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At least 289 records · Page 16Linked to original sources
PubMed2003

Analysis of phospholipid molecular species in brains from patients with infantile and juvenile neuronal-ceroid lipofuscinosis using liquid chromatography-electrospray ionization mass spectrometry.

Phospholipids (PL) in cerebral cortex from patients with infantile (INCL or CLN1) and juvenile (JNCL or CLN3) forms of neuronal ceroid-lipofuscinosis (NCL) and controls were analysed by normal phase HPLC and on-line electrospray ionization ion-trap mass spectrometric detection (LC-ESI-MS). The method provided quantitative data on numerous molecular species of different PL classes, which are not achieved by using the conventional chromatographic methods. Compared with the controls, the INCL brains contained proportionally more phosphatidylcholine (PC), and less phosphatidylethanolamine (PE) and phosphatidylserine (PS). Different molecular species of PC, PE, PS, phosphatidylinositol and sphingomyelin were quantified using multiple internal PL standards that differed in fatty acyl chain length and thus allowed correction for chain length dependency of instrument response. In INCL cortex, which had lost 65% of the normal PL content, the proportions of polyunsaturated molecular species, especially the PS and PE that contained docosahexaenoic acid (22:6n-3), were dramatically decreased. The membranes may have adapted to this alteration by increasing the proportions of PL molecules substituted with monounsaturated and short-chain fatty acids. Lysobisphosphatidic acid was highly elevated in the INCL brain and consisted mostly of polyunsaturated species. It is possible that changes in the composition of PL membranes accelerate progression of INCL by altering signalling and membrane trafficking in neurons.

Adolescent↗
PubMed2001

An Australasian diagnostic service for the neuronal ceroid lipofuscinoses.

The neuronal ceroid lipofuscinoses (NCLs) are a family of related genetic disorders that together are believed to affect one child in every 12,500 births in the USA. Our laboratory has developed a diagnostic service for classical late infantile neuronal ceroid lipofuscinosis (LINCL) by assay of tripeptidyl-peptidase I (TPP-I) activity using the fluorogenic peptide substrate Ala-Ala-Phe aminomethylcoumarin, followed by a screen for three mutations in the CLN2 gene. In addition, we have also begun to offer a limited diagnostic service for the juvenile (JNCL) and infantile (INCL) forms of the disease on the basis of mutation analysis of the CLN3 and CLN1 genes, respectively. Retrospective analysis of Australasian patients with a clinical suspicion of NCL has revealed that six are affected by LINCL, six by JNCL and, to date, two by INCL. Mutation analysis of our LINCL patients has shown that the three screened mutations, namely, the nonsense mutation R208X and the splice mutations IVS5-1 G > C and IVS5-1 G > A, constitute 83% of alleles.

Aminopeptidases↗
PubMed2001

Hippocampal lesions in the neuronal ceroid lipofuscinoses.

Epilepsy is a common manifestation in all childhood-onset forms of neuronal ceroid lipofuscinosis. In order to document hippocampal lesions and their relationship to epilepsy we studied autopsy specimens from the hippocampi of a series of patients with the infantile (CLN1), classic late infantile (CLN2), Finnish variant late infantile (CLN5), and juvenile (CLN3) neuronal ceroid-lipofuscinosis as well as Northern epilepsy (CLN8), using a battery of histological and immunocytochemical staining methods. Despite striking differences in the overall degree of neocortical neuronal storage and loss, these genetically heterogeneous forms of neuronal ceroid lipofuscinosis showed a common lesional pattern in the hippocampi: a relative sparing of the CA1 sector and severe involvement of the neighbouring CA2 sector, with intermediate degrees of involvement of the CA3 and CA4 sectors. These findings distinguish the hippocampal pathology associated with the neuronal ceroid lipofuscinoses from classical 'mesial temporal sclerosis' and show that the selective lesional pattern in the neuronal ceroid lipofuscinoses is not a secondary anoxic-ischaemic phenomenon. It is rather a consequence of the primary metabolic defects and may be directly involved in the causation of the epileptic discharges.

Child↗
PubMed2001

New mutations in the neuronal ceroid lipofuscinosis genes.

Thirty-eight mutations and seven polymorphisms have recently been reported in the genes underlying the neuronal ceroid lipofuscinoses (NCLs) including 11 new mutations described here. A total of 114 mutations and 28 polymorphisms have now been described in the five human genes identified which cause NCL. Thirty-eight mutations are recorded for CLN1/PPT; 40 for CLN2/TTP-1, 31 for CLN3, four for CLN5, one for CLN8. Two mutations have been described in animal genes (cln8/mnd, CTSD). All mutations in NCL genes are contained in the NCL Mutation Database (http://www.ucl.ac.uk/NCL).

Child↗
PubMed2001

Turkish variant late infantile neuronal ceroid lipofuscinosis (CLN7) may be allelic to CLN8.

One variant form of late infantile neuronal ceroid lipofuscinosis (LINCL) is found predominantly within the Turkish population (CLN7). Exclusion mapping showed that CLN7 was not an allelic variant of known NCL loci (CLN1, CLN2, CLN3, CLN5 or CLN6). Using the method of homozygosity mapping, a genome-wide search was undertaken and a total of 358 microsatellite markers were typed at an average distance of about 10 cM. A region of shared homozygosity was identified on chromosome 8p23. This telomeric region contained the recently identified CLN8 gene. A missense mutation in CLN8 causes progressive epilepsy with mental retardation (EPMR) or Northern epilepsy, which has so far been reported only from Finland and is now classified as an NCL. The mouse model mnd has been shown to carry a 1 bp insertion in the orthologous Cln8 gene. Statistically significant evidence for linkage was obtained in this region, with LOD scores > 3, assuming either homogeneity or heterogeneity. Flanking recombinants defined a critical region of 14 cM between D8S504 and D8S1458 which encompasses CLN8. This suggests that Turkish variant LINCL, despite having an earlier onset and more severe phenotype, may be an allelic variant of Northern epilepsy. However mutation analysis has not so far identified a disease causing mutation within the coding or non-coding exons of CLN8 in the families. The Turkish variant LINCL disease-causing mutation remains to be delineated.

Alleles↗
PubMed2001

Clinical and neuroradiological diagnostic aspects of neuronal ceroid lipofuscinoses disorders.

Early diagnosis is mandatory for avoiding further cases in families with hereditary metabolic brain disorders. This review lists the most important clinical symptoms and neuroradiological findings at the early stage of the seven most common childhood neuronal ceroid lipofuscinoses (NCL) types. In the infantile type the typical magnetic resonance imaging (MRI) findings can be seen even before the clinical signs. In the classic late infantile type (CLN2), MRI is less informative but in this and in the variant late infantile type CLN6 the characteristic neurophysiological findings are present at an early stage, although not in the Finnish variant CLN5. In the latter, the clinical diagnosis depends on ophthalmological and MRI findings. The combination of ophthalmological deficits and vacuolated lymphocytes is highly characteristic of the juvenile type (CLN3). A new NCL type, Northern epilepsy (CLN8), is also briefly reviewed.

Child↗
PubMed2001

Northern epilepsy syndrome (NES, CLN8)--MRI and electrophysiological studies.

Northern epilepsy syndrome (NES, EPMR, progressive epilepsy with mental retardation, CLN8), an inherited childhood-onset epilepsy with mental retardation, has been recently characterized to belong to the family of neuronal ceroid lipofuscinoses (NCLs). In this study, four patients (ages 26-44 years) with NES and eight healthy controls underwent magnetic resonance imaging (MRI) and electrophysiological evaluation with somatosensory evoked magnetic field (SEF) studies. The findings in NES were compared with the known findings in juvenile NCL (JNCL, CLN3) and Finnish variant late infantile NCL (vLINCLFIN, CLN5) that manifest around the same age as NES. Also postmortem MRI was performed on one brain. On the MRIs, slight to moderate cerebellar atrophy was seen in all patients, whereas only two patients had slightly enlarged cerebral sulci. None of the MRIs demonstrated signal intensity abnormalities that are commonly seen in JNCL and vLINCLFIN and are considered to reflect the Wallerian degeneration after neuronal death. Generally SEFs in NES were within normal limits, indicating that the disease had not impaired the function of the neurons on the somatosensory pathway. In conclusion, MRI imaging and SEF findings suggest that the cerebral neuronal death and dysfunction in NES are minimal compared with JNCL and vLINCLFIN.

Adult↗
PubMed2006

[The role of the ophthalmologist in the management of juvenile neuronal ceroid lipofuscinosis].

BACKGROUND: Neuronal ceroid lipofuscinoses (NCL) are storage diseases leading to severe somatic and mental deterioration with blindness and death. To date, there are no therapeutic options. Juvenile NCL (JNCL), also known as Batten's disease, is one of the most prevalent forms of NCL. MATERIALS AND METHODS: A 6-year-old boy with the primary diagnosis of retinitis pigmentosa was examined. The parents reported a rapid deterioration of vision during the past months. In view of this history, additional, non-ophthalmological diagnostic procedures have been performed (peripheral blood smear, molecular genetics). RESULTS: The eye examination showed a considerable reduction of visual acuity, a concentric visual field constriction, an extinguished electroretinogram and a bull's eye maculopathy. The peripheral blood smear revealed vacuolated lymphocytes. Molecular genetic investigation confirmed the diagnosis of juvenile NCL by detecting a homozygous (1-kb deletion of the CLN3-gene). CONCLUSIONS: The ophthalmologist plays a key role for an early diagnosis of juvenile NCL. An early diagnosis is important for the affected families because only then they can handle this stroke of fate.

Child↗
PubMed1997

Low molecular weight storage material in infantile ceroid lipofuscinosis (CLN1).

The identification of the genetic defect in CLN1 as a palmitoyl-protein thioesterase deficiency initiated a search for the lysosomal storage material. Pulse-chase labelling of fibroblasts and lymphoblastoid cell lines with [35S]cysteine revealed the presence of lipid [35S]cysteine material in CLN1 fibroblasts and not in controls, CLN2 or CLN3 patients or other patients with lipidosis. A single band comigrated with the acylcysteine standard and labelling with [3H]palmitate showed a band of material which eluted from the silicic acid column with the phospholipid fraction and which co-migrated with the lipid-[35S]cysteine band. The storage material is tentatively identified as palmitoylcysteine.

Adolescent↗
PubMed1997

DNA diagnosis and identification of carriers of infantile and juvenile neuronal ceroid lipofuscinoses.

The recent identification of the genes and the mutations underlying infantile neuronal ceroid lipofuscinosis and juvenile onset neuronal ceroid lipofuscinosis facilitates specific DNA-based diagnostics for the disorders. We have developed a solid-phase minisequencing test for the identification of the major Finnish INCL mutation, an A to T transversion at nucleotide position 364 of the palmitoyl protein thioesterase gene on chromosome 1. This test has been applied for prenatal diagnosis and for identification of disease carriers in INCL families. For population-based screening for INCL carriers the coverage of the test would be 98%. In addition, by combining the solid-phase minisequencing test with whole genome preamplification, we have developed a procedure that allows reliable identification of the INCLFin-mutation in single blastomeres from in-vitro-fertilized embryos. This method is applicable for preimplantation diagnosis, and thus it offers an alternative to early prenatal diagnosis in the prevention of INCL. A modification of the solid-phase minisequencing test was devised for detection of the major INCL mutation, a 1.02 kb deletion in the CLN3 gene on chromosome 16. The coverage of this test for diagnosis of INCL and identification of carriers is 90% in Finland and > 80% worldwide.

Adolescent↗
PubMed1997

The value of positron emission tomography in the diagnosis and monitoring of late infantile and juvenile lipopigment storage disorders (so-called Batten or neuronal ceroid lipofuscinoses).

Positron Emission Tomography (PET) with 2-deoxy-2 [18F]-fluoro-D-glucose provides a measure of functional brain activity, particularly in the dendritic field. In CLN3 (juvenile neuronal ceroid lipofuscinosis or juvenile Batten disease, with fingerprint inclusions) hypometabolism slowly spreads from calcarine to anterior areas, sparing subcortical structures and brainstem. In CLN2 (late infantile neuronal ceroid lipofuscinosis or Jansky-Bielschowsky disease, with curvilinear inclusions) degeneration is rapid with generalized cortical and subcortical hypometabolism. This is associated with rapidly progressive cerebral atrophy on anatomical neuroimaging. A 4-year-old child with CLN2 scanned with PET 13 months after the clinical onset showed hypometabolism, severe in the thalamus and mild in cortical areas. Three other patients with CLN2 had severe generalized hypometabolism and brain atrophy. Longitudinal PET studies in CLN may provide key insights into degenerative processes.

Blood Glucose↗
PubMed2001

Protein misfolding and temperature up-shift cause G1 arrest via a common mechanism dependent on heat shock factor in Saccharomycescerevisiae.

Accumulation of misfolded proteins in the cell at high temperature may cause entry into a nonproliferating, heat-shocked state. The imino acid analog azetidine 2-carboxylic acid (AZC) is incorporated into cellular protein competitively with proline and can misfold proteins into which it is incorporated. AZC addition to budding yeast cells at concentrations sufficient to inhibit proliferation selectively activates heat shock factor (HSF). We find that AZC treatment fails to cause accumulation of glycogen and trehalose (Msn2/4-dependent processes) or to induce thermotolerance (a protein kinase C-dependent process). However, AZC-arrested cells can accumulate glycogen and trehalose and can acquire thermotolerance in response to a subsequent heat shock. We find that AZC treatment arrests cells in a viable state and that this arrest is reversible. We find that cells at high temperature or cells deficient in the ubiquitin-conjugating enzymes Ubc4 and Ubc5 are hypersensitive to AZC-induced proliferation arrest. We find that AZC treatment mimics temperature up-shift in arresting cells in G1 and represses expression of CLN1 and CLN2. Mutants with reduced G1 cyclin-Cdc28 activity are hypersensitive to AZC-induced proliferation arrest. Expression of the hyperstable Cln3-2 protein prevents G1 arrest upon AZC treatment and temperature up-shift. Finally, we find that the EXA3-1 mutation, encoding a defective HSF, prevents efficient G1 arrest in response to both temperature up-shift and AZC treatment. We conclude that nontoxic levels of misfolded proteins (induced by AZC treatment or by high temperature) selectively activate HSF, which is required for subsequent G1 arrest.

Azetidinecarboxylic Acid↗
PubMed1996

The cyclin-dependent kinase inhibitor p40SIC1 imposes the requirement for Cln G1 cyclin function at Start.

In yeast, commitment to cell division (Start) is catalyzed by activation of the Cdc28 protein kinase in late G1 phase by the Cln1, Cln2, and Cln3 G1 cyclins. The Clns are essential, rate-limiting activators of Start because cells lacking Cln function (referred to as cln-) arrest at Start and because CLN dosage modulates the timing of Start. At or shortly after Start, the development of B-type cyclin Clb-Cdc28 kinase activity and initiation of DNA replication requires the destruction of p40SIC1, a specific inhibitor of the Clb-Cdc28 kinases. I report here that cln cells are rendered viable by deletion of SIC1. Conversely, in cln1 cln2 cells, which have low CLN activity, modest increases in SIC1 gene dosage cause inviability. Deletion of SIC1 does not cause a general bypass of Start since (cln-)sic1 cells remain sensitive to mating pheromone-induced arrest. Far1, a pheromone-activated inhibitor of Cln-Cdc28 kinases, is dispensable for arrest of (cln-)sic1 cells by pheromone, implying the existence of an alternate Far1-independent arrest pathway. These observations define a pheromone-sensitive activity able to catalyze Start only in the absence of p40SIC1. The existence of this activity means that the B-type cyclin inhibitor p40SIC1 imposes the requirement for Cln function at Start.

CDC28 Protein Kinase, S cerevisiae↗
PubMed1999

Phenotypic reversal of the btn1 defects in yeast by chloroquine: a yeast model for Batten disease.

BTN1 of Saccharomyces cerevisiae encodes an ortholog of CLN3, the human Batten disease gene. We have reported previously that deletion of BTN1, btn1-Delta, resulted in a pH-dependent resistance to D-(-)-threo-2-amino-1-[p-nitrophenyl]-1,3-propanediol (ANP). This phenotype was caused by btn1-Delta strains having an elevated ability to acidify growth medium through an elevated activity of the plasma membrane H(+)-ATPase, resulting from a decreased vacuolar pH during early growth. We have determined that growing btn1-Delta strains in the presence of chloroquine reverses the resistance to ANP, decreases the rate of medium acidification, decreases the activity of plasma membrane H(+)-ATPase, and elevates vacuolar pH. However, an additional effect of this phenotypic reversal is that activity of plasma membrane H(+)-ATPase is decreased further and vacuolar pH is increased further as btn1-Delta strains continue to grow. This phenotypic reversal of btn1-Delta can be considered for developing a therapy for Batten disease.

Chloroquine↗
PubMed2001

Transcript leader regions of two Saccharomyces cerevisiae mRNAs contain internal ribosome entry sites that function in living cells.

In higher eukaryotes, translation of some mRNAs occurs by internal initiation. It is not known, however, whether this mechanism is used to initiate the translation of any yeast mRNAs. In this report, we identify naturally occurring nucleotide sequences that function as internal ribosome entry sites (IRESes) within the 5' leader sequences of Saccharomyces cerevisiae YAP1 and p150 mRNAs. When tested in the 5' untranslated regions of monocistronic reporter genes, both leader sequences enhanced translation efficiency in vegetatively growing yeast cells. Moreover, when tested in the intercistronic region of dicistronic mRNAs, both sequences were shown to contain IRESes that functioned in living cells. The activity of the p150 leader was much greater than that of the YAP1 leader. The second cistron was not expressed in control dicistronic constructs that lacked these sequences or contained the 5' leader sequence of the CLN3 mRNA in the intercistronic region. Further analyses of the p150 IRES revealed that it contained several nonoverlapping segments that were able independently to mediate internal initiation. These results suggested a modular composition for the p150 IRES that resembled the composition of IRESes contained within some cellular mRNAs of higher eukaryotes. Both YAP1 and p150 leaders contain several complementary sequence matches to yeast 18S rRNA. The findings are discussed in terms of our understanding of internal initiation in higher eukaryotes.

5' Untranslated Regions↗
PubMed2001

The retinoblastoma family of proteins directly represses transcription in Saccharomyces cerevisiae.

The retinoblastoma family of proteins are key cell cycle regulatory molecules important for the differentiation of various mammalian cell types. The retinoblastoma protein regulates transcription of a variety of genes either by blocking the activation domain of various activators or by active repression via recruitment to appropriate promoters. We show here that the retinoblastoma family of proteins functions as direct transcriptional repressors in a heterologous yeast system when fused to the DNA binding domain of Gal4. Mapping experiments indicate that either the A or the B domain of the pocket region is sufficient for repression in vivo. As is the case in mammalian cells, a phosphorylation site mutant of the retinoblastoma protein is a stronger transcriptional repressor than the wild type protein. We show that transcriptional repression by pRb is dependent on CLN3 in vivo. Furthermore, the yeast histone deacetylase components, RPD3 and SIN3, are required for transcriptional repression.

Binding Sites↗
PubMed2004

Excess mannose limits the growth of phosphomannose isomerase PMI40 deletion strain of Saccharomyces cerevisiae.

Phosphomannose isomerase (PMI40) catalyzes the conversion between fructose 6-phosphate and mannose 6-phosphate and thus connects glycolysis, i.e. energy production and GDP-mannose biosynthesis or cell wall synthesis in Saccharomyces cerevisiae. After PMI40 deletion (pmi(-)) the cells were viable only if fed with extracellular mannose and glucose. In an attempt to force the GDP-mannose synthesis in the pmi(-) strain by increasing the extracellular mannose concentrations, the cells showed significantly reduced growth rates without any alterations in the intracellular GDP-mannose levels. To reveal the mechanisms resulting in reduced growth rates, we measured genome-wide gene expression levels, several metabolite concentrations, and selected in vitro enzyme activities in central metabolic pathways. The increasing of the initial mannose concentration led to an increase in the mannose 6-phosphate concentration, which inhibited the activity of the second enzyme in glycolysis, i.e. phosphoglucose isomerase converting glucose 6-phosphate to fructose 6-phosphate. As a result of this limitation, the flux through glycolysis was decreased as was the median expression of the genes involved in glycolysis. The expression levels of RAP1, a transcription factor involved in the regulation of the mRNA levels of several enzymes in glycolysis, as well as those of cell cycle regulators CDC28 and CLN3, decreased concomitantly with the growth rates and expression of many genes encoding for enzymes in glycolysis.

Allosteric Site↗
PubMed2006

Saccharomyces cerevisiae lacking Btn1p modulate vacuolar ATPase activity to regulate pH imbalance in the vacuole.

The vacuolar H(+)-ATPase (V-ATPase) along with ion channels and transporters maintains vacuolar pH. V-ATPase ATP hydrolysis is coupled with proton transport and establishes an electrochemical gradient between the cytosol and vacuolar lumen for coupled transport of metabolites. Btn1p, the yeast homolog to human CLN3 that is defective in Batten disease, localizes to the vacuole. We previously reported that Btn1p is required for vacuolar pH maintenance and ATP-dependent vacuolar arginine transport. We report that extracellular pH alters both V-ATPase activity and proton transport into the vacuole of wild-type Saccharomyces cerevisiae. V-ATPase activity is modulated through the assembly and disassembly of the V(0) and V(1) V-ATPase subunits located in the vacuolar membrane and on the cytosolic side of the vacuolar membrane, respectively. V-ATPase assembly is increased in yeast cells grown in high extracellular pH. In addition, at elevated extracellular pH, S. cerevisiae lacking BTN1 (btn1-Delta), have decreased V-ATPase activity while proton transport into the vacuole remains similar to that for wild type. Thus, coupling of V-ATPase activity and proton transport in btn1-Delta is altered. We show that down-regulation of V-ATPase activity compensates the vacuolar pH imbalance for btn1-Delta at early growth phases. We therefore propose that Btn1p is required for tight regulation of vacuolar pH to maintain the vacuolar luminal content and optimal activity of this organelle and that disruption in Btn1p function leads to a modulation of V-ATPase activity to maintain cellular pH homeostasis and vacuolar luminal content.

Adenosine Triphosphatases↗