The bovine interleukin-4 gene: genomic organization, localization, and evolution

Area of Science:

• Immunogenetics
• Comparative Genomics
• Veterinary Science

Background:

• Interleukin-4 (IL4) plays a crucial role in immune responses, particularly T helper 2 lymphocyte activation, linking it to parasitic infections and atopic diseases.
• IL4's involvement in immune regulation makes it a significant candidate gene for disease association studies and genetic mapping in various species.

Purpose of the Study:

• To isolate and characterize the genomic organization of the bovine Interleukin-4 (IL4) gene.
• To analyze the 5' and 3' flanking regions of the bovine IL4 gene for regulatory elements and sequence conservation.
• To investigate genetic variation within the bovine IL4 locus and determine its chromosomal location.

Main Methods:

• Isolation of bovine IL4 cosmids and determination of genomic organization.
• Cloning and sequencing of exon-containing fragments and flanking regions (725 bp 5', 190 bp 3').
• Sequencing of a mixed repeat [(t/g)a]m(ca)n upstream of the IL4 gene.
• Fluorescence in situ hybridization (FISH) for chromosomal assignment.

Main Results:

• High sequence similarity (92%) was observed between the first 481 bp of the 5' flanking region of bovine and human IL4 genes, including putative promoter sequences.
• A mixed repeat [(t/g)a]m(ca)n, approximately 35 kb upstream of the IL4 gene, exhibited seven repeat length alleles in the studied animals.
• The bovine IL4 gene was assigned to chromosome 7q15-q21 using fluorescence in situ hybridization.

Conclusions:

• The conserved promoter region suggests functional similarities in IL4 regulation between cattle and humans.
• The identified polymorphic repeat region offers a potential marker for genetic studies in cattle.
• The chromosomal localization provides a basis for comparative mapping and understanding evolutionary relationships of the IL4 gene.