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991.
OCI-5/GPC3, a Glypican Encoded by a Gene That Is Mutated in the Simpson-Golabi-Behmel Overgrowth Syndrome, Induces Apoptosis in a Cell Line–specific Manner
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Alfonso Dueas Gonzalez Mitsunori Kaya Wen Shi Howard Song Joseph R. Testa Linda Z. Penn Jorge Filmus 《The Journal of cell biology》1998,141(6):1407-1414
OCI-5/GPC3 is a member of the glypican family. Glypicans are heparan sulfate proteoglycans that are bound to the cell surface through a glycosyl-phosphatidylinositol anchor. It has recently been shown that the OCI-5/GPC3 gene is mutated in patients with the Simpson-Golabi-Behmel Syndrome (SGBS), an X-linked disorder characterized by pre- and postnatal overgrowth and various visceral and skeletal dysmorphisms. Some of these dysmorphisms could be the result of deficient growth inhibition or apoptosis in certain cell types during development. Here we present evidence indicating that OCI-5/GPC3 induces apoptosis in cell lines derived from mesothelioma (II14) and breast cancer (MCF-7). This induction, however, is cell line specific since it is not observed in NIH 3T3 fibroblasts or HT-29 colorectal tumor cells. We also show that the apoptosis-inducing activity in II14 and MCF-7 cells requires the anchoring of OCI-5/GPC3 to the cell membrane. The glycosaminoglycan chains, on the other hand, are not required. MCF-7 cells can be rescued from OCI-5/GPC3–induced cell death by insulin-like growth factor 2. This factor has been implicated in Beckwith-Wiedemann, an overgrowth syndrome that has many similarities with SGBS. The discovery that OCI-5/GPC3 is able to induce apoptosis in a cell line– specific manner provides an insight into the mechanism that, at least in part, is responsible for the phenotype of SGBS patients. 相似文献
992.
The effect of temperature gradients on in vitro maturation of bovine oocytes was examined in this study. Six treatment groups were made by combining 3 different maturation periods (0 to 10 h, 10 to 18 h and 18 to 24 h) with 2 different culture temperatures (37.0 degrees C and 38.5 degrees C). The frequency of oocytes matured to the metaphase II stage was apparently gradually increased as the culture temperature was increased from 37.0 degrees C to 38.5 degrees C at 0, 10 and 18 h after the onset of culture (75.2 vs 80.5, 82.3 and 84.3%, respectively), but this difference was not significant. Neither was the minor decrease in the proportion of oocytes reaching metaphase II when the temperature was decreased from 38.5 degrees C to 37.0 degrees C at 10 and at 18 h after the onset of maturation (84.3 vs 82.4 and 78.0%, respectively). However, more oocytes cleaved (79.2%; P = 0.0653) and developed to morulae (43.6%; P = 0.0019) and blastocysts (27.4%; P = 0.1568) when they were in vitro matured at 38.5 degrees C between 0 and 10 h, and then at 37.0 degrees C from 10 to 24 h. Although only the morula group was statistically different, cleavage- (79.2 vs 69.8, 72.5, 74.2, 76.3, 74.3%, respectively) and blastocyst formation (27.4 vs 23.2, 24.6, 25.2, 19.6, 21.9%, respectively) from this group was the highest among the 6 treatments. 相似文献
993.
马尾松毛虫幼虫的捕食天敌及其捕食作用的研究 总被引:4,自引:0,他引:4
根据林间调查和室内观察资料,分析了江西省万年县不同松林中马尾松毛虫不同发生代别低龄幼虫期的主要捕食天敌种类及数量。结果表明低龄幼虫期捕食无敌有13科31种,其中以蜘蛛类最多,其次为蚂蚁类。不同林型中捕食天敌的种类和数量在年份间代别间均存在一定差异,数量差异尤其显著。在室内研究了几种主要捕食无敌对马尾松毛虫低龄幼虫的捕食作用及其功能反应,结果表明功能反应为S型,由此建立了它们的功能反应模型。 相似文献
994.
哺乳动物及人精子膜离子通道的研究进展 总被引:3,自引:0,他引:3
离子的跨膜转动对精子的生理活动起重要的作用。近年,应用膜片钳及人工膜重组等研究通道有关的电生理技术,人们直接观察到哺乳动物及人精子膜上K、Na^+、Ca^2+、Cl通道的存在。这些结果为揭示精子成熟、获能精卵结合反应等生理过程的某些细节提供了有有的资料,特别是对人精子膜的研究,还为临床应用提供了可能。 相似文献
995.
996.
Induction of sialic acid 9-O-acetylation by diverse gene products: implications for the expression cloning of sialic acid O- acetyltransferases 总被引:1,自引:0,他引:1
Sialic acids can be modified by O-acetyl esters at the 7- and/or 9-
position, altering recognition by antibodies, lectins and viruses. 9(7)-
O-acetylation is mediated by a sialic acid-specific O- acetyltransferase,
which has proven difficult to purify. Two groups have recently isolated
cDNAs possibly encoding this enzyme, by expression cloning of human
melanoma libraries in COS cells expressing the substrate ganglioside GD3.
Pursuing a similar approach, we have isolated additional clones that can
induce 9-O-acetylation. One clone present in a melanoma library encodes a
fusion protein between a bacterial tetracycline resistance gene repressor
and a sequence reported to be part of the P3 plasmid. Expression of the
open reading frame is necessary for inducing 9-O-acetylation, indicating
that this is not a reaction to the introduction of bacterial DNA. Another
clone from a rat liver cDNA library induced 9-O-acetylation on COS cells
expressing alpha2-6-linked sialic acids, and encodes an open reading frame
identical to the Vitamin D binding protein. However, truncation at the 5'
end eliminates the amino-terminal hydrophobic signal sequence, predicting
cytosolic hyperexpression of a truncated protein. Thus, diverse types of
cDNAs can indirectly induce sialic acid 9-O- acetylation in the COS cell
system, raising the possibility that the real enzyme may be composed of
multiple subunits which would not be amenable to expression cloning.
Importantly, the cDNAs we isolated are highly specific in their ability to
induce 9-O-acetylation either on alpha2-6-linked sialic acids of
glycoproteins (truncated vitamin D binding protein) or on the
alpha2-8-linked sialic acids of gangliosides (Tetrfusion protein). These
data confirm our prior suggestion that a family of O-acetyltransferases
with distinctive substrate specificities exists in mammalian systems.
相似文献
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1000.
应用免疫组织化学技术,观察了30只Wistar大鼠脑血管颈内动脉系肾上腺素能神经的起始核团。正常组脑血管颈内动脉系均可见棕褐色的免疫反应阳性纤维。手术1组作一侧颈上神经节切除术,同侧大脑前动脉、大脑中动脉和大脑后动脉的阳性纤维较正常组减少约2/3,对侧同部位动脉的阳性纤维约减少1/3;手术Ⅱ组作双侧颈上神经节切除术,双侧大脑前动脉、大脑中动脉和大脑后动脉的阳性纤维基本消失。结果提示:脑血管一侧颈内动脉系的肾上腺素能神经纤维起源于双侧颈上神经节。讨论了交感神经对脑血管可能的作用。 相似文献