Meloni I, Parri V, De Filippis R, Ariani F, Artuso R, Bruttini M, Katzaki E, Longo I, Mari F, Bellan C, Dotti C G, Renieri A
Medical Genetics Unit, Department of Molecular Biology, University of Siena, Policlinico Le Scotte, Viale Bracci 2, 53100 Siena, Italy.
Neuroscience. 2009 Mar 17;159(2):657-69. doi: 10.1016/j.neuroscience.2008.11.056. Epub 2008 Dec 24.
ACSL4 is a gene involved in non-syndromic X-linked mental retardation. It encodes for a ubiquitous protein that adds coenzyme A to long-chain fatty acids, with a high substrate preference for arachidonic acid. It presents also a brain-specific isoform deriving from an alternative splicing and containing 41 additional N-terminal amino acids. To start to unravelling the link between ACSL4 and mental retardation, we have performed molecular and cell biological studies. By retro-transcription polymerase chain reaction analyses we identified a new transcript with a shorter 5'-UTR region. By immunofluorescence microscopy in embryonic rat hippocampal neurons we report that ACSL4 is associated preferentially to endoplasmic reticulum tubules. ACSL4 knockdown by siRNAs in hippocampal neurons indicated that this protein is largely dispensable for these cells' gross architectural features (i.e. axonal and dendritic formation and final length) yet it is required for the presence of normal spines. In fact, reduced levels of ACSL4 led to a significant reduction in dendritic spine density and an alteration in spine/filopodia distribution. The possible mechanisms behind this phenotype are discussed.
ACSL4是一种与非综合征性X连锁智力迟钝相关的基因。它编码一种普遍存在的蛋白质，该蛋白质将辅酶A添加到长链脂肪酸上，对花生四烯酸具有很高的底物偏好性。它还呈现出一种源自可变剪接的脑特异性同工型，含有另外41个N端氨基酸。为了开始揭示ACSL4与智力迟钝之间的联系，我们进行了分子和细胞生物学研究。通过逆转录聚合酶链反应分析，我们鉴定出一种具有较短5'-UTR区域的新转录本。通过在胚胎大鼠海马神经元中进行免疫荧光显微镜观察，我们报告ACSL4优先与内质网小管相关联。在海马神经元中通过小干扰RNA敲低ACSL4表明，这种蛋白质对于这些细胞的总体结构特征（即轴突和树突的形成以及最终长度）在很大程度上是可有可无的，但对于正常棘突的存在却是必需的。事实上，ACSL4水平的降低导致树突棘密度显著降低以及棘突/丝状伪足分布的改变。本文讨论了这种表型背后的可能机制。
