The human mRNA encoding the Goodpasture antigen is alternatively spliced

Area of Science:

• Molecular Biology
• Immunology
• Genetics

Background:

• The noncollagenous (NC1) domain of human collagen alpha 3(IV)-chain is the Goodpasture antigen, targeted by autoantibodies in Goodpasture syndrome.
• Understanding the molecular variations of this antigen is crucial for comprehending the pathogenesis of Goodpasture syndrome.

Purpose of the Study:

• To investigate the alternative splicing of Goodpasture antigen mRNA in human tissues.
• To characterize the structural and functional implications of these alternatively spliced forms.

Main Methods:

• Analysis of Goodpasture antigen mRNA splicing patterns in various human, bovine, and rat tissues.
• Deduction of amino acid sequences for complete and alternatively spliced forms.
• Comparison of variant sequences with the complete form, focusing on epitope and cysteine residues.

Main Results:

• At least two alternatively spliced forms of Goodpasture antigen mRNA were identified in human tissues, involving the exclusion of one or two exons.
• No alternatively spliced forms were observed in bovine or rat tissues.
• Variant mRNA forms translate to shorter amino acid sequences lacking key regions for epitope formation and triple helix structure, suggesting reduced autoantibody reactivity.

Conclusions:

• Alternative splicing of Goodpasture antigen mRNA occurs in humans, producing variants potentially unable to form the Goodpasture epitope.
• The complete form of the antigen mRNA is most abundant across tissues, irrespective of Goodpasture syndrome relevance.
• No significant sequence or expression differences in antigen forms were found between normal and affected individuals' kidneys.