Dominant negative mutation of the hematopoietic-specific Rho GTPase, Rac2, is associated with a human phagocyte immunodeficiency.
Rho GTPases control a variety of cellular processes, including actin polymerization, integrin complex formation, cell adhesion, gene transcription, cell cycle progression, and cell proliferation. A patient is described who has recurrent infections and defective neutrophil cellular functions similar to those found in Rac2-deficient mice. Molecular methods were used to clone the expressed Rac2 cDNA from this patient, and a single base pair change (G-->A at nucleotide 169) in the coding sequence was identified. This results in an asparagine for aspartic acid mutation at amino acid 57 (D57N), a residue that is involved in nucleotide binding and is conserved in all mammalian Rho GTPases. The cloned cDNA was then introduced into normal bone marrow cells through retrovirus vectors, and neutrophils expressing this mutant exhibited decreased cell movement and production of superoxide in response to fMLP. The expressed recombinant protein was also analyzed biochemically and exhibited defective binding to GTP. Functional studies demonstrated that the D57N mutant behaves in a dominant-negative fashion at the cellular level. The syndrome of Rac2 dysfunction represents a human condition associated with mutation of a Rho GTPase and is another example of human disease associated with abnormalities of small G protein signaling pathways. (Blood. 2000;96:1646-1654)
Williams
D A
DA
Department of Pediatrics, Wells Center for Pediatric Research, Howard Hughes Medical Institute, Indiana University School of Medicine, Indianapolis, IN 46202-5225, USA. dwilliam@iupui.edu
Tao
W
W
Yang
F
F
Kim
C
C
Gu
Y
Y
Mansfield
P
P
Levine
J E
JE
Petryniak
B
B
Derrow
C W
CW
Harris
C
C
Jia
B
B
Zheng
Y
Y
Ambruso
D R
DR
Lowe
J B
JB
Atkinson
S J
SJ
Dinauer
M C
MC
Boxer
L
L
D016475:3T3 Cells; D019943:Amino Acid Substitution; D000818:Animals; D001483:Base Sequence; D016026:Bone Marrow Transplantation; D002465:Cell Movement; D004252:DNA Mutational Analysis; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005799:Genes, Dominant; D049452:Green Fluorescent Proteins; D006160:Guanosine Triphosphate / Q000378:metabolism; D006410:Hematopoiesis; D006801:Humans; D007223:Infant; D007964:Leukocytosis / Q000473:pathology / Q000628:therapy; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008856:Microscopy, Fluorescence; D009154:Mutation; D009504:Neutrophils / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D010586:Phagocytes / Q000166:cytology / Q000276:immunology*; D017354:Point Mutation; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012190:Retroviridae / Q000235:genetics; D013481:Superoxides / Q000378:metabolism; D020744:rac GTP-Binding Proteins / Q000235:genetics* / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism; D000097766:RAC2 GTP-Binding Protein
D018076:DNA, Complementary; D049452:Green Fluorescent Proteins; D006160:Guanosine Triphosphate; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D013481:Superoxides; D020744:rac GTP-Binding Proteins; D020830:rac1 GTP-Binding Protein; D000097766:RAC2 GTP-Binding Protein