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The 47-kD protein increased in neutrophil actin dysfunction with 47- and 89-kD protein abnormalities is
1Department of Pediatrics, University of Alabama, School of Medicine, Birmingham.
Abstract:
A male child born of related parents suffered recurrent infections because of neutrophil actin dysfunction with increased amounts of a 47-kD protein and decreased amounts of an 89-kD protein (NAD 47/89). The patient and family members were studied to define the nature of the abnormal proteins and to examine their role in the functional defects of neutrophil actin dysfunction (NAD) 47/89 polymorphonuclear neutrophils (PMNs). NAD 47/89 PMNs are defective in motility, microfilamentous cytoskeletal structure, and formyl peptide-induced actin polymerization and express increased amounts of a 47-kD protein and decreased amounts of an 89-kD proteins intermediate abnormality in amount of 47-kD and 89-kD proteins in PMNs from parents and a female sibling suggest the disease is an autosomal recessive disorder. Immunoblots with monoclonal antibody (MoAb1) and polyclonal antibody raised to 47-kD protein showed the 89-kD protein is antigenically distinct from the 47-kD protein and the 89-kD protein is not gelsolin. 125I-actin binding to one-dimensional (1 D) and 2 D gels of PMN proteins from NAD 47/89 proband, family members, and controls showed the 47-kD protein binds actin, is acidic (pl = 4.5 to 4.7), is recognized by the MoAb1, exists on 2-D gels as three distinct actin binding species (MWapp 52 kD, 47-kD, and 44-kD), and is present in control PMNs in lesser amount than in PMNs of NAD 47/89 proband or parents. Immunoaffinity purification of the 47 kD actin binding protein on MoAb1 matrix yielded a multimolecular complex with proteins of MWapp 180 kD, 71 kD, 47 kD and actin. Cloning, sequencing, and expression of a 1.58-kb cDNA selected for MoAb1 reactivity from a HL60 expression library and microsequence of native PMNs, 47-kD actin binding protein showed the overexpressed 47-kD protein is lymphocyte-specific protein 1 (LSP1), which is a known actin binding protein. The results show LSP1 is expressed in PMNs and suggest overexpression of LSP1 is related to the motility and cytoskeletal abnormalities in NAD 47/89 PMNs.
Insights
Neutrophil actin dysfunction (NAD 47/89) in a child was linked to increased lymphocyte-specific protein 1 (LSP1). This protein overexpression is associated with motility and cytoskeletal defects in neutrophils, suggesting an autosomal recessive disorder.
Area of Science:
- Immunology
- Cell Biology
- Genetics
Background:
- Neutrophil actin dysfunction (NAD 47/89) is characterized by recurrent infections and specific protein level alterations in neutrophils.
- The condition involves increased amounts of a 47-kD protein and decreased amounts of an 89-kD protein in polymorphonuclear neutrophils (PMNs).
- NAD 47/89 PMNs exhibit defects in motility, cytoskeletal structure, and actin polymerization.
Purpose of the Study:
- To characterize the abnormal proteins in NAD 47/89 and their role in neutrophil functional defects.
- To determine the genetic inheritance pattern of NAD 47/89.
- To identify the molecular identity of the 47-kD actin-binding protein.
Main Methods:
- Analysis of PMNs from patients and family members using immunoblots and 2D gel electrophoresis.
- Actin binding assays with purified proteins.
- Immunoaffinity purification and characterization of protein complexes.
- cDNA cloning, sequencing, and expression analysis.
Main Results:
- The 89-kD protein is antigenically distinct from the 47-kD protein and is not gelsolin.
- The 47-kD protein binds actin, is acidic, and exists in multiple forms.
- Overexpression of lymphocyte-specific protein 1 (LSP1) was identified as the 47-kD protein in NAD 47/89 PMNs.
- LSP1 is present in control PMNs but at lower levels than in affected individuals.
- The inheritance pattern suggests an autosomal recessive disorder.
Conclusions:
- The study identifies lymphocyte-specific protein 1 (LSP1) as the overexpressed 47-kD protein in neutrophil actin dysfunction (NAD 47/89).
- Overexpression of LSP1 in neutrophils is implicated in the observed motility and cytoskeletal abnormalities.
- NAD 47/89 is likely an autosomal recessive disorder, with implications for neutrophil function and host defense.