Poly-L-Lysine/Hyaluronan Nanocarriers As a Novel Nanosystem for Gene Delivery

The present research comes up with a novel DNA-loaded poly-l-lysine (PLL) / hyaluronan (HA) nanocarrier (DNA-loaded PLL/HA NCs) for gene delivery applications, as a promising candidate for gene delivery into diverse cells. A straightforward approach was employed to prepare such a nanosystem through masking DNA-loaded PLL molecules by HA. Fourier-transform infrared (FTIR) spectroscopy, dynamic light scattering (DLS), field emission-scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) were used to analyze the interaction of the molecules as well as the physicochemical properties of the NCs. The NCs showed a negative charge of -24 ± 3 mV, with an average size of 138 ± 6 nm, in a ellipsoid-shape with smooth surfaces. The DNA loading efficiency (LE) measured by DNA absorbance was around 95 %. The MTT assay showed that the developed NCs are non-toxic to the cells. Furthermore,the uptake of the DNA-loaded PLL/HA NCs by the human embryonic kidney (HEK)-293T cells was evaluated by a flow cytometry method, and demonstrated high potential cellular uptake over 90% for transferring the gene to HEK-293T cells at the optimized conditions. Therefore, the DNA-loaded PLL/HA NCs are the potent strategy for developing nanosystems for gene delivery applications. This article is protected by copyright. All rights reserved.

Investigations of metastable Ca2IrO4 epitaxial thin-films: systematic comparison with Sr2IrO4 and Ba2IrO4

We have synthesized thermodynamically metastable Ca2IrO4 thin-films on YAlO3 (110) substrates by pulsed laser deposition. The epitaxial Ca2IrO4 thin-films are of K2NiF4-type tetragonal structure. Transport and optical spectroscopy measurements indicate that the electronic structure of the Ca2IrO4 thin-films is similar to that of Jeff = 1/2 spin-orbit-coupled Mott insulator Sr2IrO4 and Ba2IrO4, with the exception of an increased gap energy. The gap increase is to be expected in Ca2IrO4 due to its increased octahedral rotation and tilting, which results in enhanced electron-correlation, U/W. Our results suggest that the epitaxial stabilization growth of metastable-phase thin-films can be used effectively for investigating layered iridates and various complex-oxide systems.

Anti-factor XIII A subunit (FXIII-A) autoantibodies block FXIII-A2 B2 assembly and steal FXIII-A from native FXIII-A2 B2

BACKGROUND

Autoimmune hemophilia-like disease (hemorrha-philia or hemorrhagic disorder) caused by anti-factor XIII antibodies (termed AH13) or 'autoimmune FXIII deficiency' is a life-threatening bleeding disorder. AH13 was thought to be rare worldwide.

OBJECTIVES

Because the number of diagnosed AH13 cases has recently been increasing, at least in Japan, we conducted a nationwide survey supported by the Japanese Ministry of Health, Labor, and Welfare, and explored the pathologic mechanism(s) of AH13.

METHODS

We diagnosed AH13 cases during the last 11 years according to the presence of anti-FXIII autoantibodies confirmed by a dot blot assay and ELISA, and characterized 33 of these both immunologically and biochemically.

RESULTS

The AH13 cases were immunologically classified into three types, Aa, Ab, and B. Type Aa autoantibodies, observed in 27 cases, were directed against the native FXIII A subunit (FXIII-A), and blocked FXIII activation. The autoantibodies not only prevented assembly of new FXIII-A2 B2 heterotetramers, but also removed FXIII-A from native FXIII-A2 B2 heterotetramers by forming an FXIII-A-IgG complex. Type Ab autoantibodies, detected in three cases, preferentially bound to activated FXIII-A and inhibited its activity. Type Aa and Ab autoantibodies were 'neutralizing' FXIII antibodies (or FXIII inhibitors), and thus could be screened with functional assays. Type B antibodies, detected in two cases, were non-neutralizing anti-FXIII B subunit (FXIII-B) autoantibodies that possibly accelerated the clearance of FXIII, and thus could be diagnosed exclusively with immunologic methods.

CONCLUSION

There are three major types of anti-FXIII autoantibody, with distinct targets and mechanisms that cause AH13.

Synthesis and antinociception activity of new substituted phenothiazines and ethylenediamines as antihistaminic drugs

Antihistamines play an important role in medicine when it comes to relieving seasonal or non-seasonal rhinitis, the common cold, and itching. They have also shown many various combinations of pharmacological properties such as anti-inflammatory and analgesic activities. Phenothiazines and ethylenediamines are 2 important classes of antihistamines with analgesic activities in addition to other pharmacological effects. In this study, some new derivatives of these compounds (V-IX) were synthesized and their antinociceptive behaviors were examined by pharmacological tests. The results indicated that new analogue with methyl groups produced a better analgesic activity than chlorine atoms but less than III (without any substitutions) in ethylenediamine class. Also in phenothiazine class, adding pyrimidine and pyridine substituted showed the better analgesic activity compared to other groups. Moreover, the analgesic activities proved that dimethylamine is the best group in amino alkyl side chain of these molecules relative to the substituted piperazines in new analogues.

Effects of organic and inorganic selenium supplementation during late pregnancy on colostrum and serum Se status, performance and passive immunity in Merghoz goats

This study was conducted to determine the effects of organic and inorganic selenium (Se) supplementation during late pregnancy on serum Se status, colostrum, performance and passive immunity in Merghoz goats in Iran. Thirty Merghoz goats (30 ± 3 kg) were given the same basal diet containing 0.11 mg Se/kg DM and were randomly allocated to one of three dietary treatments in a randomised complete block design. Four weeks before the expected kidding, the basal diets were supplemented with 0 (control), 0.3 mg Se/head.day in the form of L-selenomethionin (Se-Met) and 0.3 mg Se/head.day in the form of sodium selenite. Blood samples were collected from the goats in three phases: (1) a couple of days before starting the supplementation; (2) before the expected kidding; and (3) on the day of kidding. Blood samples were also taken from the newborn kids from the jugular vein at birth and 7 days of age. The serum Se and immunoglobulin G (IgG) concentrations, the white blood cells (WBC) and differential leukocyte counts were measured. The reproductive parameters such as the number of kids born per kidding, total weight of kids born per goat mating, the pregnancy period and kid birthweights were determined. The results indicated that the serum Se concentration increased in supplemented goats compared with controls. The Se concentrations also significantly increased in the colostrum of treated goats (P < 0.05). Similarly, serum Se concentrations in kids of treated goats were increased at birth. On the other hand, colostrum and daily milk production were not affected by Se supplementation. Likewise, the change in the mean serum IgG levels was not different among goats and kids (P > 0.05). However, the WBC, neutrophil and lymphocyte counts were higher in the kids of goats in the Se-Met group compared with the control group on the day of birth and 7 days of age (P < 0.05). It seemed that Se-Met could have influenced the lamb’s immunity at birth and 7 days of age. By contrast, selenite has not affected the performance and passive immunity in Merghoz goats.

Proteosomal degradation of naturally recurring R260C missense and exon-IV deletion mutants of factor XIII A-subunit expressed in mammalian cells

Congenital factor XIII (FXIII) deficiency is a severe bleeding disorder. We previously identified an Arg260Cys missense mutation and an exon-IV deletion in patients' A subunit genes, F13A. To characterize the molecular/cellular basis of this disease, we expressed a wild type and these mutant A subunits in baby hamster kidney (BHK) cells. The mutant proteins were expressed less efficiently than the wild type. These mutants gradually decreased inside BHK cells, whereas the wild type remained largely unchanged. The decline/decrease in these mutants was completely blocked/restored by a potent proteasome inhibitor, MG-132. This was consistent with the prediction by molecular modelling that the mutant molecules would lose the native structure of wild-type molecule, leading to their instability and degeneration and ultimately to degradation. These mutants might have significantly altered conformations, resulting in the rapid degradation by the proteasome inside the synthesizing cells, and ultimately leading to FXIII deficiency.

Effect of molybdenum and sulphur on copper status and mohair quality in Merghoze goat

This study was made on the effects of a normal diet containing 12.8 mg Cu kg(-1) DM which added gradually molybdenum and sulphur on the copper status and fibre quality in eight 1-year Merghoze goat. One group (n = 4 mean weight 31 +/- 2.0 kg) was treated with Mo and S supplements for 20 weeks, the second group (n = 4 mean weight 32 +/- 2.1 kg) served as controls. In addition of blood sampling for measuring copper status in plasma, the copper content and quality of fleeces were measured every 6 weeks. Mohair measurements were carried out by taking patch samples (10 x 10 cm2) from the mid-side area of the goat. The analytical set consists of plasma copper concentrations (Pl Cu), Trichloroacetic acid soluble copper concentrations (TCA-Cu), and fleece copper content. The results indicated that the addition of 20-30 mg Mo and 2-2.5 g S kg(-1) DM to the normal diet did produce sub clinical copper deficiency in treated goats. One such visual symptom was the loss of fleeces pigmentation and poorer crimp being observed. The Pl Cu minus TCA-Cu plasma became more than 2 microM in the blood of treated goat, indicating that there was a significant thiomolybdate formation in the body. The results showed that there was a significant decrease in Pl Cu (p < 0.05) along with a significant increase in thiomolybdate (MoS) production after 4 months. The sub clinical signs of copper deficiency and mohair quality are likely to be from high molybdenum intake and thiomolybdate formation in the body.

Factor XIII transglutaminase supports hematogenous tumor cell metastasis through a mechanism dependent on natural killer cell function

BACKGROUND

Multiple studies suggest that the hemostatic and innate immune systems functionally cooperate in establishing the fraction of tumor cells that successfully form metastases. In particular, platelets and fibrinogen have been shown to support metastatic potential through a mechanism coupled to natural killer (NK) cell function. As the transglutaminase that ultimately stabilizes platelet/fibrin thrombi through the covalent crosslinking of fibrin, factor (F) XIII is another thrombin substrate that is likely to support hematogenous metastasis.

OBJECTIVE

Directly define the role of FXIII in tumor growth, tumor stroma formation, and metastasis.

METHODS

Tumor growth and metastatic potential were quantitatively and qualitatively evaluated in wild-type mice and gene-targeted mice lacking the catalytic FXIII-A subunit.

RESULTS

Loss of FXIIIa function significantly diminished hematogenous metastatic potential in both experimental and spontaneous metastasis assays in immunocompetent mice. However, FXIII was not required for the growth of established tumors or tumor stroma formation. Rather, detailed analyses of the early fate of circulating tumor cells revealed that FXIII supports the early survival of micrometastases by a mechanism linked to NK cell function.

CONCLUSIONS

Factor XIII is a significant determinant of metastatic potential and supports metastasis by impeding NK cell-mediated clearance of tumor cells. Given that these findings parallel previous observations in fibrinogen-deficient mice, an attractive hypothesis is that FXIII-mediated stabilization of fibrin/platelet thrombi associated with newly formed micrometastases increases the fraction of tumor cells capable of evading NK cell-mediated lysis.

Regulation of human protein Z gene expression by liver-enriched transcription factor HNF-4alpha and ubiquitous factor Sp1

BACKGROUND AND OBJECTIVES

Protein Z (PZ), which regulates blood coagulation, is mainly synthesized in the liver. Its plasma level varies widely among individuals, and is highly sensitive to Warfarin. The mechanism for the basic transcription of the human PZ gene, however, has not been reported. The aim of this study was to elucidate the mechanism of gene regulation for PZ by characterizing its 5'-flanking region.

METHODS AND RESULTS

A reporter gene assay using the human hepatoma cell line, HepG2, identified a minimal promoter region (site A) and two enhancer regions (sites B and C) in the PZ gene. DNase I footprinting and electromobility shift assays revealed binding of the liver-enriched transcriptional factor hepatocyte nuclear factor (HNF)-4alpha to site A, the ubiquitous transcriptional factor Sp1 to sites A and C, and an unidentified factor to site B. The co-transfection of an HNF-4alpha expression vector with reporter gene constructs to the non-hepatic cell line HeLa resulted in a significant increase of PZ promoter activity.

CONCLUSIONS

HNF-4alpha plays a crucial role in human PZ gene expression in hepatocytic cells, and Sp1 is also important. These findings provide the first step toward understanding the mechanisms of the varying plasma PZ levels in individuals under physiological and pathological conditions.

Use of autologous plasmin during vitrectomy for diabetic maculopathy

PURPOSE

To evaluate the efficacy of autologous plasmin enzyme as an adjunct to vitrectomy in diabetic macular edema.

METHODS

Plasmin derived from autologous blood was injected intravitreally into seven eyes 15 min before vitreous surgery. The development and progression of a posterior vitreous detachment (PVD) was followed, and the time required for vitreous removal was measured. Both pre- and postoperative visual acuities and optical coherence tomography (OCT)-determined macular thickness were measured.

RESULTS

In the seven eyes in which plasmin was used, a PVD developed approximately 5 min after the injection and was confirmed to extend to the far periphery. In all cases, the removal of the vitreous was completed in a shorter time and no complications were observed. A restoration of the shape of the macula was observed in all cases. The visual acuity improved by two or more lines in four eyes, and remained unchanged in the remaining three eyes.

CONCLUSIONS

Autologous plasmin alone will create a full PVD, and eliminates the need for a mechanical creation of a PVD. Thus, plasmin is a safe and effective adjunct to vitreous surgery for the treatment of diabetic maculopathy.

Efficacy of autologous plasmin for idiopathic macular hole surgery

PURPOSE

To determine whether a single intravitreal injection of autologous plasmin or a combination of plasmin and intraocular gas without peeling the internal limiting membrane (ILM) will close idiopathic macular holes.

METHODS

Eight eyes of seven patients with an idiopathic macular hole were studied. The degree of posterior vitreous detachment (PVD), vitreal liquefaction, closure of the macular hole, visual acuity, and complications following intravitreal plasmin or plasmin with gas were investigated. The removed ILM was examined by electron microscopy.

RESULTS

A PVD was created in seven out of eight eyes exposed to plasmin or plasmin with gas, however, the macular hole was not closed by either. Closure occurred in two eyes using conventional vitrectomy after the plasmin with gas injection, but peeling the ILM was required in the remaining six eyes. Vitreal fibers and glial cells were not observed on the vitreal surface of the extracted ILM.

CONCLUSIONS

A PVD was created safely and reliably although closure of the macular hole did not occur with either plasmin or with plasmin and gas injection. However, vitreous surgery became easier, and it required a shorter time to close the macular hole with intravitreal plasmin.

Impaired protein folding, dimer formation, and heterotetramer assembly cause intra- and extracellular instability of a Y283C mutant of the A subunit for coagulation factor XIII

Factor XIII (XIII) is a heterotetramer consisting of two catalytic A subunits (XIIIA) and two noncatalytic B subunits (XIIIB). We examined the molecular mechanisms of a Y283C mutation which had previously been identified in a patient with XIIIA deficiency. The recombinant Y283C protein was labile when expressed in MEG-01 cells, which can endogenously synthesize XIIIA. We also included two other mutants, G562R and I464stop, previously characterized in a non-XIIIA-producing cell line. All these mutants exhibited decreased thermostability and resistance against proteolytic digestion when compared with the wild-type. Gel-filtration analysis revealed that the mutants were in monomer form, while the wild-type formed a dimer. These results were consistent with the prediction by molecular modeling that the mutant molecules would be misfolded. Although assembly of a heterotetramer with XIIIB was demonstrated for Y283C, its binding ability was 10% that of the wild-type. No complex formation was observed for the G562R or I464stop mutants. The wild-type was stabilized in plasma by complex formation with XIIIB, resulting in an increased resistance against proteolytic digestion. In contrast, the mutants were unstable in plasma even in the presence of XIIIB. Thus, impaired folding, dimer formation, and heterotetramer assembly of the mutant XIIIAs lead to both intra- and extracellular instability, which must be responsible for XIIIA deficiency in the patient.

Novel Y283C mutation of the A subunit for coagulation factor XIII: molecular modelling predicts its impaired protein folding and dimer formation

In an Italian patient with severe factor XIII deficiency, a novel mutation, Y283C (TAT to TGT), was identified heterozygously by nucleotide sequencing analysis in exon VII of the gene for the A subunit. The presence of this mutation was confirmed using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) analysis in the proband and his brother. Molecular modelling predicts that the mutant molecule would be misfolded. It is probable that the impaired folding of the mutant Y283C A subunit led to its instability, which is at least in part responsible for the factor XIII deficiency of this patient.

Truncated mutant B subunit for factor XIII causes its deficiency due to impaired intracellular transportation

Two Japanese patients were newly diagnosed as having B subunit (XIIIB) deficiency of factor XIII (former type I deficiency). Both patients have a previously described one-base deletion at the boundary between intron A/exon II in the XIIIB gene, heterozygously or homozygously. A founder effect was proposed for this mutation because 3 unrelated patients with XIIIB deficiency also share 2 3'-polymorphisms. In one patient heterozygous for the above mutation, a novel mutation was also identified: a deletion of guanosine in exon IX (delG) of the XIIIB gene. To understand the molecular and cellular pathology of the delG mutation, expression studies were performed using a cultured mammalian cell line. Pulse-chase experiments showed that a resultant truncated XIIIB remained inside the cells and could not be secreted into the culture medium. Furthermore, immunocytochemical examinations by epifluorescence, confocal, and electron microscopes indicated impaired intracellular transportation of the truncated XIIIB from the endoplasmic reticulum to the Golgi apparatus. No mutations in the gene for the A subunit (XIIIA) were identified in this patient. Therefore, secretion of the truncated XIIIB must also be impaired in vivo, leading to a secondary XIIIA deficiency. These results support a previous conclusion that genetic defects of XIIIB are the basis for the former type I factor XIII deficiency.

Molecular and genetic mechanisms of factor XIII A subunit deficiency

Factor XIII is a proenzyme for a plasma transglutaminase. Factor XIII in plasma is a tetramer (A2B2) held together by noncovalent bonds, and the A subunit contains the active site. Recently, the three-dimensional structure of the A subunit has been determined by x-ray crystallography. To understand the structure-function relationships of the factor XIII molecule and its clinical implications in factor XIII deficiency, we characterized its genetic defects and closely examined its gene products, including mRNA and protein levels. A variety of missense and nonsense mutations (Arg260-Cys, Tyr283-Cys, Gly562-Arg) and deletions/insertions with or without out-of-frame shift/premature termination and splicing abnormalities (4-bp deletion with 464Stop, T insertion at the exon IV/intron D boundary with exon IV-skipping, 20-bp deletion at the exon I/intron A boundary) has been identified in cases demonstrating A subunit deficiency. In some cases, the A subunit mRNA levels were severely reduced. Their molecular and cellular bases have also been explored by expression experiments in mammalian cells and by molecular modeling. In most cases, impaired folding and/or conformational changes of the mutant A subunits lead to both intra- and extracellular instability, which is responsible for the A subunit deficiency in the patients.

Genes for the human mitochondrial trifunctional protein alpha- and beta-subunits are divergently transcribed from a common promoter region

Human HADHA and HADHB genes encode the subunits of an enzyme complex, the trifunctional protein, involved in mitochondrial beta-oxidation of fatty acids. Both genes are located in the same region of chromosome 2p23. We isolated genomic clones, including 5' flanking regions, for HADHA and HADHB. Sequencing revealed that both of these genes are linked in a head-to-head arrangement on opposite strands and have in common a 350-bp 5' flanking region. The 5' flanking region has bidirectional promoter activity within this region; two cis elements proved critical for the activity. Transcription factor Sp1 functions as an activator for the bidirectional promoter by binding to both elements. Therefore, expression of trifunctional protein subunits are probably coordinately regulated by a common promoter and by Sp1.

Transcriptional regulation of cell type-specific expression of the TATA-less A subunit gene for human coagulation factor XIII

To study the mechanism of gene regulation for coagulation factor XIII A subunit (FXIIIA), we characterized its 5'-flanking region using a monocytoid (U937), a megakaryocytoid (MEG-01), and other cells. Our results confirmed that U937 and MEG-01 contained FXIIIA mRNA. A tentative transcription start site was determined to be 76 bases upstream from the first exon/intron boundary. Reporter gene assays revealed that a 5'-fragment (-2331 to +75) was sufficient to support basal expression in U937 and MEG-01 but not in the other cells. Deletion analysis confined a minimal promoter sequence from -114 to +75. DNase footprinting, electrophoretic mobility shift, and reporter gene assays demonstrated that promoter elements for a myeloid-enriched transcription factor (MZF-1-like protein) and two ubiquitous transcription factors (NF-1 and SP-1) in this region were important for the basal FXIII expression. It was also revealed that an upstream region (-806 to -290) had enhancer activity in MEG-01 but silencer activity in U937. DNA sequences for binding of myeloid-enriched factors (GATA-1 and Ets-1) were recognized in this region, and the GATA-1 element was found to be responsible for the enhancer activity. These transcription factors play a major role in the cell type-specific expression of FXIIIA, which differs from other transglutaminases.

Relationship between structure and substrate-chain-length specificity of mitochondrial very-long-chain acyl-coenzyme A dehydrogenase

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) is one of four enzymes which catalyze the initial step of the mitochondrial beta-oxidation with different but overlapping substrate-chain-length specificities. A450P, a variant of VLCAD identified in a patient with VLCAD deficiency, showed abnormal substrate-chain-length specificity. Based on this mutation, we studied the relationship between the structure and substrate-chain-length specificity of VLCAD. When VLCAD was treated with trypsin, a homodimer protein of a 48-kDa polypeptide deprived of both the amino-terminal 22 amino acids and the carboxyl-terminal 145 amino acids of VLCAD was obtained. Six Ala450 variants and tryptic-VLCAD exhibited similar substrate specificities. Effects of long-chain acyl-CoA on the tryptic cleavage and changes in the catalytic properties by deprivation of the carboxyl-terminal region suggest that this region interacts with the fatty acyl moiety of long-chain acyl-CoA. Thus, both Ala450 and the carboxyl-terminal region, which are not shared by other acyl-CoA dehydrogenases, are likely to be the determinating factors in the substrate-chain-length specificity of VLCAD.

Multiple novel transcripts for apolipoprotein(a)-related gene II generated by alternative splicing in tissue- and cell type-specific manners

Various Kringle 4 (K4) sequences were identified in human genomic clones and genomic DNAs amplified by PCR. These K4s were homologous to those found in the apo(a) gene and thus termed apo(a)-related genes (ARGs). The same sequences were obtained when human peripheral leukocytes were analyzed by reverse transcription-PCR in order to study the expression mode of the ARGs. It was of note that multiple transcripts with three optional exons for an ARG (ARGII) were detected in leukocytes, indicating that they were generated by alternative splicing. All these transcripts possessed the first half of the second K4 sequence, which had been reported to be skipped. The variant products of ARGII are expected to contain an additional region of either 44, 66, or 100 unique amino acids at the C-terminus of a single K4 unit. When normal human tissues and cultured tumor cells were analyzed, the multiple ARGII transcripts were detected at varying levels. The presence of the cellular state-specific alternative splicing machinery may provide not only redundancy but also diversity in the structure/function of ARGII.

A founder effect is proposed for factor XIII B subunit deficiency caused by the insertion of triplet AAC in exon III encoding the second Sushi domain

We previously concluded that genetic defects in the B subunit of factor XIII were the basis for former Type I deficiency (i.e. factor XIII B subunit deficiency). When we examined an Italian patient with the disease at the DNA level, restriction digestion and sequencing analyses of amplified DNAs revealed that the proband and her family members possessed an AAC insertion within the codon for Tyr-80 in exon III in the gene for the B subunit. a nucleotide polymorphism (A-G) in its 3'-noncoding region in exon XII, and a short tandem repeat polymorphism of (TTTA9, in the 3'-flanking region. These mutations and 3'-polymorphisms were also identified in another Italian family reported in a previous study (10). suggesting that a founder effect is responsible for factor XIII B subunit deficiency in Italians.

Reversal of severe hypertrophic cardiomyopathy and excellent neuropsychologic outcome in very-long-chain acyl-coenzyme A dehydrogenase deficiency

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is a disorder of fatty acid beta oxidation that reportedly has high rates of morbidity and mortality. We describe the outcome of a 5-year-old girl with VLCAD deficiency who was first seen at 5 months of age with severe hypertrophic cardiomyopathy, hepatomegaly, encephalopathy, and hypotonia. Biochemical studies indicated VLCAD deficiency caused by a stable yet inactive enzyme. Molecular genetic analysis of her VLCAD gene revealed a T1372C (F458L) missense mutation and a 1668 ACAG 1669 splice site mutation. After initial treatment with intravenous glucose and carnitine, the patient has thrived on a low-fat diet supplemented with medium-chain triglyceride oil and carnitine and avoidance of fasting. Her ventricular hypertrophy resolved significantly over 1 year, and cognitively, she is in the superior range for age. Clinical recognition of VLCAD deficiency is important because it is one of the few directly treatable causes of cardiomyopathy in children.

Very-long-chain acyl-CoA dehydrogenase subunit assembles to the dimer form on mitochondrial inner membrane

This paper describes the process of dimer assembly of mitochondrial very-long-chain acyl-CoA dehydrogenase (VLCAD) subunit. Mature VLCAD is a homodimer of a 70-kDa protein associated with the mitochondrial membrane. Newly synthesized VLCAD was present as a monomer and the major fraction was associated with the mitochondrial inner membrane. The association of VLCAD subunit with the mitochondrial membrane was observed early during dimer formation. In contrast, a VLCAD monomeric mutant S583W, a novel mutation identified from a patient with VLCAD deficiency, did not associate with the mitochondrial membrane after import and the major fraction remained in the mitochondrial matrix. These results suggest that association of VLCAD protein with mitochondrial inner membrane is necessary for dimer assembly and formation of mature VLCAD.

Catalytic and FAD-binding residues of mitochondrial very long chain acyl-coenzyme A dehydrogenase

Very long-chain acyl-CoA dehydrogenase (VLCAD) is one of four flavoproteins which catalyze the initial step of the mitochondrial beta-oxidation spiral. By sequence comparison with other acyl-CoA dehydrogenases, Glu-422 of VLCAD has been presumed to be the catalytic residue that abstracts the alpha-proton in the alphabeta-dehydrogenation reaction. Replacing Glu-422 with glutamine (E422Q) caused a loss of enzyme activity by preventing the formation of a charge transfer complex between VLCAD and palmitoyl-CoA. This result provides further evidence for Glu-422 being part of the active site of VLCAD. F418L is a disease-causing mutation in human VLCAD deficiency. Unlike wild-type VLCAD, F418L and F418V contained no bound FAD when expressed at extremely high levels in the baculovirus expression system. Although F418T and F418Y bound FAD at a level similar to that of wild-type VLCAD, both showed reduced Vmax values toward palmitoyl-CoA, most likely due to a decrease in the rate of enzyme-bound FAD reduction. These data suggest that Phe-418 is involved in the binding and subsequent reduction of FAD. FAD-deficient VLCADs (F418L, F418V, and apo-VLCAD) showed increased sensitivity to trypsinization. Loss of FAD may change the folding of VLCAD subunit.

Medium chain 3-ketoacyl-coenzyme A thiolase deficiency: a new disorder of mitochondrial fatty acid beta-oxidation

A Japanese male neonate died at 13 d of age after presenting at 2 d of age with vomiting, dehydration, metabolic acidosis, liver dysfunction, and terminal rhabdomyolysis with myoglobinuria. Multiple urine organic acid analyses consistently revealed a markedly elevated excretion of lactic acid, 3-hydroxybutyric acid, and saturated and unsaturated C6-C16 dicarboxylic acids, with predominant C12-C16 species. Oxidation of [1-14C]octanoic acid in cultured skin fibroblasts was significantly reduced (0.59 nmol/h/mg of protein; controls, 1.93 +/- 0.65), [1-14C]palmitic acid oxidation was 1.11 nmol/h/mg of protein (controls, 1.63 +/- 0.41). A systematic study of the catalytic activities of nine enzymes of the beta-oxidation cycle using the respective optimal substrate revealed a deficiency of a single enzyme not previously associated with a metabolic disorder, medium chain 3-ketoacyl-CoA thiolase (patient, 3.9 nmol/min/mg protein; controls (n = 6), 10.2 +/- 2.3). Immunoprecipitation with antibodies raised against medium chain 3-ketoacyl-CoA thiolase revealed a 60% decrease compared with controls.

D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein deficiency: a newly identified peroxisomal disorder

Peroxisomal beta-oxidation proceeds from enoyl-CoA through D-3-hydroxyacyl-CoA to 3-ketoacyl-CoA by the D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxy-acyl-CoA dehydrogenase bifunctional protein (d-bifunctional protein), and the oxidation of bile-acid precursors also has been suggested as being catalyzed by the d-bifunctional protein. Because of the important roles of this protein, we reinvestigated two Japanese patients previously diagnosed as having enoyl-CoA hydratase/L-3-hydroxyacyl-CoA dehydrogenase bifunctional protein (L-bifunctional protein) deficiency, in complementation studies. We found that both the protein and the enzyme activity of the d-bifunctional protein were hardly detectable in these patients but that the active L-bifunctional protein was present. The mRNA level in patient 1 was very low, and, for patient 2, mRNA was of a smaller size. Sequencing analysis of the cDNA revealed a 52-bp deletion in patient 1 and a 237-bp deletion in patient 2. This seems to be the first report of D-bifunctional protein deficiency. Patients previously diagnosed as cases of L-bifunctional protein deficiency probably should be reexamined for a possible d-bifunctional protein deficiency.

Structure of D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein

When D-3-hydroxyacyl-CoA dehydratase/D-3-hydroxyacyl-CoA dehydrogenase bifunctional protein was purified from human liver, two preparations were obtained. One contained a 77-kDa polypeptides as the main and minor smaller polypeptides including a 46-kDa polypeptide, and this preparation showed both the dehydratase and dehydrogenase activities. The other preparation was a homodimer of the 46-kDa polypeptide and showed only the dehydratase activity. Further analysis indicated that the native enzyme is a homodimer of 77-kDa polypeptide, which was proteolytically modified during purification. The cDNA for the human 77-kDa polypeptide was cloned. The amino acid sequences of the peptides derived from the components of the enzyme preparations were located in the deduced amino acid sequence of the cDNA. The preparation containing the 77-kDa polypeptide was treated with a protease, and two monofunctional fragments were separated. The dehydrogenase and dehydratase fragments were located on the amino- and carboxyl-terminal sides, respectively, of the deduced amino acid sequence of the cDNA. The protein expressed by the cDNA with the entire coding region exhibited both the dehydratase and dehydrogenase activities, and that expressed by a truncated version covering the carboxyl-terminal side exhibited only the dehydratase activity. The cloned cDNA was identical to the human 17 beta-hydroxysteroid dehydrogenase IV cDNA.

A new inhibitor of mitochondrial fatty acid oxidation

The mitochondrial enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase/3-ketoacyl-CoA thiolase trifunctional protein (trifunctional protein) plays a major role in mitochondrial fatty acid oxidation. The enzyme complex consists of four molecules of alpha-subunit containing both hydratase and dehydrogenase domains and four molecules of beta-subunit containing the thiolase domain. The primary structure of a gastrin-binding protein (GBP) was highly homologous to that of the alpha-subunit of the trifunctional protein. Here, we report that gastrin inhibits the hydratase, dehydrogenase, and thiolase activities of the trifunctional protein. The gastrin/cholecystokinin receptor antagonist benzotript, which inhibited binding of gastrin to the GBP, also inhibited all three activities of the trifunctional protein. In addition, benzotript inhibits the activities of multifunctional enzymes having similar structures, such as the peroxisomal enoyl-CoA hydratase/3-hydroxyacyl-CoA dehydrogenase bifunctional protein and the Pseudomonas fragi fatty acid oxidation enzyme complex. This reagent, however, hardly inhibited various monofunctional enzymes involved in fatty acid oxidation.

Formation of the enzyme complex in mitochondria is required for function of trifunctional beta-oxidation protein

The first Japanese patient with mitochondrial trifunctional protein deficiency has been identified. The patient's alpha and beta-subunits were synthesized, transported into the mitochondria, and converted to the mature size, but rapidly disappeared. The newly synthesized mature alpha and beta-subunits in the control cells were incorporated into the enzyme complex, alpha4beta4, whereas those in the patient's cells were present as monomers. We propose that formation of the enzyme complex is required for stabilization of trifunctional protein.

Mutation analysis of very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency: identification and characterization of mutant VLCAD cDNAs from four patients

Very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) deficiency is a newly identified disease. A 105-bp deletion in the VLCAD cDNA in two patients has been reported, and detailed molecular characterization of this disease has remained to be done. We report here five mutations identified in four patients: a 135-bp deletion encompassing bases 343-477, a C-1837-to-T transition (R613W), 3-bp deletions at the nucleotide positions 388-390 (E130del) and 895-897 (K299del), and an A-1144-to-C transversion (K382Q). Sequencing of genomic DNA amplified by PCR revealed a 135-bp deletion caused by exon skipping due to a 1-bp deletion in a 3' splice site of an intron. In cDNA expression experiments using Chinese hamster ovary (CHO) cells, we found that each of the mRNAs derived from E130del and K299del clones were unstable and that translation products from R613W, E130del, K299del, and K382Q clones were labile. Each of R613W, E130del, K299del, and K382Q proteins expressed in CHO cells appeared abnormal in dimer assembly, as shown in gel-filtration analysis. VLCAD activity was not detected in mutants' transfectants. Thus, we verified that all five mutations identified in these four patients were disease-causing alterations.

Genomic DNA organization of human mitochondrial very-long-chain acyl-CoA dehydrogenase and mutation analysis

Very-long-chain acyl-CoA dehydrogenase (VLCAD) is a major enzyme catalyzing long-chain fatty acids in the first step of mitochondrial beta-oxidation system. Inborn error of this enzyme can cause sudden infant death syndrome and hypertrophic cardiomyopathy is present at a significantly high frequency. To investigate VLCAD deficiency at the genomic DNA level, we cloned the VLCAD gene and analyzed the structure. The gene is about 5.4 kb long and contains 20 exons. We performed mutation analysis in two patients, both having a 105 bp deletion encompassing bases 1078-1182 in cDNA. A point mutation (GT-->AT) at 5' splice site of intron 11 was identified in both patients. This mutation seems to cause skipping of exon 11 corresponding to the 105 bp deletion. This is the first documentation of aberrant splicing in the VLCAD gene.

Cloning of human very-long-chain acyl-coenzyme A dehydrogenase and molecular characterization of its deficiency in two patients

Two overlapping cDNA clones (1,991 bp and 736 bp, respectively) encoding the precursor of human mitochondrial very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) were cloned and sequenced. The cDNA inserts of these clones together encompass a region of 2,177 bases, encoding the entire protein of 655 amino acids, including a 40-amino acid leader peptide and a 615-amino acid mature polypeptide. PCR-amplified VLCAD cDNAs were sequenced in cultured fibroblasts from two VLCAD-deficient patients. In both patients, a 105-bp deletion encompassing bases 1078-1182 in VLCAD cDNA was identified. The deletion seems to occur due to exon skipping during processing of VLCAD pre-mRNA. This is the first demonstration of a mutation causing VLCAD deficiency. Quantitative cDNA expression of normal human VLCAD was performed in the patients' fibroblasts, using vaccinia viral system, which demonstrated that the deficiency of the normal VLCAD protein causes impaired long-chain fatty acid beta-oxidation activity in the patients' fibroblasts. In patient fibroblasts, raising VLCAD activity to approximately 20% of normal control fibroblast activity raised palmitic acid beta-oxidation flux to the level found in control fibroblasts, which may offer important information for the rational design of future somatic gene therapy for VLCAD deficiency.

Purification of human very-long-chain acyl-coenzyme A dehydrogenase and characterization of its deficiency in seven patients

Mitochondrial very-long-chain acyl-coenzyme A dehydrogenase (VLCAD) was purified from human liver. The molecular masses of the native enzyme and the subunit were estimated to be 154 and 70 kD, respectively. The enzyme was found to catalyze the major part of mitochondrial palmitoylcoenzyme A dehydrogenation in liver, heart, skeletal muscle, and skin fibroblasts (89-97, 86-99, 96-99, and 78-87%, respectively). Skin fibroblasts from 26 patients suspected of having a disorder of mitochondrial beta-oxidation were analyzed for VLCAD protein using immunoblotting, and 7 of them contained undetectable or trace levels of the enzyme. The seven deficient fibroblast lines were characterized by measuring acyl-coenzyme A dehydrogenation activities, overall palmitic acid oxidation, and VLCAD protein synthesis using pulse-chase, further confirming the diagnosis of VLCAD deficiency. These results suggested the heterogenous nature of the mutations causing the deficiency in the seven patients. Clinically, all patients with VLCAD deficiency exhibited cardiac disease. At least four of them presented with hypertrophic cardiomyopathy. This frequency (> 57%) was much higher than that observed in patients with other disorders of mitochondrial long-chain fatty acid oxidation that may be accompanied by cardiac disease in infants.

A quantitative method for cDNA-directed expression in cultured mammalian cells

A simple technique of quantitative cDNA-directed expression was devised by using a vaccinia virus system. The technique was applied to the cDNA expression of peroxisomal acyl-coenzyme A oxidase (AOX) and microsomal cytochromes P450 1A2, 2E1, and 3A4. Quantitative cDNA expression of all four enzymes tested was successfully achieved. This represents important progress for establishing the relationship between the amount of enzyme and its function in cells. The vaccinia virus system was also used to express AOX protein in specific cellular regions.

A sensitive assay of acyl-coenzyme A oxidase by coupling with beta-oxidation multienzyme complex

A highly sensitive and reliable method for assaying acyl-CoA oxidase (EC 1.3.99.3) activity was developed. An acyl-CoA oxidase-dependent [1-14C]palmitoyl-CoA degradation to acetyl-CoA, acid-soluble products, was measured by coupling with the multienzyme complex for fatty acid oxidation from Pseudomonas fragi. The activity, more than 2 pmol/min, could be assessed using this method. The activity was dependent on the coupling enzyme (multienzyme complex), coenzymes such as NAD+ and CoA, and oxygen, and the interference of acyl-CoA dehydrogenases was excluded. The activity in human samples of cultured skin fibroblasts and lymphocytes was compatible with the expected activity calculated from the amount of acyl-CoA oxidase protein estimated by immunoblot analysis. The method which was verified in several experiments can be used for clinical diagnosis of acyl-CoA oxidase deficiency and for determination of activity in samples with a low level of acyl-CoA oxidase.

Peroxisomal acyl-coenzyme A oxidase is a rate-limiting enzyme in a very-long-chain fatty acid beta-oxidation system

The contents of peroxisomal fatty acid beta-oxidation enzymes in three rat hepatoma cell lines, i.e., H4IIEC3 (H4), N1S1, and McA-RH7777 (H7), were measured by immunoblot analysis, and a significant difference in acyl-coenzyme A oxidase (AOX) content became evident. These cell lines were respectively infected with a recombinant virus to express significant amounts of AOX protein. The expressed AOX mainly localized in organelle, supposing peroxisomes, and was catalytically active. The cDNA-expression in H4, N1S1, and H7 cells enhanced 2.6-, 2.2-, and 1.0-fold beta-oxidation activity of lignoceric acid, respectively. The enhancement in H4 and N1S1 cells suggests that AOX is a rate-limiting enzyme in the very-long-chain fatty acid beta-oxidation system, in these cell lines.

Molecular cloning and functional expression of a human peroxisomal acyl-coenzyme A oxidase

cDNA encoding the human peroxisomal acyl-coenzyme A oxidase (AOX) was cloned and sequenced. The longest cDNA insert isolated has 3083 bases and encodes the entire protein of 661-amino acids, including the carboxyl-terminal sequence (Ser-Lys-Leu) known as a minimal peroxisome-targeting signal. At the amino acid level, the significantly high homology (89%) to rat AOX was found. In the cDNA-expression experiment, significant amount of AOX was accumulated in human skin fibroblast and the expressed AOX was catalytically active, while only a limited amount was found in Zellweger syndrome patient's fibroblast not having normal peroxisomes.