Indiana University-Purdue University Indianapolis (IUPUI) / The glial cells of the retina aid in function and maintenance of the retina. The macroglia, Muller cells and the retinal astrocytes, become reactive following injury or disease in the retina, a response that is characterized by hypertrophy, dedifferentiation, loss of functionality, proliferation, and remodeling of tissue and extracellular matrix (ECM). The microglia which are the resident macrophages, also respond to injury/disease becoming activated, undergoing characteristic molecular and morphological changes, which include regulation of secreted factors, changes in inflammatory response and increased phagocytosis. Reactivity in Muller glia is thought to be the result of secreted signals, such as epidermal growth factor, ciliary neurotrophic factor, and broblast growth factor, which are released at the injury site to interact with quiescent glial cells. Furthermore, microglia and macroglia have been shown by some studies to interact following activation. While BMPs are known to be upregulated following injury in the CNS, little information is available concerning their role in reactive gliosis in the retina. We hypothesize that BMP7 indirectly triggers Muller gliosis by activating microglia. Using RT-qPCR, immunofluorescence and western blot, we assessed changes in gliosis markers in the mouse retinal glia following treatment with BMP. Our results showed that BMP7 was able to trigger Muller cell gliosis in the retina in vitro and in vivo. Furthermore, ablation of microglia lead to a subdued gliosis response in the mouse retina following BMP7 exposure. Thus, BMP7 triggers activation of retinal microglia in addition to the Muller glia. IFN-gamma and IL6 could play a role in microglia mediated activation of Muller glia, following exposure to BMP7. We also assessed the role of the Hippo/YAP pathway in the regulation of gliosis in the retina. We demonstrated that YAP was localized to the nucleus of the Muller cells of the retina and was upregulated in IFN-gamma induced gliosis in the mouse retina.

The combination of bone morphogenetic protein 7 (BMP7) and neurotrophins (e.g. brain-derived neurotrophic factor, BDNF) protects septal neurons during hypoglycemic stress. I investigated the signaling mechanisms underlying this synergistic protection. BMP7 (5 nM) increased phosphorylation and nuclear translocation of BMP-responsive Smads 1/5/8 within 30 min in cultures of rat embryonic septal neurons. BDNF (100 ng/ml) enhanced the BMP7-induced increase in phospho-Smad levels in both nucleus and cytoplasm; this effect was more pronounced after a hypoglycemic stress. BDNF increased both Akt and Erk phosphorylation, but pharmacological blockade of these kinase pathways (with wortmannin and U0126, respectively) did not reduce the Smad phosphorylation produced by the BMP7+BDNF combination. Inhibitors of casein kinase II (CK2) activity reduced the (BMP7 + BDNF)-induced Smad phosphorylation, and this trophic factor combination increased CK2 activity in hypoglycemic cultures. These findings suggest that BDNF can increase BMP-dependent Smad phosphorylation via a mechanism requiring CK2. Preliminary results indicate that a cytoplasmic component robustly inhibits CK2. Protection of septal cholinergic neurons during a hypoglycemic stress is inhibited by a CK2 inhibitor and by a Phosphatidylinositol 3-kinase inhibitor, indicating that increases in CK2 activity and in Smad phosphorylation are only part on the protective mechanisms.

As obesity and obesity-associated diseases become more prevalent in western societies, new methods to promote weight-loss and protect patients from the dangerous consequences of excess adipose tissue are needed. While both researchers and clinicians previously turned to chemical uncouplers for many decades to create a negative energy balance and thus promote weight-loss, these compounds proved to be extremely dangerous treatment options, even when taken in mild dosages. Substances like 2-4 dinitrophenol (DNP), were able to significantly induce weight loss, however many life-threatening conditions such as fatal hyperthermia are commonly attributed to these uncoupling agents. Recently, with the discovery of natural brown/beige fat reservoirs in humans, many members of the medical community have become heavily invested in the targeting of more localized, less systemic uncoupling tissues. The action of UCP-1 in human thermogenic adipose introduces an opportunity to harness a natural, yet futile cycle, and hence boost a patient’s basal metabolism without ultimately compromising their long-term health. Many challenges remain before such a treatment is viable, including deciphering the biochemical pathways that induce brown fat thermogenesis. It appears that several uncoupling signals may govern the genetic programs that lead to this thermogenic activity, and the "browning" of white adipose stores in humans. Particularly in the last ten years, many studies have uncovered new components of the thermogenic program by ablating target genes in mice. While a direct pathway of thermogenic activation does exist when subjects are placed in a cold environment, a successful, high-adoption, anti-obesity treatment through a thermogenic regimen will likely involve a gene-therapy or protein-based biopharmaceutical intervention. It is conceivable that thermogenic manipulation could play a significant role in the battle against obesity and obesity-associated diseases, however a significant intellectual breakthrough in appetite suppression and/or appetite management (i.e. a successful intervention of the orexigenic and anorexigenic physiological pathways) could in theory supplant this approach.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第22692号 / 医博第4636号 / 新制||医||1045(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 柳田 素子, 教授 斎藤 通紀, 教授 川口 義弥 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20561号 / 医博第4246号 / 新制||医||1022(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 松田 秀一, 教授 瀬原 淳子, 教授 妻木 範行 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

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