http://hdl.handle.net/2268/136 Search this channel search http://orbi.ulg.ac.be/simple-search http://hdl.handle.net/2268/150496 Title: Pax4 is not essential for beta-cell differentiation in zebrafish embryos but modulates alpha-cell generation by repressing arx gene expression. <br/> <br/>Author, co-author: Djiotsa, Joachim; Verbruggen, Vincianne; Giacomotto, Jean; Ishibashi, Minaka; Manning, Elisabeth; Rinkwitz, Silke; Manfroid, Isabelle; Voz, Marianne; Peers, Bernard <br/> <br/>Abstract: BACKGROUND: Genetic studies in mouse have demonstrated the crucial function of PAX4 in pancreatic cell differentiation. This transcription factor specifies beta- and delta-cell fate at the expense of alpha-cell identity by repressing Arx gene expression and ectopic expression of PAX4 in alpha-cells is sufficient to convert them into beta-cells. Surprisingly, no Pax4 orthologous gene can be found in chicken and Xenopus tropicalis raising the question of the function of pax4 gene in lower vertebrates such as in fish. In the present study, we have analyzed the expression and the function of the orthologous pax4 gene in zebrafish. RESULTS: pax4 gene is transiently expressed in the pancreas of zebrafish embryos and is mostly restricted to endocrine precursors as well as to some differentiating delta- and epsilon-cells but was not detected in differentiating beta-cells. pax4 knock-down in zebrafish embryos caused a significant increase in alpha-cells number while having no apparent effect on beta- and delta-cell differentiation. This rise of alpha-cells is due to an up-regulation of the Arx transcription factor. Conversely, knock-down of arx caused to a complete loss of alpha-cells and a concomitant increase of pax4 expression but had no effect on the number of beta- and delta-cells. In addition to the mutual repression between Arx and Pax4, these two transcription factors negatively regulate the transcription of their own gene. Interestingly, disruption of pax4 RNA splicing or of arx RNA splicing by morpholinos targeting exon-intron junction sites caused a blockage of the altered transcripts in cell nuclei allowing an easy characterization of the arx- and pax4-deficient cells. Such analyses demonstrated that arx knock-down in zebrafish does not lead to a switch of cell fate, as reported in mouse, but rather blocks the cells in their differentiation process towards alpha-cells. CONCLUSIONS: In zebrafish, pax4 is not required for the generation of the first beta- and delta-cells deriving from the dorsal pancreatic bud, unlike its crucial role in the differentiation of these cell types in mouse. On the other hand, the mutual repression between Arx and Pax4 is observed in both mouse and zebrafish. These data suggests that the main original function of Pax4 during vertebrate evolution was to modulate the number of pancreatic alpha-cells and its role in beta-cells differentiation appeared later in vertebrate evolution. Fri, 14 Jun 2013 12:40:01 GMT http://hdl.handle.net/2268/150447 Title: From hepatopancreatic duct formation to b-cell regeneration in zebrafish <br/> <br/>Author, co-author: Manfroid, Isabelle Fri, 14 Jun 2013 09:38:35 GMT http://hdl.handle.net/2268/150444 Title: Characterization of the zebrafish beta-cell transcriptome by RNA-seq <br/> <br/>Author, co-author: Manfroid, Isabelle; Tarifeno, Estefania; Voz, Marianne; Peers, Bernard <br/> <br/>Abstract: The loss of pancreatic insulin-producing cells (beta-cells) is a hallmark of diabetes and more knowledge is needed to find new treatments. Thus, it is crucial to identify novel regulatory genes specifically expressed in this pancreatic cell subtype. In the present study, the main pancreatic islet was dissected from transgenic Tg(insulin:GFP) adult zebrafish and beta-cells were selectively recovered by FACS with 98% of purity. Illumina RNA-seq was used to sequence the transcriptome. 20 millions of sequenced reads (paired-end) were obtained, aligned on the zebrafish genome and assembled into transcripts (Tophat/Cufflinks softwares). The zebrafish beta-cells transcriptome includes all known regulatory genes involved in beta-cell differentiation such as pdx1, mnx1, pax6b, neuroD, isl1, insm1, as well as Hopx and Hdac9 genes, both recently identified in human beta-cells. In contrast, the alpha-cell specific transcription factor arx and the acinar marker ptf1a were not detected, confirming the high purity of our beta-cell preparation. Interestingly, many miRNAs were detected, such as dre-mir-375 and dre-mir-7, as well as several lncRNA recently described at embryonic stages. We are currently applying the same approach to the Tg(somatostatin:GFP) and Tg(glucagon:GFP) transgenic lines in to characterize the transcriptome of delta- and alpha-cells. The comparison of these different data will allow us to identify coding and non-coding genes specifically expressed in the different endocrine subtype cells, paving the way for further functional studies. Fri, 14 Jun 2013 09:28:54 GMT http://hdl.handle.net/2268/149705 Title: Effects of osmotic shocks on the amino acid levels and on the organization of the chromatin in mammalian cultured PC12 cells <br/> <br/>Author, co-author: Gilles, Raymond; Delpire, Eric; Plumier, Jean-Christophe; Buche, A. Mon, 03 Jun 2013 10:10:48 GMT http://hdl.handle.net/2268/149704 Title: Differential mRNA accumulation of immediate early genes in hearts after ischemic injury <br/> <br/>Author, co-author: Plumier, Jean-Christophe; Currie, R. William Mon, 03 Jun 2013 10:02:45 GMT http://hdl.handle.net/2268/149701 Title: transgenic mice expressing high levels of the human HSP70 have improved post-ischemic myocardial recovery <br/> <br/>Author, co-author: Currie, R. William; Plumier, Jean-Christophe; Ross, Brenda M.; Angelidis, C.E.; Kollias, G.; Pagoulatos, G.N. Mon, 03 Jun 2013 09:43:47 GMT http://hdl.handle.net/2268/149700 Title: Differential mRNA acculmulation of immediate early genes and heat shock genes in hearts after ischemic injury and heat shock <br/> <br/>Author, co-author: Plumier, Jean-Christophe; Currie, R. William Mon, 03 Jun 2013 09:37:30 GMT http://hdl.handle.net/2268/149699 Title: Gene expression following hypoxia/ischemia injury <br/> <br/>Author, co-author: Plumier, Jean-Christophe; Armstrong, John N.; Currie, R. William Mon, 03 Jun 2013 09:29:42 GMT http://hdl.handle.net/2268/149697 Title: Transgenic mice expressing the human HSP70 have improved post-ischemic myocardial recovery <br/> <br/>Author, co-author: Plumier, Jean-Christophe; Ross, Brenda M.; Currie, R. William; Angelidis, C. E.; kazlaris, H.; Kollias, G.; Pagoulatos, G. N. Mon, 03 Jun 2013 09:25:15 GMT http://hdl.handle.net/2268/149696 Title: Heat-shock treatment modifies gene expression following brain injury <br/> <br/>Author, co-author: Plumier, Jean-Christophe; David, Jean-claude; Robertson, Harold A.; Currie, R. William Mon, 03 Jun 2013 09:18:45 GMT http://hdl.handle.net/2268/149692 Title: Neuronal and glial expression of the inducible HSP70 in forebrain ischemia <br/> <br/>Author, co-author: Xu, D.; Plumier, Jean-Christophe; Robertson, Harold A.; Currie, R. William Mon, 03 Jun 2013 09:11:02 GMT http://hdl.handle.net/2268/149691 Title: expression of the inducible 70-kDa heat shock protein following kainic acid-induced status epilepticus in rat <br/> <br/>Author, co-author: Armstrong, John Norman; Plumier, Jean-Christophe; Robertson, Harold A.; Currie, R. William Mon, 03 Jun 2013 09:06:34 GMT http://hdl.handle.net/2268/149688 Title: Effects of cerebral injury on transgenic mice expressing the human HSP70 <br/> <br/>Author, co-author: Plumier, Jean-Christophe; Arsmtrong, John Norman; Robertson, Harold A.; Currie, R. William; Angelidis, C.E.; Kazlaris, H.; Kollias, G.; Pagoulatos, G.N. Mon, 03 Jun 2013 08:41:45 GMT http://hdl.handle.net/2268/149565 Title: Increased Cell Proliferation and Mucocyte Density in the Sea Anemone Aiptasia pallida Recovering from Bleaching <br/> <br/>Author, co-author: Fransolet, David; Roberty, Stéphane; Herman, Anne-Catherine; Tonk, Linda; Hoegh-Guldberg, Ove; Plumier, Jean-Christophe Fri, 31 May 2013 08:04:57 GMT http://hdl.handle.net/2268/149560 Title: The role of Bergmann glial cells in cerebellar development <br/> <br/>Author, co-author: Leprince, Pierre Fri, 31 May 2013 07:47:52 GMT http://hdl.handle.net/2268/149046 Title: Neurogenesis and neural stem cells as therapeutic strategies for Parkinson's disease <br/> <br/>Author, co-author: Plumier, Jean-Christophe Thu, 23 May 2013 11:05:26 GMT http://hdl.handle.net/2268/149044 Title: Neuronal replacement in the ischemic brain <br/> <br/>Author, co-author: Plumier, Jean-Christophe Thu, 23 May 2013 11:02:44 GMT http://hdl.handle.net/2268/149043 Title: Protéines de stress dans le système nerveux <br/> <br/>Author, co-author: Plumier, Jean-Christophe Thu, 23 May 2013 10:59:07 GMT http://hdl.handle.net/2268/149041 Title: HSP25 expression in the nervous system of the adult rat <br/> <br/>Author, co-author: Plumier, Jean-Christophe Thu, 23 May 2013 10:52:57 GMT http://hdl.handle.net/2268/149040 Title: Protection against ischemic injury and cell death by heat shock proteins <br/> <br/>Author, co-author: Plumier, Jean-Christophe Thu, 23 May 2013 10:48:37 GMT