The present invention refers to a transgenic mouse model of myelin pathologies (or transgenic oligodendrocytes and/or neurons derived thereof). Moreover, the present invention also refers to the use of the mouse model of the invention (or oligodendrocytes and/or neurons derived thereof) in a method for screening candidate compounds for treating myelin pathologies.
1. Transgenic knock-out R-Ras2-/- mouse model of myelin pathologies, or transgenic oligodendrocytes and/or neurons derived thereof, characterized by the disruption or inactivation of the gene R-Ras2. 2. Transgenic double knock-out R-Rasl-/- and R-Ras2-/- mouse model of myelin pathologies, or transgenic oligodendrocytes and/or neurons derived thereof, according to claim 1, characterized by the disruption or inactivation of the genes R-Ras2 and R-Ras1. 3. Transgenic knock-out mouse, according to any of the claims 1 or 2, characterized in that it is a model of a myelin pathology selected from the group comprising: amyotrophic lateral sclerosis, neuromyelitis optica, multiple sclerosis, Charcot Marie Tooth disease and leukodystrophies. 4. An in vitro method for screening candidate compounds for treating myelin pathologies, which comprises: a) determining in the mouse model or the oligodendrocytes or neurons of claim 1 the level of expression of R-Ras2 after administering the candidate molecule and b) where, if after administering the candidate molecule, the level of expression of R-Ras2 is higher as compared with the level of expression determined before administering the candidate molecule, this is indicative that the candidate molecule is effective in the treatment myelin pathologies. 5. An in vitro method for screening candidate compounds for treating myelin pathologies, according to claim 4, which comprises: a) determining in the mouse model or the oligodendrocytes or neurons of claim 2 the level of expression of R-Ras2 and R-Ras1 after administering the candidate molecule and b) where, if after administering the candidate molecule, the level of expression of R-Ras2 and R-Ras1 is higher as compared with the level of expression determined before administering the candidate molecule, this is indicative that the candidate molecule is effective in the treatment myelin pathologies. 6. In vitro method, according to any of the claims 4 or 5, which further comprises determining, after the administration of the candidate molecule, whether the oligodendrocytes and/or neurons have evolved to mature oligodendrocytes and/or neurons, wherein if immature oligodendrocytes and/or neurons have evolved to mature oligodendrocytes and/or neurons, this is indicative that the candidate molecule is effective in the treatment myelin pathologies. 7. In vitro method, according to claim 6, wherein the determination of the maturity degree of the oligodendrocytes/neurons is carried out by determining the expression level of the following biomarkers: PDGFRalfa, A2B5, NG2, PSA-NCAM, O4, NKX2 and/or TCF7L2, wherein an increased level of expression of these biomarkers is indicative that the oligodendrocytes and/or neurons have evolved to mature oligodendrocytes and/or neurons. 8. In vitro method, according to any of the claims 4 or 5, which further comprises determining, after the administration of the candidate molecule, whether the oligodendrocytes and/or neurons are able to generate myelin, wherein if the oligodendrocytes and/or neurons are able to generate myelin, this is indicative that the candidate molecule is effective in the treatment myelin pathologies. 9. In vitro method, according to claim 8, wherein the determination whether the oligodendrocytes and/or neurons are able to generate myelin is carried out by determining the expression level of the following biomarkers: MBP, MAG, MOG, PLP and/or CNPasa, wherein an increased level of expression of these biomarkers is indicative that the oligodendrocytes and/or neurons are able to generate myelin. 10. In vitro method, according to any of the claims 4 to 9, wherein the myelin pathology is selected from the group comprising: amyotrophic lateral sclerosis, neuromyelitis optica, multiple sclerosis, Charcot Marie Tooth disease and leukodystrophies. 11. In vitro method for obtaining a transgenic mouse model of myelin pathologies, or transgenic oligodendrocytes and/or neurons derived thereof, which comprises the disruption or inactivation of the gene R-Ras2. 12. In vitro method, according to claim 11, further comprising the disruption or inactivation of the gene R-Ras1. 13. In vitro method, according to any of the claims 11 or 12, wherein the myelin pathology is selected from the group comprising: amyotrophic lateral sclerosis, neuromyelitis optica, multiple sclerosis, Charcot Marie Tooth disease and leukodystrophies.