Sonic hedgehog (Shh)/Gli modulates the spatial organization of neuroepithelial cell proliferation in the developing chick optic tectum

BMC Neuroscience

Vladimir Flores²  Verónica Palma³  Matías Elliot³  Santiago Duarte²  Gustavo Cerda³  Joao Botelho³  Melina Rapacioli¹ 

[1] Interdisciplinary Group in Theoretical Biology, Department Biostructural Sciences, Favaloro University, Solís 453 (1078), Buenos Aires, Argentina;Institute of Cell Biology and Neurosciences, School of Medicine, University of Buenos Aires-CONICET, Paraguay 2155 (1121), Buenos Aires, Argentina;FONDAP Center for Genome Regulation, Faculty of Science, University of Chile, Santiago, Chile

关键词: Purmorphamine;    In ovo cyclopamine treatment;    Non-linear signal analyses;    Optic tectum;    Neuroepithelial cell proliferation;    Shh/Gli pathway;   

Others  :  1140932
DOI  :  10.1186/1471-2202-13-117

 received in 2011-12-08, accepted in 2012-09-26,  发布年份 2012

【 摘 要 】

Background

Sonic hedgehog (Shh)/Gli pathway plays an important regulatory role on the neuroepithelial cells (NEc) proliferation in the dorsal regions of the developing vertebrate Central Nervous System. The aim of this paper was to analyze the effect of the Shh/Gli signaling pathway activation on the proliferation dynamics and/or the spatial organization of the NEc proliferation activity during early stages of the developing chick optic tectum (OT). In ovo pharmacological gain and loss of hedgehog function approaches were complemented with in vivo electroporation experiments in order to create ectopic sources of either Shh or Gli activator (GliA) proteins in the OT. NEc proliferating activity was analyzed at ED 4/4.5 by recording the spatial co-ordinates of the entire population of mitotic NEc (mNEc) located along OT dorsal-ventral sections. Several space signals (numerical sequences) were derived from the mNEc spatial co-ordinate records and analyzed by different standardized non-linear methods of signal analysis.

Results

In ovo pharmacologic treatment with cyclopamine resulted in dramatic failure in the OT expansion while the agonist purmorphamine produced the opposite result, a huge expansion of the OT vesicle. Besides, GliA and Shh misexpressions interfere with the formation of the intertectal fissure located along the dorsal midline. This morphogenetic alteration is accompanied by an increase in the mNEc density. There is a gradient in the response of NEcs to Shh and GliA: the increase in mNEc density is maximal near the dorsal regions and decrease towards the OT-tegmental boundary. Biomathematical analyses of the signals derived from the mNEc records show that both Shh and GliA electroporations change the proliferation dynamics and the spatial organization of the mNEc as revealed by the changes in the scaling index estimated by these methods.

Conclusions

The present results show that the Shh/Gli signaling pathway plays a critical role in the OT expansion and modelling. This effect is probably mediated by a differential mitogenic effect that increases the NEc proliferation and modulates the spatial organization of the NEc proliferation activity.

【 授权许可】

   
2012 Rapacioli et al.; licensee BioMed Central Ltd.

【 图 表 】

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