δ-Crystallin gene expression and patterns of hypomethylation demonstrate two levels of regulation for the δ-crystallin genes in embryonic chick tissues

Sullivan, Caroline; O'Farrell, Susan; Grainger, Robert M.

doi:10.1016/0012-1606(91)90211-k

Cited by 25 publications

(9 citation statements)

References 29 publications

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“…In lens, methylation studies of several crystallin gene promoters were consistent with the standard model in which methylated DNA inhibits gene expression (Sullivan et al ., 1991; Klok et al ., 1998). In retina, site-specific hypomethylation of inter-photoreceptor retinoid-binding protein regulates its expression in photoreceptors as the promoter is hypermethylated in other retinal cells (Boatright et al ., 2000).…”

Section: Dna Methylationsupporting

confidence: 69%

Epigenetic regulatory mechanisms in vertebrate eye development and disease

Cvekl

Mitton

2010

Heredity

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Eukaryotic DNA is organized as a nucleoprotein polymer termed chromatin with nucleosomes serving as its repetitive architectural units. Cellular differentiation is a dynamic process driven by activation and repression of specific sets of genes, partitioning the genome into transcriptionally active and inactive chromatin domains. Chromatin architecture at individual genes/loci may remain stable through cell divisions, from a single mother cell to its progeny during mitosis, and represents an example of epigenetic phenomena. Epigenetics refers to heritable changes caused by mechanisms distinct from the primary DNA sequence. Recent studies have shown a number of links between chromatin structure, gene expression, extracellular signaling, and cellular differentiation during eye development. This review summarizes recent advances in this field, and the relationship between sequence-specific DNA-binding transcription factors and their roles in recruitment of chromatin remodeling enzymes. In addition, lens and retinal differentiation is accompanied by specific changes in the nucleolar organization, expression of non-coding RNAs, and DNA methylation. Epigenetic regulatory mechanisms in ocular tissues represent exciting areas of research that have opened new avenues for understanding normal eye development, inherited eye diseases and eye diseases related to aging and the environment.

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Section: Dna Methylationsupporting

confidence: 69%

Epigenetic regulatory mechanisms in vertebrate eye development and disease

Cvekl

Mitton

2010

Heredity

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“…Later studies employed immunofluorescence using antibodies to the lens (Karkinen-Jääskeläinen, 1978) or to the major lens protein, delta-crystallin (Barabanov and Fedtsova, 1982). A potential complication with using delta-crystallin (and many other crystallins) as a marker of lens differentiation is that the messenger RNA for this protein has been detected in a variety of non-lens tissues in chicken embryos (Agata et al, 1983;Jeanny et A B D al., 1985;Sullivan et al, 1991b). We find, however, that a combination of morphological changes associated with lens differentiation and the synthesis the delta-crystallin protein, confirmed by immunoblot analysis (Sullivan et al, 1998), provide a definitive assay for lens formation.…”

Section: Introductionmentioning

confidence: 62%

A re-examination of lens induction in chicken embryos: in vitro studies of early tissue interactions

Sullivan¹,

Braunstein²,

Hazard-Leonards³

et al. 2004

Int. J. Dev. Biol.

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Early studies on lens induction suggested that the optic vesicle, the precursor of the retina, was the primary inducer of the lens; however, more recent experiments with amphibians establish an important role for earlier inductive interactions between anterior neural plate and adjacent presumptive lens ectoderm in lens formation. We report here experiments assessing key inductive interactions in chicken embryos to see if features of amphibian systems are conserved in birds. We first examined the issue of specification of head ectoderm for a lens fate. A large region of head ectoderm, in addition to the presumptive lens ectoderm, is specified for a lens fate before the time of neural tube closure, well before the optic vesicle first contacts the presumptive lens ectoderm. This positive lens response was observed in cultures grown in a wide range of culture media. We also tested whether the optic vesicle can induce lenses in recombinant cultures with ectoderm and find that, at least with the ectodermal tissues we examined, it generally cannot induce a lens response. Finally, we addressed how lens potential is suppressed in non-lens head ectoderm and show an inhibitory role for head mesenchyme. This mesenchyme is infiltrated by neural crest cells in most regions of the head. Taken together, these results suggest that, as in amphibians, the optic vesicle cannot be solely responsible for lens induction in chicken embryos; other tissue interactions must send early signals required for lens specification, while inhibitory interactions from mesenchyme suppress lens-forming ability outside of the lens area.

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“…In this study, we determined that very few embryonic chick tissues contain detectable levels of the delta-crystallin protein even though delta-crystallin mRNA is widespread [1,4,15,33,34]. In addition, only lenses and some regions of cultured head ectoderm show both synthesis of this protein and cell elongation.…”

Section: Discussionmentioning

confidence: 99%

“…Included in this list were Rathke's pouch, brain, heart, limb bud and non-lens eye tissue from stage-22 (84 h) chicken embryos. Therefore, the aim of the experiments described here was to use antibodies to delta-crystallin to determine whether the mRNA for this protein is ever translat-ed in any of the non-lens tissues where transcripts have been detected [1,33]. Second, we show that the combination of immunoblot analysis of delta-crystallin synthesis and cell elongation are suitable criteria for assessing a lens response when studying lens differentiation in vitro.…”

Section: Introductionmentioning

confidence: 90%

“…The delta-crystallin protein is first detected in the lens at stage-14 (50 h) [5,41], when elongation of induced lens cells is beginning. A potential difficulty with using delta-crystallin as a strict lens marker is that the messenger RNA (mRNA) for this protein has been detected in many non-lens tissues by northern blot analysis [1,4,33] and by in situ hybridization [15,34]. Included in this list were Rathke's pouch, brain, heart, limb bud and non-lens eye tissue from stage-22 (84 h) chicken embryos.…”

Section: Introductionmentioning

confidence: 99%

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