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- Karlsson, Miriam, et al.
(författare)
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Overlapping and specific patterns of GDNF, c-ret and GFR mRNA expression in the developing chicken retina
- 2002
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Ingår i: Mechanisms of Development. - 0925-4773 .- 1872-6356. ; 114:1-2, s. 161-165
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Tidskriftsartikel (refereegranskat)abstract
- GDNF and the GDNF receptors, c-Ret, GFR alpha 1 and 2 mRNA is expressed in the developing chicken retina. GDNF labelling was mainly found in embryonic day 4-5 retina but weak labelling could also be found over scattered retinal cells at later stages. c-ret labelling was found over ganglion cells, amacrine and horizontal cells; the preferred GDNF receptor (GFR alpha 1) over amacrine and horizontal cells; and the less preferred GDNF receptor (GFR alpha 2) over ganglion cells, amacrine cells and photoreceptors.
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| 5. |
- Lindqvist, Niclas
(författare)
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Neurotrophic Factor Receptors in the Normal and Injured Visual System : Focus on Retinal Ganglion Cells
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The focus of this thesis is the life and death of adult retinal ganglion cells (RGCs). RGCs are neurons that convey visual information from the retina to higher centers in the brain. If the optic nerve is transected (ONT), adult RGCs die by a form of cell death called apoptosis, and a general hypothesis is that neurotrophic factors can support the survival of injured neurons.With the intention to gain knowledge about systems that can be used to decrease RGC death after ONT, we have studied growth factor receptors belonging to the tyrosine kinase family of receptors (RTK), known to mediate important cell survival signals. We found that the RTK Ret and its coreceptor GFRα1 were expressed by RGCs, and to test the above-mentioned hypothesis, we intraocularly administered glial cell-line derived factor, which activates a Ret-GFRα1 complex, and found transiently mediated RGC survival after ONT.To identify new, potential neurotrophic factor receptors expressed by RGCs, with the aim to improve RGC survival after ONT, we developed a method for the molecular analysis of acutely isolated RGCs. The method involves retrograde neuronal tracing, mechanical retinal layer-separation, and isolation of individual RGCs under UV-light for RT-PCR analysis. Using this method, in combination with degenerate PCR directed towards the tyrosine kinase domain, several RTKs were identified. Axl, Sky, VEGFR-2, VEGFR-3, CSF-1R, and PDGF-βR are expressed by adult RGCs, and considered to be receptors with potential neurotrophic activity. Other results have shown that RGCs may require depolarization or increase in intracellular cAMP levels in order to fully respond to exogenously added trophic factors. We found that melanocortin receptors (MCRs) were expressed by RGCs, and MCRs can mediate elevation of intracellular AMP. We observed that α-MSH induced neurite outgrowth from embryonic retinal cells, indicating that MCR ligands have direct effects on retinal cells. RTKs and their ligands may be involved in endogenous systems for neuronal repair within the visual system. BDNF, NT-3, FGF2, and HGFR all increased in the retina after ONT and may be a part of an activated system for neuronal repair locally within the retina.Adult axotomized RGCs die by apoptosis, therefore we examined the regulation of apoptotic genes after ONT. Bim and Bax increased in the retina after ONT, and may promote death of axotomized RGCs, whereas the increase in Bcl-2 may contribute to limit RGC apoptosis after ONT.All in all, this thesis provides insights into the expression and regulation of molecules involved in the death and survival of RGCs. The results have revealed a number of potential neurotrophic receptors expressed by RGCs, and both identified RTKs and MCRs will serve as new targets in therapeutic approaches aiming at counteraction of RGC death after injury.
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| 6. |
- Lindqvist, Niclas, et al.
(författare)
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Proopiomelanocortin and melanocortin receptors in the adult rat retino-tectal system and their regulation after optic nerve transection
- 2003
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Ingår i: European Journal of Pharmacology. - : Elsevier BV. - 0014-2999 .- 1879-0712. ; 482:1-3, s. 85-94
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to characterise the expression of the melanocortin system in the normal and injured rat visual system. Using real-time polymerase chain reaction and immunohistochemistry, we detected melanocortin MC3, MC4 and MC5 receptors and proopiomelanocortin in adult retina and superior colliculus. Melanocortin MC4 receptor mRNA was the most abundant receptor. Melanocortin MC3, MC4 and MC5 receptors were localised to the ganglion cell and inner nuclear layers and the melanocortin MC3 and MC4 receptors were localised to retinal ganglion cells. Transection of the optic nerve leads to ganglion cell death and both melanocortin receptor and proopiomelanocortin expression decreased in superior colliculus after transection whereas the expression was unchanged or even increased in the retina. α-Melanocyte-stimulating hormone elicited neurite outgrowth from embryonic retinal explants. Together, these data implicate a role for the melanocortin system in the adult rat retina and that melanocortins can stimulate neurite growth from retinal neurons.
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| 7. |
- Lindqvist, Niclas, et al.
(författare)
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Single cell RT-PCR analysis of tyrosine kinase receptor expression in adult rat retinal ganglion cells isolated by retinal sandwiching
- 2002
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Ingår i: Brain Research Protocols. - 1385-299X .- 1872-809X. ; 10:2, s. 75-83
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Tidskriftsartikel (refereegranskat)abstract
- We describe a protocol for analysis of gene expression in single, acutely dissociated adult rat retinal ganglion cells using RT-PCR. Retrograde tracing of retinal ganglion cells from the superior colliculi was conducted using Fluorogold. Retinas were dissected and ganglion cells isolated using retinal layer separation (sandwiching). Single, fluorescently labelled retinal ganglion cells were aspirated using a micropipette and used for PCR. Two PCR protocols are described where single cell cDNA was analysed for TrkB and GAPDH or TrkB, TrkC, Ret, Met, ErbB2 and Beta-actin by multiplex-PCR. All five tyrosine kinase receptors were amplified from single retinal ganglion cells. The method will prove useful for the molecular characterization of adult retinal ganglion cells.
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| 8. |
- Näpänkangas, Ulla, et al.
(författare)
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Rat retinal ganglion cells upregulate the pro-apoptotic BH3-only protein Bim after optic nerve transection
- 2003
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Ingår i: Brain Research. Molecular Brain Research. - : Elsevier BV. - 0169-328X .- 1872-6941. ; 120:1, s. 30-37
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Tidskriftsartikel (refereegranskat)abstract
- Increased expression of Bim, a pro-apoptotic member of the Bcl-2 family, has been shown to be critical for neuronal apoptosis. To study the involvement of Bim in injury-induced cell death in retina, Bim expression was studied in normal rat retina and in retina after optic nerve transection using quantitative RT-PCR and immunohistochemistry. As a complement to this, the apoptotic regulators Bax, Bcl-2, caspase-3 and phosphorylated c-jun were studied. The relative levels of Bim mRNA in retina were significantly higher 4 days after optic nerve transection and below normal levels at 14 days after transection. A parallel increase in the number of Bim-immunoreactive cells in the retinal ganglion cell layer could be seen. Bim-immunoreactivity localized to retrogradely True Blue-labeled retinal ganglion cells. The relative mRNA levels for both Bax and Bcl-2 were higher at 4 days after transection when compared to normal. Immunoreactivity for Bax, Bcl-2 as well as for caspase-3 and phosphorylated c-jun, indicative of cell death, localized to True Blue-identified retinal ganglion cells 4 days after injury. Bcl-2 immunoreactivity was also seen on other cells, most likely Müller glia cells. In addition, optic nerve transection caused an increase in Bim, Bax, and Bcl-2 mRNA levels in optic nerve and superior colliculus. Our results suggest that Bim is involved in injury-induced retinal ganglion cell death and indicate that the increase in Bim and Bax expression promote cell death of axotomized retinal ganglion cells whereas the elevation in Bcl-2 in retina may contribute to the control of the extent of apoptosis after the optic nerve transection.
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