Kadhim, A. B. | Search bioRxiv

bioRxiv2023

Finding Expression of MUC1 and MUC4 in the Respiratory System of the Iraqi Common Quail (Coturnix coturnix)

BackgroundThis study focused on the major components of mucus, known as mucins, within the mucosal epithelium of the respiratory system in Iraqi Common Quail. Six quail were utilized in accordance with animal ethics guidelines from the College of Veterinary Medicine at the University of Al-Qadisiyah. Histological analysis, utilizing H&E staining, aimed to identify key respiratory system structures. PAS plus Alcian blue stains were employed to identify specific carbohydrates in the trachea, bronchi, and lungs. RT-qPCR was used to assess the gene expression levels of MUC1 and MUC4. ResultsThe trachea and bronchi encompassed four distinct layers: tunica mucosa, tunica submucosa, hyaline cartilage, and tunica adventitia. The mucosa consisted of pseudostratified epithelium that transitioned into simple columnar cells toward the primary and secondary bronchioles. This transition further progressed into simple cuboidal and squamous epithelium at smaller tertiary branches of the secondary bronchioles. Notably, the bronchial tunica submucosa was thinner than the trachea. While hyaline cartilage was prominently present in the trachea, it became fragmented in the bronchi and diminished towards the lungs and secondary bronchioles. Lung tissue was characterized by numerous lobules housing alveoli connected to alveolar ducts and sacs, alongside an intricate network of blood vessels. The respiratory tissues, including the trachea, bronchi, and lungs, exhibited a strong affinity for PAS-combined Alcian blue stains. This confirmed the substantial presence of both acidic and neutral mucins within the epithelial cells and glands. The trachea demonstrated significantly elevated levels of acidic mucins and a concentrated amount? of neutral mucins. Transcriptome analysis indicated the expression of both MUC1 and MUC4 genes. Importantly, MUC4 expression surpassed that of MUC1 in the trachea, bronchi, and lungs. ConclusionThis study highlights the similarity of histological structures in the trachea, bronchi, and lungs of quail to typical avian species. Moreover, it underscored the substantial presence of both acidic and neutral mucins, with MUC4 being the predominant mucin, potentially playing a pivotal role in regulating mucosal barrier functions and interacting with pathogens. Nonetheless, further investigation is warranted to elucidate MUC4s role in respiratory epithelial cells.

molecular biology↗

bioRxiv2023

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

BackgroundMucins 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 methodsThis 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. ResultsThe 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. ConclusionThe 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.

physiology↗