Expression of Sonic Hedgehog During Cell Proliferation in the Human Cerebellum

Haldipur, Parthiv and Bharti, Upasna and Govindan, Subashika and Sarkar, Chitra and Iyengar, Soumya and Gressens, Pierre and Mani, Shyamala (2012) Expression of Sonic Hedgehog During Cell Proliferation in the Human Cerebellum. In: Stem Cells and Development, 21 (7). pp. 1059-1068.

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Abstract

The regulation of cell proliferation in the external granular layer (EGL) of the developing cerebellum is important for its normal patterning. An important signal that regulates EGL cell proliferation is Sonic hedgehog (Shh). Shh is secreted by the Purkinje cells (PC) and has a mitogenic effect on the granule cell precursors of the EGL. Deregulation of Shh signaling has been associated with abnormal development, and been implicated in medulloblastomas, which are tumors that arise from the cerebellum. Given the importance of the Shh pathway in cerebellum development and disease, there has been no systematic study of its expression pattern during human cerebellum development. In this study, we describe the expression pattern of Shh, its receptor patched, smoothened, and its effectors that belong to the Gli family of transcription factors, during normal human cerebellum development from 10 weeks of gestational age, and in medulloblastomas that represents a case of abnormal cell proliferation in the cerebellum. This expression pattern is compared to equivalent stages in the normal development of cerebellum in mouse, as well as in tumors. Important differences between human and mouse that reflect differences in the normal developmental program between the 2 species are observed. First, in humans there appears to be a stage of Shh signaling within the EGL, when the PC are not yet the source of Shh. Second, unlike in the postnatal mouse cerebellum, expression of Shh in the PC in the postnatal human cerebellum is downregulated. Finally, medulloblastomas in the human but not in patched heterozygote mouse express Shh. These results highlight cross-species differences in the regulation of the Shh signaling pathway.

Item Type:	Journal Article
Publication:	Stem Cells and Development
Publisher:	Mary Ann Liebert
Additional Information:	Copyright of this article is belongs to Mary Ann Liebert.
Keywords:	MOUSE CEREBELLUM;PURKINJE-CELLS;MEDULLOBLASTOMA;PATHWAY; GENE;GLI1;DIFFERENTIATION;HISTOGENESIS;ACTIVATION;COMPONENTS
Department/Centre:	Division of Biological Sciences > Centre for Neuroscience
Date Deposited:	21 Aug 2012 05:33
Last Modified:	22 Aug 2012 06:46
URI:	http://eprints.iisc.ac.in/id/eprint/44438

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