Browsing by Author "Saha, Ankita"

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    Class I histone deacetylases in retinal progenitors and differentiating ganglion cells
    (Elsevier, 2018-12) Saha, Ankita; Tiwari, Sarika; Dharmarajan, Subramanian; Otteson, Deborah C.; Belecky-Adams, Teri L.; Biology, School of Science
    Background The acetylation state of histones has been used as an indicator of the developmental state of progenitor and differentiating cells. The goal of this study was to determine the nuclear localization patterns of Class I histone deacetylases (HDACs) in retinal progenitor cells (RPCs) and retinal ganglion cells (RGCs), as the first step in understanding their potential importance in cell fate determination within the murine retina. Results The only HDAC to label RPC nuclei at E16 and P5 was HDAC1. In contrast, there was generally increased nuclear localization of all Class I HDACs in differentiating RGCs. Between P5 and P30, SOX2 expression becomes restricted to Müller glial, cholinergic amacrine cells, and retinal astrocytes. Cholinergic amacrine showed a combination of changes in nuclear localization of Class I HDACs. Strikingly, although Müller glia and retinal astrocytes express many of the same genes, P30 Müller glial cells showed nuclear localization only of HDAC1, while retinal astrocytes were positive for HDACs 1, 2, and 3. Conclusion These results indicate there may be a role for one or more of the Class I HDACs in retinal cell type-specific differentiation.
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    Potential role of histone deacetylases in the development of the chick and murine retina
    (2014-09-04) Saha, Ankita; Belecky-Adams, Teri; Stocum, David L.; Meyer, Jason S.; Atkinson, Simon
    The epigenetic state of any cell is, in part, regulated by the interaction of DNA with nuclear histones. Histone tails can be modified in a number of ways that impact on the availability of DNA to interact with transcriptional complexes, including methylation, acetylation, phosphorylation, ubiquituination, and sumoylation. Histones are acetylated by a large family of enzymes, histone acetyl transferases (HATs), and deacetylated by the histone deacetylases (HDACs). Acetylated histones are generally considered markers of genomic regions that are actively being transcribed, whereas deacetylated and methylated histones are generally markers of regions that are inactive. The goal of the present study was to 1) study the epigenetic state with regard to the presence of euchromatin and heterochromatin in the developing chick and murine retina, 2) study and compare the localization patterns of the classical HDACs in the developing chick and murine retina with respect retinal progenitors and early differentiated cell types 3) to test the hypothesis that overall HDAC activity is required for dividing retinal progenitors to leave the cell cycle and differentiate. Our results showed that the classical HDACs were ubiquitously expressed in the developing chick and murine retinas. Species specific differences as well as stage dependent variations were observed in the localization of the HDACs in the cell types that were studied in the chick and murine retina. Our preliminary results also showed that HDAC inhibition may lead to the inability of the cell types to leave the cell cycle and a subsequent increase in the number of progenitor cells present in the developing chick retina.