Yamada T, Taniwaki T, Shinnoh N, Uchiyama A, Shimozawa N, Ohyagi Y, Asahara H, Kira J
Department of Neurology, Neurological Institute, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Neurology. 1999 Feb;52(3):614-6. doi: 10.1212/wnl.52.3.614.
To clarify the function of adrenoleukodystrophy protein (ALDP) using our ALDP-deficient mice established by gene targeting.
X-linked adrenoleukodystrophy (ALD) is characterized biochemically by the accumulation of very long-chain fatty acids (VLCFA) in tissues and body fluids, and is caused by impairment of peroxisomal beta-oxidation. In ALD, very long-chain acyl-coenzyme A synthetase (VLACS), which is necessary for peroxisomal beta-oxidation, does not function.
The ALDP-deficient mice and C57BL/6J mice were used. VLACS or ALDP were transiently expressed by lipofection in murine fibroblasts, and VLCFA beta-oxidation was assayed. Liver peroxisomes were purified by sequential centrifugations and a Nycodenz gradient centrifugation. The peroxisomal localization of VLACS was compared between the mutant and control mice using a Western blot analysis.
Impairment of VLCFA beta-oxidation in ALDP-deficient fibroblasts was not corrected by the additional expression of VLACS alone but was by the coexpression of VLACS and ALDP. Although the tissue-specific expression of VLACS was similar in ALDP-deficient and normal mice, peroxisomal VLACS was clearly lower in ALDP-deficient than in normal mice.
ALDP plays a role in the peroxisomal localization of VLACS, and VLACS does not function unless localized in the peroxisome.
利用我们通过基因靶向建立的肾上腺脑白质营养不良蛋白（ALDP）缺陷小鼠来阐明ALDP的功能。
X连锁肾上腺脑白质营养不良（ALD）在生化上的特征是组织和体液中极长链脂肪酸（VLCFA）的积累，其由过氧化物酶体β氧化受损引起。在ALD中，过氧化物酶体β氧化所必需的极长链酰基辅酶A合成酶（VLACS）不起作用。
使用ALDP缺陷小鼠和C57BL/6J小鼠。通过脂质体转染在鼠成纤维细胞中瞬时表达VLACS或ALDP，并测定VLCFAβ氧化。通过连续离心和Nycodenz梯度离心纯化肝脏过氧化物酶体。使用蛋白质免疫印迹分析比较突变小鼠和对照小鼠中VLACS的过氧化物酶体定位。
在ALDP缺陷的成纤维细胞中，VLCFAβ氧化的损伤不能仅通过额外表达VLACS来纠正，而是通过VLACS和ALDP的共表达来纠正。尽管VLACS在ALDP缺陷小鼠和正常小鼠中的组织特异性表达相似，但ALDP缺陷小鼠中的过氧化物酶体VLACS明显低于正常小鼠。
ALDP在VLACS的过氧化物酶体定位中起作用，并且VLACS除非定位于过氧化物酶体中否则不起作用。
