| 1. |
- Rebellato, Paola
(författare)
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Calcium signaling in neurogenesis: regulation of proliferation, differentiation and migration of neural stem cells
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The calcium ion (Ca2+) is a highly versatile and ubiquitous signaling messenger in all cell types. Signal transduction occurs through changes in the cytosolic Ca2+ concentration after the opening of Ca2+ channels in the plasma membrane (PM) and endoplasmic reticulum (ER). The difference in Ca2+ concentration between the extracellular space and the cytosol is large, around 10,000 fold, creating a steep gradient that causes Ca2+ to rapidly flow into the cell. Signaling via Ca2+ is fundamental for triggering numerous vital processes in the cell, ranging from fertilization to cell death. Calcium signaling is also critical for regulating neurogenesis in various ways, some of which have been explored in this work. Proliferation of neural progenitors is dependent on spontaneous Ca2+ activity that occurs in small-scale networks. Ca2+ activity is correlated with electrical activity both in vitro and in vivo and depends on connexin 43 gap junction and PM channels. Differentiation of neural progenitors is also regulated by Ca2+ signaling. We have found that T α1h voltage-dependent Ca2+ channels promote spontaneous Ca2+ activity and direct the differentiation of human neuroepithelial stem cells towards neurons, depending on caspase-3 enzymatic activity. These results were confirmed with T α1h knockout mice that showed a decreased number of neurons in the dorsal cortex. Neuronal migration also depends on Ca2+ signaling. We demonstrated that glial derived neurotrophic factor (GDNF) stimulates a Ca2+ response through the activation of the receptor tyrosine kinase (RET). The subsequent downstream signaling cascade includes phospholipase Cγ, which binds to RET Tyr1015. Mutating RET at Tyr1015 inhibits neuronal progenitor migration towards the cortical plate. We also showed that neurogenesis was altered by the addition of non-cytotoxic concentrations of polychlorinated biphenyls that disrupt spontaneous Ca2+ activity. Polychlorinated biphenyls are common food contaminants. In addition, methyl mercury, another food contaminant, disrupts neuronal differentiation in the opposite direction. Altogether, these data demonstrate the huge impact of Ca2+ signaling on the development of the embryonic brain. To conclude, we have analyzed Ca2+ signaling during three critical steps of neurogenesis: proliferation, differentiation, and migration. All of these processes are known to be dependent on Ca2+. A deeper understanding of how Ca2+ regulates such different physiological processes is crucial for the field of regenerative medicine, in which control of the expansion and differentiation of neural stem cells can increase the production of neuronal cells in vitro for use in cell replacement therapies.
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| 2. |
- Rodin, Sergey, et al.
(författare)
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Isotopic resonance at 370 ppm deuterium negatively affects kinetics of luciferin oxidation by luciferase
- 2018
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Ingår i: Scientific Reports. - : NATURE PUBLISHING GROUP. - 2045-2322. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Since 1930s, it has been known that some biochemical and biological processes exhibit abnormal kinetics at a deuterium concentration in the local environment of 250-600 ppm, which is 2-4 times higher that the normal concentration of 150 ppm D. We sought to test if the kinetics of firefly luciferase oxidizing luciferin, the reaction widely used as a read-out in various biochemical assays, is also affected by an elevated deuterium content. To this end, both luciferase and luciferin substrate solutions were prepared based on water with extra deuterium added to a concentration ranging from 150 ppm and up to 10,000 ppm (1%). Upon mixing the solutions, the luminescence intensity at different times was compared with that of the corresponding control solutions with 150 ppm D. A broad negative resonance was detected (p < 10(-6)), with a approximate to 20% drop in luminescence at 370 ppm D. Given that, on average, about half of hydrogen atoms in proteins are not exchangeable in solution, this value corresponds to approximate to 260 ppm of deuterium in all enzyme's hydrogens, in a very good agreement with the prediction of the Isotopic resonance hypothesis.
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| 3. |
- Smedler, Erik, et al.
(författare)
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Disrupted Cacna1c gene expression perturbs spontaneous Ca2+ activity causing abnormal brain development and increased anxiety.
- 2022
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 119:7
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Tidskriftsartikel (refereegranskat)abstract
- The L-type voltage-gated Ca2+ channel gene CACNA1C is a risk gene for various psychiatric conditions, including schizophrenia and bipolar disorder. However, the cellular mechanism by which CACNA1C contributes to psychiatric disorders has not been elucidated. Here, we report that the embryonic deletion of Cacna1c in neurons destined for the cerebral cortex using an Emx1-Cre strategy disturbs spontaneous Ca2+ activity and causes abnormal brain development and anxiety. By combining computational modeling with electrophysiological membrane potential manipulation, we found that neural network activity was driven by intrinsic spontaneous Ca2+ activity in distinct progenitor cells expressing marginally increased levels of voltage-gated Ca2+ channels. MRI examination of the Cacna1c knockout mouse brains revealed volumetric differences in the neocortex, hippocampus, and periaqueductal gray. These results suggest that Cacna1c acts as a molecular switch and that its disruption during embryogenesis can perturb Ca2+ handling and neural development, which may increase susceptibility to psychiatric disease.
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| 4. |
- Tofighi, Roshan, et al.
(författare)
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Non-dioxin like polychlorinated biphenyls interfere with neuronal differentiation of embryonic neural stem cells
- 2011
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Ingår i: Toxicological Sciences. - : Oxford Journals. - 1096-6080 .- 1096-0929. ; 124:1, s. 192-201
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Tidskriftsartikel (refereegranskat)abstract
- Developmental exposure to food contaminants, such as polychlorinated biphenyls (PCBs), has been considered as a possible cause of neurodevelopmental disorders. We have investigated the effects of non-cytotoxic concentrations of PCB 153 and 180 on spontaneous differentiation of rat embryonic neural stem cells (NSCs). Upon removal of basic fibroblast growth factor to induce spontaneous differentiation, cells were exposed to 100 nM of the selected PCBs for 48 h and analyzed after 5 days. Both PCB 153 and 180 induced a significant increase in the number of neurite-bearing Tuj1 positive cells with a concomitant decrease in proliferating cells, as detected by Fucci-transfection and EdU-staining. Measurements of spontaneous Ca(2+) oscillations showed a decreased number of cells with Ca(2+) activity after PCB exposure, further confirming the increase in neuronal cells. Conversely, exposure to methylmercury (MeHg), which we evaluated in parallel, led to an increased number of cells with Ca(2+) activity, in agreement with the previously observed inhibition of neuronal differentiation. Analysis with q-PCR of the Notch pathway revealed that PCBs has a repressive action on Notch signaling, whereas MeHg activates it. All together, the data indicate that nM concentrations of the selected non-dioxin like PCBs and MeHg interfere in opposite directions with neuronal spontaneous differentiation of NSCs through Notch signaling. Combined exposures to PCBs and MeHg resulted in an induction of apoptosis and an antagonistic interaction on spontaneous neuronal differentiation. NSCs are further proven to be a valuable in vitro model to identify potential developmental neurotoxicants.
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