| 1. |
- Brännvall, Karin, 1974-
(författare)
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Hormonal Regulation of Neural Stem Cell Proliferation and Fate Determination
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Stem cells have the capacity for both self renewal, and to form all cell types in the body. Interestingly, so called neural stem cells (NSCs) are found in the adult human brain, which is of significance both out of a developmental perspective and from a clinical point of view. At the present moment, the regulation of neural stem cell (NSC) proliferation and fate determination is not completely understood.The overall aim of this thesis was to study the mechanisms that regulate NSC proliferation and fate determination in vitro and in vivo. In particular, the roles of the female sex hormone estrogen and the testosterone analogue nandrolone, as well as the melanocortin α-melanocyte stimulating hormone (α-MSH), were analyzed in this context. Also, the breast cancer susceptibility gene one (BRCA-1), was studied in the brain with emphasis on regions containing NSCs.Our findings show that estrogen and nandrolone have similar effects on NSCs; both decreased NSC proliferation and increased neurogenesis. Estrogen's ability to reduce proliferation was due to increased levels of p21, an inhibitor of cyclin dependent kinases. In contrast, no change in p21 was observed in the case of nandrolone, indicating differential regulation. Adult rats subjected to nandrolone injections had 30% reduced NSC proliferation in the dentate gyrus, indicating profound effects on NSCs in vivo.The melanocortin α-MSH acted as a mitogen by increasing levels of cyclinD1 and retinoblastoma protein; as a result NSC proliferation was doubled.Finally, BRCA-1 is expressed while NSCs proliferate, but is drastically down regulated upon differentiation, indicating that BRCA-1 could be used as a possible NSC marker.In summary, in this thesis estrogen and nandrolone were identified as NSC regulators which decrease proliferation and positively influence neurogenesis. Also, we have identified the hormone α-MSH as a NSC mitogen, and BRCA-1 as a possible NSC marker.
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| 2. |
- Grenklo, Staffan, 1959-
(författare)
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Cross-linked Profilin:actin - A tool to study actin dynamics in non-muscle cells
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The microfilament system, consisting of actin and a number of auxiliary proteins, is fundamental for cell motility. Its dynamic organization depends on receptor-mediated signals, leading to rapid polymerizations and depolymerizations of actin. Profilin binds to non-filamentous actin, inhibits spontaneous filament formation, and functions as a regulator of actin polymerization. The profilin:actin complex, is thought to be the principal source of actin for filament formation although the role of profilin is not fully elucidated. In this thesis, a cross-linked profilin:actin complex (PxA), that retains the properties of ordinary profilin:actin, except for being non-dissociable, has been used to characterize the role of profilin and profilin:actin in non-muscle cells. A rapid screening method, employing PxA and based on the far western technique and mass-spectrometry, was designed to identify cellular components that specifically bind profilin:actin. Microinjection of PxA into cells infected with the bacteria Listeria monocytogenes impaired bacterial motility but a mutant PxA, unable to bind proline-rich sequences had no effect, demonstrating that profilin:actin is vital for the activity of the actin polymer-forming complex that the pathogen recruits to its surface upon infection. Fluorescence microscopy using two distinct sets of affinity-purified actin and profilin antibodies generated against PxA enabled localization of monomeric actin in cells. One of the actin and both profilin antibodies resulted in a dotted pattern of fluorescence partially aligning with microtubules whereas the other actin antibody detected filamentous actin. The result demonstrates extensive variability in epitope recognition, and indicates that unpolymerized actin, i.e. profilin:actin and maybe other complex-bound forms of actin, distributes in small packages that might be transported along microtubules. Microinjection of PxA into lamprey axons demonstrated the involvement of actin polymerization during synaptic signaling.
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| 3. |
- Korhonen, Laura, Professor, 1974-, et al.
(författare)
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Multivariate analyses of immune markers reveal increases in plasma EN-RAGE in first-episode psychosis patients
- 2023
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Ingår i: Translational Psychiatry. - : Springer. - 2158-3188. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- Immune cells and cytokines are largely recognized as significant factors in the pathophysiology of neuropsychiatric disorders. The possible role of other blood cells such as leukocytes in events of acute psychosis is in contrast only emerging. To study blood-born markers in acute psychosis we here evaluated plasma proteins in drug-naive first-episode psychosis (FEP) patients and healthy controls using a multiplex proximity extension assay technique. We analyzed a panel of 92 immune markers and plasma samples from 60 FEP patients and 50 controls and evaluated the changes obtained using multivariate statistical methods followed by protein pathway analyses. Data showed that 11 proteins are significantly different between FEP patients and healthy controls We observed increases in pro-inflammatory proteins such as interleukin-6, oncostatin-M, and transforming growth factor-alpha in FEP patients compared with controls. Likewise, the extracellular newly identified RAGE-binding protein (EN-RAGE) that regulates the expression of various cytokines was also elevated in the plasma of FEP patients. The results indicate that neutrophil-derived EN-RAGE could play an important role during the early phase of acute psychosis by stimulating cytokines and the immune response targeting thereby likely also the brain vasculature.
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| 4. |
- Steen, Håkan, 1978-
(författare)
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Novel Interactors of X-linked Inhibitor of Apoptosis Protein : Expression and Effects on Tumor Cell Death
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Programmed cell death, or apoptosis, has during the last decade received a lot of attention due to its involvement in a large number of pathological conditions. Since death is always irreversible, it is important for cells to fully control the initiation and execution of this process. One of many apoptosis-regulatory proteins is XIAP, which blocks the action of caspases, a family of proteases that are important during apoptosis. However, apoptosis inhibitors have to be tightly controlled since too little cell death can lead to the development of tumors and other diseases. This thesis is the result of an aspiration to fully understand the function and regulation of XIAP.By using the yeast-2-hybrid system, we identified two novel binding partners of XIAP. The first, GPS2, was found to bind XIAP and inhibit its ability to block caspase-activity. In addition, GPS2 induced caspase-mediated cell death in two different tumour cell lines and XIAP inhibited this effect.The second binding partner, Nulp1, preferentially bound XIAP in the presence of the apoptosis-inducer staurosporine. Nulp1 induced or sensitized cell lines to cell death when overexpressed, but this was not blocked by caspase-inhibitors or XIAP, suggesting a different reason for binding than apoptosis regulation. With the aim to understand the Nulp1-XIAP interaction, we continued to study Nulp1 in vivo and in vitro. We studied three different splice variants of Nulp1 and found that they were regulated by poly-ubiquitination and nuclear shuttling. Also, Nulp1 was expressed in embryonic mice, especially in the cortical plate, hippocampal neurons and cerebellar granular neurons. Expression of Nulp1 decreased with age but was still present in cerebellar deep nuclei and Purkinje cells of adult mice. To summarize, we have identified GPS2 as an apoptosis-inducing factor and an inhibitor of XIAP in vitro, and Nulp1 as a XIAP-interacting protein during staurosporine-induced apoptosis.
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