UDP/P2Y6 receptor signaling regulates IgE-dependent degranulation in human basophils.
BACKGROUND
P2Y purinergic receptors (P2YR) are G protein-coupled receptors that are stimulated by extracellular nucleotides. They mediate cellular effects by regulating cAMP production, protein kinase C activation, inositol trisphosphate generation, and Ca2+release from intracellular stores. The P2Y6 receptor of this family is selectively stimulated by UDP, and selectively inhibited by MRS2578. In the present study, we examined the effect of UDP/P2Y6 receptor signaling on IgE-dependent degranulation in human basophils.


METHODS
Basophils were purified from human peripheral blood. The mRNA expression of genes encoding P2YR and ecto-nucleoside triphosphate diphosphohydrolase (ENTPDase) was measured by RT-PCR. Intracellular Ca2+influx via UDP/P2Y6 receptor signaling in basophils was detected using a calcium probe. The effect of UDP/P2Y6 receptor signaling on IgE-dependent degranulation in basophils was confirmed by measuring CD63 expression by flow cytometry. Autocrine secretion of nucleotides was detected by HPLC analysis.


RESULTS
We showed that purified basophils express P2Y6 mRNA and that UDP increased intracellular Ca2+, which was reduced by MRS2578 treatment. UDP promoted IgE-dependent degranulation. Furthermore, MRS2578 inhibited IgE-dependent degranulation in basophils. HPLC analysis indicated that basophils spontaneously secrete UTP. In addition, basophils expressed the extracellular nucleotide hydrolases ENTPDase2, ENTPDase3, and ENTPDase8.


CONCLUSIONS
This study showed that UDP/P2Y6 receptor signaling is involved in the regulation of IgE-dependent degranulation in basophils, which might stimulate the P2Y6 receptor via the autocrine secretion of UTP. Thus, this receptor represents a potential target to regulate IgE-dependent degranulation in basophils during allergic diseases.
Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Aomori, Japan; Research Center for Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Aomori, Japan. Electronic address: mnakano@hirosaki-u.ac.jp.
Manabu
M
Nakano
Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Aomori, Japan; Research Center for Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Aomori, Japan.
Koichi
K
Ito
Department of Medical Technology, Hirosaki University School of Health Sciences, Aomori, Japan.
Takeo
T
Yuno
Department of Medical Technology, Hirosaki University School of Health Sciences, Aomori, Japan.
Nobuyuki
N
Soma
Department of Medical Technology, Hirosaki University School of Health Sciences, Aomori, Japan.
Syun
S
Aburakawa
Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Aomori, Japan; Research Center for Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Aomori, Japan.
Kosuke
K
Kasai
Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Aomori, Japan; Research Center for Biomedical Sciences, Hirosaki University Graduate School of Health Sciences, Aomori, Japan.
Toshiya
T
Nakamura
Department of Bioscience and Laboratory Medicine, Hirosaki University Graduate School of Health Sciences, Aomori, Japan.
Hideki
H
Takami
D000328:Adult; D001491:Basophils / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D015550:Cell Degranulation / Q000187:drug effects / Q000276:immunology*; D002470:Cell Survival / Q000187:drug effects / Q000276:immunology; D015870:Gene Expression; D064368:Healthy Volunteers; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood / Q000276:immunology*; D017879:Isothiocyanates / Q000494:pharmacology; D011755:Pyrophosphatases / Q000235:genetics / Q000378:metabolism; D018048:Receptors, Purinergic P2 / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D013890:Thiourea / Q000031:analogs & derivatives / Q000494:pharmacology; D014530:Uridine Diphosphate / Q000378:metabolism*; D014544:Uridine Triphosphate / Q000378:metabolism; D055815:Young Adult
D017879:Isothiocyanates; C541384:N,N''-1,4-butanediylbis(N'-(3-isothiocyanatophenyl))thiourea; D018048:Receptors, Purinergic P2; C099845:purinoceptor P2Y6; D007073:Immunoglobulin E; D014530:Uridine Diphosphate; D011755:Pyrophosphatases; C439652:nucleoside-triphosphate diphosphohydrolase 3; D013890:Thiourea; D002118:Calcium; D014544:Uridine Triphosphate
Basophil; IgE-dependent degranulation; MRS2578; P2Y6; UDP