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‣ Identification of CANT1 Mutations in Desbuquois Dysplasia

Huber, Céline; Oulès, Bénédicte; Bertoli, Marta; Chami, Mounia; Fradin, Mélanie; Alanay, Yasemin; Al-Gazali, Lihadh I.; Ausems, Margreet G.E.M.; Bitoun, Pierre; Cavalcanti, Denise P.; Krebs, Alexander; Le Merrer, Martine; Mortier, Geert; Shafeghati,
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 13/11/2009 Português
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368.96324%
Desbuquois dysplasia is a severe condition characterized by short stature, joint laxity, scoliosis, and advanced carpal ossification with a delta phalanx. Studying nine Desbuquois families, we identified seven distinct mutations in the Calcium-Activated Nucleotidase 1 gene (CANT1), which encodes a soluble UDP-preferring nucleotidase belonging to the apyrase family. Among the seven mutations, four were nonsense mutations (Del 5′ UTR and exon 1, p.P245RfsX3, p.S303AfsX20, and p.W125X), and three were missense mutations (p.R300C, p.R300H, and p.P299L) responsible for the change of conserved amino acids located in the seventh nucleotidase conserved region (NRC). The arginine substitution at position 300 was identified in five out of nine families. The specific function of CANT1 is as yet unknown, but its substrates are involved in several major signaling functions, including Ca2+ release, through activation of pyrimidinergic signaling. Importantly, using RT-PCR analysis, we observed a specific expression in chondrocytes. We also found electron-dense material within distended rough endoplasmic reticulum in the fibroblasts of Desbuquois patients. Our findings demonstrate the specific involvement of a nucleotidase in the endochondral ossification process.

‣ Mutations in the SPTLC2 Subunit of Serine Palmitoyltransferase Cause Hereditary Sensory and Autonomic Neuropathy Type I

Rotthier, Annelies; Auer-Grumbach, Michaela; Janssens, Katrien; Baets, Jonathan; Penno, Anke; Almeida-Souza, Leonardo; Van Hoof, Kim; Jacobs, An; De Vriendt, Els; Schlotter-Weigel, Beate; Löscher, Wolfgang; Vondráček, Petr; Seeman, Pavel; De Jonghe, Pe
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 08/10/2010 Português
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368.96324%
Hereditary sensory and autonomic neuropathy type I (HSAN-I) is an axonal peripheral neuropathy associated with progressive distal sensory loss and severe ulcerations. Mutations in the first subunit of the enzyme serine palmitoyltransferase (SPT) have been associated with HSAN-I. The SPT enzyme catalyzes the first and rate-limiting step in the de novo sphingolipid synthesis pathway. However, different studies suggest the implication of other genes in the pathology of HSAN-I. Therefore, we screened the two other known subunits of SPT, SPTLC2 and SPTLC3, in a cohort of 78 HSAN patients. No mutations were found in SPTLC3, but we identified three heterozygous missense mutations in the SPTLC2 subunit of SPT in four families presenting with a typical HSAN-I phenotype. We demonstrate that these mutations result in a partial to complete loss of SPT activity in vitro and in vivo. Moreover, they cause the accumulation of the atypical and neurotoxic sphingoid metabolite 1-deoxy-sphinganine. Our findings extend the genetic heterogeneity in HSAN-I and enlarge the group of HSAN neuropathies associated with SPT defects. We further show that HSAN-I is consistently associated with an increased formation of the neurotoxic 1-deoxysphinganine, suggesting a common pathomechanism for HSAN-I.

‣ Prodynorphin Mutations Cause the Neurodegenerative Disorder Spinocerebellar Ataxia Type 23

Bakalkin, Georgy; Watanabe, Hiroyuki; Jezierska, Justyna; Depoorter, Cloë; Verschuuren-Bemelmans, Corien; Bazov, Igor; Artemenko, Konstantin A.; Yakovleva, Tatjana; Dooijes, Dennis; Van de Warrenburg, Bart P.C.; Zubarev, Roman A.; Kremer, Berry; Knapp, P
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Publicado em 12/11/2010 Português
Relevância na Pesquisa
368.96324%
Spinocerebellar ataxias (SCAs) are dominantly inherited neurodegenerative disorders characterized by progressive cerebellar ataxia and dysarthria. We have identified missense mutations in prodynorphin (PDYN) that cause SCA23 in four Dutch families displaying progressive gait and limb ataxia. PDYN is the precursor protein for the opioid neuropeptides, α-neoendorphin, and dynorphins A and B (Dyn A and B). Dynorphins regulate pain processing and modulate the rewarding effects of addictive substances. Three mutations were located in Dyn A, a peptide with both opioid activities and nonopioid neurodegenerative actions. Two of these mutations resulted in excessive generation of Dyn A in a cellular model system. In addition, two of the mutant Dyn A peptides induced toxicity above that of wild-type Dyn A in cultured striatal neurons. The fourth mutation was located in the nonopioid PDYN domain and was associated with altered expression of components of the opioid and glutamate system, as evident from analysis of SCA23 autopsy tissue. Thus, alterations in Dyn A activities and/or impairment of secretory pathways by mutant PDYN may lead to glutamate neurotoxicity, which underlies Purkinje cell degeneration and ataxia. PDYN mutations are identified in a small subset of ataxia families...