Alpha-synuclein is one of a family of neuronal proteins with unknown cellular functions, and is centrally involved in neurodegeneration in Parkinson’s disease. In order to develop a genetically- and chemically-tractable system in which to study the functions of synucleins and their pathogenic roles in Parkinson’s disease, we cloned and characterized zebrafish synucleins. Zebrafish express three synuclein genes: sncg1 and sncg2, encoding γ1- and γ2-synucleins; and sncb, encoding β-synuclein. These genes show extensive conservation of sequence and genomic organization with respect to their human paralogues. Abundant sncb and sncg1 mRNA transcripts were expressed in the CNS from early development through adulthood, whereas sncg2 transcripts were detected in the notochord but not in the CNS. sncb was expressed prominently in the forebrain while sncg1 showed more robust expression in the hindbrain; both sncb and sncg1 were expressed in catecholaminergic neurons throughout the CNS. In contrast to mammals and other fish species, no evidence of a zebrafish α-synuclein orthologue was found; our analysis suggested that the genomic region containing an ancestral SNCA gene may have been deleted from the zebrafish genome during evolution. Transient abrogation of γ1- or β-synuclein expression during development, using morpholino oligonucleotides, did not result in any visible morphological abnormalities, CNS malformations, or alterations in the number or position of dopamine neurons. However nervous system functions were impaired after knockdown of either gene: abnormal locomotor behavior and alterations in catecholamine levels were observed in sncb- or sncg1-knockdown larvae compared with wild-type, control morpholino- or buffer-injected larvae. We conclude that zebrafish β- and γ1-synucleins have important functions in the physiology of catecholaminergic neurons; similar to the situation in rodents, zebrafish synucleins do not influence morphological development of the CNS. The zebrafish model will allow elucidation of the neuronal functions of synucleins, by exploiting the extensive molecular toolbox available for in vivo analyses . The absence of an α-synuclein orthologue from the zebrafish CNS may have important implications for the construction of zebrafish models of Parkinson’s disease.
Molecular and functional analysis of zebrafish synucleins
Milanese, Chiara;
2011-01-01
Abstract
Alpha-synuclein is one of a family of neuronal proteins with unknown cellular functions, and is centrally involved in neurodegeneration in Parkinson’s disease. In order to develop a genetically- and chemically-tractable system in which to study the functions of synucleins and their pathogenic roles in Parkinson’s disease, we cloned and characterized zebrafish synucleins. Zebrafish express three synuclein genes: sncg1 and sncg2, encoding γ1- and γ2-synucleins; and sncb, encoding β-synuclein. These genes show extensive conservation of sequence and genomic organization with respect to their human paralogues. Abundant sncb and sncg1 mRNA transcripts were expressed in the CNS from early development through adulthood, whereas sncg2 transcripts were detected in the notochord but not in the CNS. sncb was expressed prominently in the forebrain while sncg1 showed more robust expression in the hindbrain; both sncb and sncg1 were expressed in catecholaminergic neurons throughout the CNS. In contrast to mammals and other fish species, no evidence of a zebrafish α-synuclein orthologue was found; our analysis suggested that the genomic region containing an ancestral SNCA gene may have been deleted from the zebrafish genome during evolution. Transient abrogation of γ1- or β-synuclein expression during development, using morpholino oligonucleotides, did not result in any visible morphological abnormalities, CNS malformations, or alterations in the number or position of dopamine neurons. However nervous system functions were impaired after knockdown of either gene: abnormal locomotor behavior and alterations in catecholamine levels were observed in sncb- or sncg1-knockdown larvae compared with wild-type, control morpholino- or buffer-injected larvae. We conclude that zebrafish β- and γ1-synucleins have important functions in the physiology of catecholaminergic neurons; similar to the situation in rodents, zebrafish synucleins do not influence morphological development of the CNS. The zebrafish model will allow elucidation of the neuronal functions of synucleins, by exploiting the extensive molecular toolbox available for in vivo analyses . The absence of an α-synuclein orthologue from the zebrafish CNS may have important implications for the construction of zebrafish models of Parkinson’s disease.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
