A mammalian monothiol glutaredoxin, Grx3, is critical for cell cycle progression during embryogenesis

<jats:p>Glutaredoxins (Grxs) have been shown to be critical in maintaining redox homeostasis in living cells. Recently, an emerging subgroup of Grxs with one cysteine residue in the putative active motif (monothiol Grxs) has been identified. However, the biological and physiological functions of this group of proteins have not been well characterized. Here, we characterize a mammalian monothiol Grx (Grx3, also termed TXNL2/PICOT) with high similarity to yeast ScGrx3/ScGrx4. In yeast expression assays, mammalian Grx3s were localized to the nuclei and able to rescue growth defects of <jats:italic>grx3grx4</jats:italic> cells. Furthermore, Grx3 inhibited iron accumulation in yeast <jats:italic>grx3gxr4</jats:italic> cells and suppressed the sensitivity of mutant cells to exogenous oxidants. In mice, <jats:italic>Grx3</jats:italic> mRNA was ubiquitously expressed in developing embryos, adult tissues and organs, and was induced during oxidative stress. Mouse embryos absent of <jats:italic>Grx3</jats:italic> grew smaller with morphological defects and eventually died at 12.5 days of gestation. Analysis in mouse embryonic fibroblasts revealed that <jats:italic>Grx3</jats:italic><jats:sup>−/−</jats:sup> cells had impaired growth and cell cycle progression at the G<jats:sub>2</jats:sub>/M phase, whereas the DNA replication during the S phase was not affected by <jats:italic>Grx3</jats:italic> deletion. Furthermore, Grx3‐knockdown HeLa cells displayed a significant delay in mitotic exit and had a higher percentage of binucleated cells. Therefore, our findings suggest that the mammalian Grx3 has conserved functions in protecting cells against oxidative stress and deletion of <jats:italic>Grx3</jats:italic> in mice causes early embryonic lethality which could be due to defective cell cycle progression during late mitosis.</jats:p><jats:p><jats:bold>Structured digital abstract</jats:bold></jats:p><jats:p><jats:list list-type="explicit-label"> <jats:list-item><jats:p> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.uniprot.org/uniprot/Q9CQM9">MmGRX3</jats:ext-link> and <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.uniprot.org/uniprot/Q03835">ScGRX3</jats:ext-link> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0403">colocalize</jats:ext-link> by <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://www.ebi.ac.uk/ontology-lookup/?termId=MI:0416">fluorescence microscopy</jats:ext-link> <jats:ext-link xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="http://mint.bio.uniroma2.it/mint/search/interaction.do?interactionAc=MINT-8174940">(View interaction)</jats:ext-link></jats:p></jats:list-item> </jats:list></jats:p>