Stem-loop binding protein localization, expression patterns, and regulation of histone mRNA in wild-type and transgenic mouse oocytes

Abstract

Histone proteins are essential for the cell cycle and are massively accumulated during S-phase of cell division in somatic cells and during early oogenesis. Histone mRNA differs from the majority of metazoan mRNA by terminating with a highly conserved stem-loop in its 3’-untranslated region. The stem-loop binding protein (SLBP) is the only known protein specifically binding to histone mRNA stem-loops and is believed to be responsible for the regulation of histone translation. SLBP is thought to also control mRNA levels through stabilization and post-transcriptional processing. We studied the localization and expression pattern of SLBP in ovaries of wild-type and transgenic mice using immunohistochemistry and immunofluorescence techniques. Our data show that SLBP translocates from the cytoplasm of developing oocytes to the nucleus shortly after release from meiotic arrest. SLBP subsequently localizes back out into the cytoplasm as the oocyte continues its maturation. Our transgenic mice show a significant decrease in SLBP expression levels. The results present encouraging evidence for the role and localization of SLBP during oogenesis.