Localization of wild-type and mutant neuronal ceroid lipofuscinosis CLN8 proteins in non-neuronal and neuronal cells
Localization of wild-type and mutant neuronal ceroid lipofuscinosis CLN8 proteins in non-neuronal and neuronal cells
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DOI：
10.1002/jnr.20133
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发表时间：
2004-06-15
影响因子：
4.2
通讯作者：
Jalanko, A
中科院分区：
文献类型：
--
作者：
Lonka, L;Salonen, T;Jalanko, A
神经性ceroid lipofuscinosis （NCLs）是一组儿童期发病的神经退行性疾病，其特征是在许多组织中，特别是在神经元中积累自身荧光脂色素。CLN8基因突变是北方癫痫（进行性癫痫伴智力迟钝[EPMR]， OMIM 600143）和土耳其变体晚期婴儿NCL的一个亚群的基础，但其发病机制仍不明确。CLN8跨膜蛋白是一种内质网（ER）驻留蛋白，在非神经元细胞内质网和ER-高尔基中间室（ERGIC）之间循环。为了探索疾病机制，我们表征了野生型CLN8蛋白的神经元定位以及代表患者突变的CLN8蛋白。Semliki Forest病毒介导的CLN8蛋白定位于小鼠海马原代神经元内质网与亚细胞标记物的免疫荧光分析我们还分析了CLN8可能的极化靶向，并在极化上皮CaCo-2细胞中观察到基底外侧靶向，这表明CLN8可能位于内质网外或内质网的一个特殊亚室中。然而，我们无法证明CLN8在神经元轴突和树突之间的差异分布。小鼠脑组织的分离表明，内源性小鼠Cln8存在于轻膜组分中，与内质网不同，这进一步表明Cln8在极化细胞中的定位存在差异。疾病突变不影响CLN8在非神经元细胞或神经元细胞中的细胞内定位。因此，在蛋白定位水平上没有明显的基因型-表型相关性，因此；突变很可能直接影响CLN8的重要功能域。(C) 2004 Wiley-Liss, Inc。
Neuronal ceroid lipofuscinoses (NCLs) are a group of childhood-onset neurodegenerative disorders characterized by accumulation of autofluorescent lipopigment in many tissues, especially in neurons. Mutations in the CLN8 gene underlie Northern epilepsy (progressive epilepsy with mental retardation [EPMR], OMIM 600143) and a subset of Turkish variant late infantile NCL, but the pathogenetic mechanisms have remained elusive. The CLN8 transmembrane protein is an endoplasmic reticulum (ER) resident protein that recycles between ER and ER-Golgi intermediate compartment (ERGIC) in nonneuronal cells. To explore the disease mechanisms, we have characterized the neuronal localization of wild-type CLN8 protein as well as CLN8 proteins representing patient mutations. Semliki Forest virus-mediated CLN8 protein localized in the ER of mouse hippocampal primary neurons when compared to subcellular markers by immunofluorescence analysis. We also analyzed the possible polarized targeting of CLN8 and observed basolateral targeting in polarized epithelial CaCo-2 cells, suggesting that CLN8 may locate outside the ER or in a specialized subcompartment of the ER. We were not able, however, to demonstrate differential distribution of CLN8 between axons and dendrites of neurons. Fractionation of mouse brain tissue indicated that endogenous mouse Cln8 is observed in light membrane fractions, different from ER, which further suggested differential localization for CLN8 in polarized cells. The disease mutations did not affect intracellular localization of CLN8 in non-neuronal or neuronal cells. Consequently, there is no obvious genotype-phenotype correlation at the level of protein localization and thus; mutations most likely directly affect functionally important domains of CLN8. (C) 2004 Wiley-Liss, Inc.