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Lazarillo-related Lipocalins confer long-term protection against type I Spinocerebellar Ataxia degeneration contributing to optimize selective autophagy.

del Caño-Espinel M, Acebes JR, Sanchez D, Ganfornina MD - Mol Neurodegener (2015)

Bottom Line: GLaz beneficial effects persist throughout aging, and appears when expressed by degenerating neurons or by retinal support and glial cells.GLaz gain-of-function reduces cell death and the extent of ubiquitinated proteins accumulation, and decreases the expression of Atg8a/LC3, p62 mRNA and protein levels, and GstS1 induction.Down-regulation of selective autophagy causes similar and non-additive rescuing effects.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, c/ Sanz y Forés 3, 47003, Valladolid, Spain. manuela@ibgm.uva.es.

ABSTRACT

Background: A diverse set of neurodegenerative disorders are caused by abnormal extensions of polyglutamine (poly-Q) stretches in various, functionally unrelated proteins. A common feature of these diseases is altered proteostasis. Autophagy induction is part of the endogenous response to poly-Q protein expression. However, if autophagy is not resolved properly, clearance of toxic proteins or aggregates cannot occur effectively. Likewise, excessive autophagy induction can cause autophagic stress and neurodegeneration. The Lipocalins ApoD, Glial Lazarillo (GLaz) and Neural Lazarillo (NLaz) are neuroprotectors upon oxidative stress or aging. In this work we test whether these Lipocalins also protect against poly-Q-triggered deterioration of protein quality control systems.

Results: Using a Drosophila retinal degeneration model of Type-1 Spinocerebellar Ataxia (SCA1) combined with genetic manipulation of NLaz and GLaz expression, we demonstrate that both Lipocalins protect against SCA1 neurodegeneration. They are part of the endogenous transcriptional response to SCA1, and their effect is non-additive, suggesting participation in a similar mechanism. GLaz beneficial effects persist throughout aging, and appears when expressed by degenerating neurons or by retinal support and glial cells. GLaz gain-of-function reduces cell death and the extent of ubiquitinated proteins accumulation, and decreases the expression of Atg8a/LC3, p62 mRNA and protein levels, and GstS1 induction. Over-expression of GLaz is able to reduce p62 and ubiquitinated proteins levels when rapamycin-dependent and SCA1-dependent inductions of autophagy are combined. In the absence of neurodegeneration, GLaz loss-of-function increases Atg8a/LC3 mRNA and p62 protein levels without altering p62 mRNA levels. Knocking-down autophagy, by interfering with Atg8a or p62 expression or by expressing dominant-negative Atg1/ULK1 or Atg4a transgenes, rescues SCA1-dependent neurodegeneration in a similar extent to the protective effect of GLaz. Further GLaz-dependent improvement is concealed.

Conclusions: This work shows for the first time that a Lipocalin rescues neurons from pathogenic SCA1 degeneration by optimizing clearance of aggregation-prone proteins. GLaz modulates key autophagy genes and lipid-peroxide clearance responsive genes. Down-regulation of selective autophagy causes similar and non-additive rescuing effects. These data suggest that SCA1 neurodegeneration concurs with autophagic stress, and places Lazarillo-related Lipocalins as valuable players in the endogenous protection against the two major contributors to aging and neurodegeneration: ROS-dependent damage and proteostasis deterioration.

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GLaz expression and rescue with the GAL4/UAS system of the SCA1 neurodegeneration model in Drosophila. A, RT-qPCR levels of GLaz transcripts in 5–6 day old fly heads. Statistical differences assayed by Mann–Whitney U-test. *p < 0.05. B, Native over-expression of GLaz using the direct reporter transgene glaz:GLaz-GFP[FX]. Arrows point to GLaz-positive retinal support cells, and arrowhead indicates GLaz-positive basal glial cells. C-F, Adult (5-6d old) Drosophila eye morphology of control (gmr > +), degenerated (gmr > hATXN182Q) and rescue test (gmr > hATXN182Q + GLaz2). Representative examples of light microscopy (C), surface filter-processed image of the central retinal region in C (D), hematoxilin/eosin histochemistry of paraffin sections (E), and Ataxin 1 immunohistochemistry on paraffin sections (F) are shown. Double arrows mark the retina thickness in the histological sections (E), and arrows point to inclusion bodies of the poly-Q protein (F).
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Fig1: GLaz expression and rescue with the GAL4/UAS system of the SCA1 neurodegeneration model in Drosophila. A, RT-qPCR levels of GLaz transcripts in 5–6 day old fly heads. Statistical differences assayed by Mann–Whitney U-test. *p < 0.05. B, Native over-expression of GLaz using the direct reporter transgene glaz:GLaz-GFP[FX]. Arrows point to GLaz-positive retinal support cells, and arrowhead indicates GLaz-positive basal glial cells. C-F, Adult (5-6d old) Drosophila eye morphology of control (gmr > +), degenerated (gmr > hATXN182Q) and rescue test (gmr > hATXN182Q + GLaz2). Representative examples of light microscopy (C), surface filter-processed image of the central retinal region in C (D), hematoxilin/eosin histochemistry of paraffin sections (E), and Ataxin 1 immunohistochemistry on paraffin sections (F) are shown. Double arrows mark the retina thickness in the histological sections (E), and arrows point to inclusion bodies of the poly-Q protein (F).

Mentions: To assay expression of the Drosophila Lipocalins in a poly-Q-based neurodegenerative disease, we have used the GAL4/UAS system to express a pathogenic version of human Ataxin 1 with an expanded glutamine tract (hATXN182Q) in Drosophila retinal photoreceptors using the gmr:GAL4 driver. In this model of SCA1 [30] photoreceptors accumulate nuclear inclusions of the human protein and start degenerating during late pupal stage when flies develop at 25°C. We first tested GLaz expression. Figure 1A shows that its expression increases 3-fold in the photoreceptors degeneration model of SCA1 when assaying mRNA levels in 5–6 days old fly heads.Figure 1


Lazarillo-related Lipocalins confer long-term protection against type I Spinocerebellar Ataxia degeneration contributing to optimize selective autophagy.

del Caño-Espinel M, Acebes JR, Sanchez D, Ganfornina MD - Mol Neurodegener (2015)

GLaz expression and rescue with the GAL4/UAS system of the SCA1 neurodegeneration model in Drosophila. A, RT-qPCR levels of GLaz transcripts in 5–6 day old fly heads. Statistical differences assayed by Mann–Whitney U-test. *p < 0.05. B, Native over-expression of GLaz using the direct reporter transgene glaz:GLaz-GFP[FX]. Arrows point to GLaz-positive retinal support cells, and arrowhead indicates GLaz-positive basal glial cells. C-F, Adult (5-6d old) Drosophila eye morphology of control (gmr > +), degenerated (gmr > hATXN182Q) and rescue test (gmr > hATXN182Q + GLaz2). Representative examples of light microscopy (C), surface filter-processed image of the central retinal region in C (D), hematoxilin/eosin histochemistry of paraffin sections (E), and Ataxin 1 immunohistochemistry on paraffin sections (F) are shown. Double arrows mark the retina thickness in the histological sections (E), and arrows point to inclusion bodies of the poly-Q protein (F).
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4374295&req=5

Fig1: GLaz expression and rescue with the GAL4/UAS system of the SCA1 neurodegeneration model in Drosophila. A, RT-qPCR levels of GLaz transcripts in 5–6 day old fly heads. Statistical differences assayed by Mann–Whitney U-test. *p < 0.05. B, Native over-expression of GLaz using the direct reporter transgene glaz:GLaz-GFP[FX]. Arrows point to GLaz-positive retinal support cells, and arrowhead indicates GLaz-positive basal glial cells. C-F, Adult (5-6d old) Drosophila eye morphology of control (gmr > +), degenerated (gmr > hATXN182Q) and rescue test (gmr > hATXN182Q + GLaz2). Representative examples of light microscopy (C), surface filter-processed image of the central retinal region in C (D), hematoxilin/eosin histochemistry of paraffin sections (E), and Ataxin 1 immunohistochemistry on paraffin sections (F) are shown. Double arrows mark the retina thickness in the histological sections (E), and arrows point to inclusion bodies of the poly-Q protein (F).
Mentions: To assay expression of the Drosophila Lipocalins in a poly-Q-based neurodegenerative disease, we have used the GAL4/UAS system to express a pathogenic version of human Ataxin 1 with an expanded glutamine tract (hATXN182Q) in Drosophila retinal photoreceptors using the gmr:GAL4 driver. In this model of SCA1 [30] photoreceptors accumulate nuclear inclusions of the human protein and start degenerating during late pupal stage when flies develop at 25°C. We first tested GLaz expression. Figure 1A shows that its expression increases 3-fold in the photoreceptors degeneration model of SCA1 when assaying mRNA levels in 5–6 days old fly heads.Figure 1

Bottom Line: GLaz beneficial effects persist throughout aging, and appears when expressed by degenerating neurons or by retinal support and glial cells.GLaz gain-of-function reduces cell death and the extent of ubiquitinated proteins accumulation, and decreases the expression of Atg8a/LC3, p62 mRNA and protein levels, and GstS1 induction.Down-regulation of selective autophagy causes similar and non-additive rescuing effects.

View Article: PubMed Central - PubMed

Affiliation: Instituto de Biología y Genética Molecular-Departamento de Bioquímica y Biología Molecular y Fisiología, Universidad de Valladolid-CSIC, c/ Sanz y Forés 3, 47003, Valladolid, Spain. manuela@ibgm.uva.es.

ABSTRACT

Background: A diverse set of neurodegenerative disorders are caused by abnormal extensions of polyglutamine (poly-Q) stretches in various, functionally unrelated proteins. A common feature of these diseases is altered proteostasis. Autophagy induction is part of the endogenous response to poly-Q protein expression. However, if autophagy is not resolved properly, clearance of toxic proteins or aggregates cannot occur effectively. Likewise, excessive autophagy induction can cause autophagic stress and neurodegeneration. The Lipocalins ApoD, Glial Lazarillo (GLaz) and Neural Lazarillo (NLaz) are neuroprotectors upon oxidative stress or aging. In this work we test whether these Lipocalins also protect against poly-Q-triggered deterioration of protein quality control systems.

Results: Using a Drosophila retinal degeneration model of Type-1 Spinocerebellar Ataxia (SCA1) combined with genetic manipulation of NLaz and GLaz expression, we demonstrate that both Lipocalins protect against SCA1 neurodegeneration. They are part of the endogenous transcriptional response to SCA1, and their effect is non-additive, suggesting participation in a similar mechanism. GLaz beneficial effects persist throughout aging, and appears when expressed by degenerating neurons or by retinal support and glial cells. GLaz gain-of-function reduces cell death and the extent of ubiquitinated proteins accumulation, and decreases the expression of Atg8a/LC3, p62 mRNA and protein levels, and GstS1 induction. Over-expression of GLaz is able to reduce p62 and ubiquitinated proteins levels when rapamycin-dependent and SCA1-dependent inductions of autophagy are combined. In the absence of neurodegeneration, GLaz loss-of-function increases Atg8a/LC3 mRNA and p62 protein levels without altering p62 mRNA levels. Knocking-down autophagy, by interfering with Atg8a or p62 expression or by expressing dominant-negative Atg1/ULK1 or Atg4a transgenes, rescues SCA1-dependent neurodegeneration in a similar extent to the protective effect of GLaz. Further GLaz-dependent improvement is concealed.

Conclusions: This work shows for the first time that a Lipocalin rescues neurons from pathogenic SCA1 degeneration by optimizing clearance of aggregation-prone proteins. GLaz modulates key autophagy genes and lipid-peroxide clearance responsive genes. Down-regulation of selective autophagy causes similar and non-additive rescuing effects. These data suggest that SCA1 neurodegeneration concurs with autophagic stress, and places Lazarillo-related Lipocalins as valuable players in the endogenous protection against the two major contributors to aging and neurodegeneration: ROS-dependent damage and proteostasis deterioration.

Show MeSH
Related in: MedlinePlus