Over-expression of methionine sulfoxide reductase A in the endoplasmic reticulum increases resistance to oxidative and ER stresses

Abstract

MsrA and MsrB catalyze the reduction of methionine-Ssulfoxide and methionine-R-sulfoxide, respectively, to methionine in different cellular compartments of mammalian cells. One of the three MsrBs, MsrB3, is an endoplasmic reticulum (ER)-type enzyme critical for stress resistance including oxidative and ER stresses. However, there is no evidence for the presence of an ER-type MsrA or the ER localization of MsrA. In this work, we developed an ER-targeted recombinant MsrA construct and investigated the potential effects of methionine-S-sulfoxide reduction in the ER on stress resistance. The ER-targeted MsrA construct contained the N-terminal ER-targeting signal peptide of human MsrB3A (MSPRRSLPRPLSLCLSLCLCLCLAAALGSAQ) and the C-terminal ER-retention signal sequence (KAEL). The over-expression of ER-targeted MsrA significantly increased cellular resistance to H 2 O 2 -induced oxidative stress. The ER-targeted MsrA over-expression also significantly enhanced resistance to dithiothreitol-induced ER stress; however, it had no positive effects on the resistance to ER stresses induced by tunicamycin and thapsigargin. Collectively, our data suggest that methionine-S-sulfoxide reduction in the ER compartment plays a protective role against oxidative and ER stresses.

Antagonistic relationship between the unfolded protein response and myocardin‐driven transcription in smooth muscle

“…Fifty‐eight genes were found in the overlap between these data sets (Figure 5a), and when individually scrutinized, the gene MSRB3 captured our attention. MSRB3 encodes a methionine sulfoxide reductase that resides in the ER and that was shown to antagonize ER stress and UPR activation (Kim, Kim, Kwak, Oh, & Kim, 2014; Kwak & Kim, 2017). In keeping with the view that MSRB3 is a novel SMC marker, we found that it correlated tightly with other SMC markers, such as MYH11 , and with MYOCD and SRF across human tissues (Figure 5b–d).…”

“…Induction of The coupling between the SMC and UPR gene programs may be reciprocal because we find that forced SMC differentiation by overexpression of MYOCD/MRTF-A also mitigates UPR activation. Using bioinformatics we identified MSRB3 as a possible mediator of this effect (Kim et al, 2014;Kwak & Kim, 2017), and we could demonstrate that MSRB3 is a direct target gene of MYOCD/MRTF-A. Silencing of MSRB3 did however not mitigate the anti-UPR effect of MYOCD/MRTF-A (reduced CALR induction), leaving this effect unexplained.…”

“…Expression of UPR (blue) and SMC markers (red) were determined by RT-qPCR alongside cell viability (black). DTT, dithithreitol; ER, endoplasmic reticulum; FC, fold change; RT-qPCR, reverse transcription quantitative polymerase chain reaction; SMC, smooth muscle cell; TN, tunicamycin; UPR, unfolded protein response that resides in the ER and that was shown to antagonize ER stress and UPR activation (Kim, Kim, Kwak, Oh, & Kim, 2014;Kwak & Kim, 2017). In keeping with the view that MSRB3 is a novel SMC marker, we found that it correlated tightly with other SMC markers, such as MYH11, and with MYOCD and SRF across human tissues (Figure 5b-d).…”

The Oxidized Protein Repair Enzymes Methionine Sulfoxide Reductases and Their Roles in Protecting against Oxidative Stress, in Ageing and in Regulating Protein Function

“…The role for MsrA in the prevention against the accumulation of protein and cellular oxidative damage provoked by H 2 O 2 -induced oxidative stress was also studied in fibroblast cells [119] and was associated in these cells to MsrA-dependent differentially expression proteins implicated in protection against oxidative stress, apoptosis, and premature ageing [120]. Even though overexpression of MsrA in the endoplasmic reticulum of mammalian cells increases their resistance to oxidative and endoplasmic reticulum stresses [121], the resistance to an endoplasmic reticulum stress is mainly conferred by MsrB3 [41,122]. Finally, in human skin cells, the behavior of the MsrA enzyme seems to be dependent on the type of ultraviolet (UV) exposure and the dose applied, suggesting a hormetic response to environmental stress.…”

Structure and Electron-Transfer Pathway of the Human Methionine Sulfoxide Reductase MsrB3

“…1A ). Experimentally fusing the MsrB3 signal peptide and ER retention signal onto MsrA rerouted it to the ER, indicating that these sequences are functional for organelle targeting ( 24 ). Interestingly, an in-depth study of Lys-Asp-Glu-Leu-like ER retention signals revealed that MsrB3 remains localized to the ER even when truncated before its Lys-Ala-Glu-Leu (KAEL) sequence ( 42 ).…”