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Proc Biol Sci
2016 Mar 16;2831826:20152978. doi: 10.1098/rspb.2015.2978.
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Substituting mouse transcription factor Pou4f2 with a sea urchin orthologue restores retinal ganglion cell development.
Mao CA
,
Agca C
,
Mocko-Strand JA
,
Wang J
,
Ullrich-Lüter E
,
Pan P
,
Wang SW
,
Arnone MI
,
Frishman LJ
,
Klein WH
.
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Pou domain transcription factor Pou4f2 is essential for the development of retinal ganglion cells (RGCs) in the vertebrate retina. A distant orthologue of Pou4f2 exists in the genome of the sea urchin (class Echinoidea) Strongylocentrotus purpuratus (SpPou4f1/2), yet the photosensory structure of sea urchins is strikingly different from that of the mammalian retina. Sea urchins have no obvious eyes, but have photoreceptors clustered around their tube feet disc. The mechanisms that are associated with the development and function of photoreception in sea urchins are largely unexplored. As an initial approach to better understand the sea urchin photosensory structure and relate it to the mammalian retina, we asked whether SpPou4f1/2 could support RGC development in the absence of Pou4f2. To answer this question, we replaced genomic Pou4f2 with an SpPou4f1/2 cDNA. In Pou4f2-null mice, retinas expressing SpPou4f1/2 were outwardly identical to those of wild-type mice. SpPou4f1/2 retinas exhibited dark-adapted electroretinogram scotopic threshold responses, indicating functionally active RGCs. During retinal development, SpPou4f1/2 activated RGC-specific genes and in S. purpuratus, SpPou4f2 was expressed in photoreceptor cells of tube feet in a pattern distinct from Opsin4 and Pax6. Our results suggest that SpPou4f1/2 and Pou4f2 share conserved components of a gene network for photosensory development and they maintain their conserved intrinsic functions despite vast morphological differences in mouse and sea urchin photosensory structures.
Figure 1. Sequence alignment of SpPou4f1/2 and Pou4f and generation of the Pou4f2SpPou4f1/2 KI allele. (a) Generation of Pou4f2SpPou4f1/2 KI allele, FRT indicates FLP recombinase sites to remove the Neo selection cassette (brown box) by a Rosa26-FLPeR mouse line. SpPou4f1/2 cDNA sequences (green box) were fused in frame to a HA-epitope tag (yellow box). The dark purple thick lines indicate the site of recombination into a construct carrying the Pou4f2 coding region and upstream regulatory regon. TK (orange box) indicates the TK cassette used for negative selection. The BamHI site was used for Southern genotyping, p1 and p2 are PCR primers to detect wild-type mouse Pou4f2 allele, and p3 and p4 are primers to detect knock in SpPou4f1/2 allele. (b) Phylogeny analysis of SpPou4f1/2 and Pou4f genes from other organisms. The tree was constructed with MEGA software v. 5.2. using neighbour-joining method with 1000 bootstrap repeats. Ci, Ciona intestinalis; Dr, Danio rerio; Mm, Mus musculus; Sp, Strogylocentrotus purpuratus; Xt, Xenopus tropicalis.
Figure 3. Normal RGC differentiation programme in Pou4f2SpPou4f1/2/Z retinas. TUNEL assay shows lesser cell death in retinas of Pou4f2Z/+ (a), Pou4f2SpPou4f1/2/Z (b) compared with Pou4f2Z/Z (c). SpPou4f1/2 activates Pou4f2 downstream RGC genes Pou4f1 and Tbr2 in the absence of Pou4f2 (d–i). Immunostaining of retina from E15 embryos with anti-Pou4f1/Brn3a (d–f) and anti-Tbr2 (g–i).
Figure 4. ERG recordings of Pou4f2SpPou4f1/2/SpPou4f1/2 retinas. (a) Scotopic full-field flash ERG responses recorded from one mouse in each of the three genotypes. From left to right, Pou4f2+/+ (+/+), Pou4f2SpPou4f1/2/SpPou4f1/2 (SP/SP), Pou4f2−/− (−/−). Stimulus strength increases from bottom to top. Arrows in the right column indicated missing STRs in this animal. (b–d) Stimulus versus ERG amplitude plots measured for the three genotypes. Pou4f2+/+(+/+; n = 4), Pou4f2SpPou4f1/2/SpPou4f1/2 (Sp/Sp; n = 4), Pou4f2−/− (−/−; n = 4). (b) pSTR (box) and b-wave amplitudes. (c) nSTR amplitudes and (d) a-wave amplitudes. The nSTR amplitudes saturated around −4.1 log sc cd-s m−2, and then a larger negative wave of unknown origin emerged. The error bars are standard errors.
Figure 5. Co-expression analysis of SpPou4f1/2, SpPax6 and SpOpsin4 in S. purpuratus tube feet. (a) Schematic view of a sea urchin tube feet displaying the morphology of tube feet stalk (tfs), disc (tfd) and rosette (ros); the nervous system (green) is represented by tube feet nerve (tfn), ganglion (ga) and disc ring nerve (drn). Sp-Opsin4 positive photoreceptor cells (red) are located at the rim of the disc and in a depression of the skeleton (ske) at the base of the tube feet. (b,c,e,f,g,h) Z-stack projection of tube feet disc. (b) Bottom view (seen from the stalk), (c,e,f,g,h) top view, showing SpPou4f1/2 and SpPax6 mRNA expression and Sp-Opsin4 protein in disc photoreceptors. The whole tube feet disc is shown in (b) while (c), (e–g) display only a quadrant of it. SpPou4f1/2 mRNA is shown in yellow/green (b) or green (c,f–h), SpPax6 mRNA in red (b) or purple (c), SpOpsin4 protein in red (c,e,g and h). (b) SpPou4f1/2 mRNA expression associated with skeletal rosettes, SpPax6 mRNA in stalk and disc. (b′ and b″) are details of (b) as indicated. (c) Expression of SpPou4f1/2 corresponds to neuronal tissue and axonal projection area of photoreceptors. SpPax6 expression in the area between skeletal rosette elements correlates with localization of photoreceptor cell bodies and SpOpsin4 protein in the apical part of the photoreceptor cells. (d) Three-dimensional reconstruction of serial TEM sections clarifies cell position and identity in SpPou4f1/2, SpPax6 and SpOpsin4 expression regions. Skeletal rosette (grey) with associated nerve tissue (yellow) and two photoreceptors (purple and blue). (e–g) Different overlays showing coexpression of SpPou4f1/2 mRNA and SpOpsin4 protein in the apical region of photoreceptors. (h) A twofold zoom of the area indicated by the rectangle in (e–g) showing a single photoreceptor (arrow shows nucleus).
Agca,
Neurosensory and neuromuscular organization in tube feet of the sea urchin Strongylocentrotus purpuratus.
2011, Pubmed,
Echinobase
Agca,
Neurosensory and neuromuscular organization in tube feet of the sea urchin Strongylocentrotus purpuratus.
2011,
Pubmed
,
Echinobase
Andersen,
POU domain factors in the neuroendocrine system: lessons from developmental biology provide insights into human disease.
2001,
Pubmed
Badea,
Distinct roles of transcription factors brn3a and brn3b in controlling the development, morphology, and function of retinal ganglion cells.
2009,
Pubmed
Blevins,
Spatial vision in the echinoid genus Echinometra.
2004,
Pubmed
,
Echinobase
Burke,
A genomic view of the sea urchin nervous system.
2006,
Pubmed
,
Echinobase
Cole,
Two ParaHox genes, SpLox and SpCdx, interact to partition the posterior endoderm in the formation of a functional gut.
2009,
Pubmed
,
Echinobase
Czerny,
DNA-binding and transactivation properties of Pax-6: three amino acids in the paired domain are responsible for the different sequence recognition of Pax-6 and BSAP (Pax-5).
1995,
Pubmed
,
Echinobase
Erkman,
Role of transcription factors Brn-3.1 and Brn-3.2 in auditory and visual system development.
1996,
Pubmed
Farley,
Widespread recombinase expression using FLPeR (flipper) mice.
2000,
Pubmed
Gan,
POU domain factor Brn-3b is required for the development of a large set of retinal ganglion cells.
1996,
Pubmed
Gan,
POU domain factor Brn-3b is essential for retinal ganglion cell differentiation and survival but not for initial cell fate specification.
1999,
Pubmed
Gehring,
The genetic control of eye development and its implications for the evolution of the various eye-types.
2002,
Pubmed
Gold,
The early expansion and evolutionary dynamics of POU class genes.
2014,
Pubmed
Gonzalez,
Cross-repression, a functional consequence of the physical interaction of non-liganded nuclear receptors and POU domain transcription factors.
2002,
Pubmed
Lesser,
Sea urchin tube feet are photosensory organs that express a rhabdomeric-like opsin and PAX6.
2011,
Pubmed
,
Echinobase
Mao,
Eomesodermin, a target gene of Pou4f2, is required for retinal ganglion cell and optic nerve development in the mouse.
2008,
Pubmed
Mao,
T-box transcription regulator Tbr2 is essential for the formation and maintenance of Opn4/melanopsin-expressing intrinsically photosensitive retinal ganglion cells.
2014,
Pubmed
Mu,
Gene regulation logic in retinal ganglion cell development: Isl1 defines a critical branch distinct from but overlapping with Pou4f2.
2008,
Pubmed
Peter,
Evolution of gene regulatory networks controlling body plan development.
2011,
Pubmed
Phillips,
The virtuoso of versatility: POU proteins that flex to fit.
2000,
Pubmed
Popodi,
Hox genes in a pentameral animal.
2001,
Pubmed
,
Echinobase
Raible,
Opsins and clusters of sensory G-protein-coupled receptors in the sea urchin genome.
2006,
Pubmed
,
Echinobase
Robson,
The rod-driven a-wave of the dark-adapted mammalian electroretinogram.
2014,
Pubmed
Saszik,
The scotopic threshold response of the dark-adapted electroretinogram of the mouse.
2002,
Pubmed
Silver,
Signaling circuitries in development: insights from the retinal determination gene network.
2005,
Pubmed
Smith,
Contribution of retinal ganglion cells to the mouse electroretinogram.
2014,
Pubmed
Sweeney,
Tbr2 is required to generate a neural circuit mediating the pupillary light reflex.
2014,
Pubmed
Tamura,
MEGA5: molecular evolutionary genetics analysis using maximum likelihood, evolutionary distance, and maximum parsimony methods.
2011,
Pubmed
Treisman,
A conserved blueprint for the eye?
1999,
Pubmed
Trieu,
Autoregulatory sequences are revealed by complex stability screening of the mouse brn-3.0 locus.
1999,
Pubmed
Ullrich-Lüter,
Unique system of photoreceptors in sea urchin tube feet.
2011,
Pubmed
,
Echinobase
