ABCC7 p.His667Asp
| Predicted by SNAP2: | A: D (63%), C: D (63%), D: D (75%), E: D (71%), F: D (66%), G: D (71%), I: D (66%), K: N (61%), L: N (53%), M: D (59%), N: D (63%), P: D (80%), Q: D (53%), R: N (93%), S: N (61%), T: D (63%), V: D (63%), W: D (75%), Y: D (63%), |
| Predicted by PROVEAN: | A: N, C: N, D: N, E: N, F: N, G: N, I: N, K: N, L: N, M: N, N: N, P: N, Q: N, R: N, S: N, T: N, V: N, W: N, Y: N, |
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[hide] Adrenoleukodystrophy: subcellular localization and... J Neurochem. 2007 Jun;101(6):1632-43. Takahashi N, Morita M, Maeda T, Harayama Y, Shimozawa N, Suzuki Y, Furuya H, Sato R, Kashiwayama Y, Imanaka T
Adrenoleukodystrophy: subcellular localization and degradation of adrenoleukodystrophy protein (ALDP/ABCD1) with naturally occurring missense mutations.
J Neurochem. 2007 Jun;101(6):1632-43., [PMID:17542813]
Abstract [show]
Mutation in the X-chromosomal adrenoleukodystrophy gene (ALD; ABCD1) leads to X-linked adrenoleukodystrophy (X-ALD), a severe neurodegenerative disorder. The encoded adrenoleukodystrophy protein (ALDP/ABCD1) is a half-size peroxisomal ATP-binding cassette protein of 745 amino acids in humans. In this study, we chose nine arbitrary mutant human ALDP forms (R104C, G116R, Y174C, S342P, Q544R, S606P, S606L, R617H, and H667D) with naturally occurring missense mutations and examined the intracellular behavior. When expressed in X-ALD fibroblasts lacking ALDP, the expression level of mutant His-ALDPs (S606L, R617H, and H667D) was lower than that of wild type and other mutant ALDPs. Furthermore, mutant ALDP-green fluorescence proteins (S606L and H667D) stably expressed in CHO cells were not detected due to rapid degradation. Interestingly, the wild type ALDP co-expressed in these cells also disappeared. In the case of X-ALD fibroblasts from an ALD patient (R617H), the mutant ALDP was not detected in the cells, but appeared upon incubation with a proteasome inhibitor. When CHO cells expressing mutant ALDP-green fluorescence protein (H667D) were cultured in the presence of a proteasome inhibitor, both the mutant and wild type ALDP reappeared. In addition, mutant His-ALDP (Y174C), which has a mutation between transmembrane domain 2 and 3, did not exhibit peroxisomal localization by immunofluorescense study. These results suggest that mutant ALDPs, which have a mutation in the COOH-terminal half of ALDP, including S606L, R617H, and H667D, were degraded by proteasomes after dimerization. Further, the region between transmembrane domain 2 and 3 is important for the targeting of ALDP to the peroxisome.
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No. Sentence Comment
218 R617H and H667D are located in the Walker B region and in the COOH-terminal region, respectively (Fig. 1).
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ABCC7 p.His667Asp 17542813:218:10
status: NEW220 First, we found for the first time that mutant ALDPs (R617H and H667D) were degraded by proteasomes based on the following evidence: (i) The expression levels of these mutant His-ALDPs were relatively low in X-ALD fibroblasts in terms of transient expression (Figs 3b and c, and Table 2).
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ABCC7 p.His667Asp 17542813:220:64
status: NEW222 (iii) ALDP-GFP (H667D) in the CHO cells and endogenous ALDP (R617H) in X-ALD fibroblasts were detectable by immunoblotting after treatment with lactacystin or MG132 (Figs 5a and 7).
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ABCC7 p.His667Asp 17542813:222:16
status: NEW224 We tried to detect ubiqutination of the mutant ALDP (H667D) in the presence of a proteasome inhibitor, but no polyubiqitinated forms of the mutant ALDP were detected in the present study.
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ABCC7 p.His667Asp 17542813:224:53
status: NEW226 In addition, interestingly, we found that wild type ALDP disappeared in CHO cells expressing mutant ALDP-GFP (H667D), but reappeared with mutant ALDP-GFP by the treatment with a proteasome inhibitor.
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ABCC7 p.His667Asp 17542813:226:110
status: NEW228 In fact, mutant ALDP-GFP (H667D) was found to be located in peroxisomes with treatment by a proteasome inhibitor (Fig. 6).
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ABCC7 p.His667Asp 17542813:228:26
status: NEW229 Recently Lie et al. investigated the dimerization of the COOH-terminal half of ALDP by a yeast two-hybrid assay and found that it could dimerize Table 2 Expression and localization of missense ALDPs Mutant ALDP Transient Stable Expressiona Localizationb b-Oxidationc Expressiona Localizationb Wild +++ Px + ++ Px R104Cd , G116R, S342P, Q544R, S606P +++ Px ) ++ Px Y174C +++ mis ) + mis S606L ++ Px ) ) ) R617H, H667D + ) ) ) ) Wild and mutant His-ALDPs or ALDP-GFPs were transiently expressed in X-ALD fibroblasts or stably expressed in CHO cells, respectively.
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ABCC7 p.His667Asp 17542813:229:411
status: NEW239 Therefore, mutant ALDP (R617H and H667D) might be misfolded on the peroxisomal membranes and unable to interact correctly with each other or with wild type ALDP and are recruited to proteasomes for degradation.
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ABCC7 p.His667Asp 17542813:239:34
status: NEW244 In Fig. 4, the wild type ALDP would dimerize each other or with endogenous ALDP and could be stabilized, but such complex could not be detected on sucrose gradient of CHO cells expressing mutant ALDP (S606L and H667D).
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ABCC7 p.His667Asp 17542813:244:211
status: NEW257 Although we did not show any effects of E-64d on the mutant ALDP (R617H and H667D) stability, the possibility cannot be ruled out that other proteases are also involved in the degradation of some of the mutant ALDPs.
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ABCC7 p.His667Asp 17542813:257:76
status: NEW271 In this study, we found that mutant ALDP (S606L, R617H, and H667D) was degraded by proteasomes together with wild type ALDP.
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ABCC7 p.His667Asp 17542813:271:60
status: NEW273 In the presence of proteasome inhibitors, H667D became to localize in peroxisomes (Fig. 6).
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ABCC7 p.His667Asp 17542813:273:42
status: NEW[hide] [Adrenoleukodystrophy: structure and function of A... Yakugaku Zasshi. 2007 Jan;127(1):163-72. Takahashi N, Morita M, Imanaka T
[Adrenoleukodystrophy: structure and function of ALDP, and intracellular behavior of mutant ALDP with naturally occurring missense mutations].
Yakugaku Zasshi. 2007 Jan;127(1):163-72., [PMID:17202797]
Abstract [show]
Adrenoleukodystrophy (ALD) is an inherited disorder characterized by progressive demyelination of the central nervous system and adrenal dysfunction. The biochemical characterization is based on the accumulation of pathgnomonic amounts of saturated very long-chain fatty acid (VLCFA; C>22) in all tissues, including the brain white matter, adrenal glands, and skin fibroblasts, of the patients. The accumulation of VLCFA in ALD is linked to a mutation in the ALD (ABCD1) gene, an ABC subfamily D member. The ALD gene product, so-called ALDP (ABCD1), is thought to be involved in the transport of VLCFA or VLCFA-CoA into the peroxisomes. ALDP is a half-sized peroxisomal ABC protein and it has 745 amino acids in humans. ALDP is thought to be synthesized on free polysomes, posttranslationally transported to peroxisomes, and inserted into the membranes. During this process, ALDP interacts with Pex19p, a chaperone-like protein for intracellular trafficking of peroxisomal membrane protein (PMP), the complex targets Pex3p on the peroxisomal membranes, and ALDP is inserted into the membranes. After integration into the membranes, ALDP is thought to form mainly homodimers. Here, we chose nine arbitrary mutations of human ALDP with naturally occurring missense mutations and examined the intracellular behavior of their ALDPs. We found that mutant ALDP (S606L, R617H, and H667D) was degraded together with wild-type ALDP by proteasomes. These results suggest that the complex of mutant and wild-type ALDP is recognized as misfolded proteins and degraded by the protein quality control system associated with proteasomes. Further, we found fragmentation of mutant ALDP (R104C) on peroxisomes and it was not inhibited by proteasomes inhibitors, suggesting that an additional protease(s) is also involved in the quality control of mutant ALDP. In addition, mutation of ALDP (Y174C) suggests that a loop between transmembrane domains 2 and 3 is important for the targeting of ALDP to peroxisomes.
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No. Sentence Comment
49 変異型 ALDP の分解過程の解析 新生タンパク質が正しいフォールディングを受け ることは,そのタンパク質の正常な機能発現のため に必須である．遺伝子変異などが存在すると,タン パク質がミスフォールディングされる．このミスフ ォールドタンパクが細胞外へ分泌されたり,細胞内 に蓄積したりすると生体にとって極めて有害になる ため,このようなタンパクはプロテアソーム,リソ ソーム等によって迅速に分解される．ちなみに,嚢 胞性線維症の原因タンパク質 CFTR は細胞膜イオ ンチャネルとして機能する ABC タンパク質である が,変異 CFTR は小胞体膜からプロテアソームに リクルートされ分解されることが報告されてい る．32,33) しかしながら,変異型 ALDP を始めとし て,ペルオキシソーム膜タンパク質についての解析 はほとんど行われていない． 変異型 ALDP の一過性発現と安定過剰発現実験 より,ALDP(S606L, R617H, H667D, R104C)は, プロテアーゼにより分解されていると推定された． そこで,ALDP-GFP(H667D)を発現している CHO 細胞に各種プロテアーゼ阻害剤を処理し,解 析を行った．その結果,プロテアソーム阻害剤であ る lactacystin を処理した細胞では ALDP-GFP 及び ALDP の バ ン ド が 出 現 し た ( Fig. 4 )． 一 方 , leupeptin, AEBSF, E64d には効果がなかった．ま た他のプロテアソーム阻害剤である MG132 も有効 であった．さらにプロテアソーム阻害剤により分解 を逃れた変異型 ALDP-GFP(H667D)の細胞内局 在を蛍光抗体法で観察すると,ペルオキシソームに 局在していることが確認された．一方,変異型 ALDP(R104C)のフラグメント化は上記プロテアー ゼ処理では阻害されなかった． さらに ALD 患者由来細胞の内因性変異 ALDP の分解とプロテアソーム分解系の関与について確認 するため,変異型 ALDP(R617H)を持つ患者由 来線維芽細胞を用いてタンパク分解の阻害実験を行 った．その結果,lactacystin と MG132 処理により, ALDP のバンドが出現した．以上の結果より,ペ ルオキシソーム膜上にはミスフォールドしたタンパ ク質を認識する仕組みが存在し,プロテアソーム及 び他のプロテアーゼを介して排除していることが示 唆された． 一方,山田らは ALD 患者線維芽細胞を［35 S］メチ オニンでパルスチェイスすることにより,変異型 ALDP(G512S, R660W)の分解が E-64 と leupepu- tin により抑制されることを報告している．34) 彼ら の実験ではプロテアソーム阻害剤については実験し ていないので,プロテアソームの関与は不明である が,変異型 ALDP の分解には,複数のプロテアー ゼが関与している可能性がある． 7.
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ABCC7 p.His667Asp 17202797:49:2784
status: NEWX
ABCC7 p.His667Asp 17202797:49:3026
status: NEW