Hippocampal NMDA receptor mRNA undergoes subunit specific changes during developmental lead exposure

The N-methyl- -aspartate (NMDA) receptor has shown to play an important role in the cognitive deficits associated with developmental lead (Pb) exposure. In this study, we examined the effects of low-level Pb exposure on NMDA receptor subunit gene expression in the developing rat brain. The pattern of NR1, NR2A, NR2B, and NR2C subunit mRNA in situ hybridization was consistent with previous studies. Brain levels of NR1 and NR2A mRNAs were lowest shortly after birth, increasing to reach peak levels by 14 or 21 days of age and subsequently decreasing at 28 days of age. NR2B mRNA levels were highest during early development and decreased as the animals aged. NR2C subunit mRNA was restricted to the cerebellum and a signal was not detectable until the second week of life. Lead exposure resulted in significant and opposite effects in NR1 and NR2A subunit mRNA expression with no changes in NR2B or NR2C subunit expression. The Pb-induced changes in NR1 and NR2A subunit mRNA were mainly present in the hippocampus. Hippocampal NR1 mRNA levels were significantly increased in the CA1 (15.3%) and CA4 (26.8%) pyramidal cells from 14-day-old Pb-exposed rats. At 21 days of age, only the NR1 mRNA at the CA4 subfield remained significantly elevated (10.3%). Lead exposure caused reductions of NR2A mRNA levels (11.9–19.3%) in the pyramidal and granule cell layers of the hippocampus at 14 and 21 days of age. NR1 mRNA levels were also significantly increased (14.0%) in the cerebellum of 28-day-old rats with no change in NR2A mRNA at any age. No significant changes in subunit mRNA levels were present in cortical or subcortical regions at any age. The Pb-induced changes in hippocampal NMDA receptor subunit mRNA expression measured in the present study may lead to modifications in receptor levels or subtypes and alter the development of defined neuronal connections which require NMDA receptor activation.     

Differential regulation of cytokine genes in gingival epithelial cells challenged by Fusobacterium nucleatum and Porphyromonas gingivalis

IL-8 mRNA in human gingival epithelial cells (HGECs) is up-regulated by Fusobacterium nucleatum, and up-/down-regulated by Porphyromonas gingivalis in a complex interaction in the early stages (< or = 4 h) after infection. The mechanisms involved in this regulation in response to F. nucleatum and/or P. gingivalis infection, and identification of co-regulated cytokine genes, are the focus of this investigation. Heat, formalin or protease treatment of F. nucleatum cells attenuated the IL-8 mRNA up-regulation. NF-kappaB, mitogen-activated protein kinase (MAPK) p38 and MAPK kinase/extracellular signal-regulated kinase (MEK/ERK) pathways were involved in IL-8 mRNA induction by F. nucleatum. Pretreatment of P. gingivalis with heat, formalin or protease enhanced IL-8 mRNA induction. NF-kappaB, MARK p38, and MEK/ERK pathways were also involved in this induction. In contrast, down-regulation of IL-8 mRNA by P. gingivalis involved MEK/ERK, but not NF-kappaB or MAPK p38 pathways. cDNA arrays analysis revealed that mRNA down-regulation by P. gingivalis is a specific reaction that only a number of genes, e.g. IL-1beta, IL-8, macrophage inflammatory protein-2alpha, and migration inhibitory factor-related protein-14, are affected based on examination of 278 cytokine/receptor genes. These data indicate that F. nucleatum and P. gingivalis trigger specific and differential gene regulation pathways in HGECs.     

BicD-dependent localization processes: from Drosophilia development to human cell biology

Many eukaryotic cells depend on proper cell polarization for their development and physiological function. The establishment of these polarities often involve the subcellular localization of a specific subset of proteins, RNAs and organelles. In Drosophila, the microtubule-dependent BicD (BicaudalD) localization machinery is involved in the proper localization of mRNA during oogenesis and embryogenesis and the proper positioning of the oocyte and photoreceptor nuclei. BicD acts together with the minus-end directed motor dynein as well as Egl and Lis-1. The finding that the mammalian homologs of BicD function in retrograde Golgi-to-ER transport has supported the view that BicD may be part of a repeatedly used and evolutionary conserved localization machinery. In this review we focus on the various processes in which BicD is involved during Drosophilian development and in mammals. In addition, we evaluate the interactions between BicD, the dynein localization machinery and associated factors.     

人外周血淋巴细胞激活与CD2mRNA表达

对 PHA、抗 CD3单克隆抗体 RW2—8C8、胸腺肽、抗 CD2与抗 CD3等对人 T 淋巴细胞的增殖现象及动力学进行了观察,除抗 CD3与抗 CD2单抗联合应用为抑制效应外,前三者均呈正效应且动力学完全一致.在此基础上,应用反义 CD2mRNA 探针检测了 mRNA 在激活24小时以后的变化,发现 T 细胞活化者均显示 mRNA 量呈上升;反之则不见变化或低于未激活 T 细胞对照组水平.本研究证明了小牛胸腺肽有激活 T 细胞和提高 mRNA 水平的作用,为首次报导.本文对上述在基因水平上观察的结果进行了讨论.     

含生长抑素mRNA神经元在移植视网膜发育中的表达

将６０例鼠龄１４ｄＳＤ大鼠视网膜移植到出生后１ｄ大鼠中脑偏左侧处，同时摘除新生鼠的右眼。术后１０ｄ至２２ｄ分别取移植视网膜及其中脑，在相应的年龄取正常视网膜作对照，应用原位杂交组化技术──地高辛标记的生长抑素的ｃＲＮＡ探针检测移植和正常视网膜中含生长抑素ｍＲＮＡ神经元出现时间、发育规律及定位分布。同时用免疫组化方法显示生长抑素免疫反应神经元的形态，以作对照和补充。原位杂交组化实验结果表明：在出生当天的移植视网膜节细胞层已出现阳性表达，出生后４ｄ，外核层也出现小的含生长抑素ｍＲＮＡ神经元，此种神经元随后减少、消失；与此同时内核层及节细胞层内含生长抑素ｍＲＮＡ神经元逐渐增多，至生后１２ｄ接近成年水平。通过对非移植大鼠视网膜进行正常对照观察，移植视网膜与非移植的正常视网膜生后发育的结果相似。生长抑素免疫反应神经元与原位杂交含生长抑素ｍＲＮＡ神经元的表达部位是一致的，但生长抑素免疫反应神经元可见其突起。