Cytoglobin regulates NO-dependent cilia motility and organ laterality during development

Area of Science:

• Biochemistry
• Developmental Biology
• Cell Biology

Background:

• Cytoglobin (CYGB) is a heme protein with an unclear physiological role.
• Human conditions linked to ciliary dysfunction and low nitric oxide (NO) production involve left-right cardiac determination defects.
• Zebrafish cytoglobin (cygb2) genetic deletion results in cardiac developmental abnormalities.

Purpose of the Study:

• To investigate the physiological function of cytoglobin, specifically its role in cilia function and organ laterality.
• To elucidate the molecular mechanisms underlying cytoglobin's function in relation to nitric oxide signaling.

Main Methods:

• Utilized zebrafish (cygb2) mutants and cytoglobin knockout mice models.
• Investigated co-localization of Cygb2 with cilia and nitric oxide synthase (Nos2b).
• Assessed cilia structure and function, organ laterality, and nitric oxide levels.

Main Results:

• Cygb2 was found to co-localize with cilia and Nos2b in zebrafish Kupffer's vesicle, with disrupted cilia structure and function in cygb2 mutants.
• Depletion of Nos2b or guanylate cyclase (gucy1a) phenocopied the ciliary and laterality defects.
• Defects were rescued by NO donors, guanylate cyclase stimulators, or Nos2b overexpression in zebrafish.
• Cytoglobin knockout mice exhibited impaired airway cilia structure and reduced NO levels.

Conclusions:

• Cytoglobin acts as a positive regulator of the nitric oxide synthase-soluble guanylate cyclase-cyclic GMP signaling pathway.
• This pathway is critical for normal cilia motility and left-right patterning.
• Cytoglobin's role in NO signaling is conserved across species, impacting both embryonic development and airway function.