Evidence for the expression of transient receptor potential proteins in guinea pig airway smooth muscle cells.
OBJECTIVE
The present study investigates the expression of transient receptor potential (TRPC) proteins in airway smooth muscle (ASM) cells in order to determine whether these proteins may be candidate molecular counterparts of plasma membrane Ca2+-permeable channels involved in the contraction of ASM.


METHODS
Expression of TRPC mRNA was detected using specific primers and RT-PCR. Expression of the TRPC1, TRPC3 and TRPC6 proteins was detected using antibodies in immunoprecipitation and Western blot.


RESULTS
Guinea pig ASM cells exhibited thapsigargin- and acetylcholine-initiated Ca2+ inflow but none by 1-oleoyl-2-acetyl-sn-glycerol. mRNA encoding each of the TRPC1 to TRPC6 proteins was detected in ASM cells. mRNA encoding TRPC1, TRPC3, TRPC4 and TRPC6 was detected in ASM cells at a concentration approximately equivalent to that in guinea pig brain. mRNA encoding TRPC2 and TRPC5 was more abundant in ASM cells than in brain. The TRPC1 protein, but not the TRPC3 or TRPC6 proteins, was detected in extracts of ASM cells, while all three proteins were detected in brain.


CONCLUSIONS
The results provide evidence for a low level of expression of the TRPC1 to TRPC6 proteins in ASM cells. These proteins may function as store-operated Ca2+ and/or second messenger-activated non-selective cation channels in ASM cells.
Ong
Hwei L
HL
Department of Medical Biochemistry, School of Medicine, Flinders University, Adelaide, South Australia, Australia.
Brereton
Helen M
HM
Harland
M Lyn
ML
Barritt
Greg J
GJ
D000403:Airway Resistance / Q000235:genetics; D000818:Animals; D001249:Asthma / Q000235:genetics / Q000503:physiopathology; D001483:Base Sequence; D001921:Brain / Q000166:cytology; D015220:Calcium Channels / Q000235:genetics*; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D006168:Guinea Pigs; D007473:Ion Channels; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D009130:Muscle, Smooth / Q000166:cytology; D012333:RNA, Messenger / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D050053:TRPM Cation Channels; D014132:Trachea / Q000166:cytology
D015220:Calcium Channels; D007473:Ion Channels; D008565:Membrane Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human