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- Lööv, Camilla, 1982-
(författare)
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Cellular and Molecular Responses to Traumatic Brain Injury
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traumatic brain injury (TBI) is a relatively unknown disease considering the tens of millions of people affected around the world each year. Many TBI patients die from their injuries and survivors often suffer from life-long disabilities. The primary injury initiates a variety of cellular and molecular processes that are both beneficial and detrimental for the brain, but that are not fully understood. The focus of this thesis has been to study the role of astrocytes in clearance of dead cells after TBI and to identify injury specific proteins that may function as biomarkers, by using cell cultures, animal models and in cerebrospinal fluid (CSF) from TBI patients.The result demonstrates a new function in that astrocytes, the most numerous cell type in the brain, engulf dead cells after injury both in cell cultures and in adult mice and thereby save neurons from contact-induced apoptosis. Astrocytes are effective phagocytes, but degrade the ingested dead cells very slowly. Moreover, astrocytes express the lysosome-alkalizing proteins Rab27a and Nox2 as well as major histocompatibility complex class II, the receptors on which antigens are being presented. By lowering the pH of the lysosomes with acidic nanoparticles, the degradation increases, but the astrocytes still remained less effective than macrophages. Taken together, the data indicates that the low acidification in astrocytes can preserve antigens and that astrocytes may be able to activate T cells.The expression and secretion of injury-specific proteins was studied in a cell culture model of TBI by separate mass spectrometry analysis of cells and medium. Interestingly, close to 30 % of the injury-specific proteins in medium are linked to actin, for example ezrin of the ezrin/radixin/moesin (ERM) protein family. Ezrin, but none of the other ERM proteins or actin, is actively secreted after injury. Extracellular ezrin also increases in CSF in response to experimental TBI in rats and is present in CSF from TBI patients, indicating that ezrin is a potential biomarker for TBI.
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| 2. |
- Sjöstedt, Evelina, 1985-
(författare)
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Towards a deeper understanding of the human brain
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Identifying the proteome variation in different parts of the body provides fundamental molecular details, enabling further findings and mapping of tissue specific proteins. By combining quantitative transcriptomics with qualitative antibody based proteomics, the Human Protein Atlas (HPA) project aims to protein profile each human protein-coding gene. Genes with varying expression levels in the different tissue types are categorized as tissue elevated in one tissue compared to others, thus connecting genes to potential tissue specific functions. This thesis focuses on the most complex organ in the human body, the brain. With its billions of neurons specifically organized and interconnected, the ability of not only controlling the body but also responsible for higher cognitive functions, the brain is still not fully understood.In my search for brain important proteins, genes were classified at different stages based on expression levels. In Paper I and II the transcriptome of cerebral cortex was compared with peripheral organs to classify genes with elevated expression in the brain. Brain expression information was expanded by including external data (GTEx and FANTOM5) into the analysis, in Paper III. Thereafter, in Paper IV, the three datasets (HPA, GTEx and FANTOM5) were aligned and combined, enabling a consensus classification with an improved representation of the brain complexity. The most recent classification provided whole body gene expression profiles and out of the 19,670 protein-coding genes, 2,501 were expressed at elevated levels in the brain compared to the other tissue types. Twelve individual regions represented the brain as an organ, and were further analyzed and compared for regional classification of gene expression. One thousand genes showed regional variation in expression level, thus classified as regionally elevated within the brain. Interestingly, less than 500 of the genes classified as brain elevated on the whole body level, and were also regionally elevated in the brain. Many genes with regionally variable expression within the brain showed higher expression in a peripheral organ than in the brain when comparing whole body expression. Based on elevated expression in the brain or brain regions, more than 3,000 genes were suggested to be of high importance to the brain.In addition, this high-throughput approach to combine transcriptomics and protein profiles in tissues and cells further generated new knowledge in several different other aspects: better understanding of uncharacterized and “missing proteins” (Paper III), validation of an antibody improving classification of pituitary adenoma (Paper V) and in Paper VI the possibility to explore cancer specific expression in relation to clinical data and normal tissue expression.There are multiple diseases of the brain that are poorly understood on both a cellular and molecular level. While my work mainly focused on identifying and understanding the molecular organization of the normal brain, the ultimate goal of mapping and studying the normal expression baseline is to understand the molecular aspects of disease and identify ways to prevent, treat and cure diseases.
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