MACUB (2021) Conference

Abstract: The United States is currently home to an obesity epidemic where 34% of adults and 15-20% of children are obese. The high number of those suffering from obesity are also at risk of developing cancer, coronary artery disease and diabetes. Those with metabolic disorders, diabetes and high levels of fat in the blood are at risk of developing fatty liver disease. Non-alcoholic fatty liver disease (NAFLD), also known as metabolic (dysfunction) associated fatty liver disease (MAFLD), is excessive fat build-up in the liver without another clear cause such as alcohol use. Inositol hexakisphosphate kinase 1 (IP6K1) is an enzyme in the inositol phosphate pathway which has recently been found to play a major role in obesity and associated comorbidities. In this presentation, a detailed review of the effect of IP6K1 on NAFLD will be presented. Our presentation will focus on studies conducted on rodent models where IP6K1 gene was deleted or pharmacologically inhibited. Gene deletion and pharmacology studies will confirm that IP6K1 can be potential drug target for treating NAFLD.

Abstract: The African cichlid, Astatotilapia burtoni, is a favorable model to communicate the cellular substrates of plasticity in connection with behavior. Adjustments in their immediate surroundings facilitate modified behavior through gradual modifications in neural processes and their inherent structure and function. A. burtoni can abruptly alter their color and behavior with varied habitats and social cues. To study this, we are looking at the anatomical differences in the Gonadotropin-releasing hormone-1 (GnRH1) neurons in animals that are blue or yellow. GnRH1 neurons are fundamental to the hypothalamic-pituitary-gonadal axis of an animal’s reproductive behavior. Our approach uses coupled study of behavior and neuroanatomical analysis of GnRH1 neurons with tissue clearing and genetic labeling with a green fluorescent protein (GFP). This project will contribute to our understanding of phenotypic plasticity and behavior. We hypothesize that environmental influences shape neural differences in the GnRH1 between blue and yellow male morphs. Based on our preliminary data, each color morph has its own behavioral profile. Blue males present as being more reproductively inclined than the yellow males who present to be more territorial and aggressive. This project will present a more nuanced view of neuroplasticity in this emerging model system for the study of neuroscience and social behavior.

Abstract: Glioblastoma multiforme (GBM) is the most common and most aggressive primary tumor of the brain, and is associated with one of the worst 5-year survival rates among all human cancers. Extensive analysis of patient data has shown a sex-based disparity in GBM, reporting that males are 1.5 to 3.5 times more likely to develop brain tumors than females, and subsequently have more extensive tumor necrosis and reduced survival compared to females. Contributing to the progression of this disease are the resident immune cells of the brain and spinal cord known as microglia; while inflammatory microglia function in an anti-tumorigenic manner, gliomas can disrupt this by releasing factors that polarize microglia to an immunosuppressive phenotype, which in turn secrete cytokines that support tumor growth and spread. Therefore, a shift in microglial populations towards more pro- or anti-inflammatory behavior could greatly impact GBM progression. We hypothesized that the sexual dimorphism seen in GBM could be explained by differential responses of male- and female-derived microglia, in that male cells would potentially respond in a more anti-inflammatory manner than female microglia. To investigate this hypothesis, we obtained two microglial cell lines – N9 cells, which are of male origin, and BV2 cells, which are of female origin. These cell lines were investigated for their ability to release pro-and anti-inflammatory cytokines in response to lipopolysaccharide and interleukin-4 stimulation. We noted a differential expression pattern of cytokines between these cell lines, and thus wanted to further observe the effects of these cells on the growth and proliferation of GL261 glioblastoma cells. As the sex-linked steroid hormone estrogen is more prevalent in females, we hypothesized that estrogen may play a role in promoting a pro-inflammatory shift in microglial populations, as well as function in a suppressive manner towards glioblastoma cells. Interestingly, we found that estrogen polarizes N9 microglia to an anti-inflammatory phenotype, but suppresses GBM migration. In conclusion, N9 microglia showed a more anti-inflammatory, pro-tumorigenic phenotype than BV2 microglia, yet estrogen surprisingly acts in an immunosuppressive manner. These data indicate that the worse outcomes seen with GBM in males could in part be due to sexually dimorphic microglial function outside of hormonal effects.

Abstract: Gill lateral cells of Crassostrea virginica are innervated by dopamine (DA) and serotonin nerves. DA slows down lateral cell cilia beating rates and serotonin accelerates them. DA receptors are classified as D1R and D2R. Physiology and cell biology work of our lab found the DA receptors involved in gill lateral cell cilia inhibition are D2R-like in the gill cells and D1R-like in the cerebral and visceral ganglia. Our HPLC studies found DA in various tissues, including gill, cerebral and visceral ganglia of Crassostrea virginica. Using immunofluorescence techniques, we showed the presence of DA neurons in cerebral and visceral ganglia as well as D2R-like postsynaptic receptors in gill lateral cells and D1R-like postsynaptic receptors in cerebral and visceral ganglia. Recently the genomes of C. virginica and other bivalves have begun to be mapped. By conducting searches of the NCBI (National Center for Biotechnology Information) database using DNA and protein sequences of C. virginica and other invertebrate and mammalian species we found matches for D1R genes on chromosomes 4 and 5, and D2R genes on chromosomes 3 and 5 of C. virginica. BLASTS of the receptors found matches with very low Expect Values (E values) and high Percent Identity of the D1R and D2R receptors to those in other bivalves, gastropods, insects, mice, rats and humans. Various invertebrates had Percent Identity above 60%, while humans and mice had Percent Identity of 30 - 40%. We hypothesize that the ligand binding sites (LBS) for D1R and D2R receptors in C. virginica are evolutionarily conserved and will closely match those of other animals. To study this, we searched the NCBI database for D1R and D2R LBS of C. virginica and compared them to other animals. We found D2R LBS contained 17 amino acids (W, D, V, S, F, T, L, S, S, S, W, F, F, N, F, T, Y) with very highly conserved (70 - 100%) to LBS of other bivalves, gastropods, insects, mice, rats and humans. D1R LBS have not yet been identified in C. virginica, nor in the other animals we searched for, except for humans where it contained 17 amino acids (W, D, I, S, T, S, A, S, S, S, W, F, F, N, F, V, W). The study complements our physiology and cell biology studies demonstrating the presence and function for DA in C. virginica, and shows the genome of C. virginica contains genes to produce DA receptor LBS that are similar to those of other animals. This new information is valuable as it shows that the simple nervous system of C. virginica can be used to expand studies on DA neurotransmission. This work was supported in part by grant 2R25GM06003 of the Bridge Program of NIGMS, NIH grant K12GM093854 07A1 IRACDA Program of Rutgers University and PSC CUNY grants 62344 00 50 and 63434 00 51.

Abstract: The inflammatory response is characterized by a transient loss of function of the vascular barrier, manifested in a rapid increase in endothelial permeability (hyperpermeability) to macromolecules, which leads to tissue swelling. Pro-inflammatory molecules released by injured tissues or cells activate vascular endothelial cells (EC), which in turn respond by rearranging intercellular junctions, thus increasing paracellular transport of fluids and solutes across the vascular wall. EC activation leads to mobilization of the endothelial nitric oxide synthase (eNOS) from the cell membrane, and nitric oxide (NO) production and delivery to subcellular targets. We have observed that cAMP signalling via Exchange protein activated by cAMP-1 (Epac1) triggers the mobilization of eNOS back to the membrane, concomitant with the termination of hyperpermeability. However, less is known about the cellular localization of these factors in this context. Radixin, a member of the ezrin/radixin/moesin (ERM) family of proteins, has been shown to regulate the localization of exogenously expressed Epac1 to the plasma membrane, but whether this is a relevant mechanism in EC remains unclear. We hypothesize that radixin may regulate endothelial response to pro-inflammatory stimuli by modulating Epac1 localization. We used immunocytochemistry to test the localization of eNOS, Epac1, and radixin in EAhy926 cells stimulated with platelet-activating factor (PAF) to simulate inflammation, and with 8cPT-cAMP, an Epac1-selective cAMP analog, to model the cAMP-mediated termination of hyperpermeability. Our results indicate that radixin localizes to intercellular junctions PAF challenge, and that Epac1 stimulation with 8cPT-cAMP mobilizes an additional pool of radixin. Together, these data suggest that Radixin plays a relevant role in the termination of endothelial hyperpermeability.

Abstract:

Neurons do not undergo mitosis. They terminally differentiate into lifetime-lasting cells where their neurodevelopment and hemostatic maintenance depend greatly on the autophagy process. Autophagy is a cellular catabolic pathway that degrades dysfunctional cellular components, like mitochondria, endoplasmic reticulum, and proteins, and recycles the breakdown products into cellular metabolic pathways. Autophagy is of great interest in neurons, as defects in the process have been linked to many neurodegenerative diseases. Both Microtubule-associated protein 1A/1B-light chain 3 (LC3) and Gamma-aminobutyric acid receptor-associated protein (GABARAP) are vital proteins in the autophagy process. While LC3 is involved in autophagosome elongation, maturation and is used as an autophagy marker, GABARAP is a receptor-associated protein that may be responsible for autophagosome fusion to the lysosome. GABARAP is also known to play a significant role in the regulation of its associated surface receptor, the gamma-aminobutyric acid (GABA) type neurotransmitter receptor (GABAR). Whether there is any link between the role of GABARAP in autophagy and its regulation of GABARs is unknown. In this study, the effect of GABARAP on the ɣ2 subunit of GABA receptor expression was examined in the presence and absence of autophagy-inducing treatments.

Results suggest GABARAP has an effect of increasing the GABARAP ɣ2 receptor expression in co-transfected cells. Preliminary results suggest that induction of autophagy through starvation and chloroquine treatment may enhance this effect.

Abstract:

Chronic pain is one of the major healthcare issues in the United States and worldwide. Despite its prevalence, to date, there are no satisfactory, mechanism-based treatments available to patients. One mechanism by which an acute painful injury becomes chronic is due to alterations in select brain areas, including the hippocampus. In particular, we have found neuronal cytoarchitectural changes, increased numbers of glial and astrocytic cells, as well as decreased rigidity in the extracellular matrix.

In our murine model of chronic neuropathic pain (spared nerve injury), we plan on investigating how changes in the biochemical and biophysical properties of the extracellular matrix can affect glial morphology and function in vitro. We will study morphological (soma size, cell size, and shape) and functional (phagocytosis, proliferation, and migration ability) changes in BV2 microglial cells grown on artificial matrices of differing rigidities as well as decellularized hippocampi from injured and control mice. Our future studies will include neuron-glia co-cultures to evaluate neuronal dendritic pruning by microglia grown on different matrices.

Understanding microglial modulation by the extracellular matrix can help us understand how pain-related brain plasticity may evolve and how extracellular effects may modulate microglial behavior vis-a-vis neurons. Such efforts are crucial in developing mechanism-based therapies for the millions of chronic pain sufferers worldwide.