A calcium channel in human submandibular duct cell line, HSG cells, not regulated by P2U purinergic receptor-mediated intracellular calcium mobilization.
Signal transduction via P2 purinergic receptors was investigated in HSG cells, a continuous cell line originally derived from an irradiated human salivary gland. Ligand specificity for nucleotide receptors in HSG cells was investigated with various nucleotides and their analogues. Inositol 1,4,5-trisphosphate (IP3) production was significantly increased by ATP, UTP and ATP gamma S. The ligand specificity of this effect agreed well with that of the P2U purinergic receptor. On the other hand, 45Ca2+ influx was stimulated by ATP, UTP > ATP gamma S, ADP, UDP > ADP beta S > AMPPNP, GTP, TTP > CTP, GDP, TDP, AMPPCP, AMPCPP. This ligand specificity of 45Ca2+ influx was much broader than IP3 production. Also pertussis and cholera toxin had no effect on both IP3 production and 45Ca2+ influx by ATP or UTP. 3'-O-(4-benzoylbenzoyl)adenosine 5'-triphosphate (Bz-ATP) stimulates 45Ca2+ influx more effectively than IP3 formation. A 53-kDa membrane protein was photolabelled with [alpha-32P]Bz-ATP. This 53-kDa protein is a putative P2 purinergic receptor. In particular, the labelling was inhibited by a ligand profile that corresponded to that for 45Ca2+ influx. These findings suggest that nucleotides stimulate 45Ca2+ influx and IP3 formation by separate pathways via pertussis and cholera toxin-insensitive G proteins. Thus, in HSG cells, IP3 formation is coupled to the P2U subclass, while 45Ca2+ influx is coupled to another subclass, such as P2X, that regulates calcium channels.
Kurihara
K
K
Department of Oral Physiology, Meikai University School of Dentistry, Saitama, Japan. kkinji@dent.meikai.ac.jp
Nakanishi
N
N
Ueha
T
T
D000227:Adenine Nucleotides / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000345:Affinity Labels; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000187:drug effects*; D002132:Calcium Radioisotopes; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D003570:Cytidine Triphosphate / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000187:drug effects; D006153:Guanosine Diphosphate / Q000494:pharmacology; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D008024:Ligands; D008565:Membrane Proteins / Q000187:drug effects; D037342:Pertussis Toxin; D019275:Radiopharmaceuticals; D011983:Receptors, Purinergic / Q000187:drug effects*; D018987:Salivary Ducts / Q000166:cytology / Q000187:drug effects*; D015398:Signal Transduction / Q000187:drug effects*; D013363:Submandibular Gland / Q000166:cytology / Q000187:drug effects*; D013379:Substrate Specificity; D013873:Thionucleotides / Q000494:pharmacology; D013942:Thymine Nucleotides / Q000494:pharmacology; D014544:Uridine Triphosphate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D000227:Adenine Nucleotides; D000345:Affinity Labels; D015220:Calcium Channels; D002132:Calcium Radioisotopes; D008024:Ligands; D008565:Membrane Proteins; D019275:Radiopharmaceuticals; D011983:Receptors, Purinergic; D013873:Thionucleotides; D013942:Thymine Nucleotides; D010566:Virulence Factors, Bordetella; D006153:Guanosine Diphosphate; D000266:Adenylyl Imidodiphosphate; C005147:5'-adenylyl (beta,gamma-methylene)diphosphonate; C030812:adenosine 5'-O-(2-thiodiphosphate); C022571:adenosine 5'-O-(3-thiotriphosphate); C033901:3'-O-(4-benzoyl)benzoyladenosine 5'-triphosphate; D000244:Adenosine Diphosphate; D003570:Cytidine Triphosphate; D015544:Inositol 1,4,5-Trisphosphate; D000255:Adenosine Triphosphate; D002772:Cholera Toxin; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; C024157:thymidine 5'-triphosphate; D002118:Calcium; D014544:Uridine Triphosphate