Browsing by Author "Belecky-Adams, Teri L."

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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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    Mechanisms of spinophilin-dependent pancreas dysregulation in obesity
    (American Physiological Society, 2024) Stickel, Kaitlyn C.; Shah, Nikhil R.; Claeboe, Emily T.; Orr, Kara S.; Mosley, Amber L.; Doud, Emma H.; Belecky-Adams, Teri L.; Baucum, Anthony J.; Biology, School of Science
    Spinophilin is an F-actin binding and protein phosphatase 1 (PP1) targeting protein that acts as a scaffold of PP1 to its substrates. Spinophilin knockout (Spino-/-) mice have decreased fat mass, increased lean mass, and improved glucose tolerance, with no difference in feeding behaviors. Although spinophilin is enriched in neurons, its roles in nonneuronal tissues, such as β cells of the pancreatic islets, are unclear. We have corroborated and expanded upon previous studies to determine that Spino-/- mice have decreased weight gain and improved glucose tolerance in two different models of obesity. We have identified multiple putative spinophilin-interacting proteins isolated from intact pancreas and observed increased interactions of spinophilin with exocrine, ribosomal, and cytoskeletal protein classes that normally act to mediate peptide hormone production, processing, and/or release in Leprdb/db and/or high-fat diet-fed (HFF) models of obesity. In addition, we have found that spinophilin interacts with proteins from similar classes in isolated islets, suggesting a role for spinophilin in the pancreatic islet. Consistent with a pancreatic β cell type-specific role for spinophilin, using our recently described conditional spinophilin knockout mice, we found that loss of spinophilin specifically in pancreatic β cells improved glucose tolerance without impacting body weight in chow-fed mice. Our data further support the role of spinophilin in mediating pathophysiological changes in body weight and whole body metabolism associated with obesity. Our data provide the first evidence that pancreatic spinophilin protein interactions are modulated by obesity and that loss of spinophilin specifically in pancreatic β cells impacts whole body glucose tolerance. NEW & NOTEWORTHY: To our knowledge, these data are the first to demonstrate that obesity impacts spinophilin protein interactions in the pancreas and identify spinophilin specifically in pancreatic β cells as a modulator of whole body glucose tolerance.
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    Mechanisms of spinophilin-dependent pancreas dysregulation underlying diabesity
    (Cold Spring Harbor Laboratory, 2023-02-08) Stickel, Kaitlyn C.; Mosley, Amber L.; Doud, Emma H.; Belecky-Adams, Teri L.; Baucum, Anthony J., II; Biology, School of Science
    Objective: Spinophilin is an F-actin binding and protein phosphatase 1 (PP1) targeting protein that acts as a scaffold of PP1 to its substrates. Spinophilin knockout (Spino-/-) mice have decreased fat mass, increased lean mass, and improved glucose tolerance, with no difference in feeding behaviors. While spinophilin is enriched in neurons, its roles in non-neuronal tissues, such as beta cells of the pancreatic islets, are unclear. Methods & results: We have corroborated and expanded upon previous studies to determine that Spino-/- mice have decreased weight gain and improved glucose tolerance in two different models of obesity. Using proteomics and immunoblotting-based approaches we identified multiple putative spinophilin interacting proteins isolated from intact pancreas and observed increased interactions of spinophilin with exocrine, ribosomal, and cytoskeletal protein classes that mediate peptide hormone production, processing, and/or release in Leprdb/db and/or high fat-fed (HFF) models of obesity. Moreover, loss of spinophilin specifically in pancreatic beta cells improved glucose tolerance without impacting body weight. Conclusion: Our data further support a role for spinophilin in mediating pathophysiological changes in body weight and whole-body metabolism associated with obesity and provide the first evidence that spinophilin mediates obesity-dependent pancreatic dysfunction that leads to deficits in glucose homeostasis or diabesity.
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    Microglia activation is essential for BMP7-mediated retinal reactive gliosis
    (BioMed Central, 2017) Dharmarajan, Subramanian; Fisk, Debra L.; Sorenson, Christine M.; Sheibani, Nader; Belecky-Adams, Teri L.; Department of Biology, School of Science
    Our previous studies have shown that BMP7 is able to trigger activation of retinal macroglia. However, these studies showed the responsiveness of Müller glial cells and retinal astrocytes in vitro was attenuated in comparison to those in vivo, indicating other retinal cell types may be mediating the response of the macroglial cells to BMP7. In this study, we test the hypothesis that BMP7-mediated gliosis is the result of inflammatory signaling from retinal microglia.
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    Standardizing methods and procedures for mouse retinal flat mounts and glial cell counts
    (Office of the Vice Chancellor for Research, 2015-04-17) Anderson III, Richard; Dharmarajan, Subramanian; Belecky-Adams, Teri L.
    Introduction: The mammalian retina contains neuronal cells as well as a number of non-neuronal glial cells. The different types of glial cells include Müller glia, retinal astrocytes, and microglia. Müller glial cells and astrocytes nourish neurons and microglia act as sentinels that respond to injury or disease within the nervous system. The long-term goal of our laboratory has been to study interactions between microglia, Muller glia and astrocytes in healthy and diseased tissue. The focus of the present study was to develop a technique that would allow the laboratory to study changes in cell number in retinal flat mounts and cultures. Methods: Immunohistochemistry (IHC) was performed to fluorescently label mature murine retinal tissue. Retinal flat-mounts were stained with SOX2, a nuclear marker for glial cells or IBA1 for microglial cells, and counter-stained with Hoechst solution to label all nuclei. Pure cultures of mouse microglial cells treated with liposomal clodronate (a drug which specifically targets and ablates microglia) and vehicle were counter stained with Hoechst solution. Cell counts were performed on the images of the fluorescently labeled samples using Image-J software. Results: Convolutions were used to filter images of immunolabeled cultures and retinal flat mounts to make the images clear enough to capture cell number. The cell count assistance protocol yielded acceptable cell count results of the stained cells and determined a detectable difference in the number of clodronate treated cells versus vehicle treated control cells. The images produced of the retinal flat-mounts were analyzed to determine the percentage of SOX2 positive Müller glia in the mature murine retinal tissue. Conclusion: A modified Image J program could be used to determine cellular number in cultures and retinal flat mounts. Mentor: Teri L Belecky-Adams, Department of Biology, Indiana University-Purdue University Indianapolis
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    TAK1 inhibition increases proliferation and differentiation of chick retinal cells
    (Frontiers Media, 2022-09-13) Carrillo, Casandra; Ravi, Vagisha; Tiwari, Sarika; Chernoff, Ellen A.; Belecky-Adams, Teri L.; Biology, School of Science
    The factors necessary for the differentiation of cell types within the retina are incompletely understood. The transforming growth factor beta (TGF-β) superfamily, including TGF-β1 and 2, the bone morphogenetic proteins, and the activins have all been implicated in differentiation; however, the mechanisms by which these factors affect differentiation are only partially understood. The studies herein focus on a potential role for transforming growth factor β-activated kinase 1 (TAK1), a hub kinase that lies at the intersection of multiple signaling pathways, in the differentiation of cell types within the chick retina. Previous studies have focused predominantly on the role this kinase plays in the inflammation process and axonal growth. TAK1 is downstream of multiple signaling pathways that are critical to development of the central nervous system, including transforming growth factor β (TGFβ), bone morphogenetic proteins (BMPs), and activins. The present study indicates that activated TAK1 is found throughout the developing retina; however, it is localized at higher levels in dividing and differentiating cells. Further, ex ovo retinal studies using TAK1 inhibitor 5Z-7-oxozeaenol increased both progenitor and differentiating cell populations, accompanied by a substantial increase in proliferation and a smaller increase in cell death. These results indicate a unique role for TAK1 in differentiating and proliferating retinal cells.