The level of gene expression was found to correlate to H4K5ac enrichment such that the highest expressed genes had the highest coverage for H4K5ac, while the least expressed genes had the lowest coverage. This applied to both groups regardless of training, suggesting that H4K5ac is a general feature of expressed genes. We also confirmed Gemcitabine HCl that H4K12ac correlated with the level of gene expression. There was no correlation between gene expression and IgG IP coverage. These results indicate a clear association between both H4K5ac and H4K12ac and gene expression. We then identified genes acetylated above average and performed a cross wise comparison between experimental groups. Based on the average promoter read count of 45 in our dataset, we considered genes with more than 50 reads in the promoter as above average.

From a total of 23,235 genes in the dataset, 7,103 genes were identified in the FC Inhibitors,Modulators,Libraries group, and 7,708 genes in the control. Using this criteria, 742 genes were specific for FC, 1,273 genes were specific for control, and 6,029 genes were common to both groups. We then looked at whether genes with above average H4K5ac after 2 days of CFC were also associated with H4K12ac after one session Inhibitors,Modulators,Libraries of CFC. Using an adjusted threshold of 10 reads in promoter due to the lower aver age coverage, approximately 9 reads in promoter, in the H4K12ac dataset, we identified 4,259 unique genes with above average H4K12ac, of which 2,772 genes over lapped with genes with above average H4K5ac in FC, and 2,846 genes with above average H4K5ac in controls. 2,440 genes over lapped all three groups using this criteria.

The results of these analyses extend our findings that in control conditions most nucleosomes are not only acety lated for H4K5 above the average of all genes, but are also acetylated for H4K12. Interestingly, nearly two thirds of genes with above average H4K12ac after one session of CFC was found to overlap with Inhibitors,Modulators,Libraries above average H4K5ac after 2 days of CFC or context. This suggests that the same set of genes, associated with H4K12ac and induced imme diately after CFC, may be upregulated following reinforced training, regardless of the associated histone acetylation used to identify the genes. It also suggests that the same set of genes may be activated Inhibitors,Modulators,Libraries after initial learning, during the formation of contextual fear memory, and after memory re trieval, independently of the CFC paradigm.

H4K5ac is associated Inhibitors,Modulators,Libraries with both promoter and coding regions Nucleosome occupancy studies have shown that acety lated and methylated histones are enriched in the pro moter of highly expressed selleck chemicals genes, but subsequently removed or replaced in the CDS. To investigate the positional effect of nucleosomes with H4K5ac on tran scription, we clustered genes based on their acetylation profile 2 kb relative to the TSS.

Antileukotrienes These agents have been advocated as adjuncts to INS for the treatment of CRSwNP.Modest benefit has been noted after 1 3 months of montelukast or the 5 lipoxygenase selleck screening library inhibitor zileuton in studies lacking pla cebo control.However,placebo controlled studies have mostly failed to demonstrate benefit of montelukast for nasal polyposis,and zileuton has not been subjected to a placebo controlled trial.Adjunctive therapies A Cochrane review Inhibitors,Modulators,Libraries of 8 studies using various forms of sa line sprays and irrigation performed 1 4 times daily found that intranasal saline is an effective adjunctive treatment for CRS.Saline irrigation provides a subjective sense of freshening,rinses away allergens and irritants,removes secretions,improves mucociliary clearance,and reduces postnasal drainage.

An isotonic concentration is generally preferred to hypertonic saline.Intranasal lavage can be performed with over the counter devices Inhibitors,Modulators,Libraries such as squeeze bottles,sy ringes and pots.Appropriate cleaning is required to avoid contamination of the device.The evidence does not currently support the use of mucolytics,oral decongestants,or protracted adminis tration of intranasal decongestants for CRS.However,therapies of associated conditions may aid the manage ment of CRS.These include antihistamines,environ mental control to reduce problematic exposures and allergen immunotherapy for patients Inhibitors,Modulators,Libraries with allergic rhin itis,and H2 antagonists and proton pump inhibitors for patients with laryngopharyngeal reflux.

For patients with aspirin exacerbated respiratory disease,aspirin desensitization followed by daily aspirin therapy has been reported as beneficial for control of nasal polyps,although placebo controlled trials have not been con ducted.CRS Pharmacotherapy There is a relative paucity of controlled studies for this Inhibitors,Modulators,Libraries indication.The design and interpretation of CRS clinical trials has been hindered by the heterogeneity of the dis ease,a deficiency of uniform definitions for disease subtypes,incomplete understanding of the underlying pathologies,and a lack of useful Inhibitors,Modulators,Libraries and standardized clin ical and laboratory endpoints to measure response to therapy.The most comprehensive treatment recom mendations for CRS are put forth in the EPOS consen sus document.Recommendations are categorized www.selleckchem.com/products/Cisplatin.html into 3 major subtypes,CRSsNP,CRSwNP and AFRS.Recommendations are also stratified according to disease severity,using a visual analogue scale of 0 to 10.CRSsNP 1.Initially intranasal saline and INS 2.If after 3 months not improved,perform culture,institute long term macrolide therapy 3.If improved,continue intranasal saline and INS with without macrolide therapy 4.

Antileukotrienes These agents have been advocated as adjuncts to INS for the treatment of CRSwNP.Modest benefit has been noted after 1 3 months of montelukast or the 5 lipoxygenase selleck chemicals llc inhibitor zileuton in studies lacking pla cebo control.However,placebo controlled studies have mostly failed to demonstrate benefit of montelukast for nasal polyposis,and zileuton has not been subjected to a placebo controlled trial.Adjunctive therapies A Cochrane review Inhibitors,Modulators,Libraries of 8 studies using various forms of sa line sprays and irrigation performed 1 4 times daily found that intranasal saline is an effective adjunctive treatment for CRS.Saline irrigation provides a subjective sense of freshening,rinses away allergens and irritants,removes secretions,improves mucociliary clearance,and reduces postnasal drainage.

An isotonic concentration is generally preferred to hypertonic saline.Intranasal lavage can be performed with over the counter devices Inhibitors,Modulators,Libraries such as squeeze bottles,sy ringes and pots.Appropriate cleaning is required to avoid contamination of the device.The evidence does not currently support the use of mucolytics,oral decongestants,or protracted adminis tration of intranasal decongestants for CRS.However,therapies of associated conditions may aid the manage ment of CRS.These include antihistamines,environ mental control to reduce problematic exposures and allergen immunotherapy for patients Inhibitors,Modulators,Libraries with allergic rhin itis,and H2 antagonists and proton pump inhibitors for patients with laryngopharyngeal reflux.

For patients with aspirin exacerbated respiratory disease,aspirin desensitization followed by daily aspirin therapy has been reported as beneficial for control of nasal polyps,although placebo controlled trials have not been con ducted.CRS Pharmacotherapy There is a relative paucity of controlled studies for this Inhibitors,Modulators,Libraries indication.The design and interpretation of CRS clinical trials has been hindered by the heterogeneity of the dis ease,a deficiency of uniform definitions for disease subtypes,incomplete understanding of the underlying pathologies,and a lack of useful Inhibitors,Modulators,Libraries and standardized clin ical and laboratory endpoints to measure response to therapy.The most comprehensive treatment recom mendations for CRS are put forth in the EPOS consen sus document.Recommendations are categorized selleck products into 3 major subtypes,CRSsNP,CRSwNP and AFRS.Recommendations are also stratified according to disease severity,using a visual analogue scale of 0 to 10.CRSsNP 1.Initially intranasal saline and INS 2.If after 3 months not improved,perform culture,institute long term macrolide therapy 3.If improved,continue intranasal saline and INS with without macrolide therapy 4.

Antibodies and polychromatic flow cytometry analysis Fluorochrome conjugated Abs used for polychromatic flow cytometry. The viability TSA dye Aqua Vivid was used to exclude dead cells from our analysis. Cells were analyzed by FACS using the BD LSRII cytometer, and BD Diva and FlowJo softwares. Positivity gates were placed using fluorescence Inhibitors,Modulators,Libraries minus one, as previously described. Magnetic and fluorescence activated cell sorting Memory Th1Th17 and Th1 were sorted as previously described. Briefly, total CD4 T cells were sorted from PBMCs by negative selection using magnetic beads, memory Th1Th17 and Th1 subsets were sorted by FACS upon staining with anti CD45RA APC Cy7, CCR4 PE Cy7, CXCR3 PE Cy5, CCR6 PE and a cocktail of FITC conju gated Abs to exclude CD8 T cells, NK cells, and B cells.

The sorting Inhibitors,Modulators,Libraries gate was set on CD45RA FITC CCR4 CXCR3 cells expressing or not CCR6. The purity of the cells was typically 98% for memory CD4 T cells and 95% for Th1Th17 and Th1 sub sets. The median frequency of memory Th1 and Inhibitors,Modulators,Libraries Th1Th17 cells within total CD4 T cells is 17. 6% and 6. 5%, respectively. Typically, 4106 Th1Th17 cells can be isolated by MACS and FACS from approximately 108 total CD4 T cells and 109 PBMC. For other ex periments, memory CD4 T cells were sorted by negative selection using magnetic beads at a purity 98% as dem Inhibitors,Modulators,Libraries onstrated by staining with CD3, CD4, and CD45RA Abs. RNA isolation and microarray analysis Sorted Th1Th17 and Th1 subsets were stimulated with immobilized CD3 and soluble CD28 Abs for 3 days. Total RNA was isolated using the RNeasy kit according to the manufacturers protocol and quantified by Pearl nanophotometer.

Genome wide analysis of gene expression was performed on total RNA extracted from Th1Th17 and Th1 cells of four different HIV uninfected donors by G��nome Qu��bec using the Affymetrix technology. Briefly, the quality of total RNA was first tested using an Agilent 2100 Bioanalyzer Inhibitors,Modulators,Libraries chip. Then, high quality RNA was reverse transcribed and hybridized on the GeneChip Human Genome U133 Plus 2. 0 Array. This chip includes 54,675 probe sets on a single array. Gene expression data was analyzed using Bioconductor, an open source soft ware Library for the analyses of genomic data based on R, a programming language and environment for statistical computing and graphics. The R soft ware package was used to preprocess and normalize the probes intensities using RMA method for the four matched Th1Th17 and kinase inhibitor Imatinib Mesylate Th1 cell subsets. Microarray data analysis Genes were filtered by detection call and by variance filters to allow a reduction in the number of tests and a corresponding increase in power of the differential gene expression analysis.

An increased frequency of Th1 cells in HIV infected subjects may be deleterious given the ability of these cells to produce pro inflammatory cytokines such as TNF. In addition, the finding that Th1 vs. Th1Th17 cells over expressed the CDH1 mRNA, known to inhibit HIV specific inhibitor Regorafenib CD8 T cell functions via interaction with its receptor KLRG1, suggests a deleterious role of Th1 cells in HIV pathogenesis. In addition to known Th17 specific transcription factors, we demonstrate that Th1Th17 vs. Th1 expressed at superior levels the transcription factors RUNX1, known to mediate the transactivation of RORC ATF5, involved in T cell activation ARTNL, a component of the circadian clock and an HIV dependency factor PPAR and also KLF11, which is a PPAR co regulator and direct transcriptional target.

HIV permissiveness in Th1Th17 cells was also associated with Inhibitors,Modulators,Libraries superior expression of the costimulatory molecules CD28 and CD40LGCD154, molecules involved in the regulation Inhibitors,Modulators,Libraries of apoptosis such as FASLG, and cyto kines such as IL 2 and IL 15. The expression of TGFBR1 TGFBR2 and IL23R on Th1Th17 cells is indicative of their ability to respond to TGF B and IL 23, respectively. TGF B is essential to Th17 differentiation, while IL 23 is involved in the maintenance of the Th17 polari zation and critical for the development of a pathogenic Th17 profile. The expression of genes important for signal transduc tion downstream of the TCR andor cytokine receptors also indicates a greater susceptibility of Th1Th17 cells to activation and a potential contribution to inflammation.

Inhibitors,Modulators,Libraries For example, Th1Th17 cells preferentially express MAP KAPK2MK2, a kinase involved in the production of TNF and IL 6 and MAP3K4, a kinase involved the p38 JNK pathway activation in response to TGF B. Indeed, signaling through p38 is important for HIV replication. In contrast to Th1Th17, Th1 cells expressed Inhibitors,Modulators,Libraries at superior levels several 10 genes of the zinc finger family, including the ZNF382, a tumor suppressor acting via the inhibition of the NF B signaling pathway. Also, Th1 cells preferentially express GRK5 and CNKSR2 KSR2, two molecules that can inhibit the transcriptional activity of NF B. Interestingly, Inhibitors,Modulators,Libraries genome wide siRNA screens for HIV dependency factor identified NF B pathway as being key for HIV permissiveness. It was also shown that the HIV LTR promoters have binding sites for NF B that are important for the transcription of the virus.

It would be of interest to determine whether the expression of kinases GRK5 and CNKSR2 limits NF B translocation in Th1 cells thus, explaining their resistance to HIV infection. One major finding of our study is the identification www.selleckchem.com/products/kpt-330.html of PPAR as an intrinsic negative regulator of HIV permis siveness in Th1Th17 cells. PPAR is a ligand dependent nuclear receptor that acts as a transcriptional repressor in macrophages and T cells. The localization of PPAR in the nucleus vs.

Confocal microscopy analysis revealed not only an increased fre quency of PPAR expressing cells, but also superior nuclear vs. cytoplasmic localization of PPAR protein in Th1Th17 vs. Th1 cells, suggesting the existence of endogenous ligands triggering PPAR nuclear translocation in Th1Th17 cells upon TCR engagement. Whether PPAR vs. PPAR cells within selleck chemicals llc the Th1Th17 and also the Th1 pool are particularly permissive to infection and whether the nuclear localization of PPAR contribute to limiting HIV permissiveness in such cells remains unknown. Future studies are needed to determine the role of PPAR en dogenous ligands in controlling HIV permissiveness in primary cells. Our results demonstrate that PPAR activation pathway controls HIV dissemination by acting on HIV infected cells and also by Inhibitors,Modulators,Libraries preventing new integrative infection.

We found that siRNA against PPAR led to Inhibitors,Modulators,Libraries a significant increase in HIV DNA integration and subsequent viral replication when cells were exposed to wt HIV 24 h after PPAR knock down. Of note, similar results were obtained when cells were exposed to single round VSV G pseudotyped virions that enter cells independently of CD4 and core ceptors. Thus, we provide evidence that PPAR exerts its inhibitory effects post entry and prior HIV DNA in tegration. The activation of the PPAR pathway using the synthetic agonist RGZ upon HIV exposure demonstrated a strong inhibition of HIV replication. Consistent with previous studies on dendritic cells, RGZ did not affect the expression of CD4 and CCR5 thus providing further evidence that PPAR activation interferes with HIV replication at post entry levels.

Treatment with RGZ Inhibitors,Modulators,Libraries induced a complete nuclear translocation of PPAR, and this phenomenon was reversed by simultaneous exposure to Inhibitors,Modulators,Libraries the antagonist T007907. The effects of RGZ on HIV DNA integration was observed at late but not early time points post treatment thus, suggesting that nuclear trans location of PPAR in HIV infected cells limits viral replica tion by regulating directly or indirectly HIV transcription and subsequent HIV dissemination. Unexpectedly, the natural PPAR agonist PGJ2 exerted no effect on HIV replication, in contrast to previous studies on different cell types, suggesting that PGJ2 effects are cell dependent. One potential explanation is related to the fact that PGJ2 exerts PPAR independent effects.

Another explanation may be that Th1Th17 selectively ex press transcripts for hydroxyprostaglandin dehydrogenase 15, an enzyme involved in PGs degradation. Inhibitors,Modulators,Libraries Whether, HPGD degrades exogenous PGJ2 remains unknown. Finally, we observed that RGZ dramatically decreased HIV replication in sorted Sunitinib clinical trial Th1Th17 cells thus demonstrating that PPAR indeed negatively controls the HIV permissiveness program in these cells. The ability of RGZ to control HIV replication in Th1Th17 cells but also in total CD4 T cells is of interest in view of future therapies targeting PPAR nuclear translocation in vivo.

On the other hand, at D7 this expression was similar in both CS groups, highlighting the need for early evaluation of such markers, since along with oxidative stress, this pathway is only discriminant in the early days of reperfu sion. In these conditions, apoptosis EPZ5676 markers could be primarily detected in tubular cells as previously de scribed in human cadaveric kidney allograft. Taken together, these results support that ischemia condition and duration could influence the level and the local isation of the apoptotic Inhibitors,Modulators,Libraries process. Our Inhibitors,Modulators,Libraries study investigates the chronological development of early immunity in various preclinical ischemic condi tions. Endothelial activation, a prerequisite in the initial recruitment of leukocytes to the site of injury, is a key of innate immunity response initiation commonly assessed by vascular endothelium markers expression such as se lectin adhesion molecules.

In our conditions, P selectin mRNA expression was increased early after reperfusion in CS and WI CS groups then reached control values at D7. However, WI did not affect this expression. Early immunity could be partially mediated by Damage Associated Molecular Pattern molecules which bind the TLRs. These DAMPs are released by cells that Inhibitors,Modulators,Libraries have been damaged by IR and thus closely asso ciated to oxidative stress, apoptosis and necrosis. TLRs constitute an integral part of the innate immune re sponse and play a pivotal role in IRI, though the role of each receptor is still unclear. The stimulated TLRs pathway induces the production of pro inflammatory cytokines such as IL 1B, TNF, IL 6, IL 8 as well as ex pression of cell adhesion molecules like VCAM 1 on endothelial cells.

In a recent study using deficient TLR4 mice, Pulskens et al. show that TLR4 initiates an ex aggerated pro inflammatory response upon renal IRI and subsequently Inhibitors,Modulators,Libraries controls the induction of an innate immune response. In our study, TLR2 expression followed the level of renal injury, particularly Inhibitors,Modulators,Libraries after D3. TLR4 over expression was found in CS and WI CS, but was not sig nificantly different between both groups. Thus, TLR4 expression appears due to cold ischemic injury while TLR2 is a more discriminant marker of ischemic stress level. MCP 1 was significantly overexpressed in WI CS from D3 supporting that the degree of injury seems to modulate the MCP 1 response.

MCP 1 recruits selleck chemicals FTY720 mono cytes and dendritic cells to the sites of tissue injury and in flammation. In addition, DAMPs are known to stimulate IL 1B secretion from the NLRP3 inflammasome inducing pro inflammatory cy tokines production and immune cells invasion. As IL 1B, IL 6 could be produced by macrophages to stimulate immune response in damaged tissue leading to expand in flammation. Interestingly, we observed an IL1Rn mRNA in creased expression at D3 which could be appearing in re sponse to IL 1B production. We reported an IL 10 mRNA over expression by high intensity of IRI up to one week after reperfusion.

In the literature, it has been reported that adaptive responses to hypoxia are regulated by several transcription factors, including HIF 1, HIF 2, ETS 1, cAMP response element binding protein, activator pro tein 1 and nuclear http://www.selleckchem.com/products/Calcitriol-(Rocaltrol).html factor B. Hence, we exam ined various possible transcription factors and found that the active form of NFB1, NFBp50, is translocated into the nucleus of the human monocytes as a reaction towards a pO2 of 2%. In good agreement with this observation, Battaglia et al. have previously shown DNA binding of NFBp50 under hypoxia in primary human monocytes Inhibitors,Modulators,Libraries by means of a supershift analysis. Furthermore, Oliver et al. have described the selective activation of the canonical NFB pathway via p65 by intermittent and sustained hypoxia in HeLa cells.

The non canonical NFB pathway via p52 is not impacted by hypoxia. Our results Inhibitors,Modulators,Libraries are consistent with these findings as we show, to our knowledge for the first time in primary monocytes, that p50 is part of the canonical pathway induced by sustained hypoxia. We therefore suggest that NFB1 serves as a key reg Inhibitors,Modulators,Libraries ulator enabling the immediate adaptation of monocytes to hypoxia during migration from blood into the tissue environment. We suggest that, during the differentiation process of human monocytes into macrophages, the more potent and possibly more robust HIF 1 system is activated. The HIF 1 system may be needed for the rapid adaptation to varying oxygen concentrations, which is of essential functional importance for long liv ing tissue macrophages.

Indeed, we demonstrate here that the stimulation of the monocytes with PMA and the more physiological induction of monocyte differentiation by means of M CSF cause the translocation of HIF 1a into the nucleus of long living tissue macrophages. The presence of HIF 1a in the nucleus of macrophages or hMDMs under hypoxia has already been verified by other groups. HIF 1a was also detectable Inhibitors,Modulators,Libraries in the nucleus of different myeloid cell lines under hypoxic con ditions. Although often used as experimental models of monocytes, these cell line cells are highly proliferative and malignant cells with numerous differences from macrophages, hMDMs, and monocytes. With regard to the HIF 1 pathways, these cell lines behave like macro phages or hMDMs, but not like monocytes. This should be considered when using these cell lines as models to analyze the bioenergetic functions of monocytes and or macrophages in inflammatory Inhibitors,Modulators,Libraries arthritis. Our observation that both PMA stimulation and M CSF induced differentiation of monocytes into macro phages causes the translocation of HIF 1a into the nucleus prompted a search for potential regulators. Since PKC a b1 is strongly activated selleck inhibitor by PMA stimula tion, we hypothesized that this protein kinase enzyme could play a key role.

Collectively, these results suggest that upon retina removal at E4, the quiescent cells of the RPE dedifferentiate to become progenitor like cells similar to the cells of the optic vesicle that express the Crizotinib molecular weight combination of eye field transcriptional factors and the factors sox2, c myc and klf4. This process is transient and not sustained if no growth factors are present. FGF2 allows for the sustained transcriptional activity of sox2, c myc and klf4 in retinal pigmented epithelium undergoing reprogramming towards retina progenitors To analyze the effect on the levels of expression of the pluripotency inducing factors during the Inhibitors,Modulators,Libraries process of RPE transdifferentiation, we performed surgeries at E4 in which FGF2 heparin coated beads were placed in the optic cup as previously described.

Thereafter, the embryos were collected at different times. In contrast with the expression patterns during injury in the absence of FGF2, the alternative splice variants pax6 5a and 5a were up regulated Inhibitors,Modulators,Libraries sim ultaneously from 6 h to 72 h. RPE transdif ferentiation was confirmed by a significant decrease in expression of mitf and tyr at 72 h PR. Immu nostaining revealed that c Myc, Sox2, Klf4 and the retina progenitor markers Pax6 and Chx10 were present at 72 h PR in the transdifferentiated RPE. In the absence of FGF2 at 72 h PR, the RPE did not trans differentiate and remained pigmented, Inhibitors,Modulators,Libraries expressing only c Myc, Klf4 and Lin 28, just as it does during normal development. As ex pected, in addition to transdifferentiated RPE, we also observed retina regeneration from the pool of stem progenitor cells located in the ciliary margin of the chick eye.

Thus, we conclude that FGF2 allows the sustained expression of sox2 and c myc in retina progenitor Inhibitors,Modulators,Libraries cells along with eye field transcrip tional factors to complete the transdifferentiation pro gram of the RPE. In agreement with our results, destruction of photore ceptors by acute light lesions in zebrafish central retina re sults in M��ller glia dedifferentiation 4 to 8 h post lesion, exemplified by a strong Rx1 immunoreactivity. We found a significant up regulation of rx1 transcript at 6 h post injury during the transient dedifferentiation of the RPE. Moreover, at 24 h post lesion, a per centage of the activated zebrafish M��ller glia cells re enter the cell cycle, just as the chick Inhibitors,Modulators,Libraries RPE does in the presence of FGF2.

Interestingly, M��ller glia cells respond by dedifferenti ating after local loss of contact with photoreceptors, however, this dedifferentiation is not enough to promote re entry to the cell cycle. Similarly, it is possible that the loss of contact between the RPE and the retina triggers the process of RPE dediffer entiation, or that the customer review process involves an inflammation molecule such as TNF, as in zebrafish, or even ana phylatoxins such as C3a or interleukins like IL 6, which have been shown to play a role in chick retina regeneration.

Collectively, these results suggest that upon retina removal at E4, the quiescent cells of the RPE dedifferentiate to become progenitor like cells similar to the cells of the optic vesicle that express the selleckchem AZD9291 combination of eye field transcriptional factors and the factors sox2, c myc and klf4. This process is transient and not sustained if no growth factors are present. FGF2 allows for the sustained transcriptional activity of sox2, c myc and klf4 in retinal pigmented epithelium undergoing reprogramming towards retina progenitors To analyze the effect on the levels of expression of the pluripotency inducing factors during the process of RPE transdifferentiation, we performed surgeries at E4 in which FGF2 heparin coated beads were placed in the optic cup as previously described.

Thereafter, the embryos were collected at different times. In contrast with the expression patterns during injury in the absence of FGF2, the alternative splice variants pax6 5a and 5a were up regulated sim ultaneously from 6 h to 72 h. RPE transdif ferentiation was confirmed by a significant decrease in expression of mitf and tyr at 72 h PR. Immu nostaining revealed that c Myc, Sox2, Klf4 and the retina progenitor markers Pax6 and Chx10 were present at 72 h PR in the transdifferentiated RPE. In the absence of FGF2 at 72 h PR, the RPE did not trans differentiate and remained pigmented, expressing only c Myc, Klf4 and Lin 28, just as it does during normal development. As ex pected, in addition to transdifferentiated RPE, we also observed retina regeneration from the pool of stem progenitor cells located in the ciliary margin of the chick eye.

Thus, we conclude that FGF2 allows the sustained expression of sox2 and c myc in retina progenitor cells along with eye field transcrip tional factors to complete the transdifferentiation pro gram of the RPE. In agreement with our results, destruction of photore ceptors by acute light lesions in zebrafish central retina re sults in M��ller glia dedifferentiation 4 to 8 h post lesion, exemplified by a strong Rx1 immunoreactivity. We found a significant up regulation of rx1 transcript at 6 h post injury during the transient dedifferentiation of the RPE. Moreover, at 24 h post lesion, a per centage of the activated zebrafish M��ller glia cells re enter the cell cycle, just as the chick RPE does in the presence of FGF2.

Interestingly, M��ller glia cells respond by dedifferenti ating after local loss of contact with photoreceptors, however, this dedifferentiation is not enough to promote re entry to the cell cycle. Similarly, it is possible that the loss of contact between the RPE and the retina triggers the process of RPE dediffer entiation, or that the research use process involves an inflammation molecule such as TNF, as in zebrafish, or even ana phylatoxins such as C3a or interleukins like IL 6, which have been shown to play a role in chick retina regeneration.