The visual system is affected by neurodegenerative diseases caused by the degeneration of specific retinal neurons,the leading cause of irreversible blindness in humans.Throughout vertebrate phylogeny,the retina has t...The visual system is affected by neurodegenerative diseases caused by the degeneration of specific retinal neurons,the leading cause of irreversible blindness in humans.Throughout vertebrate phylogeny,the retina has two kinds of specialized niches of constitutive neurogenesis:the retinal progenitors located in the circumferential marginal zone and Müller glia.The proliferative activity in the retinal progenitors located in the circumferential marginal zone in precocial birds such as the chicken,the commonest bird model used in developmental and regenerative studies,is very low.This region adds only a few retinal cells to the peripheral edge of the retina during several months after hatching,but does not seem to be involved in retinal regeneration.Müller cells in the chicken retina are not proliferative under physiological conditions,but after acute damage some of them undergo a reprogramming event,dedifferentiating into retinal stem cells and generating new retinal neurons.Therefore,regenerative response after injury occurs with low efficiency in the precocial avian retina.In contrast,it has recently been shown that neurogenesis is intense in the retina of altricial birds at hatching.In particular,abundant proliferative activity is detected both in the circumferential marginal zone and in the outer half of the inner nuclear layer.Therefore,stem cell niches are very active in the retina of altricial birds.Although more extensive research is needed to assess the potential of proliferating cells in the adult retina of altricial birds,it emerges as an attractive model for studying different aspects of neurogenesis and neural regeneration in vertebrates.展开更多
Background:Rods and cones are critical for light detection.Although there has been considerable work done in elucidating the molecular mechanisms involved in rod development,not much is known about how the cone cell f...Background:Rods and cones are critical for light detection.Although there has been considerable work done in elucidating the molecular mechanisms involved in rod development,not much is known about how the cone cell fate decision is made by the multipotent retinal progenitor cells during development.Analysis of the promoter regions of Nrl and trβ2,rod and cone differentiation factors respectively,revealed DNA binding motifs of two POU-domain containing transcription factors,Pou2f1 and Pou2f2.Preliminary experiments showed that Pou2f1/2 are expressed during the peak of cone genesis in the embryonic retina.Therefore,we hypothesize that Pou2f1/2 specify cone cell fate in the developing retina.Methods:We used immunofluorescence and in situ hybridization to establish the spatiotemporal expression of Pou2f1/2 during retinogenesis.We performed in vivo electroporation in post-natal mice to misexpress Pou2f1/2 and used antibodies specific to proteins expressed in cones such as Rxrγand S-opsin to count cones.Using ex vivo electroporation of embryonic retinal explants,we knocked out Pou2f1 and Pou2f2 using CRISPR/Cas9 gRNAs at the peak of cone production window.Finally,we transfected post-natal retinal explants with a combination of regulatory elements of Nrl or thrb with control backbone vector,Pou2f1 or Pou2f2 using electroporation.Results:We found that Pou2f1/2 are expressed in retinal progenitor cells in the developing retina and subsequently in the differentiated cones.Pou2f1/2 misexpression outside the cone genesis window led to an increase in cones at the expense of rods.Pou2f1/2 indel knockouts generated by CRISPR/Cas9 gRNAs led to a decrease in cones and a converse increase in rods.Finally,we found that Pou2f1/2 activate the cis-regulatory module(CRM)of the thrb gene and repress the activity of the CRM of Nrl.Conclusions:These results uncover novel players that establish the complex gene regulatory network for cone photoreceptor fate specification in the retinal progenitor cells.We anticipate that this work should help us devise improved replacement therapies in the future utilizing stem cells for retinal degenerative diseases such as aged-related macular degeneration(AMD)and Stargardt’s disease.展开更多
基金This work was supported by grants from the Spanish Ministerio de Ciencia y Tecnología(BFU2007-67540)Ministerio de Economía y Competitividad(CGL2015-64650P)+1 种基金Dirección General de Investigación del Ministerio de Educación y Ciencia(BFU2017-85547-P)Junta de Extremadura,Fondo Europeo de Desarrollo Regional,“Una manera de hacer Europa”(GR15158,GR18114,IB18113).
文摘The visual system is affected by neurodegenerative diseases caused by the degeneration of specific retinal neurons,the leading cause of irreversible blindness in humans.Throughout vertebrate phylogeny,the retina has two kinds of specialized niches of constitutive neurogenesis:the retinal progenitors located in the circumferential marginal zone and Müller glia.The proliferative activity in the retinal progenitors located in the circumferential marginal zone in precocial birds such as the chicken,the commonest bird model used in developmental and regenerative studies,is very low.This region adds only a few retinal cells to the peripheral edge of the retina during several months after hatching,but does not seem to be involved in retinal regeneration.Müller cells in the chicken retina are not proliferative under physiological conditions,but after acute damage some of them undergo a reprogramming event,dedifferentiating into retinal stem cells and generating new retinal neurons.Therefore,regenerative response after injury occurs with low efficiency in the precocial avian retina.In contrast,it has recently been shown that neurogenesis is intense in the retina of altricial birds at hatching.In particular,abundant proliferative activity is detected both in the circumferential marginal zone and in the outer half of the inner nuclear layer.Therefore,stem cell niches are very active in the retina of altricial birds.Although more extensive research is needed to assess the potential of proliferating cells in the adult retina of altricial birds,it emerges as an attractive model for studying different aspects of neurogenesis and neural regeneration in vertebrates.
文摘Background:Rods and cones are critical for light detection.Although there has been considerable work done in elucidating the molecular mechanisms involved in rod development,not much is known about how the cone cell fate decision is made by the multipotent retinal progenitor cells during development.Analysis of the promoter regions of Nrl and trβ2,rod and cone differentiation factors respectively,revealed DNA binding motifs of two POU-domain containing transcription factors,Pou2f1 and Pou2f2.Preliminary experiments showed that Pou2f1/2 are expressed during the peak of cone genesis in the embryonic retina.Therefore,we hypothesize that Pou2f1/2 specify cone cell fate in the developing retina.Methods:We used immunofluorescence and in situ hybridization to establish the spatiotemporal expression of Pou2f1/2 during retinogenesis.We performed in vivo electroporation in post-natal mice to misexpress Pou2f1/2 and used antibodies specific to proteins expressed in cones such as Rxrγand S-opsin to count cones.Using ex vivo electroporation of embryonic retinal explants,we knocked out Pou2f1 and Pou2f2 using CRISPR/Cas9 gRNAs at the peak of cone production window.Finally,we transfected post-natal retinal explants with a combination of regulatory elements of Nrl or thrb with control backbone vector,Pou2f1 or Pou2f2 using electroporation.Results:We found that Pou2f1/2 are expressed in retinal progenitor cells in the developing retina and subsequently in the differentiated cones.Pou2f1/2 misexpression outside the cone genesis window led to an increase in cones at the expense of rods.Pou2f1/2 indel knockouts generated by CRISPR/Cas9 gRNAs led to a decrease in cones and a converse increase in rods.Finally,we found that Pou2f1/2 activate the cis-regulatory module(CRM)of the thrb gene and repress the activity of the CRM of Nrl.Conclusions:These results uncover novel players that establish the complex gene regulatory network for cone photoreceptor fate specification in the retinal progenitor cells.We anticipate that this work should help us devise improved replacement therapies in the future utilizing stem cells for retinal degenerative diseases such as aged-related macular degeneration(AMD)and Stargardt’s disease.
