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An investigation of membrane transporter proteins in the distal vertebrate retina: excitatory amino acid transporters and sodium potassium chloride cotransporters
Title
An investigation of membrane transporter proteins in the distal vertebrate retina: excitatory amino acid transporters and sodium potassium chloride cotransporters.
Creator
Purpura, Lauren Angeline, Shen, Wen, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Neurons are able to maintain membrane potential and synaptic integrity by an intricate equilibrium of membrane transporter proteins and ion channels. Two membrane proteins of particular importance in the vertebrate retina are the excitatory amino acid transporters (EAATs) which are responsible for the reuptake of glutamate into both glial and neuronal cells and the sodium potassium chloride cotransporters (NKCCs) that are responsible for the uptake of chloride ions into the cell. NKCCs are...
Show moreNeurons are able to maintain membrane potential and synaptic integrity by an intricate equilibrium of membrane transporter proteins and ion channels. Two membrane proteins of particular importance in the vertebrate retina are the excitatory amino acid transporters (EAATs) which are responsible for the reuptake of glutamate into both glial and neuronal cells and the sodium potassium chloride cotransporters (NKCCs) that are responsible for the uptake of chloride ions into the cell. NKCCs are electro-neutral with the uptake of 2 Cl- coupled to an exchange of a potassium and Na+ ion into the cells. Therefore, there is little change of cell membrane potential in the action of NKCCs. In this study the localization and function of EAATs in the distal retina is investigated. Whole cell patch clamp recordings in lower vertebrate retina have demonstrated that EAAT2 is the main synaptic EAATs in rod photoreceptors and it is localized to the axon terminals. Furthermore, the action of the transporter seems to be modified by intracellular calcium concentration. There is also evidence that EAAT2 might be regulated by feedback from the neuron network by glycinergic and GABAergic mechanisms. The second half of this study investigates expression of NKCCs in the retina by western blot analysis and quantitative polymerase chain reaction. There are two forms of NKCCs, NKCC1 and NKCC2. NKCC1 is mostly expressed in the central nervous system and NKCC2 was thought to only be expressed in the kidneys. NKCC1 is responsible for the majority of chloride uptake into neuronal and epithelial cells and NKCC1 is expressed in the distal retina where photoreceptors synapse on second order horizontal and bipolar cells. This study found the expression of NKCC1 in the distal retina to be regulated by temporal light and dark adaptation. Light adaptation increased phosphorylated NKCC1 expression (the active form of the cotransporter). The increase in NKCC1 expression during light adaptation was modulated by dopamine. Specifically, a D1 receptor agonist increased phosphorylated NKCC1 expression. Dopamine is an essential chemical and receptor known for initiating light adaptation in retina. Finally, an NKCC1 knockout mouse model was examined and it revealed that both forms of NKCC are expressed in the vertebrate retina.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004224, http://purl.flvc.org/fau/fd/FA00004224
Subject Headings
Biological transport, Carrier proteins, Cellular signal transduction, Neural receptors, Retina -- Cytology
Format
Document (PDF)
The Impact of Pharmacological Targeting of Abnormal Tumor Metabolism with 3-Bromopyruvate on Dendritic Cell Mediated Tumoral Immunity
Title
The Impact of Pharmacological Targeting of Abnormal Tumor Metabolism with 3-Bromopyruvate on Dendritic Cell Mediated Tumoral Immunity.
Creator
Lang, Kevin, Hartmann, James X., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Studies have shown that tumor cells are susceptible to pharmacological targeting of their altered glycolytic metabolism with a variety of compounds that result in apoptosis. One such compound, 3-bromopyruvate (3-BP), has been shown to eradicate cancer in an animal model. However, no studies have shown whether the apoptotic fragments resulting from 3-BP treatment have the capacity to elicit an immunogenic cell death that activates dendritic cells, the primary antigen presenting cell in the...
Show moreStudies have shown that tumor cells are susceptible to pharmacological targeting of their altered glycolytic metabolism with a variety of compounds that result in apoptosis. One such compound, 3-bromopyruvate (3-BP), has been shown to eradicate cancer in an animal model. However, no studies have shown whether the apoptotic fragments resulting from 3-BP treatment have the capacity to elicit an immunogenic cell death that activates dendritic cells, the primary antigen presenting cell in the immune system. Immunogenic cell death is critical to eliciting an effective adaptive immune response that selectively kills additional target cells and generates immunological memory. We demonstrated that 3-bromopyruvate induced apoptosis in a number of different murine breast cancer cell lines, including the highly metastatic 4T1 line. The dying tumor cells stimulated immature dendritic cells (DCs) of the immortal JAWS II cell line to produce high levels of the pro-inflammatory cytokine IL-12, and increased their expression of key co-stimulatory molecules CD80 and CD86. The activated dendritic cells showed increased uptake of fragments from dying tumor cells that correlated with the increased levels of calreticulin on the surface and release of high group motility box 1 (HMGB1) of the latter following 3-BP treatment. Additionally, the anti-phagocytic signal CD47 present on breast cancer cells was reduced by treatment with 3-bromopyruvate when compared to the levels on untreated 4T1 cells. 3-BP treated breast cancer cells were able to activate dendritic cells through TLR4 signaling. Signaling was dependent on both the expression of surface calreticulin and on the extracellular release of high mobility group box 1 protein (HMGB1) during the process of immunogenic cell death. Killing by 3-BP was compared to mitoxantrone and doxorubicin, among the few chemotherapeutics that induce immunogenic cell death. 3-BP killing was likewise compared to camptothecin, a compound that fails to induce immunogenic cell death. Importantly, 3-BP did not markedly decrease the levels of the key peptide presenting molecule MHC I on DCs that were co-cultivated with dying tumor cells. Treatment of the highly aggressive triple negative BT-20 human breast cancer cell line with 3-BP also induced an immunogenic cell death, activating human dendritic cells in vitro.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004834
Subject Headings
Apoptosis., Cellular signal transduction., Cell death., Breast--Cancer--Treatment., Carrier proteins., Cancer--Molecular aspects., Biological interfaces.
Format
Document (PDF)
Using ATR-IR spectroscopy to study the conformation of cell-penetrating peptides
Title
Using ATR-IR spectroscopy to study the conformation of cell-penetrating peptides.
Creator
Fontoura, Luiza, Rezler, Evonne
Date Issued
2012-04-06
PURL
http://purl.flvc.org/fcla/dt/3351389
Subject Headings
Cell-Penetrating Peptides, Antennapedia Homeodomain Protein, Homeodomain Proteins --chemistry, Spectroscopy, Fourier Transform Infrared --methods, Spectrum Analysis, Amides --chemistry, Carrier Progeins
Format
Document (PDF)