Evidence that a specific interaction between an 18-base cis-element in the 5'-untranslated region of human folate receptor-α mRNA and a 46-kDa cytosolic trans-factor is critical for translation

Xin Lai Sun, Aśok C. Antony

Research output: Contribution to journalArticle

36 Scopus citations

Abstract

Folate receptors (FR) are inversely regulated by the extracellular folate concentration at the translational level in cervical carcinoma cells. Accordingly, the potential for interaction of cis-elements in FR-α mRNA and trans-factors in these cells was determined. Gel-shift assays identified two signals that were specifically derived from the interaction of cytosolic proteins with the 5'-untranslated region of FR-α mRNA. RNase T1 mapping revealed that the RNA sequences interacting with these proteins were located between nucleotides -133 to -116 (18-bases) and -158 to -116 (43-bases), upstream of the translation start site. However, selective RNase H cleavage indicated that the 18-base RNA sequence was the cis-element. The RNA-protein interaction was competed by poly(C), but not by poly(U), homopolymers. UV cross-linking and Northwestern blot analysis confirmed that the trans- factors were 46-kDa proteins. An 18-base antisense oligodeoxynucleotide complementary to the cis-element specifically quenched the RNA-protein interaction and also completely inhibited translation of FR-α mRNA without changing its stability. Thus, the interaction of the 18-base cis-element and the 46-kDa trans-factors likely have an important role in translational regulation of FR. In addition, because the 46-kDa proteins were widely distributed in cells expressing little to no FR-α, these species probably have additional functions that are unrelated to translation of FR.

Original languageEnglish (US)
Pages (from-to)25539-25547
Number of pages9
JournalJournal of Biological Chemistry
Volume271
Issue number41
StatePublished - Oct 19 1996

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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