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This Article Full Text Full Text (PDF) All Versions of this Article: 296/6/C1373    most recent 00053.2009v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Google Scholar Articles by Thongon, N. Articles by Charoenphandhu, N. PubMed PubMed Citation Articles by Thongon, N. Articles by Charoenphandhu, N.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Enhancement of calcium transport in Caco-2 monolayer through PKC-dependent Ca_v1.3-mediated transcellular and rectifying paracellular pathways by prolactin

¹Consortium for Calcium and Bone Research (COCAB) and ²Department of Physiology, Faculty of Science, Mahidol University, Bangkok, Thailand; and ³Department of Medical Science, Faculty of Science, Burapha University, Chonburi, Thailand

Submitted 28 January 2009 ; accepted in final form 29 March 2009

Previous investigations suggested that prolactin (PRL) stimulated the intestinal calcium absorption through phosphoinositide 3-kinase (PI3K), protein kinase C (PKC), and RhoA-associated coiled-coil forming kinase (ROCK) signaling pathways. However, little was known regarding its detailed mechanisms for the stimulation of transcellular and voltage-dependent paracellular calcium transport. By using Ussing chamber technique, we found that the PRL-induced increase in the transcellular calcium flux and decrease in transepithelial resistance of intestinal-like Caco-2 monolayer were not abolished by inhibitors of gene transcription and protein biosynthesis. The PRL-stimulated transcellular calcium transport was completely inhibited by the L-type calcium channel blockers (nifedipine and verapamil) and plasma membrane Ca²⁺-ATPase (PMCA) inhibitor (trifluoperazine) as well as small interfering RNA targeting voltage-dependent L-type calcium channel Ca_v1.3, but not TRPV6 or calbindin-D_9k. As demonstrated by ⁴⁵Ca uptake study, PI3K and PKC, but not ROCK, were essential for the PRL-enhanced apical calcium entry. In addition, PRL was unable to enhance the transcellular calcium transport after PKC knockdown or exposure to inhibitors of PKC, but not of PKC, PKC_β, PKC, PKC_µ, or protein kinase A. Voltage-clamping experiments further showed that PRL markedly stimulated the voltage-dependent calcium transport and removed the paracellular rectification. Such PRL effects on paracellular transport were completely abolished by inhibitors of PI3K (LY-294002) and ROCK (Y-27632). It could be concluded that the PRL-stimulated transcellular calcium transport in Caco-2 monolayer was mediated by Ca_v1.3 and PMCA, presumably through PI3K and PKC pathways, while the enhanced voltage-dependent calcium transport occurred through PI3K and ROCK pathways.

calcium uptake; protein kinase C; rectification; small interfering RNA; voltage-dependent calcium transport

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