Structure-function studies of galectin-14, an important effector molecule in embryology

Area of Science:

• Biochemistry
• Structural Biology
• Immunology

Background:

• Galectin-14 (Gal-14) is highly expressed in the human placenta, indicating potential roles in pregnancy and fetal development.
• Understanding Gal-14's structure and function is crucial for elucidating its biological significance.

Purpose of the Study:

• To determine the crystal structure of dimeric Gal-14.
• To investigate its carbohydrate-binding properties and cellular localization.
• To explore its potential interactions with signaling pathways.

Main Methods:

• X-ray crystallography to solve the dimeric Gal-14 structure.
• Hemagglutination assays to assess lectin activity.
• Isothermal titration calorimetry to study lactose binding.
• Fluorescence microscopy to determine cellular localization and colocalization studies.

Main Results:

• The Gal-14 structure revealed a unique fold with extended β-strands contributing to the carbohydrate-binding domain.
• Gal-14 induced chicken erythrocyte agglutination, but this activity was not inhibited by lactose, indicating weak or absent lactose binding.
• Amino acid substitutions in the canonical sugar-binding site (Gln53, His57) explain the weak lactose interaction.
• EGFP-tagged Gal-14 localized primarily to the nucleus and colocalized with c-Rel (NF-κB family member) in HeLa cells.

Conclusions:

• Gal-14 possesses a distinct structure and weak carbohydrate-binding affinity compared to other galectins.
• Nuclear localization and interaction with c-Rel suggest Gal-14 may regulate signal transduction pathways, potentially through NF-κB hubs.
• These findings provide a foundation for further research into Gal-14's function in embryology and immune tolerance during pregnancy.