cDNA Cloning and mRNA Expression of the Human Adrenoleukodystrophy Related Protein (ALDRP), a Peroxisomal ABC Transporter

doi:10.1006/bbrc.1997.7391

Biochemical and Biophysical Research Communications

Volume 239, Issue 1, 9 October 1997, Pages 261-264

https://doi.org/10.1006/bbrc.1997.7391 Get rights and content

Abstract

We have cloned the cDNA containing the complete coding region of the human adrenoleukodystrophy related (ALDR) gene. The 2220-bp open reading frame encodes a 740-amino-acid polypeptide with a predicted molecular weight of 83.3 kDa. The human ALDR protein displays high similarity (62.8% identical amino acid residues) to the human adrenoleukodystrophy (ALD) gene. Analysis of ALDR expression revealed the presence of ALDR mRNA in a variety of human tissues, predominantly in brain and heart. This expression pattern is different from all other known peroxisomal ABC-transporters. Defects in the ALD gene are the primary cause of adrenoleukodystrophy, a demyelinating disorder of the central nervous system. The ALD protein (ALDP) and the ALDR gene product are peroxisomal membrane proteins belonging to the superfamily of transporters containing an ATP-binding cassette (ABC-transporters). All known peroxisomal ABC-transporters represent only one-half of a functional transporter. They are expected to form dimers either as a homodimer or as a heterodimer. ALDRP is a potential dimerization partner of ALDP or other peroxisomal ABC-transporters. The ALDR gene is a candidate for a modifier gene, accounting for the strikingly varying clinical courses of ALD observed even within a family.

References (0)

Cited by (77)

Genome-wide CRISPR-Cas9 screening identifies the CYTH2 host gene as a potential therapeutic target of influenza viral infection
2022, Cell Reports
Citation Excerpt :
A low input of NP viral RNA (vRNA) levels were determinate by qRT-PCR (Figure S1G), and these results were further supported by IFA in Figure S1H. CYTH2 (also known as ARNO) is a guanine nucleotide exchange factor (GEF) that replaces ARF1-, ARF3-, and ARF6-guanosine diphosphate (GDP) with guanosine triphosphate (GTP) and is involved in vesicular transport (Chardin et al., 1996; Frank et al., 1998). ABCD2 is a member of the ATP-binding cassette transporter superfamily and is involved in peroxisomal transport (Holzinger et al., 1997). These results suggest that CYTH2 and ABCD2 may function in virus internalization and transportation in the cytoplasm.
Host genes critical for viral infection are effective antiviral drug targets with tremendous potential due to their universal characteristics against different subtypes of viruses and minimization of drug resistance. Accordingly, we execute a genome-wide CRISPR-Cas9 screen with multiple rounds of survival selection. Enriched in this screen are several genes critical for host sialic acid biosynthesis and transportation, including the cytohesin 2 (CYTH2), tetratricopeptide repeat protein 24 (TTC24), and N-acetylneuraminate synthase (NANS), which we confirm are responsible for efficient influenza viral infection. Moreover, we reveal that CYTH2 is required for the early stage of influenza virus infection by mediating endosomal trafficking. Furthermore, CYTH2 antagonist SecinH3 blunts influenza virus infection in vivo. In summary, these data suggest that CYTH2 is an attractive target for developing host-directed antiviral drugs and therapeutics against influenza virus infection.
LXR antagonists induce ABCD2 expression
2014, Biochimica et Biophysica Acta - Molecular and Cell Biology of Lipids
Citation Excerpt :
ABCD1 encodes for a peroxisomal half ABC transporter, which is responsible for the entry of very-long-chain fatty acyl-CoA into the peroxisome, the unique site of their β-oxidation [4]. Two homologous peroxisomal ABC transporters, ABCD2 [5,6] and ABCD3 [7], have been proven to compensate for ABCD1 deficiency when overexpressed in X-ALD fibroblasts [8–11]. Functional redundancy is also recognized in vivo since reversion of the adrenomyeloneuropathy-like phenotype has been observed in Abcd1 null mice overexpressing Abcd2 in a ubiquitous manner [12].
X-linked adrenoleukodystrophy (X-ALD) is a rare neurodegenerative disorder characterized by the accumulation of very-long-chain fatty acids resulting from a β-oxidation defect. Oxidative stress and inflammation are also key components of the pathogenesis. X-ALD is caused by mutations in the ABCD1 gene, which encodes for a peroxisomal half ABC transporter predicted to participate in the entry of VLCFA-CoA into the peroxisome, the unique site of their β-oxidation. Two homologous peroxisomal ABC transporters, ABCD2 and ABCD3 have been proven to compensate for ABCD1 deficiency when overexpressed. Pharmacological induction of these target genes could therefore represent an alternative therapy for X-ALD patients. Since LXR activation was shown to repress ABCD2 expression, we investigated the effects of LXR antagonists in different cell lines. Cells were treated with GSK(17) (a LXR antagonist recently discovered from the GlaxoSmithKline compound collection), 22(S)-hydroxycholesterol (22S-HC, another LXR antagonist) and 22R-HC (an endogenous LXR agonist). We observed up-regulation of ABCD2, ABCD3 and CTNNB1 (the gene encoding for β-catenin, which was recently demonstrated to induce ABCD2 expression) in human HepG2 hepatoma cells and in X-ALD skin fibroblasts treated with LXR antagonists. Interestingly, induction in X-ALD fibroblasts was concomitant with a decrease in oxidative stress. Rats treated with 22S-HC showed hepatic induction of the 3 genes of interest. In human, we show by multiple tissue expression array that expression of ABCD2 appears to be inversely correlated with NR1H3 (LXRα) expression. Altogether, antagonists of LXR that are currently developed in the context of dyslipidemia may find another indication with X-ALD.
Pathophysiology of X-linked adrenoleukodystrophy
2014, Biochimie
Citation Excerpt :
In fibroblasts, the peroxisomal import and degradation of C26:0-CoA could be blocked using anti-ABCD1 antibodies [15]. In addition to ABCD1, two other ABC transporters, ABCD2 and ABCD3, are localized in the peroxisomal membrane [16–18]. The functional unit of the ABCD1 transporter is a dimer; in vivo, in the peroxisomal membrane, apparently predominantly homodimers are formed, although also heterodimers with ABCD2 or ABCD3, the other two peroxisomal members of the ABCD family are possible [19].
Currently the molecular basis for the clinical heterogeneity of X-linked adrenoleukodystrophy (X-ALD) is poorly understood. The genetic bases for all different phenotypic variants of X-ALD are mutations in the gene encoding the peroxisomal ATP-binding cassette (ABC) transporter, ABCD1 (formerly adrenoleukodystrophy protein, ALDP). ABCD1 transports CoA-activated very long-chain fatty acids from the cytosol into the peroxisome for degradation. The phenotypic variability is remarkable ranging from cerebral inflammatory demyelination of childhood onset, leading to death within a few years, to adults remaining pre-symptomatic through more than five decades. There is no general genotype–phenotype correlation in X-ALD. The default manifestation of mutations in ABCD1 is adrenomyeloneuropathy, a slowly progressive dying-back axonopathy affecting both ascending and descending spinal cord tracts as well as in some cases, a peripheral neuropathy. In about 60% of male X-ALD patients, either in childhood (35–40%) or in adulthood (20%), an initial, clinically silent, myelin destabilization results in conversion to a devastating, rapidly progressive form of cerebral inflammatory demyelination. Here, ABCD1 remains a susceptibility gene, necessary but not sufficient for inflammatory demyelination to occur. Although the accumulation of very long-chain fatty acids appears to be essential for the pathomechanism of all phenotypes, the molecular mechanisms underlying these phenotypes are fundamentally different. Cell autonomous processes such as oxidative stress and energy shortage in axons as well as non-cell autonomous processes involving axon–glial interactions seem pertinent to the dying-back axonopathy. Various dynamic mechanisms may underlie the initiation of inflammation, the altered immune reactivity, the propagation of inflammation, as well as the mechanisms leading to the arrest of inflammation after hematopoietic stem cell transplantation. An improved understanding of the molecular mechanisms involved in these events is required for the development of urgently needed therapeutics.
Impaired very long-chain acyl-CoA β-oxidation in human X-linked adrenoleukodystrophy fibroblasts is a direct consequence of ABCD1 transporter dysfunction
2013, Journal of Biological Chemistry
X-linked adrenoleukodystrophy (X-ALD), an inherited peroxisomal disorder, is caused by mutations in the ABCD1 gene encoding the peroxisomal ATP-binding cassette (ABC) transporter ABCD1 (adrenoleukodystrophy protein, ALDP). Biochemically, X-ALD is characterized by an accumulation of very long-chain fatty acids and partially impaired peroxisomal β-oxidation. In this study, we used primary human fibroblasts from X-ALD and Zellweger syndrome patients to investigate the peroxisomal β-oxidation defect. Our results show that the degradation of C26:0-CoA esters is as severely impaired as degradation of unesterified very long-chain fatty acids in X-ALD and is abolished in Zellweger syndrome. Interestingly, the β-oxidation rates for both C26:0-CoA and C22:0-CoA were similarly affected, although C22:0 does not accumulate in patient fibroblasts. Furthermore, we show that the β-oxidation defect in X-ALD is directly caused by ABCD1 dysfunction as blocking ABCD1 function with a specific antibody reduced β-oxidation to levels observed in X-ALD fibroblasts. By quantification of mRNA and protein levels of the peroxisomal ABC transporters and by blocking with specific antibodies, we found that residual β-oxidation activity toward C26:0-CoA in X-ALD fibroblasts is mediated by ABCD3, although the efficacy of ABCD3 appeared to be much lower than that of ABCD1. Finally, using isolated peroxisomes, we show that β-oxidation of C26:0-CoA is independent of additional CoA but requires a cytosolic factor of >10-kDa molecular mass that is resistant to N-ethylmaleimide and heat inactivation. In conclusion, our findings in human cells suggest that, in contrast to yeast cells, very long-chain acyl-CoA esters are transported into peroxisomes by ABCD1 independently of additional synthetase activity.
Background: ABCD1 is a peroxisomal ABC transporter whose dysfunction causes X-linked adrenoleukodystrophy (X-ALD).
Results: β-Oxidation of C26:0 and C22:0 acyl-CoA esters is impaired in X-ALD. ABCD3 accounts for residual β-oxidation activity in X-ALD fibroblasts.
Conclusion: ABCD1 mediates very long-chain acyl-CoA ester β-oxidation without need for additional re-esterification by an acyl-CoA synthetase.
Significance: Our study provides proof of deficient acyl-CoA ester β-oxidation in X-ALD.
Peroxisomal ABC transporters: Structure, function and role in disease
2012, Biochimica et Biophysica Acta - Molecular Basis of Disease
ATP-binding cassette (ABC) transporters belong to one of the largest families of membrane proteins, and are present in almost all living organisms from eubacteria to mammals. They exist on plasma membranes and intracellular compartments such as the mitochondria, peroxisomes, endoplasmic reticulum, Golgi apparatus and lysosomes, and mediate the active transport of a wide variety of substrates in a variety of different cellular processes. These include the transport of amino acids, polysaccharides, peptides, lipids and xenobiotics, including drugs and toxins. Three ABC transporters belonging to subfamily D have been identified in mammalian peroxisomes. The ABC transporters are half-size and assemble mostly as a homodimer after posttranslational transport to peroxisomal membranes. ABCD1/ALDP and ABCD2/ALDRP are suggested to be involved in the transport of very long chain acyl-CoA with differences in substrate specificity, and ABCD3/PMP70 is involved in the transport of long and branched chain acyl-CoA. ABCD1 is known to be responsible for X-linked adrenoleukodystrophy (X-ALD), an inborn error of peroxisomal β-oxidation of very long chain fatty acids. Here, we summarize recent advances and important points in our advancing understanding of how these ABC transporters target and assemble to peroxisomal membranes and perform their functions in physiological and pathological processes, including the neurodegenerative disease, X-ALD. This article is part of a Special Issue entitled: Metabolic Functions and Biogenesis of Peroxisomes in Health and Disease.
The absence of ABCD2 sensitizes mice to disruptions in lipid metabolism by dietary erucic acid
2012, Journal of Lipid Research
ABCD2 (D2) is a peroxisomal transporter that is highly abundant in adipose tissue and promotes the oxidation of long-chain MUFA. Erucic acid (EA, 22:1ω9) reduces very long chain saturated fatty acids in patients with X-linked adrenoleukodystrophy but promotes dyslipidemia and dilated cardiomyopathy in rats. To determine the role of D2 in the metabolism of EA, we challenged wild-type and D2 deficient mice (D2 KO) with an enriched EA diet. In D2 KO mice, dietary EA resulted in the rapid expansion of adipose tissue, adipocyte hypertrophy, hepatic steatosis, and the loss of glycemic control. However, D2 had no impact on the development of obesity phenotypes in two models of diet-induced obesity. Although there was a significant increase in EA in liver of D2 KO mice, it constituted less than 2% of all fatty acids. Metabolites of EA (20:1, 18:1, and 16:1) were elevated, particularly 18:1, which accounted for 50% of all fatty acids. These data indicate that the failure to metabolize EA in adipose results in hepatic metabolism of EA, disruption of the fatty acid profile, and the development of obesity and reveal an essential role for D2 in the protection from dietary EA.

View all citing articles on Scopus

^☆: Sequence data from this article have been deposited with the EMBL/NCBI–Genbank Data Libraries under Accession No. AJ000327.

²: To whom correspondence should be addressed. Fax: (49) 89 5160 4192. E-mail: [email protected].

View full text

Regular ArticlecDNA Cloning and mRNA Expression of the Human Adrenoleukodystrophy Related Protein (ALDRP), a Peroxisomal ABC Transporter☆

Abstract

Regular Article
cDNA Cloning and mRNA Expression of the Human Adrenoleukodystrophy Related Protein (ALDRP), a Peroxisomal ABC Transporter☆