TRPC7 is a receptor-operated DAG-activated channel in human keratinocytes.
Muscarinic and purinergic receptors expressed in keratinocytes are an important part of a functional system for cell growth. While several aspects of this process are clearly dependent on Ca(2+) homeostasis, less is known about the mechanisms controlling Ca(2+) entry during epidermal receptor stimulation. We used patch-clamp technique to study responses to carbachol (CCh) and adenosine triphosphate (ATP) in HaCaT human keratinocytes. Both agonists induced large currents mediated by cation-selective channels about three times more permeable to Ca(2+) than Na(+), suggesting that they play an important role in receptor-operated Ca(2+) entry. CCh- and ATP-induced currents were inhibited by 1-[6-([(17beta)-3-methoxyestra-1,3,5(10)-trien-17-yl]amino)hexyl]-1H-pyrrole-2,5-dione, a phospholipase C (PLC) blocker. Investigation of the pathways downstream of PLC activation revealed that InsP(3) did not affect the agonist responses. In contrast, 1-oleoyl-2-acetyl-sn-glycerol (OAG), a membrane-permeable analog of 1,2-diacylglycerol (DAG), evoked a similar cation current. This action appears to be direct, since the effects of activators or inhibitors of protein kinase C were comparatively small. Finally, transient receptor potential canonical 7 (TRPC7) specific knockdown by antisense oligonucleotides led to a decrease in ATP- and CCh-induced calcium entry, as well as OAG-evoked current. We concluded that activation of both muscarinic and purinergic receptors via a common DAG-dependent link opens Ca(2+)-permeable TRPC7 channels.
Beck
Benjamin
B
Laboratoire de Physiologie Cellulaire, inserm, U800, Equipe labellisée par la Ligue contre le cancer, Villeneuve d'Ascq, France.
Zholos
Alexander
A
Sydorenko
Vadym
V
Roudbaraki
Morad
M
Lehen'kyi
V'yacheslav
V
Bordat
Pascal
P
Prevarskaya
Natalia
N
Skryma
Roman
R
D000255:Adenosine Triphosphate / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D018679:Cholinergic Agonists / Q000494:pharmacology; D004075:Diglycerides / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000166:cytology / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D018408:Patch-Clamp Techniques; D011976:Receptors, Muscarinic / Q000502:physiology; D011983:Receptors, Purinergic / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D050052:TRPC Cation Channels / Q000235:genetics / Q000502:physiology*
D018679:Cholinergic Agonists; D004075:Diglycerides; D016376:Oligonucleotides, Antisense; D011976:Receptors, Muscarinic; D011983:Receptors, Purinergic; D050052:TRPC Cation Channels; C498501:TRPC7 protein, human; D000255:Adenosine Triphosphate; D002217:Carbachol; D002118:Calcium