| 1. |
- Adlerz, Linda, et al.
(författare)
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Accumulation of the amyloid precursor-like protein APLP2 and reduction of APLP1 in retinoic acid-differentiated human neuroblastoma cells upon curcumin-induced neurite retraction
- 2003
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Ingår i: Brain Research. Molecular Brain Research. - : Elsevier BV. - 0169-328X .- 1872-6941. ; 119:1, s. 62-72
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid precursor protein (APP) belongs to a conserved gene family, also including the amyloid precursor-like proteins, APLP1 and APLP2. The function of these three proteins is not yet fully understood. One of the proposed roles of APP is to promote neurite outgrowth. The aim of this study was to investigate the regulation of the expression levels of APP family members during neurite outgrowth. We observed that retinoic acid (RA)-induced neuronal differentiation of human SH-SY5Y cells resulted in increased expression of APP, APLP1 and APLP2. We also examined the effect of the NFκB, AP-1 and c-Jun N-terminal kinase inhibitor curcumin (diferuloylmethane) on the RA-induced expression levels of these proteins. We found that treatment with curcumin counteracted the RA-induced mRNA expression of all APP family members. In addition, we observed that curcumin treatment resulted in neurite retraction without any effect on cell viability. Surprisingly, curcumin had differential effects on the APLP protein levels in RA-differentiated cells. RA-induced APLP1 protein expression was blocked by curcumin, while the APLP2 protein levels were further increased. APP protein levels were not affected by curcumin treatment. We propose that the sustained levels of APP and the elevated levels of APLP2, in spite of the reduced mRNA expression, are due to altered proteolytic processing of these proteins. Furthermore, our results suggest that APLP1 does not undergo the same type of regulated processing as APP and APLP2.
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| 2. |
- Adlerz, Linda, et al.
(författare)
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Down-regulation of amyloid precursor protein by peptide nucleic acid oligomer in cultured rat primary neurons and astrocytes
- 2003
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Ingår i: Neuroscience Letters. - 0304-3940 .- 1872-7972. ; 336:1, s. 55-59
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Tidskriftsartikel (refereegranskat)abstract
- The amyloid precursor protein (APP) and its proteolytic cleavage products, the amyloid P peptides, have been implicated as a cause of Alzheimer's disease. Peptide nucleic acids (PNA), the DNA mimics, have been shown to block the expression of specific proteins at both transcriptional and translational levels. Generally, the cellular uptake of PNA is low. However, recent studies have indicated that the effect of unmodified antisense PNA uptake is more pronounced in nervous tissue. In this study we have shown that biotinylated PNA directed to the initiator codon region of the APP mRNA (-4 - +11) was taken up into the cytoplasm of primary rat cerebellar granule cells and cortical astrocytes, using fluorescence and confocal microscopy studies. Uptake of PNA was faster in neurons than in astrocytes. Western blotting analysis showed that APP was strongly down-regulated in both neurons and astrocytes. Thus, unmodified PNA can be used for studies on the function of APP in neurons and astrocytes.
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| 3. |
- Ahn, Young Hwan, et al.
(författare)
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Ultrastructural characterization of dissociated embryonic ventral mesencephalic tissue treated with neuroprotectants.
- 2003
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Ingår i: Cell Transplantation. - 1555-3892. ; 12:3, s. 235-241
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Tidskriftsartikel (refereegranskat)abstract
- Poor survival and differentiation of grafted dopamine neurons limits the application of clinical transplantation in Parkinson’s disease. The survival of grafted dopamine neurons is only improved by a factor of 2–3 by adding neuroprotectants during tissue preparation. We used dye exclusion cell viability and electron microscopy to investigate the effects of the caspase inhibitor ac-YVAD-cmk and the lazaroid tirilazad mesylate on ultrastructural changes in dissociated embryonic mesencephalic cells. In addition, we examined whether the neuroprotectants selectively counteracted specific signs of neurodegeneration. Cell viability decreased significantly over time in both control and treated cell suspensions, but the number of viable cells remaining was significantly higher in tirilazad mesylate-treated cell suspensions. In control samples, the proportion of cells with an ultrastructure consistent with healthy cells decreased from 70%, immediately after dissociation, to 30% after 8 h of incubation. Similar changes were also observed in cell suspensions treated with neuroprotectants. Thus, the neuroprotectants examined did not block the development of specific morphological signs of neurodegeneration. However, when also taking into account that dead cells lysed and disappeared from each cell suspension with time, we found that the total number of remaining viable cells with healthy nuclear chromatin or intact membrane integrity was significantly higher in the tirilazad mesylate-treated group. The results indicate that tirilazad mesylate protects only a small subpopulation of embryonic mesencephalic cells from degeneration induced by mechanical trauma during tissue dissection and dissociation.
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| 4. |
- Andersson, M, et al.
(författare)
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Time course of striatal DeltaFosB-like immunoreactivity and prodynorphin mRNA levels after discontinuation of chronic dopaminomimetic treatment.
- 2003
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Ingår i: European Journal of Neuroscience. - : Wiley. - 1460-9568 .- 0953-816X. ; 17:3, s. 661-666
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Tidskriftsartikel (refereegranskat)abstract
- DFosB-like proteins are particularly stable transcription factors that accumulate in the brain in response to chronic perturbations. In this study we have compared the time-course of striatal FosB/DFosB-like immunoreactivity and prodynorphin mRNA expression after discontinuation of chronic cocaine treatment to intact rats and chronic L-DOPA treatment to unilaterally 6-hydroxydopamine (6-OHDA) lesioned rats. The animals were killed between 3 h and 16 days after the last drug injection. In both treatment paradigms, the druginduced FosB/DFosB immunoreactivity remained significantly elevated in the caudate putamen even at the longest withdrawal period examined. The concomitant upregulation of prodynorphin mRNA, a target of DFosB, paralleled the time-course of DFosB-like immunoreactivity in the 6-OHDA-lesion/L-DOPA model, but was more transient in animals treated with cocaine. These results suggest that DFosB-like proteins have exceptional in vivo stability. In the dopamine-denervated striatum, these proteins may exert sustained effects on the expression of their target genes long after discontinuation of L-DOPA pharmacotherapy.
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| 5. |
- Andersson, Malin
(författare)
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Transcriptional dysregulation in L-DOPA-induced dyskinesia
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This study explores the role of transcriptional regulation important in the development of L-DOPA-induced dyskinesia in a rat model of Parkinson’s disease. In patients with Parkinson’s disease, dyskinesia is one of the most difficult complications of the DA-replacement therapy by L-DOPA. The underlying mechanisms are still unknown, but a role of abnormal striatal plasticity has been proposed. The transcription factor cyclic AMP response element-binding protein (CREB) is believed to play a key role in DA receptor-mediated gene expression and neuroplasticity. This thesis demonstrates that the requirement of CREB depends on the experimental paradigm. CREB was required for both basal and cocaine-induced gene expression of c-Fos, FosB/?FosB, and prodynorphin mRNA (PDyn). But more importantly, CREB was not required for L-DOPA to induce the same genes in the DA-denervated striatum. An analysis of DNA-protein interactions showed that the transcription factors ?FosB and JunD appeared to supersede CREB in the binding to regulatory elements of the PDyn gene. The functional significance of ?FosB and JunD was studied using an antisense approach, whereby a local reduction of either ?FosB or JunD in the striatum was obtained. Antisense-mediated knockdown of ?FosB or JunD demonstrated that these transcription factors are causally linked with both PDyn gene expression and the development of dyskinesia in the rat model of Parkinson’s disease. A comparative analysis of FosB/?FosB and JunD at both the mRNA and protein levels disclosed a remarkably similar pattern of changes after acute and chronic L-DOPA treatment. First, junD and fosB/?fosB mRNA expression was induced by acute L-DOPA administration but declined upon repeated treatment. Second, the most prominent upregulation at the protein level was seen after chronic but not acute L-DOPA treatment. This effect was clearly dissociated from the changes in gene expression and led us to propose a new model of ?FosB/JunD induction on the gene and protein level, predicting that repeated administrations of L-DOPA progressively attenuate the transcription of the fosB and junD genes, while the respective proteins accumulate over time probably due to a lack of degradation. The findings of this thesis have implications for the development of therapies that minimize the motor complications of antiparkinsonian medications.
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| 6. |
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| 7. |
- Andreasen, Niels, et al.
(författare)
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Cerebrospinal fluid levels of total-tau, phospho-tau and A beta 42 predicts development of Alzheimer's disease in patients with mild cognitive impairment.
- 2003
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Ingår i: Acta neurologica Scandinavica. Supplementum. - : Hindawi Limited. - 0065-1427 .- 0001-6314. ; 179, s. 47-51
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Tidskriftsartikel (refereegranskat)abstract
- Cerebrospinal fluid (CSF) biochemical diagnostic markers may be valuable to help in the diagnosis early in the course of Alzheimer's disease (AD), especially in the phase before clinically overt dementia, i.e. in patients with mild cognitive impairment (MCI). We studied 44 patients with MCI who, at 1-year follow-up investigation, had progressed to AD with dementia, and 32 controls. Three CSF biomarkers related to the central pathogenic processes in AD were analysed, including CSF total-tau (T-tau) (as a marker for neuronal degeneration), CSF phospho-tau (P-tau) (as a marker for hyperphosphorylation of tau and possibly for the formation of neurofibrillary tangles), and CSF A beta 42 (as a marker for A beta metabolism, and possibly for the formation of senile plaques). At baseline, 35/44 (79.5%) of the MCI patients had high CSF T-tau, 31/44 (70.4%) high CSF P-tau, while 34/44 (77.3%) had low CSF-A beta 42 levels. The positive likelihood ratio was 8.45 for CSF T-tau, 7.49 for CSF P-tau and 8.20 for CSF A beta 42. These findings suggest that these CSF-markers are abnormal before the onset of clinical dementia, and that they may help to identify MCI patients that will progress to AD. CSF diagnostic markers will be especially important when drugs with potential effects on the progression of AD (e.g. gamma-secretase inhibitors) will reach the clinical phase.
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| 8. |
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| 9. |
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| 10. |
- Beckman, Marie, 1961-
(författare)
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Temporal events in neuronal differentiation and cell death : expression and processing of the Alzheimer's amyloid precursor protein family and a protein at the nuclear pore
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The present study had two major objectives: 1) to elucidate the involvement of Alzheimer’s amyloid precursor protein (APP) family in neuronal differentiation, and the effect of the Alzheimer’s disease (AD)-linked mutation APPV642I on signal transduction; 2) to investigate the fate of the nuclear pore complex protein POM121 during apoptosis and to examine the possibility of using green fluorescent protein (GFP)-labelled POM121 as a non-invasive sensor of apoptosis in living (non-fixed) cells.APP is the parent protein of the b-amyloid peptide, which is the major peptide constituent in the “senile plaques” of AD. APP and the homologous amyloid precursor-like proteins, APLP1 and APLP2, are members of the APP family. We compared the temporal expression patterns of these proteins during retinoic acid (RA)-induced neuronal differentiation of human neuroblastoma cells. To this end, we established a quantitative non-radioactive Northern blot assay for APLP1, APLP2 and APP. We found that the transcripts of all three APP family members were increased in response to RA. This occurred simultaneously with progressive neurite outgrowth and increased expression of neuronal markers. In addition, we observed that the increase in APLP2 mRNA was similar to that of APP mRNA, whereas the increase in APLP1 mRNA was significantly higher. The elevated mRNA levels also resulted in an in-creased protein expression of APLP1, APLP2 and the neuronal APP695 isoform. Studies using curcumin (diferuloylmethane), an inhibitor of the transcription factors NFkB/AP-1, and the mitogen-activated protein kinase (MAPK) JNK (c-Jun N-terminal kinase), revealed a diffe-rential regulation of APLP1 and APLP2. Curcumin suppressed the RA-induced mRNA expression of the APP family, in particular that of APLP1. On the protein level, curcumin also reduced the expression of APLP1. In contrast, curcumin induced an accumulation of APLP2, which we propose is due to inhibition of its proteolytic processing. Furthermore, curcumin induced neurite retraction in RA-differentiated cells without affecting their viability. Our results suggest that NFkB/AP-1 signal transduction pathways mediate a co-ordinated regula-tion of the mRNA expression of the APP family and that APLP1 processing is not regulated by the same mechanisms as the processing of APLP2 and APP. Our results are in agreement with important functions for APLP1, APLP2 and APP within the period of neurite extension and synaptic maturation, and a proposed role for these proteins in neuronal differentiation and synaptic plasticity.Using a doxycycline-controlled gene expression system (Tet-On), we investigated the effect of wild-type APP695 and the pathogenic familial AD-linked APPV642I mutant on signal transduction. Overexpression was induced at different levels in rat pheochromocytoma (PC12) Tet-On cells. We observed a nerve growth factor-dependent increase in the levels of phosphorylated extracellular regulated kinases 1 and 2 in response to expression of mutant APP. Our results support that increased signalling via MAPKs may have a role in the development of AD. In addition, we found that the inducing agent doxycycline in itself affected cell signalling and protected against oxidative stress. This information is critical for evaluation of the effects of transgene expression using Tet systems.Finally, we showed that POM121 is cleaved by a caspase-3-dependent mechanism at aspartate 531 during apoptosis. Characterising the degradation of POM121-GFP in relation to other apoptotic events, revealed that it can be applied as an early non-invasive sensor of nuc-lear apoptosis in living cells using fluorescence microscopy or fluorimetric analysis.
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