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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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Molecular analysis of Nes-R26Met and R26LacZ−stop−Met mice in adult lumbar spinal cords on transversal sections. (a and b) In situ hybridization using lacZ riboprobes. (c and d) Enlarged view of the ventral regions, showing lacZ expression in distinct cell types characterized by large cell nuclei resembling MNs in R26LacZ−stop−Met and a decrease in its levels after nestin-cre-mediated recombination in Nes-R26Met. (e and f) Section showing the overlap of X-Gal activity and DAPI staining in lumbar spinal cords. X-Gal-negative cells with large nuclei were predominantly found in Nes-R26Met, but not in R26LacZ−stop−Met transgenics. Arrows and arrowheads points to X-Gal-negative and X-Gal-positive cells with large nuclei, respectively. (g) Quantification analysis of X-Gal-positive (blue) and X-Gal-negative cells with large nuclei (resembling MNs; white) in Nes-R26Met mice, showing that nestin-cre-mediated lacZ excision occurred in approximately 56% of these cells. Values are expressed as means±S.E.M. (h–k) Expression of the met chimeric transgene in lumbar spinal cords. Panels (j and k) show an enlarged view of ventral spinal cords and met transgenic expression in cells resembling MNs
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fig3: Molecular analysis of Nes-R26Met and R26LacZ−stop−Met mice in adult lumbar spinal cords on transversal sections. (a and b) In situ hybridization using lacZ riboprobes. (c and d) Enlarged view of the ventral regions, showing lacZ expression in distinct cell types characterized by large cell nuclei resembling MNs in R26LacZ−stop−Met and a decrease in its levels after nestin-cre-mediated recombination in Nes-R26Met. (e and f) Section showing the overlap of X-Gal activity and DAPI staining in lumbar spinal cords. X-Gal-negative cells with large nuclei were predominantly found in Nes-R26Met, but not in R26LacZ−stop−Met transgenics. Arrows and arrowheads points to X-Gal-negative and X-Gal-positive cells with large nuclei, respectively. (g) Quantification analysis of X-Gal-positive (blue) and X-Gal-negative cells with large nuclei (resembling MNs; white) in Nes-R26Met mice, showing that nestin-cre-mediated lacZ excision occurred in approximately 56% of these cells. Values are expressed as means±S.E.M. (h–k) Expression of the met chimeric transgene in lumbar spinal cords. Panels (j and k) show an enlarged view of ventral spinal cords and met transgenic expression in cells resembling MNs

Mentions: We next characterized the R26LacZ−stop−Met mice before and after recombination by following the expression of the lacZ-stop cassette and mettg transcript in adult brains and spinal cords. We found a decrease in β-galactosidase activity and lacZ transcripts in Nes-R26Met compared with R26LacZ−stop−Met transgenics, indicating that recombination in several brain regions occurred as expected (Figures 2a–d, Supplementary Figures 1 and 2). Conversely, mettg was expressed in brains only after recombination in a pattern complementary to lacZ distribution (Figures 2e and f). High levels were found in the hippocampus, cerebellum, cerebral cortex, and cervical spinal cord (Figures 2g–i). Expression studies performed on adult lumbar spinal cord sections revealed also a complementary distribution pattern. In particular, lacZ or mettg were found in cells with large nuclei resembling MNs of R26LacZ−stop−Met and Nes-R26Met, respectively (Figure 3). Quantification analysis revealed that cre-mediated excision occurred in approximately 56% of these cells (56.3±1.1; P<0.0001; Figure 3g).


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)

Molecular analysis of Nes-R26Met and R26LacZ−stop−Met mice in adult lumbar spinal cords on transversal sections. (a and b) In situ hybridization using lacZ riboprobes. (c and d) Enlarged view of the ventral regions, showing lacZ expression in distinct cell types characterized by large cell nuclei resembling MNs in R26LacZ−stop−Met and a decrease in its levels after nestin-cre-mediated recombination in Nes-R26Met. (e and f) Section showing the overlap of X-Gal activity and DAPI staining in lumbar spinal cords. X-Gal-negative cells with large nuclei were predominantly found in Nes-R26Met, but not in R26LacZ−stop−Met transgenics. Arrows and arrowheads points to X-Gal-negative and X-Gal-positive cells with large nuclei, respectively. (g) Quantification analysis of X-Gal-positive (blue) and X-Gal-negative cells with large nuclei (resembling MNs; white) in Nes-R26Met mice, showing that nestin-cre-mediated lacZ excision occurred in approximately 56% of these cells. Values are expressed as means±S.E.M. (h–k) Expression of the met chimeric transgene in lumbar spinal cords. Panels (j and k) show an enlarged view of ventral spinal cords and met transgenic expression in cells resembling MNs
© Copyright Policy - open-access
Related In: Results  -  Collection

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

fig3: Molecular analysis of Nes-R26Met and R26LacZ−stop−Met mice in adult lumbar spinal cords on transversal sections. (a and b) In situ hybridization using lacZ riboprobes. (c and d) Enlarged view of the ventral regions, showing lacZ expression in distinct cell types characterized by large cell nuclei resembling MNs in R26LacZ−stop−Met and a decrease in its levels after nestin-cre-mediated recombination in Nes-R26Met. (e and f) Section showing the overlap of X-Gal activity and DAPI staining in lumbar spinal cords. X-Gal-negative cells with large nuclei were predominantly found in Nes-R26Met, but not in R26LacZ−stop−Met transgenics. Arrows and arrowheads points to X-Gal-negative and X-Gal-positive cells with large nuclei, respectively. (g) Quantification analysis of X-Gal-positive (blue) and X-Gal-negative cells with large nuclei (resembling MNs; white) in Nes-R26Met mice, showing that nestin-cre-mediated lacZ excision occurred in approximately 56% of these cells. Values are expressed as means±S.E.M. (h–k) Expression of the met chimeric transgene in lumbar spinal cords. Panels (j and k) show an enlarged view of ventral spinal cords and met transgenic expression in cells resembling MNs
Mentions: We next characterized the R26LacZ−stop−Met mice before and after recombination by following the expression of the lacZ-stop cassette and mettg transcript in adult brains and spinal cords. We found a decrease in β-galactosidase activity and lacZ transcripts in Nes-R26Met compared with R26LacZ−stop−Met transgenics, indicating that recombination in several brain regions occurred as expected (Figures 2a–d, Supplementary Figures 1 and 2). Conversely, mettg was expressed in brains only after recombination in a pattern complementary to lacZ distribution (Figures 2e and f). High levels were found in the hippocampus, cerebellum, cerebral cortex, and cervical spinal cord (Figures 2g–i). Expression studies performed on adult lumbar spinal cord sections revealed also a complementary distribution pattern. In particular, lacZ or mettg were found in cells with large nuclei resembling MNs of R26LacZ−stop−Met and Nes-R26Met, respectively (Figure 3). Quantification analysis revealed that cre-mediated excision occurred in approximately 56% of these cells (56.3±1.1; P<0.0001; Figure 3g).

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