Association of a four-amino acid residue insertion polymorphism of the HS1 gene with systemic lupus erythematosus: molecular and functional analysis.
OBJECTIVE
To investigate whether polymorphism(s) or mutation(s) in the hematopoietic cell-specific Lyn substrate 1 (HS1) gene are involved in the pathogenesis of systemic lupus erythematosus (SLE).


METHODS
The entire coding region of the HS1 gene was analyzed by reverse transcriptase-polymerase chain reaction/single-strand conformational polymorphism analysis. HS1-transfected WEHI-231 cells or B lymphocytes from patients with SLE were studied for apoptosis, activation, and proliferation by flow cytometric analysis and MTT assay.


RESULTS
We identified a glutamic acid-proline-glutamic acid-proline insertion between codons 366 and 367 (EPEP366-367ins) and 2 amino acid substitutions (A235T and E361K). The genotype frequency among individuals homozygous for the EPEP+ allele was 0.184 in 201 patients with SLE but only 0.098 in 184 healthy individuals (P = 0.016). The allele frequency of EPEP366-367ins was 0.408 in patients with SLE; this frequency was significantly higher than that in healthy controls (0.312) (P = 0.006). WEHI-231 cells transfected with EPEP+ HS1 were 100-fold more sensitive to B cell receptor (BCR)-mediated apoptosis than were those transfected with HS1 without EPEP. B lymphocytes from SLE patients with the EPEP+ allele were significantly more apoptotic without BCR stimulation and less activated after BCR stimulation than were those from SLE patients without the EPEP allele.


CONCLUSIONS
These results suggest that HS1 with the EPEP insertion polymorphism transmits accelerated signals from BCR and is involved in the pathogenesis of SLE.
Otsuka
Junji
J
Kyushu University Graduate School of Medical Sciences, Fukuoka, Japan.
Horiuchi
Takahiko
T
Yoshizawa
Shigeru
S
Tsukamoto
Hiroshi
H
Sawabe
Takuya
T
Kikuchi
Yuji
Y
Himeji
Daisuke
D
Koyama
Takako
T
Mitoma
Hiroki
H
Watanabe
Takeshi
T
Harada
Mine
M
D048868:Adaptor Proteins, Signal Transducing; D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D001402:B-Lymphocytes; D001483:Base Sequence; D001798:Blood Proteins / Q000235:genetics*; D016022:Case-Control Studies; D002460:Cell Line; D004247:DNA; D004251:DNA Transposable Elements; D018076:DNA, Complementary; D005260:Female; D005787:Gene Frequency; D015894:Genome, Human; D018698:Glutamic Acid / Q000235:genetics*; D006801:Humans; D008180:Lupus Erythematosus, Systemic / Q000235:genetics* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D011110:Polymorphism, Genetic / Q000235:genetics*; D011392:Proline / Q000235:genetics*; D014162:Transfection
D048868:Adaptor Proteins, Signal Transducing; D001798:Blood Proteins; D004251:DNA Transposable Elements; D018076:DNA, Complementary; C061909:HCLS1 protein, human; D018698:Glutamic Acid; D004247:DNA; D011392:Proline