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A functional misexpression screen uncovers a role for enabled in progressive neurodegeneration.

Rezával C, Berni J, Gorostiza EA, Werbajh S, Fagilde MM, Fernández MP, Beckwith EJ, Aranovich EJ, Sabio y García CA, Ceriani MF - PLoS ONE (2008)

Bottom Line: One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain.Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant.Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Genética del Comportamiento, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas-Buenos Aires (IIB-BA, CONICET), Buenos Aires, Argentina.

ABSTRACT
Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenerative mechanisms. One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain. Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant. Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor. Thus, this mutant recapitulates two important features of human neurodegenerative diseases, i.e., vulnerability of certain neuronal populations and progressive degeneration, offering a unique scenario in which to unravel the specific mechanisms in an easily tractable organism.

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ena down-regulation correlates with progressive cell death.(A) Quantitative analysis of apoptotic cell death in adult brains of increasing age as indicated in the figure. A representative image of the extent of cell death in 30 day-old flies of the indicated genotypes is shown in the inset (upper corner, left). Twenty to fifty brain hemispheres were analyzed in each time point with exception of 30 day-old elav>APP (n = 11). The degree of apoptosis in the affected individuals is significantly different from a wild type control (* p<0.05, ** p<0.001). (B–C) Degenerative phenotypes associated to enarev are rescued by p35 expression. (B) Frontal sections at approximately the same depth of aged control and elav>enarev, p35 brains highlight the extent of the morphological rescue. The asterisk denotes a region where small vacuoles can still be found in one of the few brains in which the rescue was not complete. (C) Functional rescue of ena- derived behavioral phenotypes. Representative actograms of old pdf>enarev, p35 and control lines are included (left panel). The percentage of rhythmic individuals is also shown (right panel, * p<0.05).
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pone-0003332-g007: ena down-regulation correlates with progressive cell death.(A) Quantitative analysis of apoptotic cell death in adult brains of increasing age as indicated in the figure. A representative image of the extent of cell death in 30 day-old flies of the indicated genotypes is shown in the inset (upper corner, left). Twenty to fifty brain hemispheres were analyzed in each time point with exception of 30 day-old elav>APP (n = 11). The degree of apoptosis in the affected individuals is significantly different from a wild type control (* p<0.05, ** p<0.001). (B–C) Degenerative phenotypes associated to enarev are rescued by p35 expression. (B) Frontal sections at approximately the same depth of aged control and elav>enarev, p35 brains highlight the extent of the morphological rescue. The asterisk denotes a region where small vacuoles can still be found in one of the few brains in which the rescue was not complete. (C) Functional rescue of ena- derived behavioral phenotypes. Representative actograms of old pdf>enarev, p35 and control lines are included (left panel). The percentage of rhythmic individuals is also shown (right panel, * p<0.05).

Mentions: Reduced ena levels correlated with positive TUNEL staining in the larval brain; however young adult flies did not develop behavioral or anatomical defects. During metamorphosis the development of novel neuronal clusters and connections could generate a new architecture susceptible to ena down-regulation, which only in time would display such defects. In control brains a minimum level of TUNEL staining was observed scattered throughout the brain, which did not significantly increase in older flies (Fig. 7A). However, when elav>enarev brains were stained, an increasing number of apoptotic neurons in the optic lobe was observed, albeit to a lower level than after APP overexpression. This data is consistent with a scenario in which constantly reduced ena levels lead to neuronal dysfunction and eventually trigger apoptosis, in time affecting a larger and differentially susceptible neuronal population, thus accounting for the progressive behavioral and anatomical defects.


A functional misexpression screen uncovers a role for enabled in progressive neurodegeneration.

Rezával C, Berni J, Gorostiza EA, Werbajh S, Fagilde MM, Fernández MP, Beckwith EJ, Aranovich EJ, Sabio y García CA, Ceriani MF - PLoS ONE (2008)

ena down-regulation correlates with progressive cell death.(A) Quantitative analysis of apoptotic cell death in adult brains of increasing age as indicated in the figure. A representative image of the extent of cell death in 30 day-old flies of the indicated genotypes is shown in the inset (upper corner, left). Twenty to fifty brain hemispheres were analyzed in each time point with exception of 30 day-old elav>APP (n = 11). The degree of apoptosis in the affected individuals is significantly different from a wild type control (* p<0.05, ** p<0.001). (B–C) Degenerative phenotypes associated to enarev are rescued by p35 expression. (B) Frontal sections at approximately the same depth of aged control and elav>enarev, p35 brains highlight the extent of the morphological rescue. The asterisk denotes a region where small vacuoles can still be found in one of the few brains in which the rescue was not complete. (C) Functional rescue of ena- derived behavioral phenotypes. Representative actograms of old pdf>enarev, p35 and control lines are included (left panel). The percentage of rhythmic individuals is also shown (right panel, * p<0.05).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2553195&req=5

pone-0003332-g007: ena down-regulation correlates with progressive cell death.(A) Quantitative analysis of apoptotic cell death in adult brains of increasing age as indicated in the figure. A representative image of the extent of cell death in 30 day-old flies of the indicated genotypes is shown in the inset (upper corner, left). Twenty to fifty brain hemispheres were analyzed in each time point with exception of 30 day-old elav>APP (n = 11). The degree of apoptosis in the affected individuals is significantly different from a wild type control (* p<0.05, ** p<0.001). (B–C) Degenerative phenotypes associated to enarev are rescued by p35 expression. (B) Frontal sections at approximately the same depth of aged control and elav>enarev, p35 brains highlight the extent of the morphological rescue. The asterisk denotes a region where small vacuoles can still be found in one of the few brains in which the rescue was not complete. (C) Functional rescue of ena- derived behavioral phenotypes. Representative actograms of old pdf>enarev, p35 and control lines are included (left panel). The percentage of rhythmic individuals is also shown (right panel, * p<0.05).
Mentions: Reduced ena levels correlated with positive TUNEL staining in the larval brain; however young adult flies did not develop behavioral or anatomical defects. During metamorphosis the development of novel neuronal clusters and connections could generate a new architecture susceptible to ena down-regulation, which only in time would display such defects. In control brains a minimum level of TUNEL staining was observed scattered throughout the brain, which did not significantly increase in older flies (Fig. 7A). However, when elav>enarev brains were stained, an increasing number of apoptotic neurons in the optic lobe was observed, albeit to a lower level than after APP overexpression. This data is consistent with a scenario in which constantly reduced ena levels lead to neuronal dysfunction and eventually trigger apoptosis, in time affecting a larger and differentially susceptible neuronal population, thus accounting for the progressive behavioral and anatomical defects.

Bottom Line: One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain.Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant.Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor.

View Article: PubMed Central - PubMed

Affiliation: Laboratorio de Genética del Comportamiento, Fundación Instituto Leloir, Instituto de Investigaciones Bioquímicas-Buenos Aires (IIB-BA, CONICET), Buenos Aires, Argentina.

ABSTRACT
Drosophila is a well-established model to study the molecular basis of neurodegenerative diseases. We carried out a misexpression screen to identify genes involved in neurodegeneration examining locomotor behavior in young and aged flies. We hypothesized that a progressive loss of rhythmic activity could reveal novel genes involved in neurodegenerative mechanisms. One of the interesting candidates showing progressive arrhythmicity has reduced enabled (ena) levels. ena down-regulation gave rise to progressive vacuolization in specific regions of the adult brain. Abnormal staining of pre-synaptic markers such as cystein string protein (CSP) suggest that axonal transport could underlie the neurodegeneration observed in the mutant. Reduced ena levels correlated with increased apoptosis, which could be rescued in the presence of p35, a general Caspase inhibitor. Thus, this mutant recapitulates two important features of human neurodegenerative diseases, i.e., vulnerability of certain neuronal populations and progressive degeneration, offering a unique scenario in which to unravel the specific mechanisms in an easily tractable organism.

Show MeSH
Related in: MedlinePlus