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Nephropathic cystinosis is a lysosomal disorder caused by functional defects of cystinosin, which mediates cystine efflux into the cytosol. The protein sequence contains at least two signals that target the protein to the lysosomal compartment, one of which is located at the carboxy terminal tail (GYDQL). We have isolated from a human kidney eDNA library a cystinosin isoform, which is generated by an alternative splicing of exon 12 that removes the GYDQL motif. Based on its last three amino acids, we have termed this protein cystinosin-LKG. Contrary to the lysosomal cystinosin isoform, expression experiments performed by transient transfection of green fluorescent protein fusion plasmids in HK2 cells showed that cystinosin-LKG is expressed in the plasma membrane, in lysosomes, and in other cytosolic structures. This subcellular localization of the protein was confirmed by transmission electron microscopy. In addition, immunogold labeling was observed in the endoplasmic reticulum and in the Golgi apparatus. Expression of the protein in renal tubular structures was also directly demonstrated by immunostaining of normal human kidney sections. The plasma membrane localization of cystinosin-LKG was directly tested by [[sup.35]S]cystine flux experiments in COS-1 cells. In the presence of a proton gradient, a marked enhancement of intracellular cystine transport was observed in cells overexpressing this isoform. These data indicate that the expression of the gene products encoded by the CTNS gene is not restricted to the lysosomal compartment. These finding may help elucidate the mechanisms of cell dysfunction in this disorder. genetic disease; nephropathic cystinosis; cystine transport

The chromatin-associated protein ATRX was originally identified because mutations in the ATRX gene cause a severe form of syndromal X-linked mental retardation associated with [alpha]-thalassemia, Half of all of the disease-associated missense mutations cluster in a cysteine-rich region in the N terminus of ATRX. This region was named the ATRX-DNMT3-DNMT3L (ADD) domain, based on sequence homology with a family of DNA methyltransferases. Here, we report the solution structure of the ADD domain of ATRX, which consists of an N-terminal GATA-like zinc finger, a plant homeodomain finger, and a long C-terminal s-helix that pack together to form a single globular domain. Interestingly, the [alpha]-helix of the GATA-like finger is exposed and highly basic, suggesting a DNA-binding function for ATRX. The disease-causing mutations fall into two groups: the majority affect buried residues and hence affect the structural integrity of the ADD domain; another group affects a cluster of surface residues, and these are likely to perturb a potential protein interaction site. The effects of individual point mutations on the folding state and stability of the ADD domain correlate well with the levels of mutant ATRX protein in patients, providing insights into the molecular pathophysiology of ATR-X syndrome. ATR-X syndrome | NMR structure | zinc finger

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.cell.2005.06.042 Byline: Minghao Jin (1), Songhua Li (1), Walid N. Moghrabi (1), Hui Sun (1)(2), Gabriel H. Travis (1)(3) Abstract: The first event in light perception is absorption of a photon by an opsin pigment, which induces isomerization of its 11-cis-retinaldehyde chromophore. Restoration of light sensitivity to the bleached opsin requires chemical regeneration of 11-cis-retinaldehyde through an enzymatic pathway called the visual cycle. The isomerase, which converts an all-trans-retinyl ester to 11-cis-retinol, has never been identified. Here, we performed an unbiased cDNA expression screen to identify this isomerase. We discovered that the isomerase is a previously characterized protein called Rpe65. We confirmed our identification of the isomerase by demonstrating catalytic activity in mammalian and insect cells that express Rpe65. Mutations in the human RPE65 gene cause a blinding disease of infancy called Leber congenital amaurosis. Rpe65 with the Leber-associated C330Y and Y368H substitutions had no isomerase activity. Identification of Rpe65 as the isomerase explains the phenotypes in rpe65.sup.-/- knockout mice and in humans with Leber congenital amaurosis. Author Affiliation: (1) Jules Stein Eye Institute, UCLA School of Medicine, Los Angeles, California 90095 (2) Department of Physiology, UCLA School of Medicine, Los Angeles, California 90095 (3) Department of Biological Chemistry, UCLA School of Medicine, Los Angeles, California 90095 Article History: Received 10 April 2005; Revised 27 May 2005; Accepted 20 June 2005 Article Note: (miscellaneous) Published: August 11, 2005

Genetic defects in copper metabolism highlight the delicate balance mammalian systems have developed to maintain normal copper homeostasis. Menkes disease, the mottled mouse, the Atox-1-deficient mouse and the ctrl knockout mouse reveal the importance of adequate copper intake during embryogenesis and early development, especially in the central nervous system. The toxicity associated with excess copper as manifest in Wilson disease, the toxic milk mouse, the LEC rat and copper toxicosis in the Bedlington terrier demonstrate the profound cellular susceptibility to copper overload, in particular, in the brain and liver. Ceruloplasmin (Cp) contains 95% of the copper found in human serum, and inherited loss of this protein results in diabetes, retinal degeneration and neurodegeneration. Despite normal copper metabolism, aceruloplasminemic patients and the Cp knockout mouse have disturbed iron homeostasis and mild hepatic copper retention. These genetic disorders of copper metabolism provide valuable insight into the mechanisms regulating copper homeostasis and models to further dissect the role of this essential metal in health and disease. KEY WORDS: * copper * ceruloplasmin * Wilson disease * Menkes disease * aceruloplasminemia

We describe a case of congenital cataracts in a newborn whose mother received total parenteral nutrition (TPN) throughout her pregnancy. We discuss the potential mechanisms by which TPN may have been causally linked to cataract formation. European Journal of Clinical Nutrition (2014) 68, 943-945; doi: 10.1038/ejcn.2014.103; published online 28 May 2014, BACKGROUND Adequate maternal nutrition is essential for optimal fetal growth. Maternal malnutrition is associated with intrauterine growth retardation and increased perinatal morbidity and mortality. Total parenteral nutrition (TPN) is indicated [...]

Vitamin [B.sub.12] (cobalamin) is an essential cofactor of two enzymes, methionine synthase and methyimalonyl-CoA mutase. The conversion of the vitamin to its coenzymes requires a series of biochemical modifications for which several genetic diseases are known, comprising eight complementation groups (cblA through cblH). The objective of this study was to clone the gene responsible for the cblA complementation group thought to represent a mitochondrial cobalamin reductase. Examination of bacterial operons containing genes in close proximity to the gene for methylmalonyl-CoA mutase and searching for orthologous sequences in the human genome yielded potential candidates. A candidate gene was evaluated for deleterious mutations in cblA patient cell lines, which revealed a 4-bp deletion in three cell lines, as well as an 8-bp insertion and point mutations causing a stop codon and an amino acid substitution. These data confirm that the identified gene, MMAA, corresponds to the cblA complementation group. It is located on chromosome 4q31.1-2 and encodes a predicted protein of 418 aa. A Northern blot revealed RNA species of 1.4, 2.6, and 5.5 kb predominating in liver and skeletal muscle. The deduced amino acid sequence reveals a domain structure, which belongs to the AAA ATPase superfamily that encompasses a wide variety of proteins including ATP-binding cassette transporter accessory proteins that bind ATP and GTP. We speculate that we have identified a component of a transporter or an accessory protein that is involved in the translocation of vitamin [B.sub.12] into mitochondria.

Tuberous sclerosis complex (TSC) is an autosomal dominant genetic disorder that occurs upon mutation of either the TSC1 or TSC2 genes, which encode the protein products hamartin and tuberin, respectively. Here, we show that hamartin and tuberin function together to inhibit mammalian target of rapamycin (mTOR)-mediated signaling to eukaryotic initiation factor 4E-binding protein 1 (4E-BP1) and ribosomal protein S6 kinase 1 (S6K1). First, coexpression of hamartin and tuberin repressed phosphorylation of 4E-BP1, resulting in increased association of 4E-BP1 with eIF4E; importantly, a mutant of TSC2 derived from TSC patients was defective in repressing phosphorylation of 4E-BP1. Second, the activity of S6K1 was repressed by coexpression of hamartin and tuberin, but the activity of rapamycin-resistant mutants of S6K1 were not affected, implicating mTOR in the TSC-mediated inhibitory effect on S6K1. Third, hamartin and tuberin blocked the ability of amino acids to activate S6K1 within nutrient-deprived cells, a process that is dependent on mTOR. These findings strongly implicate the tuberin-hamartin tumor suppressor complex as an inhibitor of mTOR and suggest that the formation of tumors Within TSC patients may result from aberrantly high levels of mTOR-mediated signaling to downstream targets.

Cited2 is a cAMP-responsive element-binding protein (CBP)/p300 interacting transcriptional modulator and a proposed negative regulator for hypoxia-inducible factor (HIF)-1[alpha] through its competitive binding with HIF-1[alpha] to CBP/p300. Disruption of the gene encoding Cited2 is embryonic lethal because of defects in the development of heart and neural tube. Morphological and Doppler echocardiographic analyses of [Cited2.sup.-/-] embryos reveal severe cardiovascular abnormalities, including pulmonic arterial stenosis and ventricular septal defects accompanied by high peak outflow velocities, features of the human congenital cardiac defect termed tetralogy of Fallot. The mRNA levels of several HIF-1[alpha]-responsive genes, such as vascular endothelial growth factor (VEGF), Glut1, and phosphoglycerate kinase 1, increased in the [Cited2.sup.-/-] hearts. The increase of VEGF levels is significant, because defects in the [Cited2.sup.-/-] embryos closely resemble the major defects observed in the VEGF transgenic embryos. Finally, compared with wild-type, cultured fibroblasts from [Cited2.sup.-/-] embryos demonstrate an enhanced expression of HIF-1[alpha]-responsive genes under hypoxic conditions. These observations suggest that functional loss of Cited2 is responsible for defects in heart and neural tube development, in part because of the modulation of HIF-1 transcriptional activities in the absence of Cited2. These findings demonstrate that Cited2 is an indispensable regulatory gene during prenatal development.

Research has been conducted on the central and peripheral oscillators in the mammalian circadian system. The communication pathways between these oscillators have been investigated via the study of the mice embryo fibroblast's rhythmic behavior and the details are reported.

A general overview of the lanosterol-to-cholesterol biosynthesis pathway and information on the step-by-step synthesis are presented. Other topics are cholesterol biosynthesis in perspective, cholesterol homeostasis, and inherited diseases of cholesterol biosynthesis (CHILD (congenital hemidysplasia, ichthyosis and limb defects) syndrome, chondrodysplasia punctata (CDP), including Conradi-Hunermann syndrome, desmosterolosis, Smith-Lemli-Opitz syndrome (SLOS)). Biochemistry students of a more medical bent may want to know about the enzymes that are involved in the pathway and about other information included in the article.

Human hepatocellular carcinoma (HCC) is one of the most common cancers worldwide. In this work, we report on a comprehensive characterization of gene expression profiles of hepatitis B virus-positive HCC through the generation of a large set of 5'-read expressed sequence tag (EST) clusters (11,065 in total) from HCC and noncancerous liver samples, which then were applied to a cDNA microarray system containing 12,393 genes/ESTs and to comparison with a public database. The commercial cDNA microarray, which contains 1,176 known genes related to oncogenesis, was used also for profiling gene expression. Integrated data from the above approaches identified 2,253 genes/ESTs as candidates with differential expression. A number of genes related to oncogenesis and hepatic function/differentiation were selected for further semiquantitative reverse transcriptase-PCR analysis in 29 paired HCC/noncancerous liver samples. Many genes involved in cell cycle regulation such as cyclins, cyclin-dependent kinases, and cell cycle negative regulators were deregulated in most patients with HCC. Aberrant expression of the Wnt-[beta]-catenin pathway and enzymes for DNA replication also could contribute to the pathogenesis of HCC. The alteration of transcription levels was noted in a large number of genes implicated in metabolism, whereas a profile change of others might represent a status of dedifferentiation of the malignant hepatocytes, both considered as potential markers of diagnostic value. Notably, the altered transcriptome profiles in HCC could be correlated to a number of chromosome regions with amplification or loss of heterozygosity, providing one of the underlying causes of the transcription anomaly of HCC.

Polyglutamine diseases, inherited neurodegenerative deseases, come from a mutational mechanism altering the sequence of a protein so that glutamines are added to a polyglutamine tract in the androgen receptor via one of two possible mechanisms discussed in this review article with information on the effects of polyglutamine expansion at the protein level. Evidence that a polyglutamine tract can itself be toxic exists. Another mechanism would depend on change in the function of the full-length protein. Lessons from Huntington's, and from spinocerebellar ataxia types 1 and 2 are discussed.

Wnt signaling and cancer are discussed in this review article which emphasizes molecular defects known to promote neoplastic transformation in humans and in animal models. It has been found that wnt signaling causes cancer and that tumor promotion by the pathway can go through various genetic defects. Manifestation of cancer by aberrant wnt signaling mostly likely comes from inappropriate gene activation mediated by stabilized beta-catenin. Topics covered include receptors, ligands and related proteins, GSK3(beta), dishevelled, axin, PP2A, APC, transcription factors, and cross talk.

Mechanisms of left-right determination in vertebrates are discussed in this review article. Recent discoveries are discussed relative to four stages. The first, and perhaps most challenging, area is the initial breaking of symmetry leading to establishment of specific patterns of gene expression in/around the embryonic organizer. The second is relaying of L/R positional information from the organizer to the lateral plate mesoderm. Third is stabilization of broad domains of side-specific gene expression. Fourth comes transfer of L/R information to the organ primordia and elaboration of specific programs of asymmetric morphogenesis.

Human mitochondrial complex I, or nicotinamide adenine dinucleotide(NADH):ubiquinone oxidoreductase, has over 42 subunits, of which seven are encoded by the mitochondrial genome and the rest by the nuclear genome. The 35 known nuclear-encoded subunits for complex I proteins have been characterized. Complex I is involved in dehydrogenation of NADH and transport of electrons to coenzyme Q. Knowledge of this important protein complex is expected to expand rapidly and to contribute to the understanding of isolated complex I deficiency.

The critical region for Behcet disease in the human major histocompatibility complex (MHC) has been narrowed to a 46-kb segment centromeric of HLA-B (ital). Association analysis for Behcet disease has been carried out on eight polymorphic microsatellite markers over a 900-kb region around the HLA-B (ital) locus of the MICA (ital) gene. The HLA-B51 allele is associated with the disease, which has a frequency of 45%-60% in Asian and Eurasian ethic groups, is an inflammatory disorder that occurs spontaneously, and is often triggered by environmental factors.

A study was conducted to test whether downregulated in adenoma (DRA) is an intestinal chloride transporter and examine how mutations affect transport. Xenopus oocytes were injected with wild-type and mutagenized DRA cRNA. The uptake of Cl- and So2/4 were assayed before being transported by wild-type DRA. Experimental results indicated that DRA is a chloride transporter defective in chloride diarrhea.

Children with the genetic defect 22q11.2 deletion may be at higher risk for growth hormone deficiency. This birth defect may cause many symptoms, including heart abnormalities, defects of the palate, and altered facial appearance. Four patients with 22q11.2 deletion and short stature were evaluated for inadequate growth and found to have growth hormone deficiency. Replacement growth hormone therapy may increase the rate of growth and allow these children to attain a greater final height., The list of findings associated with the 22q11.2 deletion is quite long and varies from patient to patient. The hallmark features include: conotruncal cardiac anomalies, palatal defects, thymic aplasia or hypoplasia, T cell abnormalities, mild facial dysmorphia, and learning disabilities. The 22q11.2 deletion has been seen in associAtion with the DiGeorge sequence, velocardiofacial syndrome (VCFS), conotruncal anomaly face syndrome, isolated conotruncal cardiac anomalies, and some cases of autosomal dominant Opitz G/BBB syndrome. Short stature has been seen in one to two thirds of children reported in the literature with a diagnosis of VCFS, but growth hormone deficiency (GHD) has not been described in conjunction with this diagnosis. We present 4 patients with a 22q11.2 deletion and short stature who were found to have abnormalities in the growth hormone-insulin-like growth factor I axis. All had growth factors less than -2 SD for age and failed provocative growth hormone testing. Two patients were found to have abnormal pituitary anatomy. In our population, the incidence of GHD in 4 of 95 children with 22q11 deletion is significantly greater than the estimated incidence of GHD in the general population. Children with a 22q11.2 deletion appear to be at a greater risk for pituitary abnormalities. Therefore, those children with the 22q11.2 deletion and short stature or poor growth should be evaluated for GHD, as replacement growth hormone therapy may improve their growth velocity and final height prediction. Pediatrics 1998;101:929-932; velocardiofacial syndrome, DiGeorge sequence, 22q11.2 deletion, growth hormone, deficiency, short stature., ABBREVIATIONS. DGS, DiGeorge sequence; VCFS, velocardiofacial syndrome; CTAF, conotruncal anomaly face syndrome; GHD, growth hormone deficiency; SDS, standard deviation score; IGF-I, insulin-like growth factor I; IGFBP-3, insulin-like growth factor binding [...]

The Han:SPRD-+/+ rat models of autosomal dominant polycystic kidney disease (PKD) was analyzed by nuclear magnetic resonance (NMR) and proton NMR (H-NMR) to determine the factors that mediate the progression of PKD. NMR imaging and proton NMR analysis of Hans:SPD-+/+ rat models indicated the presence of reduced renal ion levels due to abnormal ion transport. Furthermore, the kidneys of Hans:SPD-+/+ rat models also exhibited abnormal excretion of citric acid cycle metabolites.

The role of genetic mutations in vascular dysmorphogenesis was analyzed by the chromosome mapping of the TIE2 gene in insect cells. The phosphorylation activity of TIE2 was enhanced by mutations in the R849W polymorphism which is expressed in two disparate families with dominantly inherited mucocutaneous vascular malformations. The activation of the mutant TIE2 gene also increased the number of endothelial cells compared to smooth muscle cells during venous morphogenesis.

The role of collagen alpha3(IV) in the pathogenesis of Alport syndrome was analyzed in mice exhibiting deficient collagen alpha3(IV) proteins. The mutant mice exhibited hereditary glomerulonephritis that is mediated by alterations in the composition of the renal basal lamina. Furthermore, the alterations in the renal basal lamina due to the absence of collagen alpha3(IV) contributed to a form of delayed-onset progressive renal disease that is similar to human Alport syndrome.

Niemann-Pick disease type C is a neurological disorder caused by an accumulation of cholesterol in various tissues. It is a hereditary disease that has been linked to chromosome 18. The early form can occur in infancy and is characterized by jaundice and neurologic symptoms. This form progresses very quickly. The late form progresses more slowly. It can be diagnosed by measuring the esterification of cholesterol in tissue samples. This process is deficient in patients with Niemann-Pick C disease. There is no cure for the disease.

A mutation in the gene that regulates estrogen receptors seems to affect bone growth and development in men, as well as women, but may not cause death. Physicians studied a 28-year-old man who was over six feet six inches tall. The patient continued to grow taller in adulthood and was knock kneed. X-rays revealed thinning of the bones. In addition, the patient's long bones had not fused. Blood levels of estrogen, follicle-stimulating hormone, and luteinizing hormone were high. Insulin levels in the blood were also above normal. Physicians suspected that the patient was estrogen resistant and began treatment with high doses of estrogen. After six months, the patient's hormone and metabolic levels remained abnormal. Analysis of the patient's DNA revealed a mutation in the estrogen receptor gene. Each of the man's parents carried a mutation in one of the two genes that control estrogen receptors.

An abnormality in cholesterol synthesis may interfere in the development of embryos affected by Smith-Lemli-Opitz syndrome. Smith-Lemli-Opitz syndrome is a genetic disorder characterized by a wide range of severe anatomical and physiological defects. Researchers compared concentrations of different cholesterol-containing compounds in five children with Smith-Lemli-Opitz syndrome to those of six healthy children of the same age (control). Children with Smith-Lemli-Opitz syndrome had significantly lower blood levels of cholesterol than the children in the control group. Individuals with Smith-Lemli-Opitz syndrome had elevated concentrations of a cholesterol precursor, but most of the healthy children did not have detectable levels of this substance.

* This review of the Apert syndrome, based on our research experience with 136 cases, provides a clinically relevant pediatric perspective. The brain is megalencephalic, resulting in a disporportionately high cranium and a mean birth length and weight above the 50th percentile. The growth pattern in childhood consists of a slowing of linear growth so that most values fall between the 5th and 50th percentiles. From adolescence to adulthood, slowing becomes more pronounced. Central nervous system abnormalities may occur in some cases, including malformations of the corpus callosum and limbic structures, gyral abnormalities, hypoplastic white matter, and heterotopic gray matter. Distortion ventriculomegaly is found because of the large brain in a misshapen skull. Progressive hydrocephalus is uncommon. intelligence in patients with the Apert syndrome varies from normality to mental deficiency. Early release of the coronal suture and advancement and reshaping of the frontal bone reduce further dysmorphic and unwanted growth changes in the skull, but probably do not affect mentation. Associated cardiovascular and genitourinary anomalles occur in 10% and 9.6% of cases, respectively. Other important findings reviewed include upper- and lower-airway compromise, calvarial development, cervical vertebral anomalies, limb defects, ocular and otologic manifestations, and dermatologic characteristics. (AJDC. 1993;147:989-993), The Apert syndrome is a genetic disorder characterized by a misshapen skull and syndactyly, or webbed fingers and toes. Research on 136 cases of Apert syndrome has provided information on a variety of associated structural and physiological abnormalities. Birth weight and length are usually above normal because of an overly large brain and high skull, but growth in childhood is usually between the 5th and 50th percentiles. Patients may have normal intelligence, but often display some degree of mental deficiency, from mild to severe. Surgery to correct abnormal skull fusion may be desirable, but does not seem to alter intelligence level. Two-thirds of patients have stiffness of the neck, resulting from fusion of cervical vertebrae. Approximately 10% of patients have defects of their cardiovascular or genitourinary systems. Apert syndrome may also affect the respiratory system, the eyes, skin and hearing.

Rab geranylgeranyl transferase (GG transferase) is a two-component enzyme that attaches 20-carbon isoprenoid groups to cysteine residues in Rab proteins, a family of guanosine triphosphate-binding proteins that regulate vesicular traffic. [...]