Regulation by retinoids of P2Y2nucleotide receptor mRNA in human uterine cervical cells

Abstract

Extracellular ATP stimulates acute changes in paracellular permeability across cultures of human uterine cervical epithelial cells [G. I. Gorodeski, D. E. Peterson, B. J. De Santis, and U. Hopfer. Am. J. Physiol. 270 ( Cell Physiol. 39): C1715–C1725, 1996]. In this paper, we characterize mRNA for a P2Y2nucleotide receptor in human cervical cells. Using oligonucleotide primers based on the sequence of human airway epithelium P2Y2receptor, a single 632-bp cDNA band was identified in RT-PCR experiments in extracts of human endocervical and ectocervical tissues and in lysates of human cervical CaSki cells, but not in 3T3 fibroblasts. The nucleotide sequence was homologous to the corresponding human airway epithelium P2Y2receptor. Northern blot analyses revealed hybridization of the P2Y2receptor probe to a 2.0-kb mRNA fragment, as well as to 2.2-, 3.0-, and 4.6-kb species, indicating that human cervical cells express P2Y2receptor mRNA. Incubation of CaSki cells in retinoid-free medium abolished the ATP-induced changes in permeability and decreased the expression of the P2Y2receptor mRNA; treatment with retinoids restored the responses to ATP and upregulated the P2Y2receptor mRNA, suggesting that the receptor mediates ATP-related changes in permeability. Treatment with actinomycin D decreased the expression of the P2Y2receptor RNA, but the ratio density of the receptor RNA relative to glyceraldehyde-3-phosphate dehydrogenase RNA remained unchanged, suggesting that retinoids upregulate transcription of the receptor mRNA. We conclude that retinoid-dependent modulation of the P2Y2receptor expression, and hence of the responses to ATP, may be an important mechanism for the regulation of secretion of cervical mucus in vivo.