Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0917816 (mental retardation)
 15,867 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Neuronal ceroid lipofuscinoses (NCLs) are a group of childhood-onset neurodegenerative disorders characterized by accumulation of autofluorescent lipopigment in many tissues, especially in neurons. Mutations in the CLN8 gene underlie Northern epilepsy (progressive epilepsy with mental retardation [EPMR], OMIM 600143) and a subset of Turkish variant late infantile NCL, but the pathogenetic mechanisms have remained elusive. The CLN8 transmembrane protein is an endoplasmic reticulum (ER) resident protein that recycles between ER and ER-Golgi intermediate compartment (ERGIC) in non-neuronal cells. To explore the disease mechanisms, we have characterized the neuronal localization of wild-type CLN8 protein as well as CLN8 proteins representing patient mutations. Semliki Forest virus-mediated CLN8 protein localized in the ER of mouse hippocampal primary neurons when compared to subcellular markers by immunofluorescence analysis. We also analyzed the possible polarized targeting of CLN8 and observed basolateral targeting in polarized epithelial CaCo-2 cells, suggesting that CLN8 may locate outside the ER or in a specialized subcompartment of the ER. We were not able, however, to demonstrate differential distribution of CLN8 between axons and dendrites of neurons. Fractionation of mouse brain tissue indicated that endogenous mouse Cln8 is observed in light membrane fractions, different from ER, which further suggested differential localization for CLN8 in polarized cells. The disease mutations did not affect intracellular localization of CLN8 in non-neuronal or neuronal cells. Consequently, there is no obvious genotype-phenotype correlation at the level of protein localization and thus mutations most likely directly affect functionally important domains of CLN8.
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PMID:Localization of wild-type and mutant neuronal ceroid lipofuscinosis CLN8 proteins in non-neuronal and neuronal cells. 1516 Mar 97

Progressive epilepsy with mental retardation, EPMR, belongs to a group of inherited neurodegenerative disorders, the neuronal ceroid lipofuscinoses. The CLN8 gene that underlies EPMR encodes a novel transmembrane protein that localizes to the endoplasmic reticulum (ER) and ER-Golgi intermediate compartment. Recently, CLN8 was linked to a large eukaryotic protein family of TLC (TRAM, Lag1, CLN8) domain homologues with postulated functions in lipid synthesis, transport or sensing. By using liquid chromatography/mass spectrometry we analysed molecular species of major phosholipid and simple sphingolipid classes from cerebral samples of two EPMR patients representing a progressive and advanced state of the disease. The progressive state brain showed reduced levels of ceramide, galactosyl- and lactosylceramide and sulfatide as well as a decrease in long fatty acyl chain containing molecular species within these classes. Among glycerophospholipid classes, an increase in species containing polyunsaturated acyl chains was detected especially in phosphatidylserines and phosphatidylethanolamines. By contrast, saturated and monounsaturated species were overrepresented among phosphatidylserine, phosphatidylethanolamine and phosphatidylinositol classes in the advanced state sample. The observed changes in brain sphingo- and phospholipid molecular profiles may result in altered membrane stability, lipid peroxidation, vesicular trafficking or neurotransmission and thus may contribute to the progression of the molecular pathogenesis of EPMR.
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PMID:Mass spectrometric analysis reveals changes in phospholipid, neutral sphingolipid and sulfatide molecular species in progressive epilepsy with mental retardation, EPMR, brain: a case study. 1608 86

The late-infantile-onset forms of neuronal ceroid lipofuscinosis (LINCL) are the most genetically heterogeneous group among the autosomal recessive neuronal ceroid lipofuscinoses (NCLs), with causative mutations found in CLN1, CLN2, CLN5, CLN6, CLN7 (MFSD8), and CLN8 genes. Homozygous mutations in CLN8 are associated with two distinct phenotypes: progressive epilepsy and mental retardation (EPMR), first identified in Finland; and a variant of late-infantile NCL (v-LINCL) described in a subset of Turkish and Italian patients. The function of the protein encoded by CLN8 is currently unknown. Here we report the identification of an Italian v-LINCL patient with a complete isodisomy of chromosome 8, leading to homozygosity of a maternally-inherited 3-bp deletion in CLN8 gene (c.180_182delGAA, p.Lys61del). Notably, uniparental disomy (UPD) has never been described associated with the NCLs. In addition, we provide evidence of the biological role of CLN8 characterized by expressing in different neuronal cell models the native protein, the protein carrying the mutation identified here, or three additional missense mutations previously described. Our results, validated through a gene silencing approach, indicate that CLN8 plays a role in cell proliferation during neuronal differentiation and in protection against cell death.
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PMID:A novel CLN8 mutation in late-infantile-onset neuronal ceroid lipofuscinosis (LINCL) reveals aspects of CLN8 neurobiological function. 1943 Nov 84

The neuronal ceroid lipofuscinoses (NCLs) are a group of inherited lysosomal storage diseases and the prototype of childhood onset neurodegenerative disorders. To date, 10 NCL entities (CLN1-CLN10) are known and characterized by accumulation of autofluorescent storage material, age of onset and clinical symptoms. CLN8 was first identified as the causative gene for a late-onset form with progressive epilepsy and mental retardation in Finnish patients. In addition, CLN8 phenotypes were described in Turkish, Israeli and Italian patients with a more rapid progression of visual loss, epilepsy, ataxia and mental decline. Here, we report the first mutations in German (c.611G>T) and Pakistani (c.709G>A) patients. Our findings confirm previous assumptions that the CLN8 variant can occur in many ethnic groups. So far, large CLN gene deletions are only known for the CLN3 gene. Here, we also describe a novel, large CLN8 gene deletion c.544-2566_590del2613 in a Turkish family with a slightly more severe phenotype. Our data indicate that patients with clinical signs of late infantile NCL and characteristic ultrastructural inclusions should also be screened for CLN8 mutations independent of their ethnic origin.
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PMID:Novel CLN8 mutations confirm the clinical and ethnic diversity of late infantile neuronal ceroid lipofuscinosis. 1980 37

The neuronal ceroid lipofuscinoses (NCLs) are clinically and genetically heterogeneous neurodegenerative disorders. Most are autosomal recessively inherited. Clinical features include a variable age of onset, motor and mental decline, epilepsy, visual loss, and premature death. Mutations in eight genes (PPT1/CLN1, TPP1/CLN2, CLN3, CLN5, CLN6, MFSD8/CLN7, CLN8) have been identified and several more are predicted to exist, including two provisionally named CLN4 and CLN9. Despite excessive in vitro and in vivo studies, the precise functions of the NCL proteins and the disease mechanisms remain elusive. To date 365 NCL-causing mutations are known, with 91 novel disease-causing mutations reported. These are reviewed with an emphasis on their complex correlation to phenotypes. Different mutations within the NCL spectrum can cause variable disease severity. The NCLs exemplify both phenotypic convergence or mimicry and phenotypic divergence. For example, mutations in CLN5, CLN6, MFSD8, or CLN8 can underlie the clinically similar late infantile variant NCL disease. Phenotypic divergence is exemplified by different CLN8 mutations giving rise to two very different diseases, the mild CLN8 disease, EPMR (progressive epilepsy with mental retardation), and the more severe CLN8 disease, late infantile variant. The increase in the genetic understanding of the NCLs has led to improved diagnostic approaches, and the recent proposal of a new nomenclature.
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PMID:Update of the mutation spectrum and clinical correlations of over 360 mutations in eight genes that underlie the neuronal ceroid lipofuscinoses. 2199 Jan 11

Neuronal ceroid lipofuscinoses (NCLs) are a genetically heterogeneous group of neurodegenerative diseases characterized by cognitive and motor decline, epilepsy, visual loss and by lysosomal autofluorescent inclusions. Two distinct clinical phenotypes, the progressive epilepsy with mental retardation (EPMR) and a late-infantile variant of NCLs (CLN8-vLINCL) are associated with mutations in the CLN8 gene that encodes a transmembrane protein predominantly located to the endoplasmic reticulum (ER). To gain insight into the function of CLN8 protein, we employed the split-ubiquitin membrane-based yeast two-hybrid (MYTH) system, which detects protein-protein interactions in a membrane environment, using the full-length human CLN8 as bait and a human brain cDNA library as prey. We identified several potential protein partners of CLN8 and especially referred to VAPA, c14orf1/hERG28, STX8, GATE16, BNIP3 and BNIP3L proteins that are associated with biologically relevant processes such as synthesis and transport of lipids, vesicular/membrane trafficking, autophagy/mitophagy and apoptosis. Interactions of CLN8 with VAPA and GATE16 were further validated by co-immunoprecipitation and co-localization assays in mammalian cells. Using a new C-terminal-oriented CLN8 antibody, CLN8-VAPA interaction was also confirmed by co-staining in close spatial proximity within different CNS tissues. The results of this study shed light on potential interactome networks of CLN8 and provide a powerful starting point for understanding protein function(s) and molecular aspects of diseases associated with CLN8 deficiency.
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PMID:Identifying protein partners of CLN8, an ER-resident protein involved in neuronal ceroid lipofuscinosis. 2314 42


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