Gene conversion of major histocompatibility complex genes is associated with CpG-rich regions

• We examined 32 DNA sequences of mouse and human major histocompatibility complex (MHC) genes believed to have been subjected to gene conversion events. All regions of the mouse H2 genes as well as the human HLA genes which have been implied to be involved in gene conversion events had elevated levels of CpG dinucleotides, whereas the rest of the genes showed extensive CpG suppression. Mouse MHC genes which have been suspected but not directly implied to be involved in gene conversion events also showed elevated levels of CpG dinucleotides. Moreover, both mouse and human MHC genes which have never been suspected of undergoing gene conversion had low levels of CpG throughout the genes. These results indicate that high CpG levels are correlated with gene conversion rather than with polymorphism, as non-polymorphic genes that have been implicated as gene conversion donors also have elevated levels of CpG dimers in the involved regions whereas polymorphic genes which have never been considered to undergo gene conversion events have a low level of CpG dinucleotides. We also studied the methylation pattern of CpG dimers in the Abk gene by restriction enzyme digestion of mouse testis DNA followed by Southern blot and hybridization to an Abk-specific probe. The examined CpG dimers in prepubescent mice, where the latest germline stages are spermatogonia, leptene, or pachytene, are respectively non-methylated. Accordingly, the CpG dimers appear to be non-methylated in germline DNA from the testis of prepubescent mice, where gene conversions have been reported to occur.

Subject headings

NATURVETENSKAP  -- Biologi -- Immunologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Immunology (hsv//eng)

Keyword

CpG

Gene conversion

H2

HLA

MHC

Mouse

dinucleotide

restriction endonuclease

animal cell

article

controlled study

DNA methylation

DNA sequence

histocompatibility gene

major histocompatibility complex

nonhuman

pachytene

priority journal

southern blotting

spermatogonium

Animals

Chimera

Dimerization

Dinucleoside Phosphates

Genes

MHC Class II

Germ Cells

H-2 Antigens

Histocompatibility Antigens

HLA Antigens

Humans

Liver

Male

Mice

Mice

Inbred BALB C

Mice

Inbred C3H

Sexual Maturation

Testis

Publication and Content Type

ref (subject category)

art (subject category)