PDIA3 inhibits mitochondrial respiratory function in brain endothelial cells and C. elegans through STAT3 signaling and decreases survival after OGD

Abstract

Background Protein disulfide isomerase A3 (PDIA3, also named GRP58, ER-60, ERp57) is conserved across species and mediates protein folding in the endoplasmic reticulum. PDIA3 is, reportedly, a chaperone for STAT3. However, the role of PDIA3 in regulating mitochondrial bioenergetics and STAT3 phosphorylation at serine 727 (S727) has not been described. Methods Mitochondrial respiration was compared in immortalized human cerebral microvascular cells (CMEC) wild type or null for PDIA3 and in whole organism C. Elegans WT or null for pdi-3 (worm homologue). Mitochondrial morphology and cell signaling pathways in PDIA3-/- and WT cells were assessed. PDIA3-/- cells were subjected to oxygen–glucose deprivation (OGD) to determine the effects of PDIA3 on cell survival after injury. Results We show that PDIA3 gene deletion using CRISPR-Cas9 in cultured CMECs leads to an increase in mitochondrial bioenergetic function. In C. elegans, gene deletion or RNAi knockdown of pdi-3 also increased respiratory rates, confirming a conserved role for this gene in regulating mitochondrial bioenergetics. The PDIA3-/- bioenergetic phenotype was reversed by overexpression of WT PDIA3 in cultured PDIA3-/- CMECs. PDIA3-/- and siRNA knockdown caused an increase in phosphorylation of the S727 residue of STAT3, which is known to promote mitochondrial bioenergetic function. Increased respiration in PDIA3-/- CMECs was reversed by a STAT3 inhibitor. In PDIA3-/- CMECs, mitochondrial membrane potential and reactive oxygen species production, but not mitochondrial mass, was increased, suggesting an increased mitochondrial bioenergetic capacity. Finally, PDIA3-/- CMECs were more resistant to oxygen–glucose deprivation, while STAT3 inhibition reduced the protective effect. Conclusions We have discovered a novel role for PDIA3 in suppressing mitochondrial bioenergetic function by inhibiting STAT3 S727 phosphorylation.

PDIA3 knockout abrogate effects of 1,25(OH)2D3 on cellular respiration and glycolysis in squamous cell carcinoma

“…All of the respiratory parameters of A431 cells were considerably elevated after PDIA3 deletion. Presented data are in line with results published by Keasey et al, who had shown that PDIA3 inhibits respiratory function in endothelial cells and C.elegans 12 . Previously, PDIA3 was localized within mitochondria, where it associates with mitochondrial μ-calpain, possibly playing a signi cant role in apoptotic signaling 39 .…”

“…As we didn't identify any PDIA3-dependent mtDEGs, we suggest that the main effects of 1,25(OH) 2 D 3 are genomic actions mediated by VDR and partially by RXRA (Olszewska et al 2023, under review). As PDIA3 was found also in mitochondria, the direct impact on mitochondrial structure and function cannot be excluded 12,39,46 . Data presented here, broaden our knowledge about the role of PDIA3 in 1,25(OH) 2 D 3 activities on mitochondria and open new perspectives to explore that topic.…”

Cellular Organelle-Related Transcriptomic Profile Abnormalities in Neuronopathic Types of Mucopolysaccharidosis: A Comparison with Other Neurodegenerative Diseases

“…The involvement of this glycoprotein has been confirmed by processes mediating the translocation of secretory proteins and maintaining the specificity of the murine ER, or N-glycosylating proteins. In contrast, PDIA3 encodes the protein disulfide isomerase A3, which is a thioloxidoreductase found primarily in the RE endoplasm in the cytosol or cell nucleus [ 35 ]. The product of this gene, the PDIA3 protein, is responsible for regulating the folding of newly synthesized glycoproteins and promoting the re-folding of misfolded proteins.…”

ERp57/PDIA3: new insight

“…Moreover, in ERp57/PDIA3 −/− CMECs, the mitochondrial membrane potential and reactive oxygen species production was increased, but not mitochondrial mass. Finally, ERp57/PDIA3 −/− CMECs were more resistant to oxygen–glucose deprivation [ 47 ].…”