| 1. |
- Agudo, Marta, et al.
(författare)
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Immediate Upregulation of Proteins Belonging to Different Branches of the Apoptotic Cascade in the Retina after Optic Nerve Transection and Optic Nerve Crush
- 2009
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Ingår i: Investigative Ophthalmology and Visual Science. - : Association for Research in Vision and Ophthalmology (ARVO). - 0146-0404 .- 1552-5783. ; 50:1, s. 424-431
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: To further investigate the molecular signals underlying optic nerve (ON) injury we have analyzed in adult control, ON transected and ON crushed retinas, the expression pattern and time-course regulation of the following proteins, all of which are linked to apoptosis through different pathways: Stat 1, Caspase 11 (inflammation and death), Cathepsins C and B (lysosomal death pathway), Calpain 1 (endoplasmic reticulum stress), Calreticulin (apoptosis marker), Jun (early response) and Ahr (cell cycle arrest). Methods: Adult female rats were subjected to either intraorbital optic nerve transection (IONT) or intraorbital optic nerve crush (IONC). Protein from naive and ON injured adult rat retinas was extracted at increasing time-points post-lesion and western blotting experiments carried out. For immnuhistofluorescence analyses, retinal ganglion cells (RGCs) were retrogradelly identified with fluorogold applied to the superior colliculi one week before injury. Results: Western blotting analyses revealed up-regulation of all the analyzed proteins as soon as 12 hours post-lesion (hpl) peaking at 48hpl, in agreement with our previous RNA studies1. Furthermore, immunohistofluorescence to radial sections show that all of them, but Stat1, are expressed by the primarily injured neurons, the RGCs, as seen by colocalization with FG. Conclusions: All analyzed proteins were up-regulated in the retina after IONT or IONC as soon as 12hpl, indicating that ON injury regulates several branches of the apoptotic cascade and suggesting that commitment to death might be an earlier event than previously anticipated.
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| 2. |
- Agudo, Marta, et al.
(författare)
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Time course profiling of the retinal transcriptome after optic nerve transection and optic nerve crush
- 2008
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Ingår i: Molecular Vision. - 1090-0535. ; 14, s. 1050-1063
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE:A time-course analysis of gene regulation in the adult rat retina after intraorbital nerve crush (IONC) and intraorbital nerve transection (IONT).METHODS:RNA was extracted from adult rat retinas undergoing either IONT or IONC at increasing times post-lesion. Affymetrix RAE230.2 arrays were hybridized and analyzed. Statistically regulated genes were annotated and functionally clustered. Arrays were validated by means of quantative reverse transcription polymerase chain reaction (qRT-PCR) on ten regulated genes at two times post-lesion. Western blotting and immunohistofluorescence for four pro-apoptotic proteins were performed on naïve and injured retinas. Finally, custom signaling maps for IONT- and IONC-induced death response were generated (MetaCore, Genego Inc.).RESULTS:Here we show that over time, 3,219 sequences were regulated after IONT and 1,996 after IONC. Out of the total of regulated sequences, 1,078 were commonly regulated by both injuries. Interestingly, while IONT mainly triggers a gene upregulation-sustained over time, IONC causes a transitory downregulation. Functional clustering identified the regulation of high interest biologic processes, most importantly cell death wherein apoptosis was the most significant cluster. Ten death-related genes upregulated by both injuries were used for array validation by means of qRT-PCR. In addition, western blotting and immunohistofluorescence of total and active Caspase 3 (Casp3), tumor necrosis factor receptor type 1 associated death domain (TRADD), tumor necrosis factor receptor superfamily member 1a (TNFR1a), and c-fos were performed to confirm their protein regulation and expression pattern in naïve and injured retinas. These analyses demonstrated that for these genes, protein regulation followed transcriptional regulation and that these pro-apoptotic proteins were expressed by retinal ganglion cells (RGCs). MetaCore-based death-signaling maps show that several apoptotic cascades were regulated in the retina following optic nerve injury and highlight the similarities and differences between IONT and IONC in cell death profiling.CONCLUSIONS: This comprehensive time course retinal transcriptome study comparing IONT and IONC lesions provides a unique valuable tool to understand the molecular mechanisms underlying optic nerve injury and to design neuroprotective protocols.
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| 3. |
- Apostolova, Galina, et al.
(författare)
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Neurotransmitter phenotype-specific expression changes in developing sympathetic neurons
- 2007
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Ingår i: Molecular and Cellular Neuroscience. - : Elsevier BV. - 1044-7431 .- 1095-9327. ; 35:3, s. 397-408
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Tidskriftsartikel (refereegranskat)abstract
- During late developmental phases individual sympathetic neurons undergo a switch from noradrenergic to cholinergic neurotransmission. This phenomenon of plasticity depends on target-derived signals in vivo and is triggered by neurotrophic factors in neuronal cultures. To analyze genome-wide expression differences between the two transmitter phenotypes we employed DNA microarrays. RNA expression profiles were obtained from chick paravertebral sympathetic ganglia, treated with neurotrophin 3, glial cell line-derived neurotrophic factor or ciliary neurotrophic factor, all of which stimulate cholinergic differentiation. Results were compared with the effect of nerve growth factor, which functions as a pro-noradrenergic stimulus. The gene set common to all three comparisons defined the noradrenergic and cholinergic synexpression groups. Several functional categories, such as signal transduction, G-protein-coupled signaling, cation transport, neurogenesis and synaptic transmission, were enriched in these groups. Experiments based on the prediction that some of the identified genes play a role in the neurotransmitter switch identified bone morphogenetic protein signaling as an inhibitor of cholinergic differentiation.
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| 4. |
- Bakall, Benjamin, et al.
(författare)
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Analysis of subcellular location of bestrophin in transfected RPE cell lines
- 2000
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Ingår i: Gene Function and Disease. - 1438-7506 .- 1438-826X. ; 1:3-4, s. 128-133
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Tidskriftsartikel (refereegranskat)abstract
- Best macular dystrophy is an autosomal dominant disease leading to macular degeneration and subsequent impaired vision. The disease has juvenile onset and affects the retinal pigment epithelium and adjacent photoreceptors. There are histopathological similarities between Best macular dystrophy (BMD) and age-related macular degeneration (AMD) with accumulation of lipofuscin in the outer retina. Recently, we identified the gene VMD2 causing Best macular dystrophy. The VMD2 gene has unknown function and there are no similarities between the VMD2 product, called bestrophin, and other proteins with known function. In order to gain more knowledge about the function of bestrophin we investigated its subcellular localization. DNA constructs encoding the bestrophin protein fused to the green fluorescent protein (GFP) or a c-myc tag were transiently expressed in COS-7 cells or retinal pigment epithelium cells. The observed pattern of bestrophin fusion protein was spotted and mainly perinuclear, well corresponding to the endoplasmic reticulum (ER), which was also suggested when counterstaining with an ER probe. Probes for other organelles had a different localization pattern compared to bestrophin. In conclusion, the results indicate that bestrophin is located to the endoplasmic reticulum.
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| 5. |
- Blixt, Maria, 1984-, et al.
(författare)
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A regulatory sequence from the retinoid X receptor gamma gene directs expression to horizontal cells and photoreceptors in the embryonic chicken retina
- 2016
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Ingår i: Molecular Vision. - 1090-0535. ; 22, s. 1405-1420
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Combining techniques of episomal vector gene-specific Cre expression and genomic integration using the piggyBac transposon system enables studies of gene expression-specific cell lineage tracing in the chicken retina. In this work, we aimed to target the retinal horizontal cell progenitors. METHODS: A 208 bp gene regulatory sequence from the chicken retinoid X receptor gammagene (RXRgamma208) was used to drive Cre expression. RXRgamma is expressed in progenitors and photoreceptors during development. The vector was combined with a piggyBac "donor" vector containing a floxed STOP sequence followed by enhanced green fluorescent protein (EGFP), as well as a piggyBac helper vector for efficient integration into the host cell genome. The vectors were introduced into the embryonic chicken retina with in ovo electroporation. Tissue electroporation targets specific developmental time points and in specific structures. RESULTS: Cells that drove Cre expression from the regulatory RXRgamma208 sequence excised the floxed STOP-sequence and expressed GFP. The approach generated a stable lineage with robust expression of GFP in retinal cells that have activated transcription from the RXRgamma208 sequence. Furthermore, GFP was expressed in cells that express horizontal or photoreceptor markers when electroporation was performed between developmental stages 22 and 28. Electroporation of a stage 12 optic cup gave multiple cell types in accordance with RXRgamma gene expression in the early retina. CONCLUSIONS: In this study, we describe an easy, cost-effective, and time-efficient method for testing regulatory sequences in general. More specifically, our results open up the possibility for further studies of the RXRgamma-gene regulatory network governing the formation of photoreceptor and horizontal cells. In addition, the method presents approaches to target the expression of effector genes, such as regulators of cell fate or cell cycle progression, to these cells and their progenitor.
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| 6. |
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| 7. |
- Blixt, Maria K. E., et al.
(författare)
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Zinc finger gene nolz1 regulates the formation of retinal progenitor cells and suppresses the Lim3/Lhx3 phenotype of retinal bipolar cells in chicken retina
- 2018
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Ingår i: Developmental Dynamics. - : WILEY. - 1058-8388 .- 1097-0177. ; 247:4, s. 630-641
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Tidskriftsartikel (refereegranskat)abstract
- Background: The zinc-finger transcription factor Nolz1 regulates spinal cord neuron development by interacting with the transcription factors Isl1, Lim1, and Lim3, which are also important for photoreceptors, horizontal and bipolar cells during retinal development. We, therefore, studied Nolz1 during retinal development.Results: Nolz1 expression was seen in two waves during development: one early (peak at embryonic day 3-4.5) in retinal progenitors and one late (embryonic day 8) in newly differentiated cells in the inner nuclear layer. Overexpression and knockdown showed that Nolz1 decreases proliferation and stimulates cell cycle withdrawal in retinal progenitors with effects on the generation of retinal ganglion cells, photoreceptors, and horizontal cells without triggering apoptosis. Overexpression of Nolz1 gave more p27 positive cells. Sustained overexpression of Nolz1 in the retina gave fewer Lim3/Lhx3 bipolar cells.Conclusions: We conclude that Nolz1 has multiple functions during development and suggest a mechanism in which Nolz1 initially regulates the proliferation state of the retinal progenitor cells and then acts as a repressor that suppresses the Lim3/Lhx3 bipolar cell phenotype at the time of bipolar cell differentiation.
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| 8. |
- Blixt, Maria, 1984-
(författare)
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Keeping up with retinal photoreceptors and horizontal cells : Labelling and mapping of cells in the normal and diseased embryonic chicken retina
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The childhood eye cancer retinoblastoma originates from the retina and its development is initiated while the foetus is in the uterus. Retinoblastoma has a reported incidence of 1 in 15-18 000 live births, and approximately 90% of all patients are diagnosed before the age of 5. The occurrence of retinoblastoma is usually detected by the parents and the most frequent symptoms are leukocoria (white pupillary reflex), strabismus (squinting) or if the child complains of visual problems. Retinoblastoma is diagnosed by examination under anaesthesia and documentation by RetCam. It is treated with various cytostatic agents, or by laser. If the treatment is unsuccessful, or there is a risk that the tumour cells will spread and form metastases, the eye is removed.Previous studies have indicated that the cell type from which the tumour arises, the cell-of-origin, may be the cone photoreceptors and/or their immediate interneuron, the horizontal cells. Determining the cell-of-origin for retinoblastoma is an important goal, however, understanding the molecular mechanisms that distinguish the photoreceptors and the horizontal cells from the other retinal cells may prove just as important for understanding this disease.The aim of my project has been to develop, optimise and validate methods to label, map and target expression to photoreceptors and horizontal cells in the chicken embryonic retina. We have successfully established several methods that test the expression pattern of conserved, regulatory DNA sequences, and have performed short- and long-term expression of various genes that have been reported to be involved in cell cycle regulation and cell fate determination. One of my most important findings was that a region from the RXRγ gene allowed us to specifically target the photoreceptors and horizontal cells. Our previous knowledge, together with the newly established tools, puts us an important step closer towards understanding the development and behaviour of the retinal photoreceptors and horizontal cells, however, further studies are of course needed.
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| 9. |
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| 10. |
- Blixt, Maria, et al.
(författare)
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MYCN induces cell-specific tumorigenic growth in RB1-proficient human retinal organoid and chicken retina models of retinoblastoma
- 2022
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Ingår i: Oncogenesis. - : Springer Science and Business Media LLC. - 2157-9024. ; 11:1, s. 34-
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Tidskriftsartikel (refereegranskat)abstract
- Retinoblastoma is a rare, intraocular paediatric cancer that originates in the neural retina and is most frequently caused by bi-allelic loss of RB1 gene function. Other oncogenic mutations, such as amplification and increased expression of the MYCN gene, have been found even with proficient RB1 function. In this study, we investigated whether MYCN over-expression can drive carcinogenesis independently of RB1 loss-of-function mutations. The aim was to elucidate the events that result in carcinogenesis and identify the cancer cell-of-origin. We used the chicken retina, a well-established model for studying retinal neurogenesis, and established human embryonic stem cell-derived retinal organoids as model systems. We over-expressed MYCN by electroporation of piggyBac genome-integrating expression vectors. We found that over-expression of MYCN induced tumorigenic growth with high frequency in RB1-proficient chicken retinas and human organoids. In both systems, the tumorigenic cells expressed markers for undifferentiated cone photoreceptor/horizontal cell progenitors. The over-expression resulted in metastatic retinoblastoma within 7–9 weeks in chicken. Cells expressing MYCN could be grown in vitro and, when orthotopically injected, formed tumours that infiltrated the sclera and optic nerve and expressed markers for cone progenitors. Investigation of the tumour cell phenotype determined that the potential for neoplastic growth was embryonic stage-dependent and featured a cell-specific resistance to apoptosis in the cone/horizontal cell lineage, but not in ganglion or amacrine cells. We conclude that MYCN over-expression is sufficient to drive tumorigenesis and that a cell-specific resistance to apoptosis in the cone/horizontal cell lineage mediates the cancer phenotype.
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| 11. |
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| 12. |
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| 13. |
- Boije, Henrik, et al.
(författare)
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Forkheadbox N4 (FoxN4) triggers context-dependent differentiation in the developing chick retina and neural tube
- 2013
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Ingår i: Differentiation. - : Elsevier BV. - 0301-4681 .- 1432-0436. ; 85:1-2, s. 11-19
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Tidskriftsartikel (refereegranskat)abstract
- FoxN4, a forkhead box transcription factor, is expressed in the chicken eye field and in retinal progenitor cells (RPCs) throughout development. FoxN4 labelling overlapped with that of Pax6 and Sox2, two crucial transcription factors for RPCs. Later, during neurogenesis in the retina, some cells were intensely and transiently labelled for FoxN4. These cells co-labelled for Lim1, a transcription factor expressed in early-born horizontal cells. The result suggests that high levels of FoxN4 combined with expression of Lim1 define a population of RPCs committed to the horizontal cell fate prior to their last apical mitosis. As these prospective horizontal cells develop, their FoxN4 expression is down-regulated. Previous results suggested that FoxN4 is important for the generation of horizontal and amacrine cells but that it is not sufficient for the generation of horizontal cells (Li et al., 2004). We found that over-expression of FoxN4 in embryonic day 3 chicken retina could activate horizontal cell markers Prox1 and Lim1, and that it generated numerous and ectopically located horizontal cells of both main subtypes. However, genes expressed in photoreceptors, amacrine and ganglion cells were also activated, indicating that FoxN4 triggered the expression of several differentiation factors. This effect was not exclusive for the retina but was also seen when FoxN4 was over-expressed in the mesencephalic neural tube. Combining the results from over-expression and wild-type expression data we suggest a model where a low level of FoxN4 is maintained in RPCs and that increased levels during a restricted period trigger neurogenesis and commitment of RPCs to the horizontal cell fate.
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| 14. |
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| 15. |
- Boije, Henrik, 1978-
(författare)
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Generation of Retinal Neurons : Focus on the Proliferation and Differentiation of the Horizontal Cells and their Subtypes
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- We have used the chicken retina as a model for investigating cell cycle regulation and cell fate commitment during central nervous system development. This thesis focuses on the characterization of and commitment to the horizontal cell fate in the retina. Horizontal cells are interneurons that provide intraretinal signal processing prior to information relay to the brain. We have identified molecular markers that selectively distinguish the three subtypes of horizontal cells, previously described in the chicken retina based on morphology. Subtype specific birth-dating revealed that horizontal cell subtypes are generated consecutively by biased progenitors that are sensitive to the inhibitory effects of follistatin. Follistatin stimulates proliferation in progenitors by repressing the differentiation signal of activin. Initially, injection of follistatin led to a decrease in committed horizontal cells but as the inhibitory effect dissipated it resulted in an increased number of horizontal cells. During development committed horizontal cell progenitors migrate to the vitreal side of the retina where they become arrested in G2-phase for approximately two days. When the arrest is overcome the horizontal cell progenitors undergo ectopic mitosis followed by migration to their designated layer. The G2-phase arrest is not triggered or maintained by any of the classic G2-arrest pathways such as DNA damage or stress. Nevertheless, we show that the cyclin B1-Cdk1 complex has a central role in maintaining this G2-phase arrest. Two transcription factors, FoxN4 and Ptf1a, are required for the generation of horizontal cells. We show that these factors are also sufficient to promote horizontal cell fate. Overexpression of FoxN4 and Ptf1a resulted in an overproduction of horizontal- and amacrine cells at the expense of ganglion- and photoreceptor cells. We identified Atoh7, a transcription factor required for the generation of ganglion cells, as a Ptf1a transcriptional target for downregulation. Our data support a common horizontal/amacrine lineage separated from the ganglion/photoreceptor lineage by the action of Ptf1a. In conclusion, these data describe several novel characteristics of horizontal cells enhancing our understanding of neural development and cell fate commitment.
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| 16. |
- Boije, Henrik, et al.
(författare)
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Horizontal cell progenitors arrest in G2-phase and undergo terminal mitosis on the vitreal side of the chick retina
- 2009
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Ingår i: Developmental Biology. - : Elsevier. - 0012-1606 .- 1095-564X. ; 330:1, s. 105-113
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Tidskriftsartikel (refereegranskat)abstract
- We have addressed the question when horizontal cells in the chick retina are generated and undergo their terminal mitosis. Horizontal cell progenitors replicate their DNA early and migrate bi-directionally to the horizontal cell layer. It was hypothesized that the cells undergo mitosis directly after replication and migrate as post-mitotic transition cells before differentiating to horizontal cells. However, our results show that cells expressing markers for the axon-bearing and the axon-less subtypes of horizontal cells undergo terminal mitosis while residing on the vitreal side of the retina. By combining horizontal cell transcription factors Lim1, Isl1 and Prox1 labeling with phospho-histone H3, a marker for mitosis, we demonstrate that all or a clear majority of vitreal mitoses are undertaken by the horizontal cell committed progenitors. The pattern of cells that incorporated the thymidine analogue EdU implied that the progenitors replicated their genome while migrating towards the vitreal side. Upon arrival to the vitreal retina they become arrested for about two days prior to mitosis. Hence, cells expressing horizontal cell markers are arrested in G2-phase on the vitreal side of the retina. These results support the existence of committed progenitors that give rise to horizontal cells and that those cells become arrested in G2-phase before undergoing terminal mitosis on the vitreal side of the retina followed by migration to the horizontal cell layer. The results also indicate that the regulation of the transition from G2-phase to mitosis is important for the development of these committed progenitor cells.
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| 17. |
- Boije, Henrik, et al.
(författare)
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Horizontal Cells, the Odd Ones Out in the Retina, Give Insights into Development and Disease
- 2016
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Ingår i: Frontiers in Neuroanatomy. - : Frontiers Media SA. - 1662-5129. ; 10
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Forskningsöversikt (refereegranskat)abstract
- Thorough investigation of a neuronal population can help reveal key aspects regarding the nervous system and its development. The retinal horizontal cells have several extraordinary features making them particularly interesting for addressing questions regarding fate assignment and subtype specification. In this review we discuss and summarize data concerning the formation and diversity of horizontal cells, how morphology is correlated to molecular markers, and how fate assignment separates the horizontal lineage from the lineages of other retinal cell types. We discuss the novel and unique features of the final cell cycle of horizontal cell progenitors and how they may relate to retinoblastoma carcinogenesis.
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| 18. |
- Boije, Henrik, et al.
(författare)
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Pax2 Is Expressed in a Subpopulation of Muller Cells in the Central Chick Retina
- 2010
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Ingår i: Developmental Dynamics. - : Wiley. - 1058-8388 .- 1097-0177. ; 239:6, s. 1858-1866
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Tidskriftsartikel (refereegranskat)abstract
- Muller cells in the chick retina are generally thought to be a homogeneous population. We show that the transcription factor Pax2 is expressed by Muller cells in the central chick retina and its expression was first observed at stage 32 (embryonic day [E] 7.5). Birth-dating indicated that the majority of Pax2-positive Muller cells are generated between stage 29 and 33 (E5.5-E8). At stage 42 (E16), several Muller cell markers, such as Sox2 and 2M6, had reached the peripheral retina, while the Pax2 labeling extended approximately half-way. A similar pattern was maintained in the 6-month-old chicken. Neither the Pax2-positive nor the Pax2-negative Muller cells could be specifically associated to proliferative responses in the retina induced by growth factors or N-methyl-D-aspartate. Pax2 was not detected in Muller cells in mouse, rat, guinea-pig, rabbit, or pig retinas; but the zebrafish retina displayed a similar pattern of central Pax2-expressing Muller cells.
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| 19. |
- Boije, Henrik, et al.
(författare)
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Sonic Hedgehog-Signalling Patterns the Developing Chicken Comb as Revealed by Exploration of the Pea-comb Mutation
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:12, s. e50890-
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Tidskriftsartikel (refereegranskat)abstract
- The genetic basis and mechanisms behind the morphological variation observed throughout the animal kingdom is stillrelatively unknown. In the present work we have focused on the establishment of the chicken comb-morphology byexploring the Pea-comb mutant. The wild-type single-comb is reduced in size and distorted in the Pea-comb mutant. Peacombis formed by a lateral expansion of the central comb anlage into three ridges and is caused by a mutation in SOX5,which induces ectopic expression of the SOX5 transcription factor in mesenchyme under the developing comb. Analysis ofdifferential gene expression identified decreased Sonic hedgehog (SHH) receptor expression in Pea-comb mesenchyme. Byexperimentally blocking SHH with cyclopamine, the wild-type single-comb was transformed into a Pea-comb-likephenotype. The results show that the patterning of the chicken comb is under the control of SHH and suggest that ectopicSOX5 expression in the Pea-comb change the response of mesenchyme to SHH signalling with altered combmorphogenesis as a result. A role for the mesenchyme during comb morphogenesis is further supported by the recentfinding that another comb-mutant (Rose-comb), is caused by ectopic expression of a transcription factor in combmesenchyme. The present study does not only give knowledge about how the chicken comb is formed, it also adds to ourunderstanding how mutations or genetic polymorphisms may contribute to inherited variations in the human face.
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| 20. |
- Boije, Henrik, et al.
(författare)
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Temporal and spatial expression of transcription factors FoxN4, Ptf1a, Prox1, Isl1 and Lim1 mRNA in the developing chick retina
- 2008
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Ingår i: Gene Expression Patterns. - : Elsevier BV. - 1567-133X .- 1872-7298. ; 8:2, s. 117-123
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Tidskriftsartikel (refereegranskat)abstract
- Transcription factors are pivotal in regulating cell fate and development. We analyzed five transcription factors - FoxN4, Ptf1a, Prox1, Isl1 and Lim1 - with putative functions in the formation of early-generated retinal interneurons. A full-length chicken FoxN4 cDNA was characterized and in situ as well as RT-PCR showed that FoxN4 expression commenced already in the stage 12-14 optic vesicles. Ptf1a, Prox1, Isl1 and Lim1 expression appeared later by stage 20-24, concomitant with the first post-mitotic ganglion-, amacrine- and horizontal cells. The FoxN4 and Ptf1a expression was transient with peak levels by stage 32-35. Expression disappeared as the retinal progenitor cells differentiated. Prox1, Isl1 and Lim1 expression remained in several differentiated cells including the horizontal cells. The order of expression supports a scheme where Ptf1a and Prox1 is downstream of FoxN4 and that FoxN4 and Ptf1a have transient roles during fate specification while Prox1, Isl1 and Lim1 have roles that are important for the generation of the neuronal subtypes.
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| 21. |
- Brusini, Irene, et al.
(författare)
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Changes in brain architecture are consistent with altered fear processing in domestic rabbits
- 2018
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:28, s. 7380-7385
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Tidskriftsartikel (refereegranskat)abstract
- The most characteristic feature of domestic animals is their change in behavior associated with selection for tameness. Here we show, using high-resolution brain magnetic resonance imaging in wild and domestic rabbits, that domestication reduced amygdala volume and enlarged medial prefrontal cortex volume, supporting that areas driving fear have lost volume while areas modulating negative affect have gained volume during domestication. In contrast to the localized gray matter alterations, white matter anisotropy was reduced in the corona radiata, corpus callosum, and the subcortical white matter. This suggests a compromised white matter structural integrity in projection and association fibers affecting both afferent and efferent neural flow, consistent with reduced neural processing. We propose that compared with their wild ancestors, domestic rabbits are less fearful and have an attenuated flight response because of these changes in brain architecture.
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| 22. |
- Burke, R. D., et al.
(författare)
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A genomic view of the sea urchin nervous system
- 2006
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Ingår i: Developmental Biology. - : Elsevier BV. - 0012-1606 .- 1095-564X. ; 300:1, s. 434-460
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Tidskriftsartikel (refereegranskat)abstract
- The sequencing of the Strongylocentrotus purpuratus genome provides a unique opportunity to investigate the function and evolution of neural genes. The neurobiology of sea urchins is of particular interest because they have a close phylogenetic relationship with chordates, yet a distinctive pentaradiate body plan and unusual neural organization. Orthologues of transcription factors that regulate neurogenesis in other animals have been identified and several are expressed in neurogenic domains before gastrulation indicating that they may operate near the top of a conserved neural gene regulatory network. A family of genes encoding voltage-gated ion channels is present but, surprisingly, genes encoding gap junction proteins (connexins and pannexins) appear to be absent. Genes required for synapse formation and function have been identified and genes for synthesis and transport of neurotransmitters are present. There is a large family of G-protein-coupled receptors, including 874 rhodopsin-type receptors, 28 metabotropic glutamate-like receptors and a remarkably expanded group of 161 secretin receptor-like proteins. Absence of cannabinoid, lysophospholipid and melanocortin receptors indicates that this group may be unique to chordates. There are at least 37 putative G-protein-coupled peptide receptors and precursors for several neuropeptides and peptide hormones have been identified, including SALMFamides, NGFFFamide, a vasotocin-like peptide, glycoprotein hormones and insulin/insulin-like growth factors. Identification of a neurotrophin-like gene and Trk receptor in sea urchin indicates that this neural signaling system is not unique to chordates. Several hundred chemoreceptor genes have been predicted using several approaches, a number similar to that for other animals. Intriguingly, genes encoding homologues of rhodopsin, Pax6 and several other key mammalian retinal transcription factors are expressed in tube feet, suggesting tube feet function as photosensory organs. Analysis of the sea urchin genome presents a unique perspective on the evolutionary history of deuterostome nervous systems and reveals new approaches to investigate the development and neurobiology of sea urchins. (c) 2006 Elsevier Inc. All rights reserved.
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| 23. |
- Chavarría, Teresa, et al.
(författare)
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Differential, age-dependent MEK-ERK and PI3K-Akt activation by insulin acting as a survival factor during embryonic retinal development
- 2007
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Ingår i: Developmental Neurobiology. - : Wiley. - 1932-8451 .- 1932-846X. ; 67:13, s. 1777-1788
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Tidskriftsartikel (refereegranskat)abstract
- Programmed cell death is a genuine developmental process of the nervous system, affecting not only projecting neurons but also proliferative neuroepithelial cells and young neuroblasts. The embryonic chick retina has been employed to correlate in vivo and in vitro studies on cell death regulation. We characterize here the role of two major signaling pathways, PI3K-Akt and MEK-ERK, in controlled retinal organotypic cultures from embryonic day 5 (E5) and E9, when cell death preferentially affects proliferating neuroepithelial cells and ganglion cell neurons, respectively. The relative density of programmed cell death in vivo was much higher in the proliferative and early neurogenic stages of retinal development (E3-E5) than during neuronal maturation and synaptogenesis (E8-E19). In organotypic cultures from E5 and E9 retinas, insulin, as the only growth factor added, was able to completely prevent cell death induced by growth factor deprivation. Insulin activated both the PI3K-Akt and the MEK-ERK pathways. Insulin survival effect, however, was differentially blocked at the two stages. At E5, the effect was blocked by MEK inhibitors, whereas at E9 it was blocked by PI3K inhibitors. The cells which were found to be dependent on insulin activation of the MEK-ERK pathway at E5 were mostly proliferative neuroepithelial cells. These observations support a remarkable specificity in the regulation of early neural cell death.
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| 24. |
- Dorshorst, Ben, et al.
(författare)
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A Complex Genomic Rearrangement Involving the Endothelin 3 Locus Causes Dermal Hyperpigmentation in the Chicken
- 2011
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Ingår i: PLoS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 7:12, s. e1002412-
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Tidskriftsartikel (refereegranskat)abstract
- Dermal hyperpigmentation or Fibromelanosis (FM) is one of the few examples of skin pigmentation phenotypes in the chicken, where most other pigmentation variants influence feather color and patterning. The Silkie chicken is the most widespread and well-studied breed displaying this phenotype. The presence of the dominant FM allele results in extensive pigmentation of the dermal layer of skin and the majority of internal connective tissue. Here we identify the causal mutation of FM as an inverted duplication and junction of two genomic regions separated by more than 400 kb in wild-type individuals. One of these duplicated regions contains endothelin 3 (EDN3), a gene with a known role in promoting melanoblast proliferation. We show that EDN3 expression is increased in the developing Silkie embryo during the time in which melanoblasts are migrating, and elevated levels of expression are maintained in the adult skin tissue. We have examined four different chicken breeds from both Asia and Europe displaying dermal hyperpigmentation and conclude that the same structural variant underlies this phenotype in all chicken breeds. This complex genomic rearrangement causing a specific monogenic trait in the chicken illustrates how novel mutations with major phenotypic effects have been reused during breed formation in domestic animals.
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| 25. |
- Dorshorst, Ben, et al.
(författare)
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A Genomic Duplication is Associated with Ectopic Eomesodermin Expression in the Embryonic Chicken Comb and Two Duplex-comb Phenotypes
- 2015
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Ingår i: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Duplex-comb (D) is one of three major loci affecting comb morphology in the domestic chicken. Here we show that the two Duplex-comb alleles, V-shaped (D*V) and Buttercup (D*C), are both associated with a 20 Kb tandem duplication containing several conserved putative regulatory elements located 200 Kb upstream of the eomesodermin gene (EOMES). EOMES is a T-box transcription factor that is involved in mesoderm specification during gastrulation. In D*V and D*C chicken embryos we find that EOMES is ectopically expressed in the ectoderm of the comb-developing region as compared to wild-type embryos. The confinement of the ectopic expression of EOMES to the ectoderm is in stark contrast to the causal mechanisms underlying the two other major comb loci in the chicken (Rose-comb and Pea-comb) in which the transcription factors MNR2 and SOX5 are ectopically expressed strictly in the mesenchyme. Interestingly, the causal mutations of all three major comb loci in the chicken are now known to be composed of large-scale structural genomic variants that each result in ectopic expression of transcription factors. The Duplex-comb locus also illustrates the evolution of alleles in domestic animals, which means that alleles evolve by the accumulation of two or more consecutive mutations affecting the phenotype. We do not yet know whether the V-shaped or Buttercup allele correspond to the second mutation that occurred on the haplotype of the original duplication event.
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