Mash1 promotes neuronal differentiation in the retina.
BACKGROUND
Mash1, a mammalian homologue of Drosophila achaete-scute proneural gene complex, plays an essential role in differentiation of subsets of peripheral neurones. Whereas Mash1 is expressed during retinal development, no apparent abnormalities were found during embryogenesis as well as at birth in Mash1-null retina, suggesting that early differentiating cells such as ganglion, amacrine and cone cells develop normally. Because Mash1-null mice die soon after birth, their postnatal development cannot be examined in vivo. Thus, it remains to be determined whether or not Mash1 functions in postnatal development of retina.


RESULTS
Here, Mash1 roles in postnatal development of retina was examined by using retinal explant that develops like in vivo retina. Without Mash1, differentiation of late appearing cells such as rod, horizontal, and bipolar cells was delayed and the final number of bipolar cells was significantly reduced. In contrast, vimentin-positive cells (probably Muller glial cells) were increased in Mash1-null retina.


CONCLUSIONS
These results provide evidence that Mash1 promotes neuronal differentiation during retinal development and is essential for proper ratios of retinal cell types.
Tomita
K
K
Department of Biological Sciences, Kyoto University Faculty of Medicine, Sakyo-ku, Japan.
Nakanishi
S
S
Guillemot
F
F
Kageyama
R
R
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D002454:Cell Differentiation / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D009154:Mutation; D009474:Neurons / Q000166:cytology*; D009924:Organ Culture Techniques; D012160:Retina / Q000166:cytology*; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014746:Vimentin / Q000032:analysis
D051792:Basic Helix-Loop-Helix Proteins; D004268:DNA-Binding Proteins; D014157:Transcription Factors; D014746:Vimentin; C499317:Ascl1 protein, mouse