TRPC channel expression during calcium-induced differentiation of human gingival keratinocytes.
BACKGROUND
Extracellular calcium is an important regulator of keratinocyte differentiation. An increase in intracellular calcium ion concentration is required for activation of calcium-induced keratinocyte differentiation. The signaling elements in this differentiation response include the calcium sensing receptor, phospholipase C, release of calcium ions from intracellular stores, and store-operated calcium channels. Nothing is currently known about the calcium-entry channels activated by the increase in external calcium. However, canonical transient receptor potential (TRPC) channels have been identified as store-operated calcium channels in several tissues.


OBJECTIVE
To examine the expression of TRPC channels in human gingival keratinocytes (HGKs) in primary culture under both low calcium (basal) and high calcium (differentiating) conditions, and in gingival tissue.


METHODS
TRPC channel expression was evaluated via RT-PCR, Western blots, and immunohistology.


RESULTS
TRPC1, TRPC5, TRPC6 and TRPC7 mRNAs were detected in undifferentiated keratinocytes. Their levels initially increased, then decreased during calcium-induced differentiation. TRPC1 and TRPC6 protein expression reflected these changes.


CONCLUSIONS
TRPC channels are present in both proliferating and differentiating keratinocytes in primary culture and in gingival tissue. The above expression patterns suggest that these channels may be involved in calcium-induced differentiation of keratinocytes.
Cai
Shiwei
S
Department of Oral Biology, University of Washington, Box 357132, Seattle, WA 98195-6524, USA.
Fatherazi
Sahba
S
Presland
Richard B
RB
Belton
Carol M
CM
Izutsu
Kenneth T
KT
D002118:Calcium / Q000494:pharmacology*; D015220:Calcium Channels / Q000235:genetics*; D027682:Cation Transport Proteins / Q000235:genetics*; D002454:Cell Differentiation; D002478:Cells, Cultured; D005881:Gingiva / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007473:Ion Channels / Q000235:genetics*; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics*; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D050052:TRPC Cation Channels; D000074287:TRPC6 Cation Channel; D050053:TRPM Cation Channels
D015220:Calcium Channels; D027682:Cation Transport Proteins; D007473:Ion Channels; D008565:Membrane Proteins; D011498:Protein Precursors; D012333:RNA, Messenger; D050052:TRPC Cation Channels; C491780:TRPC5 protein, human; D000074287:TRPC6 Cation Channel; C117032:TRPC6 protein, human; C498501:TRPC7 protein, human; D050053:TRPM Cation Channels; C121934:TRPM2 protein, human; C096351:transient receptor potential cation channel, subfamily C, member 1; C032253:involucrin; D002118:Calcium