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ABSTRACT: The oculocerebrorenal syndrome of Lowe (Lowe syndrome) is an X-linked disorder of phosphatidylinositol metabolism characterized
by congenital cataracts, renal proximal tubulopathy and neurological deficits. The disorder is due to the deficiency of the
phosphatidylinositol 4,5-bisphosphate (PIP2) 5-phosphatase, ocrl1. PIP2 is critical for numerous cellular processes, including cell signalling, actin reorganization and protein trafficking, and
is chronically elevated in patients with Lowe syndrome. The elevation of PIP2 cells of patients with Lowe syndrome provides the unique opportunity to investigate the roles of this phospholipid in fundamental
cellular processes. We previously demonstrated that ocrl1 deficiency causes alterations in the actin cytoskeleton. Since actin
remodelling is strongly activated by [Ca+2], which increases in response to IP3 production, we hypothesized that altered calcium signalling might contribute to the observed abnormalities in actin organization.
Here we report a specific increase in bradykinin-induced Ca+2 mobilization in Lowe fibroblasts. We show that the abnormal bradykinin signalling occurs in spite of normal total cellular
receptor content. These data point to a novel role for ocrl1 in agonist-induced calcium release.
Journal of Inherited Metabolic Disease 04/2012; 32(2):280-288. · 3.58 Impact Factor
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C F Lippa,
J E Duda,
M Grossman,
H I Hurtig,
D Aarsland,
B F Boeve,
D J Brooks,
D W Dickson,
B Dubois,
M Emre, [......],
J B Leverenz,
E Masliah,
I G McKeith, R L Nussbaum,
C W Olanow,
B M Ravina,
A B Singleton,
C M Tanner,
J Q Trojanowski,
Z K Wszolek
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ABSTRACT: For more than a decade, researchers have refined criteria for the diagnosis of dementia with Lewy bodies (DLB) and at the same time have recognized that cognitive impairment and dementia occur commonly in patients with Parkinson disease (PD). This article addresses the relationship between DLB, PD, and PD with dementia (PDD). The authors agreed to endorse "Lewy body disorders" as the umbrella term for PD, PDD, and DLB, to promote the continued practical use of these three clinical terms, and to encourage efforts at drug discovery that target the mechanisms of neurodegeneration shared by these disorders of alpha-synuclein metabolism. We concluded that the differing temporal sequence of symptoms and clinical features of PDD and DLB justify distinguishing these disorders. However, a single Lewy body disorder model was deemed more useful for studying disease pathogenesis because abnormal neuronal alpha-synuclein inclusions are the defining pathologic process common to both PDD and DLB. There was consensus that improved understanding of the pathobiology of alpha-synuclein should be a major focus of efforts to develop new disease-modifying therapies for these disorders. The group agreed on four important priorities: 1) continued communication between experts who specialize in PDD or DLB; 2) initiation of prospective validation studies with autopsy confirmation of DLB and PDD; 3) development of practical biomarkers for alpha-synuclein pathologies; 4) accelerated efforts to find more effective treatments for these diseases.
Neurology 04/2007; 68(11):812-9. · 8.31 Impact Factor
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ABSTRACT: An association between Gaucher disease and Parkinson disease has been demonstrated by the concurrence of Gaucher disease and parkinsonism in rare patients and the identification of glucocerebrosidase mutations in probands with sporadic Parkinson disease. Using a different and complementary approach, we describe 10 unrelated families of subjects with Gaucher disease where obligate or confirmed carriers of glucocerebrosidase mutations developed parkinsonism. These observations indicate that mutant glucocerebrosidase, even in heterozygotes, may be a risk factor for the development of parkinsonism. Understanding the relationship between altered glucocerebrosidase and the development of parkinsonian manifestations will provide insights into the genetics, pathogenesis, and treatment of Parkinson disease.
Journal of Medical Genetics 01/2005; 41(12):937-40. · 6.36 Impact Factor
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J Johnson,
S M Hague,
M Hanson,
A Gibson,
K E Wilson,
E W Evans,
A A Singleton,
A McInerney-Leo, R L Nussbaum,
D G Hernandez, [......],
B Ravina,
J Eerola,
R H Perry,
E Jaros,
P Tienari,
R Weiser,
K Gwinn-Hardy,
C M Morris,
J Hardy,
A B Singleton
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ABSTRACT: The authors recently have shown that triplication of the alpha-synuclein gene (SNCA) can cause Parkinson disease (PD) and diffuse Lewy body disease within the same kindred. The authors assessed 101 familial PD probands, 325 sporadic PD cases, 65 patients with dementia with Lewy bodies, and 366 neurologically normal control subjects for SNCA multiplication. The authors did not identify any subjects with multiplication of SNCA and conclude this mutation is a rare cause of disease.
Neurology 09/2004; 63(3):554-6. · 8.31 Impact Factor
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Cold Spring Harbor Symposia on Quantitative Biology 02/2003; 68:409-15.
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ABSTRACT: Mutations in the alpha-synuclein gene (SNCA) have been implicated in familial Parkinson's disease (PD) while certain polymorphic alleles at a microsatellite repeat, NACP-Rep1, located approximately 10 kb upstream of the gene, have been associated with sporadic PD. In order to study the regulation of the human alpha-synuclein gene, we performed a deletion analysis of 10.7 kb upstream of the translational start site, using the luciferase reporter assay in 293T cells and the neuroblastoma cell line SH-SY5Y. The shortest fragment, 400 bp upstream of the transcriptional start site, was sufficient for transcription in both cell lines. The other constructs led to variable expression levels, with some showing maximum expression and others showing nearly complete extinction of expression. An 880 bp fragment located approximately 10 kb upstream of the gene and containing the NACP-Rep1 polymorphism, was shown to be necessary for normal expression. Additional analysis of the NACP-Rep1 locus and surrounding DNA suggested that two domains flanking the repeat interact to enhance expression while the repeat acts as a negative modulator. Next, we measured the activity of the entire 10.7 kb upstream region in the luciferase reporter assay when each of our different NACP-Rep1 alleles were present. The expression levels varied very significantly among the different alleles over a 3-fold range in the SH-SY5Y cells but showed little or no significant variation in the 293T cells. Given that even small changes in alpha-synuclein expression may, over many decades, predispose to PD, the association of different NACP-Rep1 alleles with PD may be a consequence of polymorphic differences in transcriptional regulation of alpha-synuclein expression resulting from different NACP-Rep1 alleles.
Human Molecular Genetics 01/2002; 10(26):3101-9. · 7.64 Impact Factor
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ABSTRACT: Inpp5b is an ubiquitously expressed type II inositol polyphosphate 5-phosphatase. We have disrupted the Inpp5b gene in mice and found that homozygous mutant males are infertile. Here we examine the causes for the infertility in detail. We demonstrate that sperm from Inpp5b(-/-) males have reduced motility and reduced ability to fertilize eggs, although capacitation and acrosome exocytosis appear to be normal. In addition, fertilin beta, a sperm surface protein involved in sperm-egg membrane interactions that is normally proteolytically processed during sperm transit through the epididymis, showed reduced levels of processing in the Inpp5b(-/-) animals. Inpp5b was expressed in the Sertoli cells and epididymis and at low levels in the developing germ cells; however, mice lacking Inpp5b in spermatids and not in other cell types generated by conditional gene targeting, were fully fertile. The abnormalities in mutant sperm function and maturation appear to arise from defects in the functioning of Sertoli and epididymal epithelial cells. Our results directly demonstrate a previously unknown role for phosphoinositides in normal sperm maturation beyond their previously characterized involvement in the acrosome reaction. Inpp5b(-/-) mice provide an excellent model to study the role of Sertoli and epididymal epithelial cells in the differentiation and maturation of sperm.
Developmental Biology 01/2002; 240(2):641-53. · 4.07 Impact Factor
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ABSTRACT: alpha-Synuclein (alpha-Syn) is implicated in the pathogenesis of Parkinson's Disease, genetically through missense mutations linked to early onset disease and pathologically through its presence in Lewy bodies. alpha-Syn is phosphorylated on serine residues; however, tyrosine phosphorylation of alpha-Syn has not been established (, ). A comparison of the protein sequence between Synuclein family members revealed that all four tyrosine residues of alpha-Syn are conserved in all orthologs and beta-Syn paralogs described to date, suggesting that these residues may be of functional importance (). For this reason, experiments were performed to determine whether alpha-Syn could be phosphorylated on tyrosine residue(s) in human cells. Indeed, alpha-Syn is phosphorylated within 2 min of pervanadate treatment in alpha-Syn-transfected cells. Tyrosine phosphorylation occurs primarily on tyrosine 125 and was inhibited by PP2, a selective inhibitor of Src protein-tyrosine kinase (PTK) family members at concentrations consistent with inhibition of Src function (). Finally, we demonstrate that alpha-Syn can be phosphorylated directly both in cotransfection experiments using c-Src and Fyn expression vectors and in in vitro kinase assays with purified kinases. These data suggest that alpha-Syn can be a target for phosphorylation by the Src family of PTKs.
Journal of Biological Chemistry 03/2001; 276(6):3879-84. · 4.77 Impact Factor
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ABSTRACT: The human alpha-synuclein gene (SNCA) encodes a presynaptic nerve terminal protein that was originally identified as a precursor of the non-beta-amyloid component of Alzheimer's disease plaques. More recently, mutations in SNCA have been identified in some cases of familial Parkinson's disease, presenting numerous new areas of investigation for this important disease. Molecular studies would benefit from detailed information about the long-range sequence context of SNCA. To that end, we have established the complete genomic sequence of the chromosomal regions containing the human and mouse alpha-synuclein genes, with the objective of using the resulting sequence information to identify conserved regions of biological importance through comparative sequence analysis. These efforts have yielded approximately 146 and approximately 119 kb of high-accuracy human and mouse genomic sequence, respectively, revealing the precise genetic architecture of the alpha-synuclein gene in both species. A simple repeat element upstream of SNCA/Snca has been identified and shown to be necessary for normal expression in transient transfection assays using a luciferase reporter construct. Together, these studies provide valuable data that should facilitate more detailed analysis of this medically important gene.
Genome Research 02/2001; 11(1):78-86. · 13.61 Impact Factor
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ABSTRACT: Batten disease, the juvenile-onset form of neuronal ceroid lipofuscinosis (NCL), is a progressive neurodegenerative disorder of childhood with an age of onset of 5-10 years of age. JNCL is caused by mutations in the CLN3 gene which encodes a membrane protein of unknown function. Magnetic resonance imaging of the brain of juvenile NCL patients has revealed changes in signal intensity and tissue atrophy, predominantly in the cortex and cerebellum. A mouse model for Batten disease was created by targeted disruption of the murine Cln3 gene in order to further understanding of the pathophysiology of Batten disease and to evaluate potential therapeutic approaches. Several features of the disease are displayed by Cln3 mice including accumulation of characteristic storage material in neurons. The aim of this work was to investigate neurodegeneration in the Cln3 mouse model using high resolution magnetic resonance imaging to measure signal intensity ratios in selected regions of interest. Global changes were observed in the brains of 12-month-old mutant mice that mirror those seen in juvenile NCL patients. There is a decrease in signal intensity ratio in grey matter regions including cortex, hippocampus and cerebellum, tissues where neuronal storage accumulation and cell loss have been seen in the mouse model. The alterations seen in Cln3 mutant mice support the validity of further imaging studies and suggest that this method will have application in assessment of therapeutic approaches in the study of mutant mouse models of NCL including the Cln3 mouse.
European Journal of Paediatric Neurology 02/2001; 5 Suppl A:103-7. · 2.12 Impact Factor
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ABSTRACT: Vitamin C is known to exist in particularly high concentrations in brain tissue, and its free radical scavenging function is thought to represent a major antioxidative defense system. We have cloned, sequenced and analyzed the genomic structure of a mouse sodium-dependent vitamin C transporter gene, Slc23a1 (also known as Svct2). The mouse Slc23a1 cDNA is 6.4 kb long and was cloned directly from a mouse brain RNA preparation. Hybridization screening of a mouse genomic BAC library identified BAC 53L21 which contains at least the entire coding sequence of the mouse Slc23a1 gene. Determination of the exon-intron structure of the gene revealed 17 exons ranging from 58 bp to 4407 bp extending over 50 kb of the mouse genome, with the translation start codon located in exon 3. Its 1944 nucleotide open reading frame encodes a polypeptide of 647 aa, which is highly similar to rat and human orthologs. The mouse gene was assigned to chromosome 2qG2 by fluorescence in situ hybridization analysis. Expression of this gene was demonstrated in a wide range of tissues, with especially high levels in brain. Neurodegenerative diseases with an established role for oxidative stress in the cytoplasm may therefore be conditions of SLC23A1 dysfunction. Key words: gene structure; Vitamin C; transporter; oxidative stress
DNA Research 01/2001; 7(6):339-45. · 5.16 Impact Factor
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ABSTRACT: PtdIns(4,5)P(2) and PtdIns(4,5)P(2) 5-phosphatases play important roles in diverse aspects of cell metabolism, including protein trafficking. However, the relative importance of the PtdIns(4,5)P(2) 5-phosphatases in regulating PtdIns(4,5)P(2) levels for specific cell processes is not well understood. Ocrl1 is a PtdIns(4,5)P(2) 5-phosphatase that is deficient in the oculocerebrorenal syndrome of Lowe, a disorder characterized by defects in kidney and lens epithelial cells and mental retardation. Ocrl1 was originally localized to the Golgi in fibroblasts, but a subsequent report suggested a lysosomal localization in a kidney epithelial cell line. In this study we defined the localization of ocrl1 in fibroblasts and in two kidney epithelial cell lines by three methods: immunofluorescence, subcellular fractionation, and a dynamic perturbation assay with brefeldin A. We found that ocrl1 was a Golgi-localized protein in all three cell types and further identified it as a protein of the trans-Golgi network (TGN). The TGN is a major sorting site and has the specialized function in epithelial cells of directing proteins to the apical or basolateral domains. The epithelial cell phenotype in Lowe syndrome and the localization of ocrl1 to the TGN imply that this PtdIns(4,5)P(2) 5-phosphatase plays a role in trafficking. (J Histochem Cytochem 48:179-189, 2000)
Journal of Histochemistry and Cytochemistry 03/2000; 48(2):179-90. · 2.72 Impact Factor
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H M Mitchison,
D J Bernard,
N D Greene,
J D Cooper,
M A Junaid,
R K Pullarkat,
N de Vos,
M H Breuning,
J W Owens,
W C Mobley,
R M Gardiner,
B D Lake,
P E Taschner, R L Nussbaum
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ABSTRACT: Batten disease, a degenerative neurological disorder with juvenile onset, is the most common form of the neuronal ceroid lipofuscinoses. Mutations in the CLN3 gene cause Batten disease. To facilitate studies of Batten disease pathogenesis and treatment, a murine model was created by targeted disruption of the Cln3 gene. Mice homozygous for the disrupted Cln3 allele had a neuronal storage disorder resembling that seen in Batten disease patients: there was widespread and progressive intracellular accumulation of autofluorescent material that by EM displayed a multilamellar rectilinear/fingerprint appearance. Inclusions contained subunit c of mitochondrial ATP synthase. Mutant animals also showed neuropathological abnormalities with loss of certain cortical interneurons and hypertrophy of many interneuron populations in the hippocampus. Finally, as is true in Batten disease patients, there was increased activity in the brain of the lysosomal protease Cln2/TPP-1. Our findings are evidence that the Cln3-deficient mouse provides a valuable model for studying Batten disease.
Neurobiology of Disease 11/1999; 6(5):321-34. · 5.40 Impact Factor
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ABSTRACT: Phosphatidylinositol 3,4,5-trisphosphate is a phospholipid signaling molecule involved in many cellular functions including growth factor receptor signaling, cytoskeletal organization, chemotaxis, apoptosis, and protein trafficking. Phosphorylation at the 3 position of the inositol ring is catalyzed by many different 3-kinases (classified as types IA, IB, II, and III), but the physiological roles played by each of the different 3-kinase isozymes during embryonic development and in homeostasis in animals is incompletely understood. Mammalian type IA kinase isozymes are heterodimers that are active at 37 degrees C when the catalytic 110-kDa subunit interacts through an amino-terminal binding domain with a regulatory 85- or 55-kDa subunit. Using gene targeting in embryonic stem cells, we deleted this binding domain in the gene encoding the alpha isoform of the 110-kDa catalytic subunit (Pik3ca) of the alpha isozyme of the type IA kinases, leading to loss of expression of the p110 catalytic subunit. We show that Pik3cadel/del embryos are developmentally delayed at embryonic day (E) 9.5 and die between E9.5 and E10.5. E9. 5 Pik3cadel/del embryos have a profound proliferative defect but no increase in apoptosis. A proliferative defect is supported by the observation that fibroblasts from Pik3cadel/del embryos fail to replicate in Dulbecco's modified Eagle's medium and fetal calf serum, even with supplemental growth factors.
Journal of Biological Chemistry 05/1999; 274(16):10963-8. · 4.77 Impact Factor
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ABSTRACT: JNCL is a neurodegenerative disease of childhood caused by mutations in the CLN3 gene. A mouse model for JNCL was created by disrupting exons 1-6 of Cln3, resulting in a null allele. Cln3 null mice appear clinically normal at 5 months of age; however, like JNCL patients, they exhibit intracellular accumulation of autofluorescent material. A second approach will generate mice in which exons 7 and 8 of Cln3 are deleted, mimicking the common mutation in JNCL patients.
Molecular Genetics and Metabolism 05/1999; 66(4):309-13. · 3.19 Impact Factor
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ABSTRACT: To determine the sensitivity and specificity of ocular examination for the carrier state of Lowe syndrome in females known to be either carriers or noncarriers by direct DNA diagnosis.
Nonrandomized cohort study.
Thirty-one females at risk for carrying Lowe syndrome in 3 families.
Slit-lamp biomicroscopy after pupillary dilation was performed by a single observer (RAL) who was masked as to carrier status as determined by allele-specific detection of mutations in genomic DNA.
Carrier assessment predetermined by slit-lamp biomicroscopic examination yielded only one false-negative in a young girl 5 years of age and no false-positives among 31 female members examined.
Slit-lamp examination is a highly accurate and sensitive test for carrier detection in Lowe syndrome, particularly in women of reproductive age.
Ophthalmology 02/1999; 106(1):119-22. · 5.45 Impact Factor
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ABSTRACT: The cytoplasmic face of the Golgi contains a variety of proteins with coiled-coil domains. We identified one such protein in a yeast two-hybrid screen, using as bait the peripheral Golgi phosphatidylinositol(4,5)P2 5-phosphatase OCRL1 that is implicated in a human disease, the oculocerebrorenal syndrome. The approximately 2.8-kilobase mRNA is ubiquitously expressed and abundant in testis; it encodes a 731-amino acid protein with a predicted mass of 83 kDa. Antibodies against the sequence detect a novel approximately 84-kDa Golgi protein we termed golgin-84. Golgin-84 is an integral membrane protein with a single transmembrane domain close to its C terminus. In vitro, the protein inserts post-translationally into microsomal membranes with an N-cytoplasmic and C-lumen orientation. Cross-linking indicates that golgin-84 forms dimers, consistent with the prediction of an approximately 400-residue dimerizing coiled-coil domain in its N terminus. The dimerization potential is supported by a data base search that showed that the N-terminal 497 residues of golgin-84 contain a coiled-coil domain that when fused to the RET tyrosine kinase domain had the ability to activate it, forming the RET-II oncogene. Data base searching also indicates golgin-84 is similar in structure and sequence to giantin, a membrane protein that tethers coatamer complex I vesicles to the Golgi.
Journal of Biological Chemistry 02/1999; 274(5):2953-62. · 4.77 Impact Factor
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C Lavedan,
S Buchholtz,
G Auburger,
R L Albin,
A Athanassiadou,
J Blancato,
J A Burguera,
R E Ferrell,
V Kostic,
E Leroy, [......],
L Mota-Vieira,
T Papapetropoulos,
M A Pericak-Vance,
J Pinkus,
W K Scott,
G Ulm,
J Vasconcelos,
J J Vilchez, R L Nussbaum,
M H Polymeropoulos
DNA Research 01/1999; 5(6):401-2. · 5.16 Impact Factor
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ABSTRACT: The oculocerebrorenal syndrome of Lowe (OCRL) is a rare X-linked disorder with a severe phenotype characterized by congenital cataracts, renal tubular dysfunction and neurological deficits. The gene has been characterized and mutations have been identified in patients. Owing to the allelic heterogeneity exhibited by this gene, prenatal diagnosis by molecular analysis is limited to families in which the mutation is already known or in which linkage is informative. A more generally applicable diagnostic test would be valuable for families at risk for Lowe syndrome. Since ocrl1 is now known to encode a phosphatidylinositol 4,5-bisphosphate 5-phosphatase (Ptdlns(4,5)P2 phosphatase), we assessed whether biochemical testing could be used for prenatal diagnosis. We report here the first case of prenatal diagnosis for Lowe syndrome by measuring phosphatidylinositol 4,5-bisphosphate 5-phosphatase activity in cultured amniocytes.
Prenatal Diagnosis 12/1998; 18(11):1117-21. · 2.11 Impact Factor
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ABSTRACT: A missense mutation in the human alpha synuclein gene was recently identified in some cases of familial Parkinson's disease (FPD). We have developed an antibody that recognizes the C-terminal 12 amino acids of the human alpha synuclein protein and have demonstrated that alpha synuclein is an abundant component of the Lewy bodies found within the degenerating neurons of patients with Parkinson's disease (PD). The presence of alpha synuclein in Lewy bodies of sporadic PD patients suggests a central role for alpha synuclein in the pathogenesis of PD.
Molecular Psychiatry 12/1998; 3(6):493-9. · 13.67 Impact Factor
