| 1. |
- Andrae, Johanna, et al.
(författare)
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A 1.8kb GFAP-promoter fragment is active in specific regions of theembryonic CNS
- 2001
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Ingår i: Mechanisms of Development. - 0925-4773 .- 1872-6356. ; 107:1-2, s. 181-5
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Tidskriftsartikel (refereegranskat)abstract
- The intermediate filament glial fibrillary acidic protein (GFAP) constitutes the major cytoskeletal protein in astrocytes (J. Neuroimmunol. 8 (1985) 203) and is traditionally referred to as a specific marker for astrocytes. To identify early glial precursors, we created GFAPpromoter-lacZ transgenic mice, using a 1.8kb 5' fragment of human GFAP. The expression of the transgene was first detected in the neuroepithelium at embryonic day 9.5. It was further found in the ventricular zone of the developing telencephalon, in the cerebellar primordium, trigeminal ganglia, and radial glia. Later, scattered beta-gal+ cells were seen in pons, brain stem and glia limitans. The results indicate that GFAP activity is regulated in a region-specific manner during central nervous system (CNS) development and that the gene is turned on in different cell types independently.
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| 2. |
- Andrae, Johanna, et al.
(författare)
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A role for PDGF-C/PDGFR alpha signaling in the formation of the meningeal basement membranes surrounding the cerebral cortex
- 2016
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Ingår i: Biology Open. - : The Company of Biologists. - 2046-6390. ; 5:4, s. 461-474
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor-C (PDGF-C) is one of three known ligands for the tyrosine kinase receptor PDGFR alpha. Analysis of Pdgfc null mice has demonstrated roles for PDGF-C in palate closure and the formation of cerebral ventricles, but redundancy with other PDGFR alpha ligands might obscure additional functions. In search of further developmental roles for PDGF-C, we generated mice that were double mutants for Pdgfc(-/-) and Pdgfra(GFP/+). These mice display a range of severe phenotypes including spina bifida, lung emphysema, abnormal meninges and neuronal over-migration in the cerebral cortex. We focused our analysis on the central nervous system (CNS), where PDGF-C was identified as a critical factor for the formation of meninges and assembly of the glia limitans basement membrane. We also present expression data on Pdgfa, Pdgfc and Pdgfra in the cerebral cortex and microarray data on cerebral meninges.
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| 3. |
- Andrae, Johanna, et al.
(författare)
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Analysis of Mice Lacking the Heparin-Binding Splice Isoform of Platelet-Derived Growth Factor A
- 2013
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Ingår i: Molecular and Cellular Biology. - 0270-7306 .- 1098-5549. ; 33:20, s. 4030-4040
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Tidskriftsartikel (refereegranskat)abstract
- Platelet-derived growth factor A-chain (PDGF-A) exists in two evolutionarily conserved isoforms, PDGF-Along and PDGF-Ashort, generated by alternative RNA splicing. They differ by the presence (in PDGF-Along) or absence (in PDGF-Ashort) of a carboxyterminal heparin/heparan sulfate proteoglycan-binding motif. In mice, similar motifs present in other members of the PDGF and vascular endothelial growth factor (VEGF) families have been functionally analyzed in vivo, but the specific physiological importance of PDGF-A(long) has not been explored previously. Here, we analyzed the absolute and relative expression of the two PDGF-A splice isoforms during early postnatal organ development in the mouse and report on the generation of a Pdgfa allele (Pdgfa(Delta ex6) incapable of producing PDGF-A(long) due to a deletion of the exon 6 splice acceptor site. In situations of limiting PDGF-A signaling through PDGF receptor alpha (PDGFR alpha), or in mice lacking PDGF-C, homozygous carriers of Pdgfa(Delta ex6) showed abnormal development of the lung, intestine, and vertebral column, pinpointing developmental processes where PDGF-A(long) may play a physiological role.
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| 4. |
- Andrae, Johanna, et al.
(författare)
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Characterization of Platelet-Derived Growth Factor-A Expression in Mouse Tissues Using a lacZ Knock-In Approach
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 9:8, s. e105477-
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Tidskriftsartikel (refereegranskat)abstract
- Expression of the platelet-derived growth factor A-chain gene (Pdgfa) occurs widely in the developing mouse, where it is mainly localized to various epithelial and neuronal structures. Until now, in situ mRNA hybridization (ISH) has been the only reliable method to identify Pdgfa expression in tissue sections or whole mount preparations. Validated protocols for in situ detection of PDGF-A protein by immunohistochemistry is lacking. In particular, this has hampered understanding of Pdgfa expression pattern in adult tissues, where ISH is technically challenging. Here, we report a gene targeted mouse Pdgfa allele, Pdgfa(ex4COIN), which is a combined conditional knockout and reporter allele. Cre-mediated inversion of the COIN cassette inactivates Pdgfa coding while simultaneously activating a beta-galactosidase (lacZ) reporter under endogenous Pdgfa transcription control. The generated Pdgfa(ex4COIN-INV-lacZ) allele can next be used to identify cells carrying a Pdgfa null allele, as well as to map endogenous Pdgfa expression. We evaluated the Pdgfa(ex4COIN-INV-lacZ) allele as a reporter for endogenous Pdgfa expression patterns in mouse embryos and adults. We conclude that the expression pattern of Pdgfa(ex4COIN-INV-lacZ) recapitulates known expression patterns of Pdgfa. We also report on novel embryonic and adult Pdgfa expression patterns in the mouse and discuss their implications for Pdgfa physiology.
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| 5. |
- Andræ, Johanna
(författare)
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PDGF in cerebellar development and tumorigenesis
- 2001
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Medulloblastoma is a highly malignant cerebellar childhood tumor. As in many other brain tumors, expression of platelet-derived growth factor (PDGF) and its receptors has been shown in medulloblastoma. To reveal the importance of this growth factor in cerebellar development and tumorigenesis, analyses were performed on human medulloblastoma cell lines and on tissue from normal mouse brain at different stages of development. The in vivo effect of a forced expression of PDGF-B in the cerebellar primordium was examined in transgenic mice. In the normal mouse embryo, we found PDGF receptor-α-positive cells in the early neuroepithelium and on neuronal precursors. In the postnatal cerebellum, cells in the external germinal layer and Purkinje cells expressed the receptor. In the medulloblastoma cells, expression of all the three PDGF isoforms and PDGF receptors was seen and correlated to neuronal differentiation. Endogenously activated, i.e. tyrosine phosphorylated, PDGF receptors were identified. To reveal the role of PDGF in normal cerebellar development, we established transgenic mice where a PDGF-B cDNA was introduced via homologous recombination into the engrailed-1 gene. Engrailed-1 is specifically expressed at the mid-/hindbrain boundary of the early neural tube, i.e. in an area from which the cerebellar primordium develops. The ectopic expression of PDGF-B caused a disturbance of cerebellar development. Midline fusion of the cerebellar primordium did not occur properly, which resulted in cerebellar dysplasia in the adult mouse.In a parallel study, the expression pattern of a glial fibrillary acidic protein (GFAP)-lacZ transgene was followed in the embryonic mouse central nervous system. It was shown that the human GFAP promoter was already active by embryonic day 9.5 and as development proceeded, expression occured in different, independent cell populations. Among these cell populations were the radial glial cells in the neocortex.
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| 6. |
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| 7. |
- Andrae, Johanna, et al.
(författare)
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Platelet-derived growth factor-B and -C and active alpha-receptors in medulloblastoma cells.
- 2002
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Ingår i: Biochemical and biophysical research communications. - 0006-291X .- 1090-2104. ; 296:3, s. 604-11
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Tidskriftsartikel (refereegranskat)abstract
- The malignant childhood brain tumor medulloblastoma belongs to the group of primitive neuroectodermal tumours (PNETs). Medulloblastomas are thought to arise from remnants of the transient external germinal layer in the cerebellum. Proliferation, differentiation, and motility of cells in the central nervous system are regulated by growth factors, e.g., platelet-derived growth factor (PDGF). Recently, it was shown that higher level of PDGF alpha-receptor expression is characteristic of metastatic medulloblastomas. We have investigated five medulloblastoma/PNET cell lines and found that the PDGF alpha-receptor is actively signalling in most of them, an activity most likely driven by endogenously produced PDGF-C. PDGF-C is normally present in cells of the developing external germinal layer and our results are consistent with the idea that medulloblastomas are derived from such cells undergoing early neuronal differentiation. Moreover, the expression of PDGF and its receptors was associated with neuronal characteristics, but not with high levels of c-myc expression in the medullablastoma cells.
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| 8. |
- Andrae, Johanna, et al.
(författare)
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Platelet-derived growth factor receptor-alpha in ventricular zone cells and in developing neurons.
- 2001
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Ingår i: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 17:6
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Tidskriftsartikel (refereegranskat)abstract
- Cells in the early neuroepithelium differentiate and give rise to all cells in the central nervous system (CNS). The ways from a multipotent CNS stem cell to specialized neurons and glia are not fully understood. Using immunohistochemistry we found that neuroepithelial cells express the platelet-derived growth factor receptor-alpha (PDGFR-alpha) in the neural plate at embryonic day 8.5 and onwards in the neural tube. The protein was polarized to ventricular endfeet. Furthermore, PDGFR-alpha expression was localized to cells undergoing early neuronal development. We also found PDGFR-alpha expression in developing granule cells in the postnatal cerebellum, in Purkinje cells in the adult cerebellum and on processes of developing dorsal root ganglion cells. Previous reports mainly describe PDGFR-alpha expression in oligodendrocyte precursors and glial cells. We believe, in line with a few previous reports, that the PDGFR-alpha in addition marks a pool of undifferentiated cells, which are able to differentiate into neurons.
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| 9. |
- Dang, Thanh Chung, et al.
(författare)
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Powerful Homeostatic Control of Oligodendroglial Lineage by PDGFR alpha in Adult Brain
- 2019
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Ingår i: Cell Reports. - : CELL PRESS. - 2211-1247. ; 27:4, s. 1073-1089
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Tidskriftsartikel (refereegranskat)abstract
- Oligodendrocyte progenitor cells (OPCs) are widely distributed cells of ramified morphology in adult brain that express PDGFR alpha and NG2. They retain mitotic activities in adulthood and contribute to oligodendrogenesis and myelin turnover; however, the regulatory mechanisms of their cell dynamics in adult brain largely remain unknown. Here, we found that global Pdgfra inactivation in adult mice rapidly led to elimination of OPCs due to synchronous maturation toward oligodendrocytes. Surprisingly, OPC densities were robustly reconstituted by the active expansion of Nestin(+) immature cells activated in meninges and brain parenchyma, as well as a few OPCs that escaped from Pdgfra inactivation. The multipotent immature cells were induced in the meninges of Pdgfra-inactivated mice, but not of control mice. Our findings revealed powerful homeostatic control of adult OPCs, engaging dual cellular sources of adult OPC formation. These properties of the adult oligodendrocyte lineage and the alternative OPC source may be exploited in regenerative medicine.
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| 10. |
- De La Fuente, Alerie Guzman, et al.
(författare)
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Pericytes Stimulate Oligodendrocyte Progenitor Cell Differentiation during CNS Remyelination
- 2017
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Ingår i: Cell Reports. - : Elsevier BV. - 2211-1247. ; 20:8, s. 1755-1764
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Tidskriftsartikel (refereegranskat)abstract
- The role of the neurovascular niche in CNS myelin regeneration is incompletely understood. Here, we show that, upon demyelination, CNS-resident pericytes (PCs) proliferate, and parenchymal non-vessel-associated PC-like cells (PLCs) rapidly develop. During remyelination, mature oligodendrocytes were found in close proximity to PCs. In Pdgfb(ret/ret) mice, which have reduced PC numbers, oligodendrocyte progenitor cell (OPC) differentiation was delayed, although remyelination proceeded to completion. PC-conditioned medium accelerated and enhanced OPC differentiation in vitro and increased the rate of remyelination in an ex vivo cerebellar slice model of demyelination. We identified Lama2 as a PC-derived factor that promotes OPC differentiation. Thus, the functional role of PCs is not restricted to vascular homeostasis but includes the modulation of adult CNS progenitor cells involved in regeneration.
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