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author:("Das, ragnya")
1.  Gdnf is mitogenic, neurotrophic, and chemoattractive to enteric neural crest cells in the embryonic colon 
Glial-derived neurotrophic factor (Gdnf) is required for morphogenesis of the enteric nervous system (ENS) and it has been shown to regulate proliferation, differentiation, and survival of cultured enteric neural crest-derived cells (ENCCs). The goal of this study was to investigate its in vivo role in the colon, the site most commonly affected by intestinal neuropathies such as Hirschsprung’s disease. Gdnf activity was modulated in ovo in the distal gut of avian embryos using targeted retrovirus-mediated gene overexpression and retroviral vector-based gene silencing. We find that Gdnf has a pleiotropic effect on colonic ENCCs, promoting proliferation, inducing neuronal differentiation, and acting as a chemoattractant. Downregulating Gdnf similarly induces premature neuronal differentiation, but also inhibits ENCC proliferation, leading to distal colorectal aganglionosis with severe proximal hypoganglionosis. These results indicate an important role for Gdnf signaling in colonic ENS formation and emphasize the critical balance between proliferation and differentiation in the developing ENS.
PMCID: PMC3092856  PMID: 21465624
enteric nervous system; glial-derived neurotrophic factor; Gdnf; Ret; Hirschsprung’s disease; chick
2.  Expression analysis of the Islet-1 gene in the developing and adult gastrointestinal tract 
Gene expression patterns : GEP  2011;11(3-4):244-254.
LIM-Homeodomain genes encode a family of proteins defined by the cysteine-rich protein/protein interacting (Lin-11, Isl-1, and Mec-3) LIM domain and a highly conserved DNA-binding domain. Studies in several organisms have shown that these transcriptional regulators control multiple aspects of embryonic development and are responsible for the pathogenesis of several human diseases. Here we report the expression of Islet-1 (Isl-1) in the gastrointestinal epithelium in developing and adult mice. At embryonic day (E) 9.5–10.5, Isl-1 expression was first detected in the ventral gastric mesenchyme, and expression in the dorsal mesenchyme initiated a few days later. Isl-1 expression was first observed in the gastric epithelium at E13.5 and at E14.5 was restricted to the posterior half of the stomach. In the mature stomach, Isl-1 expression was detected only in subsets of enteroendocrine cells. Furthermore, Isl-1 expression in the intestinal epithelium was first detected at E15.5 and was restricted to subpopulations of enteroendocrine cells in adult mice. These expression analyses suggest that Isl-1 might have an early broad role in stomach and intestinal cells and a secondary role in terminal differentiation and/or maintenance of mature enteroendocrine subtypes in the gastrointestinal epithelium.
PMCID: PMC3065958  PMID: 21220053
Islet-1; stomach; intestine; gastrointestinal tract; development; transcriptional control; endocrine cell differentiation; somatostatin; gastrin; ghrelin
3.  Retinoic Acid Regulation of Eye and Testis-Specific Transcripts within a Complex Locus 
Mechanisms of development  2006;124(2):137-145.
We previously used a yeast-based enhancer trap to identify a strong, retinoic acid response element (RARE). We have now characterized testis and eye transcripts that are adjacent to this regulatory element. Bioinformatics analysis of expressed sequence tag (EST) clones and RNase protection, reverse transcription-PCR, and northern blot assays indicate that these two RNAs are transcribed from the same locus on opposite template strands. This positions the RARE upstream of the testis transcript and downstream of the eye transcript. Additionally, these two RNAs are embedded within the third intron of the 329 kbp gene that encodes the Zinc Finger and BTB domain containing 7C protein (Zbtb7C). We present the evidence indicating that the testis transcript is expressed primarily in spermatocytes and/or early round spermatids. Furthermore, our analyses of transcript levels in eyes and testes isolated from vitamin A deficient mice or from mice with defects in retinoid storage or signaling indicate that retinoids are required for expression in vivo.
PMCID: PMC1847367  PMID: 17166701
retinoids; spermatogenesis; gene regulation; eye; RAREs

Results 1-3 (3)