Characterization of expanded intermediate cell mass in zebrafish chordin morphant embryos

Anskar Y.H. Leung, Eric M. Mendenhall, Tommy T.F. Kwan, Raymond Liang, Craig Eckfeldt, Eleanor Chen, Matthias Hammerschmidt, Suzanne Grindley, Stephen C. Ekker, Catherine M. Verfaillie

Research output: Contribution to journalArticlepeer-review

38 Scopus citations

Abstract

We investigated the mechanisms of intermediate cell mass (ICM) expansion in zebrafish chordin (Chd) morphant embryos and examined the role of BMPs in relation to this phenotype. At 24 h post-fertilization (hpf), the expanded ICM of embryos injected with chd morpholino (MO) (ChdMO embryos) contained a monotonous population of hematopoietic progenitors. In situ hybridization showed that hematopoietic transcription factors were ubiquitously expressed in the ICM whereas vascular gene expression was confined to the periphery. BMP4 (but not BMP2b or 7) and smad5 mRNA were ectopically expressed in the ChdMO ICM. At 48 hpf, monocytic cells were evident in both the ICM and circulation of ChdMO but not WT embryos. While injection of BMP4 MO had no effect on WT hematopoiesis, co-injecting BMP4 with chd MOs significantly reduced ICM expansion. Microarray studies revealed a number of genes that were differentially expressed in ChdMO and WT embryos and their roles in hematopoiesis has yet to be determined. In conclusion, the expanded ICM in ChdMO embryos represented an expansion of embryonic hematopoiesis that was skewed towards a monocytic lineage. BMP4, but not BMP2b or 7, was involved in this process. The results provide ground for further research into the mechanisms of embryonic hematopoietic cell expansion.

Original languageEnglish (US)
Pages (from-to)235-254
Number of pages20
JournalDevelopmental Biology
Volume277
Issue number1
DOIs
StatePublished - Jan 1 2005

Keywords

  • BMP
  • Chordin
  • Differentiation
  • Gene expression
  • Hematopoiesis
  • Microarray
  • Morpholino
  • Zebrafish

ASJC Scopus subject areas

  • Molecular Biology
  • Developmental Biology
  • Cell Biology

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