Genetic cause of leukocyte adhesion molecule deficiency. Abnormal splicing and a missense mutation in a conserved region of CD18 impair cell surface expression of beta 2 integrins

J Biol Chem. 1992 Feb 15;267(5):3351-7.

Abstract

Patients with leukocyte adhesion molecule (CD11/CD18, beta 2 integrins) deficiency have structural defects in the common beta subunit (CD18), which prevent heterodimer formation and normal cell surface expression of these receptors, leading to life-threatening bacterial infections. To elucidate the nature of these defects in a patient with partial (type II) deficiency, abnormal CD18 cDNA clones were isolated, using the polymerase chain reaction to amplify the patient's B cell-derived cDNAs. Sequence analysis revealed two mutant alleles. cDNA clones, representing a maternal allele, contained both a 12-base pair insertion resulting in an in-frame addition of four amino acids between P247 and E248 and a C1756----T nucleotide transition, resulting in an R586----W substitution in the normal CD18 protein. The inframe insertion arose by a single nucleotide C----A transversion in the 3' terminus of an intron, generating aberrant splice acceptor site. Other cDNA clones contained an A1052----G nucleotide transition not present in either parent which resulted in an N351----S substitution. To determine the functional importance of these changes, cDNA encoding a normal alpha chain (CD11b) was cotransfected into COS with CD18 cDNAs encoding for wild-type, maternal mutant allele, or CD18 containing N351----S substitution. Immunostaining of transfectants with anti-CD18 monoclonal antibodies revealed no cell surface expression of the maternal mutant CD18, and 22% surface expression of N351----S CD18. Both the insertion and the N351----S mutations occurred in a 250 amino acid extracellular region of CD18 that is highly conserved among beta integrins supporting a role for this region in heterodimer formation.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / genetics*
  • Base Sequence
  • CD18 Antigens
  • Cell Line, Transformed
  • Cloning, Molecular / methods
  • Drosophila / genetics
  • Genetic Vectors
  • Herpesvirus 4, Human / genetics
  • Humans
  • Integrins / biosynthesis
  • Integrins / genetics*
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Mutation*
  • Oligonucleotides, Antisense
  • Polymerase Chain Reaction
  • RNA Splicing*
  • Receptors, Leukocyte-Adhesion / genetics

Substances

  • Antigens, CD
  • CD18 Antigens
  • Integrins
  • Oligonucleotides, Antisense
  • Receptors, Leukocyte-Adhesion

Associated data

  • GENBANK/D12753
  • GENBANK/M84126
  • GENBANK/M84127
  • GENBANK/M84128
  • GENBANK/M84129
  • GENBANK/M84130
  • GENBANK/S81231
  • GENBANK/S81234
  • GENBANK/S81247
  • GENBANK/S81252