和摄食机制进行了功能群的划分。共鉴别出55种栖动物,并将其划分为15种功能群类型,均表现出沿长江口南岸河口梯度的逐渐变化的分布格局,底栖动物物种数和功能群类型数主要表现出与河口盐度梯度呈正相关的动物地理分布格局,沿着河口梯度,不同的采样断面,优势功能群不同。在河口下游,功能群类型多样化,各种食性类型,不同运动能力及各种摄食机制抽功能群皆有;而生境较单一的河口上游和受污染较严重的断面,功能群类型较少,沿着河口梯度,最显著的变化是固着生活和以触手摄食的功能群的迅速消失,底栖动物功能群多样性是对河口环境梯度和生境质量的综合反映。     

老龄化引起的脂肪组织重新分布与代谢功能障碍

在生物的一生中,脂肪总量以及脂肪组织分布变化很大。在老龄阶段,脂肪组织从皮下转移到腹部内脏、骨髓、肌肉、肝脏和其他的异位位点,引发脂肪功能障碍。脂肪的异位沉积增加了代谢综合征发生的危险。随着年龄的增加,前体脂肪细胞的增殖和分化能力下降,致使机体持续处于游离脂肪酸过多所产生的脂毒性状态。前体脂肪细胞和巨噬细胞以部位依赖的方式影响着年龄相关的脂肪组织炎症。脂肪组织炎症进一步导致老年人脂肪生成减少,脂毒性增加,细胞应激通路激活,这加剧了前体脂肪细胞和免疫细胞的炎症反应,最终导致系统功能障碍。该文就老龄化引起的脂肪组织重新分布和代谢功能障碍研究进展作一简要综述。     

克隆胚胎中核有丝分裂器蛋白(NuMA)的动态变化

核有丝分裂器蛋白(NuMA)是一种负责纺缍体极装配的蛋白质。供体细胞核移入去核卵母细胞后,在供体核中未发现NuMA,在重构胚的原核中出现NuMA。克隆胚胎卵裂后,NuMA存在于卵裂球的核中。在克隆胚胎中,NuMA的缺乏会导致有丝分裂纺缍体异常,染色体排列混乱,这些异常影响克隆胚胎的正常发育。     

NuMA phosphorylation by CDK1 couples mitotic progression with cortical dynein function

Spindle positioning and spindle elongation are critical for proper cell division. In human cells, an evolutionary conserved ternary complex (NuMA/LGN/Gαi) anchors dynein at the cortex during metaphase, thus ensuring correct spindle positioning. Whether this complex contributes to anaphase spindle elongation is not known. More generally, the mechanisms coupling mitotic progression with spindle behaviour remain elusive. Here, we uncover that levels of cortical dynein markedly increase during anaphase in a NuMA‐dependent manner. We demonstrate that during metaphase, CDK1‐mediated phosphorylation at T2055 negatively regulates NuMA cortical localization and that this phosphorylation is counteracted by PPP2CA phosphatase activity. We establish that this tug of war is essential for proper levels of cortical dynein and thus spindle positioning during metaphase. Moreover, we find that upon CDK1 inactivation in anaphase, the rise in dephosphorylated NuMA at the cell cortex leads to cortical dynein enrichment, and thus to robust spindle elongation. Our findings uncover a mechanism whereby the status of NuMA phosphorylation coordinates mitotic progression with proper spindle function.     

NuMA interacts with phosphoinositides and links the mitotic spindle with the plasma membrane

The positioning and the elongation of the mitotic spindle must be carefully regulated. In human cells, the evolutionary conserved proteins LGN/Gα_i1‐3 anchor the coiled‐coil protein NuMA and dynein to the cell cortex during metaphase, thus ensuring proper spindle positioning. The mechanisms governing cortical localization of NuMA and dynein during anaphase remain more elusive. Here, we report that LGN/Gα_i1‐3 are dispensable for NuMA‐dependent cortical dynein enrichment during anaphase. We further establish that NuMA is excluded from the equatorial region of the cell cortex in a manner that depends on the centralspindlin components CYK4 and MKLP1. Importantly, we reveal that NuMA can directly associate with PtdInsP (PIP) and PtdInsP₂ (PIP₂) phosphoinositides in vitro. Furthermore, chemical or enzymatic depletion of PIP/PIP₂ prevents NuMA cortical localization during mitosis, and conversely, increasing PIP₂ levels augments mitotic cortical NuMA. Overall, our study uncovers a novel function for plasma membrane phospholipids in governing cortical NuMA distribution and thus the proper execution of mitosis.     

Phosphorylation of NuMA by Aurora‐A kinase in PC‐3 prostate cancer cells affects proliferation,survival, and interphase NuMA localization

Aurora‐A is a serine/threonine kinase that has oncogenic properties in vivo. The expression and kinase activity of Aurora‐A are up‐regulated in multiple malignancies. Aurora‐A is a key regulator of mitosis that localizes to the centrosome from the G2 phase through mitotic exit and regulates mitotic spindle formation as well as centrosome separation. Overexpression of Aurora‐A in multiple malignancies has been linked to higher tumor grade and poor prognosis through mechanisms that remain to be defined. Using an unbiased proteomics approach, we identified the protein nuclear mitotic apparatus (NuMA) as a robust substrate of Aurora‐A kinase. Using a small molecule Aurora‐A inhibitor in conjunction with a reverse in‐gel kinase assay (RIKA), we demonstrate that NuMA becomes hypo‐phosphorylated in vivo upon Aurora‐A inhibition. Using an alanine substitution strategy, we identified multiple Aurora‐A phospho‐acceptor sites in the C‐terminal tail of NuMA. Functional analyses demonstrate that mutation of three of these phospho‐acceptor sites significantly diminished cell proliferation. In addition, alanine mutation at these sites significantly increased the rate of apoptosis. Using confocal immunofluorescence microscopy, we show that the NuMA T1804A mutant mis‐localizes to the cytoplasm in interphase nuclei in a punctate pattern. The identification of Aurora‐A phosphorylation sites in NuMA that are important for cell cycle progression and apoptosis provides new insights into Aurora‐A function. J. Cell. Biochem. 114: 823–830, 2013. © 2012 Wiley Periodicals, Inc.     

NuMA in rat testis--evidence for roles in proliferative activity and meiotic cell division

NuMA is a well-characterized organizer of the mitotic spindle, which is believed to play a structural role in interphase nucleus. We studied the expression of NuMA in rat seminiferous epithelium in detail. Different stages of the cycle of the seminiferous epithelium were identified using transillumination. Corresponding areas were microdissected and analysed using immunofluorescence, immunohistochemistry, or immunoblotting. NuMA was expressed in Sertoli cells, proliferating type A and B spermatogonia, and early spermatids but it was absent in late spermatids and mature spermatozoa. Interestingly, NuMA-positive primary spermatocytes lost their nuclear NuMA at the beginning of long-lasting prophase of the first meiotic division. A strong expression was again observed at the end of the prophase and finally, a redistribution of NuMA into pole regions of the meiotic spindle was observed in first and second meiotic divisions. In immunoblotting, a single 250-kDa protein present in all stages of the rat seminiferous epithelial cycle was detected. Our results show that NuMA is not essential for the organization of nuclear structure in all cell types and suggest that its presence is more likely connected to the proliferation phase of the cells. They also suggest that NuMA may play an important role in meiotic cell division.