Network and structural analysis of quail mucins with expression pattern of MUC1 and MUC4 in the intestines of the Iraqi Common Quail (Coturnix Coturnix)

Background Mucins have vital pathophysiological role in gastrointestinal tract (GIT) of avian and other species. However, despite this very little is known about the types of mucins expressed in quail GIT. Hence in this study we examined the expression pattern of mucins (MUC1, and MUC4) in the GIT of the Iraqi Common Quail (Coturnix Coturnix) and performed the network and structural analysis of all reported types of mucins in various breeds of quails. Materials and methods This study protocol was approved by the animal ethics research committee of the College of Veterinary Medicine, University of Al-Qadisiyah, Iraq. Fresh samples of small and large intestines were used for histological and gene expression analysis of MUC1, and MUC4. Network and structural analysis of all reported types of mucins in quails was performed using the STRING Database, Chimera software and PrankWeb-Ligand Binding Site Prediction tool. Results The histological analysis using Alcian blue and PAS stains indicated that most mucins in the intestines of quails were of the acidic mucin type, with minimal prevalence of neutral mucins. The expression of acidic mucins was relatively higher in the duodenum, ileum, caecum, and colon, while the jejunum showed a relatively higher expression of neutral mucins. Gene expression analysis revealed higher expression levels of MUC1 and MUC4 mRNA in the jejunum and colon, with its least expression in the duodenum and ilium. Network analysis indicated predominantly mucin-mucin interactions, with MUC 1, 15, 16 and 24 showing preferential homologous networks while the MUC 2, 4, 5 and 6 showed heterologous networks. Detailed evaluation of intermolecular hydrogen bond formation highlighted the interactions between specific mucin combinations, with certain combinations showing higher affinity, such as MUC5A-MUC6, MUC5A-MUC5B, and MUC5B-MUC6. In contrast, MUC15, MUC16, and MUC24 exhibited limited interactions with other mucin types. Binding site analysis indicated that MUC5B and MUC6 had the most number of binding sites with high probability scores, while MUC2, MUC4, and MUC5A showed lower probability scores despite having more binding sites. In contrast MUC 1, 15, and 16 had very few binding sites (<3 binding sites) all with very low probability scores. Conclusion The findings of this study provide valuable insights into the composition, expression, network interactions, and binding sites of mucins in the quails, contributing to the understanding of mucin-related processes in gastrointestinal physiology and potential implications for gastrointestinal diseases.