RFC-1 gene expression regulates folate absorption in mouse small intestine Journal Article
| Authors: | Chiao, J. H.; Roy, K.; Tolner, B.; Yang, C. H.; Sirotnak, F. M. |
| Article Title: | RFC-1 gene expression regulates folate absorption in mouse small intestine |
| Abstract: | Mediated folate compound transport inward in isolated luminal epithelial cells from mouse small intestine was delineated as pH-dependent and non-pH- dependent components on the basis of their differential sensitivity to the stilbene inhibitor, 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid. pH dependence was manifested as higher maximum capacity (V(max)) for influx of l,L-5-CH3-H4folate at acidic pH compared with neutral or alkaline pH with no effect on saturability (K(m)). The pH-dependent component was relatively insensitive to inhibition by 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid and highly saturable (K(m) or K(i) = 2 to 4 μM) in the case of folic acid, folate coenzymes, and 4-aminofolate analogues as permeants or inhibitors. The non-pH-dependent component was highly sensitive to 4,4'- diisothiocyanatostilbene-2,2'-disulfonic acid and poorly and variably saturable (K(m) or K(i) = 20 to >2000 μM) with respect to these folate compounds. Only the pH-dependent transport component was developmentally regulated, showing much higher maximum capacity for l,L-5-CH3-H4folate influx in mature absorptive rather than proliferative crypt cells. The increase in pH-dependent influx during maturation was associated with an increase in RFC-1 gene expression in the form of a 2.5-kilobase RNA transcript and 58-kDa brush-border membrane protein detected by folate-based affinity labeling and with antimouse RFC-1 peptide antibodies. The size of this protein was the same as that encoded by RFC-1 mRNA. The treatment of mature absorptive cells with either the affinity label or the anti-RFC-1 peptide antibodies inhibited influx of l,L-[3H]-5-CH3-H4folate in a concentration-dependent manner. These results strongly suggest that pH- dependent folate absorption in this tissue is regulated by RFC-1 gene expression. |
| Keywords: | controlled study; nonhuman; polymerase chain reaction; animal cell; mouse; animals; mice; animal tissue; gene expression; membrane proteins; ph; intracellular transport; mice, inbred c57bl; animalia; messenger rna; rna, messenger; carrier proteins; membrane protein; immunoblotting; intestine epithelium cell; folic acid; epithelium; intestine, small; biological transport; aminopterin; northern blotting; affinity labeling; transport kinetics; absorption; membrane transport proteins; crypt cell; polyclonal antibody; mice, inbred dba; succinimides; tetrahydrofolates; aminopterin derivative; affinity labels; 4,4' diisothiocyanatostilbene 2,2' disulfonic acid; 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid; priority journal; article; brush border; small intestine absorption |
| Journal Title: | Journal of Biological Chemistry |
| Volume: | 272 |
| Issue: | 17 |
| ISSN: | 0021-9258 |
| Publisher: | American Society for Biochemistry and Molecular Biology |
| Date Published: | 1997-04-25 |
| Start Page: | 11165 |
| End Page: | 11170 |
| Language: | English |
| DOI: | 10.1074/jbc.272.17.11165 |
| PUBMED: | 9111015 |
| PROVIDER: | scopus |
| DOI/URL: | |
| Notes: | Article -- Export Date: 17 March 2017 -- Source: Scopus |
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