H2-EA-PS

H2-EA-PS Full Name

histocompatibility 2, class II antigen E alpha, pseudogene

H2-EA-PS Introduction

Histocompatibility 2, class II antigen E alpha, pseudogene (H2-EA-PS), also designated as H2-Ea-ps, is a non-functional pseudogene located within the murine major histocompatibility complex (H-2) on mouse chromosome 17. The H2-EA-PS pseudogene is a defective copy of the H2-Ea gene, which encodes the alpha chain of the mouse MHC class II I-E molecule. In several common inbred mouse strains, including C57BL/6 and BALB/c, the functional H2-Ea gene is absent due to a deletion, and H2-EA-PS represents a remnant pseudogene that is transcribed but does not produce a functional MHC class II alpha chain protein.

Figure 1. MHC Class II Presentation in Autoimmunity.

I-E Deficiency in Inbred Mouse Strains and Immunological Implications
The lack of functional I-E MHC class II molecules in the widely used C57BL/6 and BALB/c mouse strains is a result of a naturally occurring deletion in the H2-Ea gene promoter and first exon, rendering the strain I-E-negative. Additionally, many H-2b haplotype strains lack a functional H2-Eb gene encoding the I-E beta chain. As a result, these strains express only I-A MHC class II molecules (encoded by H2-Aa and H2-Ab) for CD4+ T cell antigen presentation. This I-E deficiency has significant immunological implications: I-E molecules present a distinct repertoire of peptides compared to I-A molecules, and their absence affects T cell repertoire selection in the thymus and peripheral immune responses. Importantly, I-E expression is required for the development of certain experimental autoimmune disease models, and the presence or absence of I-E can dramatically alter the outcome of immunological experiments, a factor that must be carefully considered when comparing results across mouse strains with different H-2 haplotypes.

Research Applications and Comparative MHC Genomics
The H2-EA-PS pseudogene and the natural I-E deficiency in certain strains have been exploited as tools in immunological research. Transgenic expression of functional Ea genes in I-E-negative strains has been used to study the role of I-E molecules in immune responses, including susceptibility to experimental autoimmune encephalomyelitis (EAE), type 1 diabetes (NOD mouse model), and collagen-induced arthritis. The H2-Ea pseudogene also provides insights into MHC evolution: the presence of pseudogenes and gene deletions in the MHC is a common feature across mammalian species, reflecting the dynamic evolutionary history of this gene-dense, highly polymorphic genomic region. Comparative analysis of functional and pseudogenized MHC genes across rodent species contributes to understanding the selective pressures that maintain MHC diversity and the consequences of MHC gene loss for immune function. The H2-EA-PS pseudogene thus serves as a useful marker in genetic studies of the mouse MHC region.

Alternate Names for H2-EA-PS

H2-Ea-ps; histocompatibility 2, class II antigen E alpha, pseudogene; Ia3; Ia-3; H-2Ea; H2-Ea; AI323765; I-Ealpha; E-alpha-f; histocompatibility 2, class II antigen E alpha