期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1999
卷号：96
期号：15
页码：8693-8698
DOI：10.1073/pnas.96.15.8693
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：A human disorder caused by mutation in nonmuscle actin has not been reported. We report here a variant of nonmuscle actin in a female patient with recurrent infections, photosensitivity, and mental retardation. She also had abnormalities in neutrophil chemotaxis, superoxide production, and membrane potential response. Two-dimensional PAGE analysis of proteins from neutrophils and other cell types from this patient demonstrated a unique protein spot migrating at 42 kDa with pI shifted slightly to neutral relative to normal {beta}- and {gamma}-actin. Digestion peptide mapping and Western blotting showed this spot to be an abnormal actin. A full-length cDNA library was constructed by using mRNA from patient's cells and cDNA encoding the mutant {beta}-actin molecule was identified by an in vitro translation method. Sequencing of the clones demonstrated a G-1174 to A substitution, predicting a glutamic acid-364 to lysine substitution in {beta}-actin and eliminating a HinfI DNase restriction site found in normal {beta}-actin sequence. By HinfI digestion and by sequencing, the mutation in one allele of patient's genomic DNA was confirmed. Though no defect in cell-free polymerization of actin was detected, this defect lies in a domain important for binding to profilin and other actin-regulatory molecules. In fact, the mutant actin bound to profilin less efficiently than normal actin did. Heterozygous expression of mutant {beta}-actin in neutrophils and other cells of this patient may act in a dominant-negative fashion to adversely affect cellular activities dependent on the function of nonmuscle actin.
