The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3

Abstract Mesodiencephalic dopamine neurons (mdDA) of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) play critical roles in regulating movement and motivation. Pitx3 is an essential transcription factor required for proper embryonic development and terminal differentiation...

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Main Authors: Willemieke M. Kouwenhoven, Edward J. Robinson, Daniek Hamberg, Lars von Oerthel, Marten P. Smidt, Lars P. van der Heide
Format: Article
Language:English
Published: Nature Publishing Group 2025-04-01
Series:Cell Death and Disease
Online Access:https://doi.org/10.1038/s41419-025-07552-w
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author Willemieke M. Kouwenhoven
Edward J. Robinson
Daniek Hamberg
Lars von Oerthel
Marten P. Smidt
Lars P. van der Heide
author_facet Willemieke M. Kouwenhoven
Edward J. Robinson
Daniek Hamberg
Lars von Oerthel
Marten P. Smidt
Lars P. van der Heide
author_sort Willemieke M. Kouwenhoven
collection DOAJ
description Abstract Mesodiencephalic dopamine neurons (mdDA) of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) play critical roles in regulating movement and motivation. Pitx3 is an essential transcription factor required for proper embryonic development and terminal differentiation of mdDA neurons. Although Pitx3 is expressed in every mdDA neuron, its ablation results only in the absence of the SNc, not the VTA. The developmental stage at which the loss of SNc first becomes apparent, as well as the underlying mechanism, remains elusive. Here, we demonstrate, using a Pitx3 knockout GFP knock-in mouse model, that this loss does not occur during embryogenesis but rather postnatally. Quantification of GFP expression revealed a significant reduction in the total number of dopamine neurons at postnatal day 3, but not at embryonic day 14.5, 15.5, and 18.5. Mechanistically this reduction is accompanied by an increase in the number of cleaved caspase 3-positive GFP neurons, suggesting apoptosis. In addition, RT-PCR performed on isolated GFP neurons, one day before the loss of dopamine neurons revealed a notable elevation in the expression of the pro-apoptotic BH3-only factor Noxa. Overexpression of Noxa in dopaminergic MN9D cells dose-dependently increases the level of cleaved caspase 3 and the number of propidium iodide-positive cells, indicating that Noxa expression is sufficient to induce cell death in dopamine cells. Additionally, Noxa expression in MN9D cells, combined with a Bax-inhibiting peptide, reduces the number of cleaved caspase 3-positive and propidium iodide-positive cells, further supporting apoptosis as the mechanistic form of cell death. Overall, our study provides insights into the cell death machinery implicated in the loss of dopamine neurons, which may hold relevance for diseases affected by the loss of dopamine neurons such as Parkinson’s disease, where this is a hallmark feature.
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spelling doaj-art-88f2d6bbacd64f0da01cb82d62e095762025-08-20T02:10:31ZengNature Publishing GroupCell Death and Disease2041-48892025-04-0116111110.1038/s41419-025-07552-wThe absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3Willemieke M. Kouwenhoven0Edward J. Robinson1Daniek Hamberg2Lars von Oerthel3Marten P. Smidt4Lars P. van der Heide5Swammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamSwammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamSwammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamSwammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamSwammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamSwammerdam Institute for Life Sciences, Molecular Neuroscience Lab, University of AmsterdamAbstract Mesodiencephalic dopamine neurons (mdDA) of the substantia nigra pars compacta (SNc) and ventral tegmental area (VTA) play critical roles in regulating movement and motivation. Pitx3 is an essential transcription factor required for proper embryonic development and terminal differentiation of mdDA neurons. Although Pitx3 is expressed in every mdDA neuron, its ablation results only in the absence of the SNc, not the VTA. The developmental stage at which the loss of SNc first becomes apparent, as well as the underlying mechanism, remains elusive. Here, we demonstrate, using a Pitx3 knockout GFP knock-in mouse model, that this loss does not occur during embryogenesis but rather postnatally. Quantification of GFP expression revealed a significant reduction in the total number of dopamine neurons at postnatal day 3, but not at embryonic day 14.5, 15.5, and 18.5. Mechanistically this reduction is accompanied by an increase in the number of cleaved caspase 3-positive GFP neurons, suggesting apoptosis. In addition, RT-PCR performed on isolated GFP neurons, one day before the loss of dopamine neurons revealed a notable elevation in the expression of the pro-apoptotic BH3-only factor Noxa. Overexpression of Noxa in dopaminergic MN9D cells dose-dependently increases the level of cleaved caspase 3 and the number of propidium iodide-positive cells, indicating that Noxa expression is sufficient to induce cell death in dopamine cells. Additionally, Noxa expression in MN9D cells, combined with a Bax-inhibiting peptide, reduces the number of cleaved caspase 3-positive and propidium iodide-positive cells, further supporting apoptosis as the mechanistic form of cell death. Overall, our study provides insights into the cell death machinery implicated in the loss of dopamine neurons, which may hold relevance for diseases affected by the loss of dopamine neurons such as Parkinson’s disease, where this is a hallmark feature.https://doi.org/10.1038/s41419-025-07552-w
spellingShingle Willemieke M. Kouwenhoven
Edward J. Robinson
Daniek Hamberg
Lars von Oerthel
Marten P. Smidt
Lars P. van der Heide
The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
Cell Death and Disease
title The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
title_full The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
title_fullStr The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
title_full_unstemmed The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
title_short The absence of Pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro-apoptotic Bcl2 factor Noxa and cleaved caspase 3
title_sort absence of pitx3 results in postnatal loss of dopamine neurons and is associated with an increase in the pro apoptotic bcl2 factor noxa and cleaved caspase 3
url https://doi.org/10.1038/s41419-025-07552-w
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