Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny
<p>Multipotent haematopoietic stem cells (HSCs) supply the organism with mature blood cells of all lineages throughout adult life. These cells first originate in the dorsal aorta (DA) of the vertebrate embryo, and a multitude of signalling pathways regulate their specification in the embryo....
| Main Authors: | , |
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| Format: | Thesis |
| Language: | English |
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2014
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| _version_ | 1797090400550256640 |
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| author | Schneider, J Janina Schneider |
| author2 | Patient, R |
| author_facet | Patient, R Schneider, J Janina Schneider |
| author_sort | Schneider, J |
| collection | OXFORD |
| description | <p>Multipotent haematopoietic stem cells (HSCs) supply the organism with mature blood cells of all lineages throughout adult life. These cells first originate in the dorsal aorta (DA) of the vertebrate embryo, and a multitude of signalling pathways regulate their specification in the embryo. The emergence of HSCs is dependent on appropriate arterial specification and vessel maturation, processes which are heavily dependent on Notch signalling. This arterial involvement of Notch obscures its later roles in HSC specification. The Notch ligand <em>dll4</em> is crucially involved in arterial development in the mammalian embryo, while zebrafish embryos deficient for <em>dll4</em> activity only exhibit minor arterial defects at the time of HSC emergence. Here, the zebrafish model has been exploited to reveal the first specific evidence for a role of <em>dll4</em> in HSC specification.</p> <p><em>Dll4</em> is required for the expression of <em>runx1</em>, a transcription factor (TF) required for HSC specification, prior to any observed effects on vascular development. HSCs and all their derivatives are depleted in <em>dll4</em> morphants. To disentangle the genetic requlatory cascade downstream of <em>dll4</em> and upstream of <em>runx1</em>, RNA-seq was employed to discover downstream effectors of this signalling. Expression and functional screening of best candidate genes revealed seven genes with novel roles in HSC development. <em>Foxc1b</em> is a <em>dll4</em> target predominantly mirroring the <em>dll4</em> phenotype, and is thus likely to be the downstream effector of <em>dll4</em>, upstream of <em>runx1</em>. Interestingly, <em>foxc1b</em> also has a later <em>dll4</em>-independent role in HSC development, remarkably similar to that of <em>cmyb</em>.</p> <p>Taken together I show here for the first time a requirement of <em>dll4</em> upstream of <em>runx1</em> in HSC specification, mediated by <em>foxc1b</em>, followed by a later <em>dll4</em>-independent phase in HSC development.</p> |
| first_indexed | 2024-03-07T03:18:03Z |
| format | Thesis |
| id | oxford-uuid:b6798f11-1970-48a9-96fe-1bbb3cb36766 |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T03:18:03Z |
| publishDate | 2014 |
| record_format | dspace |
| spelling | oxford-uuid:b6798f11-1970-48a9-96fe-1bbb3cb367662022-03-27T04:41:16ZElucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogenyThesishttp://purl.org/coar/resource_type/c_db06uuid:b6798f11-1970-48a9-96fe-1bbb3cb36766Genetics (life sciences)Development (zoology)HaematologyBiology (medical sciences)Molecular haematologyStem cells (clinical sciences)Genetics (medical sciences)Clinical laboratory sciencesEnglishOxford University Research Archive - Valet2014Schneider, JJanina SchneiderPatient, R<p>Multipotent haematopoietic stem cells (HSCs) supply the organism with mature blood cells of all lineages throughout adult life. These cells first originate in the dorsal aorta (DA) of the vertebrate embryo, and a multitude of signalling pathways regulate their specification in the embryo. The emergence of HSCs is dependent on appropriate arterial specification and vessel maturation, processes which are heavily dependent on Notch signalling. This arterial involvement of Notch obscures its later roles in HSC specification. The Notch ligand <em>dll4</em> is crucially involved in arterial development in the mammalian embryo, while zebrafish embryos deficient for <em>dll4</em> activity only exhibit minor arterial defects at the time of HSC emergence. Here, the zebrafish model has been exploited to reveal the first specific evidence for a role of <em>dll4</em> in HSC specification.</p> <p><em>Dll4</em> is required for the expression of <em>runx1</em>, a transcription factor (TF) required for HSC specification, prior to any observed effects on vascular development. HSCs and all their derivatives are depleted in <em>dll4</em> morphants. To disentangle the genetic requlatory cascade downstream of <em>dll4</em> and upstream of <em>runx1</em>, RNA-seq was employed to discover downstream effectors of this signalling. Expression and functional screening of best candidate genes revealed seven genes with novel roles in HSC development. <em>Foxc1b</em> is a <em>dll4</em> target predominantly mirroring the <em>dll4</em> phenotype, and is thus likely to be the downstream effector of <em>dll4</em>, upstream of <em>runx1</em>. Interestingly, <em>foxc1b</em> also has a later <em>dll4</em>-independent role in HSC development, remarkably similar to that of <em>cmyb</em>.</p> <p>Taken together I show here for the first time a requirement of <em>dll4</em> upstream of <em>runx1</em> in HSC specification, mediated by <em>foxc1b</em>, followed by a later <em>dll4</em>-independent phase in HSC development.</p> |
| spellingShingle | Genetics (life sciences) Development (zoology) Haematology Biology (medical sciences) Molecular haematology Stem cells (clinical sciences) Genetics (medical sciences) Clinical laboratory sciences Schneider, J Janina Schneider Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title | Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title_full | Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title_fullStr | Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title_full_unstemmed | Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title_short | Elucidating the input of notch ligand delta-like 4 (dll4) in zebrafish blood stem cell ontogeny |
| title_sort | elucidating the input of notch ligand delta like 4 dll4 in zebrafish blood stem cell ontogeny |
| topic | Genetics (life sciences) Development (zoology) Haematology Biology (medical sciences) Molecular haematology Stem cells (clinical sciences) Genetics (medical sciences) Clinical laboratory sciences |
| work_keys_str_mv | AT schneiderj elucidatingtheinputofnotchliganddeltalike4dll4inzebrafishbloodstemcellontogeny AT janinaschneider elucidatingtheinputofnotchliganddeltalike4dll4inzebrafishbloodstemcellontogeny |