A novel CD4 knockout mouse strain with a spontaneous frameshift mutation in the CD4 locus

Area of Science:

• Immunology
• Cell Biology
• Genetics

Background:

• T cells utilize CD4 and CD8 co-receptors for antigen recognition via T cell receptors.
• CD4 expression on thymic hematopoietic cells is essential for T cell development and selection.
• Defects in CD4 expression can lead to impaired T cell function and development.

Purpose of the Study:

• To identify and characterize a novel spontaneous mutation affecting CD4 expression in mice.
• To investigate the functional consequences of the CD4 mutation on T cell development.
• To establish a corrected mouse model for studying CD4+ T cells.

Main Methods:

• Identification of a spontaneous frameshift mutation in the CD4 gene.
• Analysis of CD4 protein expression and localization in thymic cells.
• CRISPR-Cas9 mediated gene editing to correct the CD4 mutation.
• Adoptive transfer experiments to evaluate the corrected mouse model.

Main Results:

• A novel CD4 mutant allele with a frameshift mutation was identified.
• The mutation resulted in a truncated CD4 protein that did not reach the plasma membrane.
• Impaired development of CD4+ helper T cells was observed in mice with the mutation.
• CRISPR-mediated correction restored membrane CD4 expression and T cell development.
• The corrected mouse model proved suitable for adoptive transfer studies of CD4+ T cells.

Conclusions:

• Spontaneous mutations in CD4 can significantly disrupt T cell development.
• CRISPR gene editing is an effective tool for correcting CD4 mutations.
• This corrected mouse model serves as a valuable platform for immunological research involving CD4+ T cells.