Genomic structure and chromosomal mapping of the human CD22 gene

• Published in: The Journal of immunology (1950) Vol. 150; no. 11; pp. 5013 - 5024
• Main Authors: Wilson, GL, Najfeld, V, Kozlow, E, Menniger, J, Ward, D, Kehrl, JH
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Am Assoc Immnol 01.06.1993; American Association of Immunologists
• Subjects: ANIMAL CELLS; ANTIGENS; Antigens, CD - genetics; Antigens, Differentiation, B-Lymphocyte - genetics; Base Sequence; BASIC BIOLOGICAL SCIENCES; Biological and medical sciences; BIOLOGICAL MATERIALS; BLOOD; BLOOD CELLS; BODY FLUIDS; CD22 antigen; Cell Adhesion Molecules; Chromosome Mapping; CHROMOSOMES; Chromosomes, Human, Pair 19; CLONING; CONNECTIVE TISSUE CELLS; DNA - isolation & purification; DNA HYBRIDIZATION; DNA SEQUENCING; DNA-CLONING; Fundamental and applied biological sciences. Psychology; gene mapping; GENE REGULATION; GENE REPRESSORS; GENES; Genes. Genome; Genome, Human; HUMAN CHROMOSOME 19; HUMAN CHROMOSOMES; Humans; HYBRIDIZATION; Lectins; LEUKOCYTES; LYMPHOCYTES; lymphocytes B; man; MAPPING; MATERIALS; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; nucleotide sequence; Promoter Regions, Genetic; Repetitive Sequences, Nucleic Acid; RNA, Messenger - chemistry; Sialic Acid Binding Ig-like Lectin 2; SOMATIC CELLS; STRUCTURAL CHEMICAL ANALYSIS 550400 > Genetics; structure; TATA Box; TRANSCRIPTION FACTORS; Transcription, Genetic; Genetic mapping; Human; Immunogenetics; Gene; Nucleotide sequence; Sequence alignment; Homology; B-Lymphocyte; Molecular cloning; Cell surface; Comparative study
• ISSN: 0022-1767; 1550-6606
• DOI: 10.4049/jimmunol.150.11.5013

The human CD22 gene is expressed specifically in B lymphocytes and likely has an important function in cell-cell interactions. A nearly full length human CD22 cDNA clone was used to isolate genomic clones that span the CD22 gene. The CD22 gene is spread over 22 kb of DNA and is composed of 15 exons. The first exon contains the major transcriptional start sites. The translation initiation codon is located in exon 3, which also encodes a portion of the signal peptide. Exons 4 to 10 encode the seven Ig domains of CD22, exon 11 encodes the transmembrane domain, exons 12 to 15 encode the intracytoplasmic domain of CD22, and exon 15 also contains the 3' untranslated region. A minor form of CD22 mRNA likely results from splicing of exon 5 to exon 8, skipping exons 6 and 7. A 4.6-kb XbaI fragment of the CD22 gene was used to map the chromosomal location of CD22 by fluorescence in situ hybridization. The hybridization locus was identified by combining fluorescent images of the probe with the chromosomal banding pattern generated by an Alu probe. The results demonstrate that CD22 is located within the band region q13.1 of chromosome 19. Two closely clustered major transcription start sites and several minor start sites were mapped by primer extension. Similarly to many other lymphoid-specific genes, the CD22 promoter lacks an obvious TATA box. Approximately 4 kb of DNA 5' of the transcription start sites were sequenced and found to contain multiple Alu elements. Potential binding sites for the transcriptional factors NF-kappa B, AP-1, and Oct-2 are located within 300 bp 5' of the major transcription start sites. A 400-bp fragment (bp -339 through +71) of the CD22 promoter region was subcloned into a pGEM-chloramphenicol acetyltransferase vector and after transfection into B and T cells was found to be active in both B and T cells. Further studies of the CD22 gene should lead to a greater understanding of the expression of CD22 during B cell development and differentiation.