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Enhanced neuronal Met signalling levels in ALS mice delay disease onset.

Genestine M, Caricati E, Fico A, Richelme S, Hassani H, Sunyach C, Lamballe F, Panzica GC, Pettmann B, Helmbacher F, Raoul C, Maina F, Dono R - Cell Death Dis (2011)

Bottom Line: Enhancing Met levels in neurons does not affect either motor neuron (MN) development or maintenance.Thus, our studies highlight the properties of RTKs to counteract toxic signals in a disease characterized by dysfunction of multiple cell types by acting in MNs.Moreover, they emphasize the relevance of genetically assessing the effectiveness of agents targeting neurons during ALS evolution.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Institute of Marseille-Luminy, UMR 6216, CNRS-Inserm-Université de la Méditerranée, Campus de Luminy-Case 907, Marseille Cedex 09, France.

ABSTRACT
Signalling by receptor tyrosine kinases (RTKs) coordinates basic cellular processes during development and in adulthood. Whereas aberrant RTK signalling can lead to cancer, reactivation of RTKs is often found following stress or cell damage. This has led to the common belief that RTKs can counteract degenerative processes and so strategies to exploit them for therapy have been extensively explored. An understanding of how RTK stimuli act at cellular levels is needed, however, to evaluate their mechanism of therapeutic action. In this study, we genetically explored the biological and functional significance of enhanced signalling by the Met RTK in neurons, in the context of a neurodegenerative disease. Conditional met-transgenic mice, namely Rosa26(LacZ-stop-Met), have been engineered to trigger increased Met signalling in a temporal and tissue-specific regulated manner. Enhancing Met levels in neurons does not affect either motor neuron (MN) development or maintenance. In contrast, increased neuronal Met in amyotrophic lateral sclerosis (ALS) mice prolongs life span, retards MN loss, and ameliorates motor performance, by selectively delaying disease onset. Thus, our studies highlight the properties of RTKs to counteract toxic signals in a disease characterized by dysfunction of multiple cell types by acting in MNs. Moreover, they emphasize the relevance of genetically assessing the effectiveness of agents targeting neurons during ALS evolution.

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Subcellular localization of chimeric met transcripts in lumbar spinal cords of adult Nes-R26Met mice. (a–c) Colocalization studies of exogenous met transcript with NeuN protein showing met expression in neuronal cell types. (d–f) Colocalization studies of exogenous met transcript with GFAP protein showing that transgenic met is not predominantly expressed in astrocytes. Panels (b and e), panels (c and f) correspond to an enlarged view of spinal cord areas indicated by red and black rectangles in (a and b), respectively. Arrowheads in (c) point to MNs co-expressing chimeric met transcript and NeuN protein. Arrows and arrowheads in (f) indicate GFAP-positive astrocytes and MN expressing chimeric met transcripts, respectively
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fig5: Subcellular localization of chimeric met transcripts in lumbar spinal cords of adult Nes-R26Met mice. (a–c) Colocalization studies of exogenous met transcript with NeuN protein showing met expression in neuronal cell types. (d–f) Colocalization studies of exogenous met transcript with GFAP protein showing that transgenic met is not predominantly expressed in astrocytes. Panels (b and e), panels (c and f) correspond to an enlarged view of spinal cord areas indicated by red and black rectangles in (a and b), respectively. Arrowheads in (c) point to MNs co-expressing chimeric met transcript and NeuN protein. Arrows and arrowheads in (f) indicate GFAP-positive astrocytes and MN expressing chimeric met transcripts, respectively

Mentions: Although the Rosa26 locus drives gene expression ubiquitously,26 we observed that the lacZ distribution in brains and spinal cords of adult R26LacZ−stop−Met mice appeared restricted to distinct cell types (Figures 2a–d and 3a–f, Supplementary Figures 1 and 2). Colocalization studies revealed β-galactosidase activity predominantly in NeuN-positive neurons, but not in glial fibrillary acidic protein (GFAP)-positive astrocytes (Figures 4a–h). The restricted neuronal lacZ expression was also observed in cultured cells (Figures 4i–n). Thus, the genetic setting we adopted (CMV-enhancer/β-actin-promoter in Rosa26) results in an animal model with a restricted expression of the transgene, indicating that mettg should be predominantly confined to neurons after nestin-cre-mediated recombination. Consistently, mettg transcripts colocalized with Smi32-positive neurons, but not with GFAP-positive astrocytes (Supplementary Figure 3). The restricted expression of mettg in neurons was also observed in Nes-R26Met adult spinal cords, where it was found in dorsal horn neurons, intermediate lateral neurons, and MNs, but not in GFAP-positive astrocytes (Figure 5). Thus, mettg is predominantly restricted to neurons in Nes-R26Met mice.


Enhanced neuronal Met signalling levels in ALS mice delay disease onset.

Genestine M, Caricati E, Fico A, Richelme S, Hassani H, Sunyach C, Lamballe F, Panzica GC, Pettmann B, Helmbacher F, Raoul C, Maina F, Dono R - Cell Death Dis (2011)

Subcellular localization of chimeric met transcripts in lumbar spinal cords of adult Nes-R26Met mice. (a–c) Colocalization studies of exogenous met transcript with NeuN protein showing met expression in neuronal cell types. (d–f) Colocalization studies of exogenous met transcript with GFAP protein showing that transgenic met is not predominantly expressed in astrocytes. Panels (b and e), panels (c and f) correspond to an enlarged view of spinal cord areas indicated by red and black rectangles in (a and b), respectively. Arrowheads in (c) point to MNs co-expressing chimeric met transcript and NeuN protein. Arrows and arrowheads in (f) indicate GFAP-positive astrocytes and MN expressing chimeric met transcripts, respectively
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3101808&req=5

fig5: Subcellular localization of chimeric met transcripts in lumbar spinal cords of adult Nes-R26Met mice. (a–c) Colocalization studies of exogenous met transcript with NeuN protein showing met expression in neuronal cell types. (d–f) Colocalization studies of exogenous met transcript with GFAP protein showing that transgenic met is not predominantly expressed in astrocytes. Panels (b and e), panels (c and f) correspond to an enlarged view of spinal cord areas indicated by red and black rectangles in (a and b), respectively. Arrowheads in (c) point to MNs co-expressing chimeric met transcript and NeuN protein. Arrows and arrowheads in (f) indicate GFAP-positive astrocytes and MN expressing chimeric met transcripts, respectively
Mentions: Although the Rosa26 locus drives gene expression ubiquitously,26 we observed that the lacZ distribution in brains and spinal cords of adult R26LacZ−stop−Met mice appeared restricted to distinct cell types (Figures 2a–d and 3a–f, Supplementary Figures 1 and 2). Colocalization studies revealed β-galactosidase activity predominantly in NeuN-positive neurons, but not in glial fibrillary acidic protein (GFAP)-positive astrocytes (Figures 4a–h). The restricted neuronal lacZ expression was also observed in cultured cells (Figures 4i–n). Thus, the genetic setting we adopted (CMV-enhancer/β-actin-promoter in Rosa26) results in an animal model with a restricted expression of the transgene, indicating that mettg should be predominantly confined to neurons after nestin-cre-mediated recombination. Consistently, mettg transcripts colocalized with Smi32-positive neurons, but not with GFAP-positive astrocytes (Supplementary Figure 3). The restricted expression of mettg in neurons was also observed in Nes-R26Met adult spinal cords, where it was found in dorsal horn neurons, intermediate lateral neurons, and MNs, but not in GFAP-positive astrocytes (Figure 5). Thus, mettg is predominantly restricted to neurons in Nes-R26Met mice.

Bottom Line: Enhancing Met levels in neurons does not affect either motor neuron (MN) development or maintenance.Thus, our studies highlight the properties of RTKs to counteract toxic signals in a disease characterized by dysfunction of multiple cell types by acting in MNs.Moreover, they emphasize the relevance of genetically assessing the effectiveness of agents targeting neurons during ALS evolution.

View Article: PubMed Central - PubMed

Affiliation: Developmental Biology Institute of Marseille-Luminy, UMR 6216, CNRS-Inserm-Université de la Méditerranée, Campus de Luminy-Case 907, Marseille Cedex 09, France.

ABSTRACT
Signalling by receptor tyrosine kinases (RTKs) coordinates basic cellular processes during development and in adulthood. Whereas aberrant RTK signalling can lead to cancer, reactivation of RTKs is often found following stress or cell damage. This has led to the common belief that RTKs can counteract degenerative processes and so strategies to exploit them for therapy have been extensively explored. An understanding of how RTK stimuli act at cellular levels is needed, however, to evaluate their mechanism of therapeutic action. In this study, we genetically explored the biological and functional significance of enhanced signalling by the Met RTK in neurons, in the context of a neurodegenerative disease. Conditional met-transgenic mice, namely Rosa26(LacZ-stop-Met), have been engineered to trigger increased Met signalling in a temporal and tissue-specific regulated manner. Enhancing Met levels in neurons does not affect either motor neuron (MN) development or maintenance. In contrast, increased neuronal Met in amyotrophic lateral sclerosis (ALS) mice prolongs life span, retards MN loss, and ameliorates motor performance, by selectively delaying disease onset. Thus, our studies highlight the properties of RTKs to counteract toxic signals in a disease characterized by dysfunction of multiple cell types by acting in MNs. Moreover, they emphasize the relevance of genetically assessing the effectiveness of agents targeting neurons during ALS evolution.

Show MeSH
Related in: MedlinePlus