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PTBP1 is required for embryonic development before gastrulation.

Suckale J, Wendling O, Masjkur J, Jäger M, Münster C, Anastassiadis K, Stewart AF, Solimena M - PLoS ONE (2011)

Bottom Line: Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation.We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst.However, further post-implantation development requires PTBP1 and stalls in homozygous animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.

View Article: PubMed Central - PubMed

Affiliation: Molecular Diabetology, Paul Langerhans Institute Dresden, School of Medicine and University Clinic Carl Gustav Carus, Dresden University of Technology, Dresden, Germany.

ABSTRACT
Polypyrimidine-tract binding protein 1 (PTBP1) is an important cellular regulator of messenger RNAs influencing the alternative splicing profile of a cell as well as its mRNA stability, location and translation. In addition, it is diverted by some viruses to facilitate their replication. Here, we used a novel PTBP1 knockout mouse to analyse the tissue expression pattern of PTBP1 as well as the effect of its complete removal during development. We found evidence of strong PTBP1 expression in embryonic stem cells and throughout embryonic development, especially in the developing brain and spinal cord, the olfactory and auditory systems, the heart, the liver, the kidney, the brown fat and cartilage primordia. This widespread distribution points towards a role of PTBP1 during embryonic development. Homozygous offspring, identified by PCR and immunofluorescence, were able to implant but were arrested or retarded in growth. At day 7.5 of embryonic development (E7.5) the mutants were about 5x smaller than the control littermates and the gap in body size widened with time. At mid-gestation, all homozygous embryos were resorbed/degraded. No homozygous mice were genotyped at E12 and the age of weaning. Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation. In addition, homozygous mutants displayed malformed ectoplacental cones and yolk sacs, both early supportive structure of the embryo proper. We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst. However, further post-implantation development requires PTBP1 and stalls in homozygous animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.

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Embryos from PTBP1 KO heterozygous parents fall into 2 size categories.Hematoxylin and eosin stained decidual sections of 2 litters were analysed for surface area and structural organisation. Embryos were grouped according to their developmental stage (left) with the furthest developed having reached neural plate stage but most embryos being at the primitive streak stage. The surface area of the embryos in the middle section was measured with the Fiji image software and ranked according to size, which turned out as equivalent to stage (right). Presumed knockouts (red) were significantly smaller than wild-type or heterozygous controls and present in a roughly Mendelian ratio of 3∶10 (ratio 0.3 vs. the expected 0.25). The size of the small embryos might have even been overestimated since it was harder to recognise the embryo in those implantations. We also encountered 2 decidua with no visible embryonic structures.
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pone-0016992-g003: Embryos from PTBP1 KO heterozygous parents fall into 2 size categories.Hematoxylin and eosin stained decidual sections of 2 litters were analysed for surface area and structural organisation. Embryos were grouped according to their developmental stage (left) with the furthest developed having reached neural plate stage but most embryos being at the primitive streak stage. The surface area of the embryos in the middle section was measured with the Fiji image software and ranked according to size, which turned out as equivalent to stage (right). Presumed knockouts (red) were significantly smaller than wild-type or heterozygous controls and present in a roughly Mendelian ratio of 3∶10 (ratio 0.3 vs. the expected 0.25). The size of the small embryos might have even been overestimated since it was harder to recognise the embryo in those implantations. We also encountered 2 decidua with no visible embryonic structures.

Mentions: To establish at which stage the lack of PTBP1 stalls embryonic development we isolated embryos working backward from E12.5. At this time 2 types of implantations were visible: small degraded and normally sized. Going further backward in development we were able to observe small implantations at E6.5, E7.5, and E8.5 (Table 1), the last time point examined at which small embryos still showed cellular structure and were not yet degraded. At E7.5, we quantified the area of the largest embryo cross-section. The small embryos were on average 0.02 mm2, significantly smaller than the large embryos with 0.11 mm2 (Figure 3). In 2 litters we observed 3 small embryos and 10 large embryos (ratio 0.3) and 2 empty deciduas.


PTBP1 is required for embryonic development before gastrulation.

Suckale J, Wendling O, Masjkur J, Jäger M, Münster C, Anastassiadis K, Stewart AF, Solimena M - PLoS ONE (2011)

Embryos from PTBP1 KO heterozygous parents fall into 2 size categories.Hematoxylin and eosin stained decidual sections of 2 litters were analysed for surface area and structural organisation. Embryos were grouped according to their developmental stage (left) with the furthest developed having reached neural plate stage but most embryos being at the primitive streak stage. The surface area of the embryos in the middle section was measured with the Fiji image software and ranked according to size, which turned out as equivalent to stage (right). Presumed knockouts (red) were significantly smaller than wild-type or heterozygous controls and present in a roughly Mendelian ratio of 3∶10 (ratio 0.3 vs. the expected 0.25). The size of the small embryos might have even been overestimated since it was harder to recognise the embryo in those implantations. We also encountered 2 decidua with no visible embryonic structures.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3040740&req=5

pone-0016992-g003: Embryos from PTBP1 KO heterozygous parents fall into 2 size categories.Hematoxylin and eosin stained decidual sections of 2 litters were analysed for surface area and structural organisation. Embryos were grouped according to their developmental stage (left) with the furthest developed having reached neural plate stage but most embryos being at the primitive streak stage. The surface area of the embryos in the middle section was measured with the Fiji image software and ranked according to size, which turned out as equivalent to stage (right). Presumed knockouts (red) were significantly smaller than wild-type or heterozygous controls and present in a roughly Mendelian ratio of 3∶10 (ratio 0.3 vs. the expected 0.25). The size of the small embryos might have even been overestimated since it was harder to recognise the embryo in those implantations. We also encountered 2 decidua with no visible embryonic structures.
Mentions: To establish at which stage the lack of PTBP1 stalls embryonic development we isolated embryos working backward from E12.5. At this time 2 types of implantations were visible: small degraded and normally sized. Going further backward in development we were able to observe small implantations at E6.5, E7.5, and E8.5 (Table 1), the last time point examined at which small embryos still showed cellular structure and were not yet degraded. At E7.5, we quantified the area of the largest embryo cross-section. The small embryos were on average 0.02 mm2, significantly smaller than the large embryos with 0.11 mm2 (Figure 3). In 2 litters we observed 3 small embryos and 10 large embryos (ratio 0.3) and 2 empty deciduas.

Bottom Line: Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation.We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst.However, further post-implantation development requires PTBP1 and stalls in homozygous animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.

View Article: PubMed Central - PubMed

Affiliation: Molecular Diabetology, Paul Langerhans Institute Dresden, School of Medicine and University Clinic Carl Gustav Carus, Dresden University of Technology, Dresden, Germany.

ABSTRACT
Polypyrimidine-tract binding protein 1 (PTBP1) is an important cellular regulator of messenger RNAs influencing the alternative splicing profile of a cell as well as its mRNA stability, location and translation. In addition, it is diverted by some viruses to facilitate their replication. Here, we used a novel PTBP1 knockout mouse to analyse the tissue expression pattern of PTBP1 as well as the effect of its complete removal during development. We found evidence of strong PTBP1 expression in embryonic stem cells and throughout embryonic development, especially in the developing brain and spinal cord, the olfactory and auditory systems, the heart, the liver, the kidney, the brown fat and cartilage primordia. This widespread distribution points towards a role of PTBP1 during embryonic development. Homozygous offspring, identified by PCR and immunofluorescence, were able to implant but were arrested or retarded in growth. At day 7.5 of embryonic development (E7.5) the mutants were about 5x smaller than the control littermates and the gap in body size widened with time. At mid-gestation, all homozygous embryos were resorbed/degraded. No homozygous mice were genotyped at E12 and the age of weaning. Embryos lacking PTBP1 did not display differentiation into the 3 germ layers and cavitation of the epiblast, which are hallmarks of gastrulation. In addition, homozygous mutants displayed malformed ectoplacental cones and yolk sacs, both early supportive structure of the embryo proper. We conclude that PTBP1 is not required for the earliest isovolumetric divisions and differentiation steps of the zygote up to the formation of the blastocyst. However, further post-implantation development requires PTBP1 and stalls in homozygous animals with a phenotype of dramatically reduced size and aberration in embryonic and extra-embryonic structures.

Show MeSH
Related in: MedlinePlus