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Combi R, Grioni D, Contri M, Redaelli S, Redaelli F, Bassi MT, Barisani D, Lavitrano ML, Tredici G, Tenchini ML, Bertolini M, Dalprà L. Clinical and genetic familial study of a large cohort of Italian children with idiopathic epilepsy. Brain Res Bull 2009; 79:89-96. [PMID: 19200853 DOI: 10.1016/j.brainresbull.2009.01.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Revised: 12/19/2008] [Accepted: 01/16/2009] [Indexed: 12/13/2022]
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Crimella C, Arnoldi A, Crippa F, Mostacciuolo ML, Boaretto F, Sironi M, D'Angelo MG, Manzoni S, Piccinini L, Turconi AC, Toscano A, Musumeci O, Benedetti S, Fazio R, Bresolin N, Daga A, Martinuzzi A, Bassi MT. Point mutations and a large intragenic deletion in SPG11 in complicated spastic paraplegia without thin corpus callosum. J Med Genet 2009; 46:345-51. [PMID: 19196735 DOI: 10.1136/jmg.2008.063321] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
BACKGROUND Hereditary spastic paraplegia (HSP) with thin corpus callosum (HSP-TCC) is a frequent subtype of complicated HSP clinically characterised by slowly progressive spastic paraparesis with cognitive impairment and thin corpus callosum (TCC). SPG11, the gene associated with the major locus involved, encodes spatacsin, a protein of unknown function. METHODS Different types of mutations were identified in patients with the complex form of HSP (cHSP) including TCC. We screened a series of 45 index patients with different types of cHSP with (n = 10) and without (n = 35) TCC. RESULTS Ten mutations, of which five are novel, were detected in seven patients. Of importance, three out of seven mutated patients present with cHSP without TCC. Among the novel mutations identified, we characterised a large intragenic rearrangement deleting 2.6 kb of the SPG11 gene. The rearrangement is due to non-allelic homologous recombination between Alu sequences flanking the breakpoints. CONCLUSIONS These findings expand the mutation spectrum of SPG11 and suggest that SPG11 mutations may occur more frequently in familial than sporadic forms of cHSP without TCC. This helps to define further clinical and molecular criteria for a correct diagnosis of the SPG11 related form of cHSP. In addition, the intragenic deletion detected here, and the mechanism involved, both provide clues to address the issue of SPG11 missing mutant alleles previously reported.
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Revenkova E, Focarelli ML, Susani L, Paulis M, Bassi MT, Mannini L, Frattini A, Delia D, Krantz I, Vezzoni P, Jessberger R, Musio A. Cornelia de Lange syndrome mutations in SMC1A or SMC3 affect binding to DNA. Hum Mol Genet 2009; 18:418-27. [PMID: 18996922 PMCID: PMC2722190 DOI: 10.1093/hmg/ddn369] [Citation(s) in RCA: 82] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2008] [Accepted: 11/04/2008] [Indexed: 01/09/2023] Open
Abstract
Cornelia de Lange syndrome (CdLS) is a clinically heterogeneous developmental disorder characterized by facial dysmorphia, upper limb malformations, growth and cognitive retardation. Mutations in the sister chromatid cohesion factor genes NIPBL, SMC1A and SMC3 are present in approximately 65% of CdLS patients. In addition to their canonical roles in chromosome segregation, the cohesin proteins are involved in other biological processes such as regulation of gene expression, DNA repair and maintenance of genome stability. To gain insights into the molecular basis of CdLS, we analyzed the affinity of mutated SMC1A and SMC3 hinge domains for DNA. Mutated hinge dimers bind DNA with higher affinity than wild-type proteins. SMC1A- and SMC3-mutated CdLS cell lines display genomic instability and sensitivity to ionizing radiation and interstrand crosslinking agents. We propose that SMC1A and SMC3 CdLS mutations affect the dynamic association between SMC proteins and DNA, providing new clues to the underlying molecular cause of CdLS.
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Riano E, Martignoni M, Mancuso G, Cartelli D, Crippa F, Toldo I, Siciliano G, Di Bella D, Taroni F, Bassi MT, Cappelletti G, Rugarli EI. Pleiotropic effects of spastin on neurite growth depending on expression levels. J Neurochem 2009; 108:1277-88. [PMID: 19141076 DOI: 10.1111/j.1471-4159.2009.05875.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Hereditary spastic paraplegia (HSP) is characterized by weakness and spasticity of the lower limbs, owing to degeneration of corticospinal axons. The most common form is due to heterozygous mutations in the SPG4 gene, encoding spastin, a microtubule (MT)-severing protein. Here, we show that neurite growth in immortalized and primary neurons responds in pleiotropic ways to changes in spastin levels. Spastin depletion alters the development of primary hippocampal neurons leading to abnormal neuron morphology, dystrophic neurites, and axonal growth defects. By live imaging with End-Binding Protein 3-Fluorescent Green Protein (EB3-GFP), a MT plus-end tracking protein, we ascertained that the assembly rate of MTs is reduced when spastin is down-regulated. Spastin over-expression at high levels strongly suppresses neurite maintenance, while slight spastin up-regulation using an endogenous promoter enhances neurite branching and elongation. Spastin severing activity is exerted preferentially on stable acetylated and detyrosinated MTs. We further show that SPG4 nonsense or splice site mutations found in hereditary spastic paraplegia patients result in reduced spastin levels, supporting haploinsufficiency as the molecular cause of the disease. Our study reveals that SPG4 is a dosage-sensitive gene, and broadens the understanding of the role of spastin in neurite growth and MT dynamics.
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Del Bo R, Moggio M, Rango M, Bonato S, D'Angelo MG, Ghezzi S, Airoldi G, Bassi MT, Guglieri M, Napoli L, Lamperti C, Corti S, Federico A, Bresolin N, Comi GP. Mutated mitofusin 2 presents with intrafamilial variability and brain mitochondrial dysfunction. Neurology 2008; 71:1959-66. [PMID: 18946002 DOI: 10.1212/01.wnl.0000327095.32005.a4] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND The axonal forms of Charcot-Marie-Tooth (CMT2) disease are a clinically and genetically heterogeneous group of disorders. Mitofusin 2 gene (MFN2) mutations are the most common cause of CMT2. Complex phenotypes have been described in association with MFN2 gene mutations, including CMT2 with pyramidal features (hereditary motor and sensory neuropathy [HSMN V]) and CMT2 with optic atrophy (HMSN VI). OBJECTIVE To report on the clinical, neurophysiologic, and neuropathologic features of an Italian family with a novel MFN2 gene mutation and investigate brain functional parameters using magnetic resonance spectroscopy (MRS). METHODS Three family members, a father and his two sons, were affected by peripheral neuropathy, cognitive impairment, and poor nocturnal vision (also optic neuropathy in one case). A member of this family also showed spastic paraparesis. The MFN2 gene sequence was analyzed. A sural nerve biopsy as well as brain (1)H-MRS and (31)P-MRS were evaluated in two patients. RESULTS Affected family members carried a novel MFN2 missense mutation, namely R104W, located within the critical GTPase domain of the protein which affects a highly conserved amino acid position. Sural nerve biopsies showed a normal mitochondrial network, particularly at the nodes of Ranvier, upon electron microscopy examination. A significant defect of high energy phosphates (HEPs) in the visual cortex was observed at rest by (31)P-MRS in the adult proband, while his son showed a defective recovery of HEPs after stimulation of the visual cortex. CONCLUSION Cognitive impairment may be another feature of the MFN2-related phenotype. The widespread peripheral and CNS involvement, as well as the neurosensorial defects, underline the similarities among MFN2-related and primary mitochondrial disorders.
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Cafforio G, Calabrese R, Morelli N, Mancuso M, Piazza S, Martinuzzi A, Bassi MT, Crippa F, Siciliano G. The first Italian family with evidence of pyramidal impairment as phenotypic manifestation of Silver syndrome BSCL2 gene mutation. Neurol Sci 2008; 29:189-91. [PMID: 18612770 DOI: 10.1007/s10072-008-0937-y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 05/30/2008] [Indexed: 10/21/2022]
Abstract
Silver syndrome (SPG17) is a rare form of hereditary spastic paraparesis. Its relationship to distal hereditary motor neuropathy (dHMN) type V is underlined by the recent discovery of causative mutation in BSCL2 gene coding for a protein termed seipin, an integral membrane protein of endoplasmic reticulum, with unknown function. Here we report the third Italian family with dHMN and SPG17 in which two affected members harbor the heterozygous N88S mutation in the BSCL2 gene. The proband developed a severe paraparetic spastic gait, while, in the other Italian families reported so far, no signs of upper motor neuron involvement were observed. This family confirms the clinical heterogeneity associated with this specific mutation. Moreover, this is the first report in which neuroimaging seems to confirm the pyramidal alterations in dHMN associated to SPG17.
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De Palma C, Falcone S, Panzeri C, Radice S, Bassi MT, Clementi E. Endothelial nitric oxide synthase overexpression by neuronal cells in neurodegeneration: a link between inflammation and neuroprotection. J Neurochem 2008; 106:193-204. [PMID: 18422522 DOI: 10.1111/j.1471-4159.2008.05351.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The roles of neuronal and inducible nitric oxide synthases in neurones have been extensively investigated; by contrast, the biological significance of endothelial nitric oxide synthase (eNOS) overexpression that occurs in several pathological conditions has not yet been studied. We have started addressing this issue in a cell model of neurodegeneration, i.e. human SKNBE neuroblastoma cells transfected with a mutant form of alsin, a protein causing an early-onset type of amyotrophic lateral sclerosis, ALS2. We found that eNOS, which is endogenously expressed by these cells, was activated by tumour necrosis factor-alpha (TNF-alpha), a proinflammatory cytokine that plays important roles in ALS2 and several neurodegenerative diseases. The TNF-alpha-dependent eNOS activation occurred through generation, by sphingosine-kinase-1, of sphingosine-1-phosphate, stimulation of its membrane receptors and activation of Akt, as determined using small interference RNA and dominant negative constructs specific for the enzymes and receptors. eNOS activation by TNF-alpha conferred cytoprotection from excitotoxicity and neurotoxic cues such as reactive oxygen species, endoplasmic reticulum stress, DNA damage, and mutated alsin itself. Our results suggest that overexpression of eNOS by neurones is a broad-range protective mechanism activated during damage and establish a link of pathophysiological relevance between this enzyme and inflammation accompanying neurodegenerative diseases. These findings also question the concept that high NO output in the presence of oxidative stress leads always to peroxynitrite formation contributing to neurodegeneration.
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Zucca C, Redaelli F, Epifanio R, Zanotta N, Romeo A, Lodi M, Veggiotti P, Airoldi G, Panzeri C, Romaniello R, De Polo G, Bonanni P, Cardinali S, Baschirotto C, Martorell L, Borgatti R, Bresolin N, Bassi MT. Cryptogenic epileptic syndromes related to SCN1A: twelve novel mutations identified. ACTA ACUST UNITED AC 2008; 65:489-94. [PMID: 18413471 DOI: 10.1001/archneur.65.4.489] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Sodium channel alpha 1 subunit gene, SCN1A, is the gene encoding the neuronal voltage-gated sodium channel alpha 1 subunit (Na(v)1.1) and is mutated in different forms of epilepsy. Mutations in this gene were observed in more than 70% of patients with severe myoclonic epilepsy of infancy (SMEI) and were also found in different types of infantile epileptic encephalopathy. OBJECTIVE To search for disease-causing mutations in SCN1A in patients with cryptogenic epileptic syndromes (ie, syndromes with an unknown cause). DESIGN Clinical characterization and molecular genetic analysis of a cohort of patients. SETTING University hospitals, rehabilitation centers, and molecular biology laboratories. PATIENTS Sixty unrelated patients with cryptogenic epileptic syndromes. MAIN OUTCOME MEASURES Samples of DNA were analyzed for mutations and for large heterozygous deletions encompassing the SCN1A gene. A search for microdeletions in the SCN1A gene was also performed in the subset of patients with SMEI/SMEI-borderland who had negative results at the point mutation screening. RESULTS No large deletions at the SCN1A locus were found in any of the patients analyzed. In contrast, 13 different point mutations were identified in 12 patients: 10 with SMEI, 1 with generalized epilepsy with febrile seizures plus, and 1 with cryptogenic focal epilepsy. An additional search for SCN1A intragenic microdeletions in the remaining patients with SMEI/SMEI-borderland and no point mutations was also negative. CONCLUSIONS These results confirm the role of the SCN1A gene in different types of epilepsy, including cryptogenic epileptic syndromes. However, large deletions encompassing SCN1A were not common disease-causing rearrangements in this group of epilepsies.
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Arnoldi A, Tonelli A, Crippa F, Villani G, Pacelli C, Sironi M, Pozzoli U, D'Angelo MG, Meola G, Martinuzzi A, Crimella C, Redaelli F, Panzeri C, Renieri A, Comi GP, Turconi AC, Bresolin N, Bassi MT. A clinical, genetic, and biochemical characterization of SPG7 mutations in a large cohort of patients with hereditary spastic paraplegia. Hum Mutat 2008; 29:522-31. [PMID: 18200586 DOI: 10.1002/humu.20682] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mutations in the SPG7 gene encoding a mitochondrial protein termed paraplegin, are responsible for a recessive form of hereditary spastic paraparesis. Only few studies have so far been performed in large groups of hereditary spastic paraplegia (HSP) patients to determine the frequency of SPG7 mutations. Here, we report the result of a mutation screening conducted in a large cohort of 135 Italian HSP patients with the identification of six novel point mutations and one large intragenic deletion. Sequence analysis of the deletion breakpoint, together with secondary structure predictions of the deleted region, indicate that a complex rearrangement, likely caused by extensive secondary structure formation mediated by the short interspersed nuclear element (SINE) retrotransposons, is responsible for the deletion event. Biochemical studies performed on fibroblasts from three mutant patients revealed mild and heterogeneous mitochondrial dysfunctions that would exclude a specific association of a complex I defect with the pathology at the fibroblast level. Overall, our data confirm that SPG7 point mutations are rare causes of HSP, in both sporadic and familial forms, while underlying the puzzling and intriguing aspects of histological and biochemical consequences of paraplegin loss.
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85
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Sztriha L, Panzeri C, Kálmánchey R, Szabó N, Endreffy E, Túri S, Baschirotto C, Bresolin N, Vekerdy Z, Bassi MT. First case of compound heterozygosity in ALS2 gene in infantile-onset ascending spastic paralysis with bulbar involvement. Clin Genet 2008; 73:591-3. [PMID: 18394004 DOI: 10.1111/j.1399-0004.2008.00993.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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Tonelli A, Gallanti A, Bersano A, Cardin V, Ballabio E, Airoldi G, Redaelli F, Candelise L, Bresolin N, Bassi MT. Amino acid changes in the amino terminus of the Na,K-adenosine triphosphatase alpha-2 subunit associated to familial and sporadic hemiplegic migraine. Clin Genet 2007; 72:517-23. [PMID: 17877748 DOI: 10.1111/j.1399-0004.2007.00892.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Familial hemiplegic migraine (FHM) is a rare subtype of migraine with aura inherited with an autosomal dominant pattern. Here, we report the genetic analysis of four families and one sporadic case with hemiplegic migraine (HM) in whom we searched for mutations in the three genes associated with the disease CACNA1A, ATP1A2 and SCN1A. Two novel amino acid changes p.Arg65Trp and p.Tyr9Asn, in the Na,K-adenosine triphosphatase (ATPase) alpha-2 subunit encoded by the ATP1A2 gene, were found in one FHM family and in the sporadic case, respectively. These mutations are peculiar for their location in the extreme N-terminus, an uncommon mutation target in this protein. Low frequency of migraine attacks in all our mutant patients with low complexity of the associated aura symptoms in the sporadic case is also observed. Besides the two novel mutations, the data here reported confirm the involvement of ATP1A2 gene in the sporadic form of HM, while the negative results on the other families tested for all genes known in HM strengthen the hypothesis of the existence of at least another locus involved in FHM.
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Ferrentino R, Bassi MT, Chitayat D, Tabolacci E, Meroni G. MID1 mutation screening in a large cohort of Opitz G/BBB syndrome patients: twenty-nine novel mutations identified. Hum Mutat 2007; 28:206-7. [PMID: 17221865 DOI: 10.1002/humu.9480] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Opitz G/BBB Syndrome (OS) is a multiple congenital anomaly disorder characterized by defects along the body midline. The disease is characterized by variable expressivity of signs that include hypertelorism, cleft lip and/or palate, laryngo-tracheo-esophageal abnormalities, cardiac defects, and hypospadias. OS patients also present with mental retardation and brain anatomical abnormalities. An autosomal dominant form mapping to chromosome 22 and an X-linked form of OS are known. The gene responsible for the X-linked form of OS, MID1, codes for a member of the Tripartite Motif family of E3 ubiquitin ligases. Here we report 29 novel mutations in 29 unrelated patients of a cohort of 140 male OS cases. These mutations are found in both familial and sporadic cases. They are scattered along the entire length of the gene and are represented by missense and nonsense mutations, insertions and deletions causing frame shift mutations, and deletion of either single exons or the entire gene. The variety of the mutations found confirms that loss-of-function is the mechanism underlying the OS phenotype. Moreover, the low percentage of MID1-mutated OS patients, 47% of the familial and 13% of the sporadic cases, suggests a wider genetic heterogeneity underlying the OS phenotype.
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Piccinelli P, Borgatti R, Nicoli F, Calcagno P, Bassi MT, Quadrelli M, Rossi G, Lanzi G, Balottin U. Relationship between migraine and epilepsy in pediatric age. Headache 2006; 46:413-21. [PMID: 16618257 DOI: 10.1111/j.1526-4610.2006.00373.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
OBJECTIVE Many studies have supported the hypothesis of alteration of cortical hyperexcitability as a possible pathological mechanism underlying the onset of migraine and epileptic attacks. Different biochemical pathways involving cellular structures may increase or decrease the excitability of neuronal membranes. The aim of this study was to identify a possible link between migraine and epilepsy from a clinical and neurophysiologic point of view. METHODS One-hundred thirty-seven children and adolescents consecutively diagnosed for tension-type headache and idiopathic migraine with and without aura were studied. Anamnestic, clinical, and instrumental data were collected by a neurological examination, a specific questionnaire, and awake electroencephalogram (EEG) registrations. EEG features of nonheadache and nonseizures control group were compared. RESULTS Fourteen cases (10.2%) had a positive history for seizures with fever, isolated seizures, or epilepsy. Distribution differed according to headache diagnosis; migraine with aura (MWA) was largely prevalent. Specific electroencephalographic abnormalities were present in 11.7% of the sample, with a significant different distribution across the groups of children with headache and the control group: specific interictal abnormalities were found in 10 of 23 (43.5%) children with MWA. Two factors, seizures and specific interictal electroencephalographic abnormalities, showed a different distribution in patients with MWA compared to other classes of headache and control group (P < or = .01). CONCLUSION The present study supports the hypothesis of a possible clinical continuum between some types of MWA and epileptic syndromes as entities due to altered neuronal excitability with similar genetic substrates.
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Crippa F, Panzeri C, Martinuzzi A, Arnoldi A, Redaelli F, Tonelli A, Baschirotto C, Vazza G, Mostacciuolo ML, Daga A, Orso G, Profice P, Trabacca A, D'Angelo MG, Comi GP, Galbiati S, Lamperti C, Bonato S, Pandolfo M, Meola G, Musumeci O, Toscano A, Trevisan CP, Bresolin N, Bassi MT. Eight novel mutations in SPG4 in a large sample of patients with hereditary spastic paraplegia. ACTA ACUST UNITED AC 2006; 63:750-5. [PMID: 16682546 DOI: 10.1001/archneur.63.5.750] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
BACKGROUND Hereditary spastic paraplegia (HSP) is a group of genetically heterogeneous disorders characterized by progressive spasticity of the lower limbs. Mutations in the SPG4 gene, which encodes spastin protein, are responsible for up to 45% of autosomal dominant cases. OBJECTIVE To search for disease-causing mutations in a large series of Italian patients with HSP. DESIGN Samples of DNA were analyzed by direct sequencing of all exons in SPG4. Samples from a subset of patients were also analyzed by direct sequencing of all exons in SPG3A, SPG6, SPG10, and SPG13. SETTING Molecular testing facility in Italy. PATIENTS Sixty unrelated Italian patients with pure (n = 50) and complicated (n = 10) HSP. MAIN OUTCOME MEASURES Mutations in SPG4, SPG3A, SPG6, SPG10, and SPG13. RESULTS We identified 12 different mutations, 8 of which were novel, in 13 patients. No mutations of any of the other HSP genes tested were found in 15 patients with sporadic pure HSP who did not have mutations in the SPG4 gene. CONCLUSIONS The overall rate of mutation in the SPG4 gene within our sample was 22%, rising to 26% when only patients with pure HSP were considered. The negative result obtained in 15 patients without mutations in SPG4 in whom 4 other genes were analyzed (SPG3A, SPG6, SPG10, and SPG13) indicate that these genes are not frequently mutated in sporadic pure HSP.
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Bedeschi MF, Bonaglia MC, Grasso R, Pellegri A, Garghentino RR, Battaglia MA, Panarisi AM, Di Rocco M, Balottin U, Bresolin N, Bassi MT, Borgatti R. Agenesis of the corpus callosum: clinical and genetic study in 63 young patients. Pediatr Neurol 2006; 34:186-93. [PMID: 16504787 DOI: 10.1016/j.pediatrneurol.2005.08.008] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/26/2005] [Revised: 02/22/2005] [Accepted: 08/02/2005] [Indexed: 11/29/2022]
Abstract
This study reports the clinical features of 63 patients with agenesis of the corpus callosum who received in-depth genetic, clinical, and laboratory testing with the aim to contribute to a better description of the large spectrum of associated malformations and to assist clinicians in the diagnosis. Thirty patients manifested complete agenesis and 33 patients displayed partial agenesis. Other associated nervous system malformations were detected in 14 patients with partial agenesis of the corpus callosum (mostly correlated to posterior fossa malformations) and in 10 patients with complete agenesis (more frequently associated with malformations of cortical development). Involvement of organs and apparatus other than the nervous system was present in 41 patients (ascribed to known syndromes in 21 cases). Cytogenetically detectable chromosomal abnormalities (7 patients) and subtelomeric rearrangements (3 patients) were found. Neuromotor skills were impaired in almost all cases (58/63). Mental retardation of different severity was present in 52 cases, whereas 2 patients were borderline and 9 patients had normal intelligence quotient. This study demonstrates that there is no unique prognosis for agenesis of the corpus callosum as this condition is associated with a broad range of clinical manifestations, oscillating between the limits of the norm and severe psychomotor delay.
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91
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Tonelli A, D'Angelo MG, Salati R, Villa L, Germinasi C, Frattini T, Meola G, Turconi AC, Bresolin N, Bassi MT. Early onset, non fluctuating spinocerebellar ataxia and a novel missense mutation in CACNA1A gene. J Neurol Sci 2005; 241:13-7. [PMID: 16325861 DOI: 10.1016/j.jns.2005.10.007] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2005] [Revised: 09/28/2005] [Accepted: 10/03/2005] [Indexed: 10/25/2022]
Abstract
Mutations in the brain-specific P/Q type Ca2+ channel alpha1 subunit gene, CACNA1A, have been identified in three clinically distinct disorders, spinocerebellar ataxia type 6 (SCA6), episodic ataxia type 2 (EA2), and familial hemiplegic migraine type 1 (FHM1). SCA6 is associated with small expansions of a CAG repeat at the 3' end of the gene, while point mutations are mostly responsible for its two allelic disorders, FHMI and EA2. From the electrophysiological point of view, while FHMI mutations lead to a gain of function [Tottene A, Fellin T, Pagnutti S, Luvisetto S, Striessnig J, Fletcher C, et al. Familial hemiplegic migraine mutations increase Ca2+ influx through single human CaV2.1 channels and decrease maximal CaV2.1 current density in neurons. Proc Natl Acad Sci 99 (20) (2002) 13284-13289.], EA2 mutations usually generate a loss of channel function [Guida S, Trettel F, Pagnutti S, Mantuano E, Tottene A, Veneziano L, et al. Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2. Am J Hum Genet 68 (3) (2001) 759-764, Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 277 (9) (2002) 6960-6966.]. In the present study, we describe a child affected by permanent non-fluctuating limb and trunk ataxia with a quite early age of onset. Interestingly, the size of the CACNA1A triplet repeat region in the patient is within the normal range while he carries a novel de novo missense mutation in this gene, p.R1664Q. Although functional data are not available, based on the literature data indicating that severe reductions in P/Q-type channel activity favour episodic and/or progressive ataxic symptoms [Wappl E, Koschak A, Poteser M, Sinnegger MJ, Walter D, Eberhart A, et al. Functional consequences of P/Q-type Ca2+ channel Cav2.1 missense mutations associated with episodic ataxia type 2 and progressive ataxia. J Biol Chem 2002;277(9):6960-6966.], we hypothesize that the functional consequence of the mutation here identified is a partial loss of the Ca channel function. In conclusion, the clinical and molecular findings reported here suggest the opportunity to screen for point mutation in this gene, even patients with a clinical phenotype for some aspects slightly different from the typical picture more commonly associated to SCA6, EA2 or FHM1 diseases.
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Bassi MT, Manzoni M, Bresciani R, Pizzo MT, Della Monica A, Barlati S, Monti E, Borsani G. Cellular expression and alternative splicing of SLC25A23, a member of the mitochondrial Ca2+-dependent solute carrier gene family. Gene 2005; 345:173-82. [PMID: 15716113 DOI: 10.1016/j.gene.2004.11.028] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2004] [Revised: 09/27/2004] [Accepted: 11/17/2004] [Indexed: 11/24/2022]
Abstract
The transport of metabolites across the inner mitochondrial membrane is mediated by a large superfamily of mitochondrial solute carrier (MSC) proteins. A novel human member of the MSC gene family named SLC25A23, with homologs in mammalian and non-mammalian species has been recently identified together with two close paralogs, SLC25A24 and SLC25A25. These genes encode the human isoforms of the ATP-Mg/Pi carrier described in whole mitochondria. We report here the cellular expression and alternative splicing of SLC25A23. The gene encodes a 468 amino acids polypeptide, named SCaMC-3, with a bipartite structure typical of calcium-binding mitochondrial solute carrier (CaMSC) proteins. The amino-terminal portion harbors three canonical EF-hand calcium-binding domains while the carboxyl-terminal portion of SCaMC-3 has the characteristic features of the MSC superfamily. Northern blot analysis reveals the presence of the transcript in brain, heart, skeletal muscle, liver and small intestine. The SLC25A23 gene undergoes alternative splicing suggesting a modular nature of the encoded product. Three out of four putative protein isoforms lack a significant portion of the third mitochondrial carrier signature. The most common SCaMC-3 isoform shows a mitochondrial subcellular localization when transfected in HeLa cells and is able to bind calcium by Ca(2+)-dependent mobility shift assays. We believe that our study will contribute to a better knowledge of this family of mitochondrial carriers.
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Borgatti R, Zucca C, Cavallini A, Ferrario M, Panzeri C, Castaldo P, Soldovieri MV, Baschirotto C, Bresolin N, Dalla Bernardina B, Taglialatela M, Bassi MT. A novel mutation in KCNQ2 associated with BFNC, drug resistant epilepsy, and mental retardation. Neurology 2004; 63:57-65. [PMID: 15249611 DOI: 10.1212/01.wnl.0000132979.08394.6d] [Citation(s) in RCA: 117] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
BACKGROUND Benign familial neonatal convulsion (BFNC) is a rare autosomal dominant disorder caused by mutations in two genes, KCNQ2 and KCNQ3, encoding for potassium channel subunits underlying the M-current. This current limits neuronal hyperexcitability by causing spike-frequency adaptation. METHODS The authors describe a BFNC family with four affected members: two of them exhibit BFNC only while the other two, in addition to BFNC, present either with a severe epileptic encephalopathy or with focal seizures and mental retardation. RESULTS All affected members of this family carry a novel missense mutation in the KCNQ2 gene (K526N), disrupting the tri-dimensional conformation of a C-terminal region of the channel subunit involved in accessory protein binding. When heterologously expressed in CHO cells, potassium channels containing mutant subunits in homomeric or heteromeric configuration with wild-type KCNQ2 and KCNQ3 subunits exhibit an altered voltage-dependence of activation, without changes in intracellular trafficking and plasma membrane expression. CONCLUSION The KCNQ2 K526N mutation may affect M-channel function by disrupting the complex biochemical signaling involving KCNQ2 C-terminus. Genetic rather than acquired factors may be involved in the pathophysiology of the phenotypic variability of the neurologic symptoms associated with BFNC in the described family.
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94
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Bassi MT, Bresolin N, Tonelli A, Nazos K, Crippa F, Baschirotto C, Zucca C, Bersano A, Dolcetta D, Boneschi FM, Barone V, Casari G. A novel mutation in the ATP1A2 gene causes alternating hemiplegia of childhood. J Med Genet 2004; 41:621-8. [PMID: 15286158 PMCID: PMC1735877 DOI: 10.1136/jmg.2003.017863] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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95
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Pineda M, Font M, Bassi MT, Manzoni M, Borsani G, Marigo V, Fernández E, Río RMD, Purroy J, Zorzano A, Nunes V, Palacín M. The amino acid transporter asc-1 is not involved in cystinuria. Kidney Int 2004; 66:1453-64. [PMID: 15458438 DOI: 10.1111/j.1523-1755.2004.00908.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND The human amino acid transporter asc-1 (SLC7A10) exhibits substrate selectivity for small neutral amino acids, including cysteine, is expressed in kidney, is located close to the cystinuria B gene and presents sequence variants (e.g., E112D) in some cystinuria patients. We have cloned human asc-1, assessed its transport characteristics, localized its expression in kidney, searched for mutations in cystinuria patients, and tested the transport function of variant E112D. METHODS We used an EST-based homology cloning strategy. Transport characteristics of asc-1 were assessed by coexpression with 4F2hc in Xenopus oocytes and HeLa cells. Localization of asc-1 mRNA in kidney was assessed by in situ hybridization. Exons and intron-exon boundaries were polymerase chain reaction (PCR)-amplified from blood cell DNA and mutational screening was performed by single-stranded conformational polymorphism (SSCP). RESULTS Asc-1 reaches the plasma membrane in HeLa cells, unlike in oocytes, most probably by interaction with endogenous 4F2hc and presents similar transport characteristics to those in oocytes coexpressing asc-1/4F2hc. Asc-1 mediates a substantial efflux of alanine in a facilitated diffusion mode of transport. Expression of asc-1 mRNA localized to Henle's loop, distal tubules, and collecting ducts. Finally, SLC7A10 polymorphisms were identified in cystinuria probands and the SLC7A10 sequence variant E112D showed full transport activity. CONCLUSION The lack of expression of asc-1 in the proximal tubule indicates that it plays no role in the bulk of renal reabsorption of amino acids. No mutations causing cystinuria have been found in SLC7A10. The facilitated diffusion mode of transport and the expression in distal nephron suggest a role for asc-1 in osmotic adaptation.
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96
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Manzoni M, Monti E, Bresciani R, Bozzato A, Barlati S, Bassi MT, Borsani G. Overexpression of wild-type and mutant mucolipin proteins in mammalian cells: effects on the late endocytic compartment organization. FEBS Lett 2004; 567:219-24. [PMID: 15178326 DOI: 10.1016/j.febslet.2004.04.080] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2003] [Revised: 04/23/2004] [Accepted: 04/24/2004] [Indexed: 01/24/2023]
Abstract
Mucolipin-1 is a 65-kDa membrane protein encoded by the MCOLN1 gene, which is mutated in patients with mucolipidosis type IV (MLIV), a rare neurodegenerative lysosomal storage disorder. We studied the subcellular localization of wild-type and three different mutant forms (T232P, F408del and F465L) of mucolipin by expressing Myc-tagged proteins in HeLa cells. The overexpressed wild-type mucolipin colocalizes to late endocytic structures and induces an aberrant distribution of these compartments. F408del and F465L MLIV mutant proteins show a distribution similar to the wild-type protein, whereas T232P is retained in the endoplasmic reticulum. Among the mutants, only F408del induces a redistribution of the late endocytic compartment. These findings suggest that the overexpression of the mucolipin cation channel influences the dynamic equilibrium of late endocytic compartments.
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Monti E, Bassi MT, Bresciani R, Civini S, Croci GL, Papini N, Riboni M, Zanchetti G, Ballabio A, Preti A, Tettamanti G, Venerando B, Borsani G. Molecular cloning and characterization of NEU4, the fourth member of the human sialidase gene family. Genomics 2004; 83:445-53. [PMID: 14962670 DOI: 10.1016/j.ygeno.2003.08.019] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2003] [Revised: 05/14/2003] [Accepted: 08/18/2003] [Indexed: 11/30/2022]
Abstract
Several mammalian sialidases have been cloned so far and here we describe the identification and expression of a new member of the human sialidase gene family. The NEU4 gene, identified by searching sequence databases for entries showing homologies to the human cytosolic sialidase NEU2, maps in 2q37 and encodes a 484-residue protein. The polypeptide contains all the typical sialidase amino acid motifs and, apart from an amino acid stretch that appears unique among mammalian sialidases, shows a high degree of homology for NEU2 and the plasma membrane-associated (NEU3) sialidases. RNA dot-blot analysis showed a low but wide expression pattern, with the highest level in liver. Transient transfection in COS7 cells allowed the detection of a sialidase activity toward the artificial substrate 4MU-NeuAc in the acidic range of pH. Immunofluorescence staining and Western blot analysis demonstrated the association of NEU4 with the inner cell membranes.
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98
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Dalpozzo F, Rossetto MG, Boaretto F, Sartori E, Mostacciuolo ML, Daga A, Bassi MT, Martinuzzi A. Infancy onset hereditary spastic paraplegia associated with a novel atlastin mutation. Neurology 2003; 61:580-1. [PMID: 12939451 DOI: 10.1212/01.wnl.0000078189.73611.df] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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99
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Purandare SM, Ware SM, Kwan KM, Gebbia M, Bassi MT, Deng JM, Vogel H, Behringer RR, Belmont JW, Casey B. A complex syndrome of left-right axis, central nervous system and axial skeleton defects in Zic3 mutant mice. Development 2002; 129:2293-302. [PMID: 11959836 DOI: 10.1242/dev.129.9.2293] [Citation(s) in RCA: 133] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
X-linked heterotaxy (HTX1) is a rare developmental disorder characterized by disturbances in embryonic laterality and other midline developmental field defects. HTX1 results from mutations in ZIC3, a member of the GLI transcription factor superfamily. A targeted deletion of the murine Zic3 locus has been created to investigate its function and interactions with other molecular components of the left-right axis pathway. Embryonic lethality is seen in approximately 50% of null mice with an additional 30% lethality in the perinatal period. Null embryos have defects in turning, cardiac development and neural tube closure. Malformations in live born null mice include complex congenital heart defects, pulmonary reversal or isomerism, CNS defects and vertebral/rib anomalies. Investigation of nodal expression in Zic3-deficient mice indicates that, although nodal is initially expressed symmetrically in the node, there is failure to maintain expression and to shift to asymmetric expression. Subsequent nodal and Pitx2 expression in the lateral plate mesoderm in these mice is randomized, indicating that Zic3 acts upstream of these genes in the determination of left-right asymmetry. The phenotype of these mice correctly models the defects found in human HTX1 and indicates an important role for Zic3 in both left-right and axial patterning.
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Bassi MT, Gasol E, Manzoni M, Pineda M, Riboni M, Martín R, Zorzano A, Borsani G, Palacín M. Identification and characterisation of human xCT that co-expresses, with 4F2 heavy chain, the amino acid transport activity system xc-. Pflugers Arch 2001; 442:286-96. [PMID: 11417227 DOI: 10.1007/s004240100537] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
We have identified a new human complementary deoxyribonucleic acid (cDNA), for the xc- amino acid transporter (HGMW-approved name SLC7A11; also known as human xCT), that, when co-expressed with the heavy chain of surface antigen 4F2 (4F2hc, also termed CD98), but not with rBAT, (related to the bo,+ amino acid transporter), induces system xc- transport activity in Xenopus oocytes. Human xCT is the seventh human member of the family of amino acid transporters that are subunits of 4F2hc or rBAT and, inview of its amino acid sequence identity (89%) with mouse xCT, is most probably the human orthologue thereof. The amino acid transport activity induced by the co-expression of human 4F2hc and xCT in Xenopus oocytes was sodium independent and specific for L-cystine, L-glutamate and L-aspartate. This activity also functioned in an exchange mode (e.g. cystine/glutamate) with a substrate stoichiometry of 1:1. Expression of human xCT alone in oocytes did not induce amino acid transport activity and the expressed xCT protein was localised intracellularly. When human xCT was co-expressed with 4F2hc, the former localised to the oocyte plasma membrane. Tissue-expression studies showed that human SLC7A11 mRNA is expressed mainly in the brain, but also in pancreas and in cultured cell lines. The transport characteristics of human xCT and the distribution of its tissue expression strongly suggest that it corresponds to the human amino acid transporter system xc-.
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