蛋白-蛋白相互作用调节多巴胺受体D3的功能(英文)

Gαi/o蛋白偶联的多巴胺受体D3在包括付隔核的边缘系统中丰富表达。其不仅能调节边缘系统功能,而且在神经精神疾病和神经退行性病变过程中起重要作用。D3受体的胞内结构,尤其是第三个细胞内环和C末端,可以和多个靠近细胞内膜的蛋白相互结合,以此来调控受体的膜表面表达及其功效。最近的研究发现,D3受体和蛋白激酶能够以此模型相互结合。突触富集的钙/钙调蛋白依赖的蛋白激酶II(CaMKII)直接与D3受体第三个细胞内环的N末端结合。这种结合是钙离子依赖的,并被CaMKII激酶的自我磷酸化所加强。在大鼠的付隔核神经元中,钙离子水平的升高能诱导CaMKII与D3结合,并磷酸化D3受体上特定的丝氨酸位点。CaMKII介导的受体磷酸化能抑制受体的功能,进而调节动物对可卡因兴奋剂的行为学反应。这些结果揭示了G蛋白偶联受体与CaMKII作用的一种新模式。蛋白间动态的结合使得D3受体的膜表达丰度、衰减周期和功能受到多种信号和酶蛋白的调节。     

Modulation of M4 muscarinic acetylcholine receptors by interacting proteins

Protein-protein interactions represent an important mechanism for posttranslational modifications of protein expression and function. In brain cells, surface-expressed and membrane-bound neurotransmitter receptors are common proteins that undergo dynamic protein-protein interactions between their intracellular domains and submembranous regulatory proteins. Recently, the Gα_i/o-coupled muscarinic M4 receptor (M4R) has been revealed to be one of these receptors. Through direct interaction with the intracellular loops or C-terminal tails of M4Rs, M4R interacting proteins (M4RIPs) vigorously regulate the efficacy of M4R signaling. A synapse-enriched protein kinase, Ca²⁺/calmodulin-dependent protein kinase II (CaMKII), exemplifies a prototype model of M4RIPs, and is capable of binding to the second intracellular loop of M4Rs. Through an activity- and phosphorylation-dependent mechanism, CaMKII potentiates the M4R/Gα_i/o-mediated inhibition of M4R efficacy in inhibiting adenylyl cyclase and cAMP production. In striatal neurons where M4Rs are most abundantly expressed, M4RIPs dynamically control M4R activity to maintain a proper cholinergic tone in these neurons. This is critical for maintaining the acetylcholine-dopamine balance in the basal ganglia, which determines the behavioral responsiveness to dopamine stimulation by psychostimulants.     

过氧化物酶体增殖激活性受体γ(PPARγ)在肝癌组织中的差异性表达

目的检测过氧化物酶体增殖激活性受体γ(PPARγ)在肝癌组织中有无差异性表达且有无突变.方法用半定量RT-PCR,Western blot,FISH,PCR-SSCP等方法进行鉴定.结果用半定量RT-PCR检测,有8/14为癌中高表达;Western blot方法检测,9/15为癌中高表达.免疫组化显示PPARγ在所有的癌旁组织中定位于细胞浆中;而在5个癌组织中定位于细胞核中;突变热点PPARγ外显子3和5在34对肝癌标本中没有突变.结论过氧化物酶体增殖激活性受体γ在肝癌组织中有差异性表达并且在肝癌标本中没有突变.提示PPARγ可能与肝癌的发展有一定的相关性.     

染色体17p13.3肿瘤杂合性缺失区域内外显子的分离

目的 在染色体１７ｐ１３．３杂合性缺失区域内进行表达的分离。方法 采用外显子搏获法对位于１７ｐ１３．３杂合性缺失区域内的ＢＡＣ基因组克隆进行外显子的分离。结果 在获得的克隆中,４个克隆为已知基因的外显子,另４个史隆属于３个上显子（２个克隆中的外显子片段序列一致）。结论 在染色体１７ｐ１３．３杂合性缺失区域内获得了一些表达序列。