Related Experiment Video
Updated: Dec 14, 2025
Development of an In Vitro Assay to Quantitate Hematopoietic Stem and Progenitor Cells HSPCs in Developing Zebrafish Embryos
Published on: November 30, 2017
Microfibril-associated glycoprotein 4 (Mfap4) regulates haematopoiesis in zebrafish
Sheena L M Ong1,2, Ivo J H M de Vos3,4, M Meroshini5
1Institute of Medical Biology, Agency for Science, Technology and Research (A*STAR), 8A Biomedical Grove, #06-06 Immunos, Singapore, 138648, Singapore.
Abstract:
Microfibril-associated glycoprotein 4 (MFAP4) is an extracellular matrix protein belonging to the fibrinogen-related protein superfamily. MFAP4 is produced by vascular smooth muscle cells and is highly enriched in the blood vessels of the heart and lung, where it is thought to contribute to the structure and function of elastic fibers. Genetic studies in humans have implicated MFAP4 in the pathogenesis of Smith-Magenis syndrome, in which patients present with multiple congenital abnormalities and mental retardation, as well as in the severe cardiac malformation left-sided congenital heart disease. Comprehensive genetic analysis of the role of MFAP4 orthologues in model organisms during development and tissue homeostasis is however lacking. Here, we demonstrate that zebrafish mfap4 transcripts are detected embryonically, resolving to the macrophage lineage by 24 h post fertilization. mfap4 null mutant zebrafish are unexpectedly viable and fertile, without ostensible phenotypes. However, tail fin amputation assays reveal that mfap4 mutants have reduced numbers of macrophages, with a concomitant increase in neutrophilic granulocytes, although recruitment of both cell types to the site of injury was unaffected. Molecular analyses suggest that loss of Mfap4 alters the balance between myeloid and lymphoid lineages during both primitive and definitive haematopoiesis, which could significantly impact the downstream function of the immune system.
Insights
Microfibril-associated glycoprotein 4 (MFAP4) is crucial for immune cell balance. Zebrafish lacking MFAP4 show altered macrophage and neutrophil populations, impacting immune system development and function.
Area of Science:
- Extracellular Matrix Biology
- Immunology
- Developmental Biology
Background:
- Microfibril-associated glycoprotein 4 (MFAP4) is an extracellular matrix protein involved in vascular structure.
- MFAP4 is linked to human genetic disorders like Smith-Magenis syndrome and congenital heart disease.
- The role of MFAP4 in organismal development and tissue homeostasis is not well understood.
Purpose of the Study:
- To investigate the function of MFAP4 during embryonic development and tissue homeostasis in a model organism.
- To analyze the impact of MFAP4 deficiency on hematopoietic lineages and immune cell populations.
Main Methods:
- Zebrafish mfap4 transcript localization during embryogenesis.
- Generation and characterization of mfap4 null mutant zebrafish.
- Tail fin amputation assay to assess immune cell response to injury.
- Molecular analyses of hematopoietic lineage balance.
Main Results:
- Zebrafish mfap4 transcripts are detected embryonically and localize to macrophages.
- mfap4 null mutants are viable and fertile but exhibit reduced macrophage numbers and increased neutrophils.
- Immune cell recruitment to injury sites is unaffected, but the overall myeloid/lymphoid lineage balance is altered.
- Loss of MFAP4 impacts both primitive and definitive hematopoiesis.
Conclusions:
- MFAP4 plays a significant role in regulating the balance of hematopoietic lineages.
- The absence of MFAP4 leads to an altered immune cell composition, potentially affecting immune system function.
- Further research is needed to elucidate the precise mechanisms by which MFAP4 influences hematopoiesis and immunity.
