TY - JOUR
T1 - Ssrp1a controls organogenesis by promoting cell cycle progression and RNA synthesis
AU - Koltowska, Katarzyna
AU - Apitz, Holger
AU - Stamataki, Despina
AU - Hirst, Elizabeth M A
AU - Verkade, Heather
AU - Salecker, Iris
AU - Ober, Elke
PY - 2013/5/1
Y1 - 2013/5/1
N2 - Tightly controlled DNA replication and RNA transcription are essential for differentiation and tissue growth in multicellular organisms. Histone chaperones, including the FACT (facilitates chromatin transcription) complex, are central for these processes and act by mediating DNA access through nucleosome reorganisation. However, their roles in vertebrate organogenesis are poorly understood. Here, we report the identification of zebrafish mutants for the gene encoding Structure specific recognition protein 1a (Ssrp1a), which, together with Spt16, forms the FACT heterodimer. Focussing on the liver and eye, we show that zygotic Ssrp1a is essential for proliferation and differentiation during organogenesis. Specifically, gene expression indicative of progressive organ differentiation is disrupted and RNA transcription is globally reduced. Ssrp1a-deficient embryos exhibit DNA synthesis defects and prolonged S phase, uncovering a role distinct from that of Spt16, which promotes G1 phase progression. Gene deletion/replacement experiments in Drosophila show that Ssrp1b, Ssrp1a and N-terminal Ssrp1a, equivalent to the yeast homologue Pob3, can substitute Drosophila Ssrp function. These data suggest that (1) Ssrp1b does not compensate for Ssrp1a loss in the zebrafish embryo, probably owing to insufficient expression levels, and (2) despite fundamental structural differences, the mechanisms mediating DNA accessibility by FACT are conserved between yeast and metazoans. We propose that the essential functions of Ssrp1a in DNA replication and gene transcription, together with its dynamic spatiotemporal expression, ensure organ-specific differentiation and proportional growth, which are crucial for the forming embryo.
AB - Tightly controlled DNA replication and RNA transcription are essential for differentiation and tissue growth in multicellular organisms. Histone chaperones, including the FACT (facilitates chromatin transcription) complex, are central for these processes and act by mediating DNA access through nucleosome reorganisation. However, their roles in vertebrate organogenesis are poorly understood. Here, we report the identification of zebrafish mutants for the gene encoding Structure specific recognition protein 1a (Ssrp1a), which, together with Spt16, forms the FACT heterodimer. Focussing on the liver and eye, we show that zygotic Ssrp1a is essential for proliferation and differentiation during organogenesis. Specifically, gene expression indicative of progressive organ differentiation is disrupted and RNA transcription is globally reduced. Ssrp1a-deficient embryos exhibit DNA synthesis defects and prolonged S phase, uncovering a role distinct from that of Spt16, which promotes G1 phase progression. Gene deletion/replacement experiments in Drosophila show that Ssrp1b, Ssrp1a and N-terminal Ssrp1a, equivalent to the yeast homologue Pob3, can substitute Drosophila Ssrp function. These data suggest that (1) Ssrp1b does not compensate for Ssrp1a loss in the zebrafish embryo, probably owing to insufficient expression levels, and (2) despite fundamental structural differences, the mechanisms mediating DNA accessibility by FACT are conserved between yeast and metazoans. We propose that the essential functions of Ssrp1a in DNA replication and gene transcription, together with its dynamic spatiotemporal expression, ensure organ-specific differentiation and proportional growth, which are crucial for the forming embryo.
KW - Animals
KW - Cell Cycle
KW - Cell Proliferation
KW - Chromatin Assembly and Disassembly
KW - DNA Replication
KW - DNA-Binding Proteins
KW - Drosophila
KW - Drosophila Proteins
KW - Embryo, Nonmammalian
KW - Endoderm
KW - Eye
KW - Female
KW - Gene Expression Regulation, Developmental
KW - High Mobility Group Proteins
KW - Imaginal Discs
KW - Liver
KW - Male
KW - Mitotic Index
KW - Mutation
KW - Organogenesis
KW - RNA
KW - Transcription, Genetic
KW - Transcriptional Elongation Factors
KW - Zebrafish
KW - Zebrafish Proteins
U2 - 10.1242/dev.093583
DO - 10.1242/dev.093583
M3 - Journal article
C2 - 23515471
SN - 0950-1991
VL - 140
SP - 1912
EP - 1918
JO - Development (Cambridge, England)
JF - Development (Cambridge, England)
IS - 9
ER -