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Whi3p Localizes To Cytoplasmic Foci During Slow Growth At High OD In Saccharyomyces cerevisiae
Author(s) -
Dégallier Joshua Paul,
Tembreull Jarrod,
Theede Kelly,
Segal Scott P.
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.934.4
Subject(s) - cytoplasm , microbiology and biotechnology , translation (biology) , cell cycle , endoplasmic reticulum , messenger rna , biology , psychological repression , p bodies , stress granule , saccharomyces cerevisiae , rna binding protein , cell cycle checkpoint , cell growth , cell , yeast , gene expression , biochemistry , gene
Regulation of cell cycle progression is necessary to ensure that cells do not undergo uncontrolled division, resulting in reduced cell volume. The cell cycle is regulated by several checkpoints, the most important of which is the G1/S checkpoint. In yeast , the G1/S checkpoint is sensitive to the levels of the mammalian cyclin D homolog Cln3p. To ensure that the cell passes through the G1/S checkpoint at the appropriate time, Cln3p levels throughout G1 phase are, in part, controlled by local translation of the CLN3 mRNA by Whi3p, an ER associated RNA binding protein. Previously, Whi3p was found to genetically interact with SBP1, which encodes a protein involved in general translational repression. This implies that Sbp1p may work in conjunction with Whi3p to control local translation of the CLN3 mRNA. In support, we found that Whi3p is found in cytoplasmic foci at high OD after nutrient exhaustion, where growth is reduced, but are not found during log phase growth. Future studies will determine whether these foci are P‐bodies or stress granules. Furthermore, strains lacking Whi3p have no change in P‐body formation at log phase. Our working model is that Sbp1p represses translation of CLN3 mRNA as it localizes to the endoplasmic reticulum. To ensure repression as the CLN3 mRNA enters the cytoplasm, Sbp1p may associate with the mRNA in the nucleus, as Sbp1p contains a 2‐3‐1 Nuclear Export Sequence.