Sdf2, or stromal cell-derived factor 2, is an endoplasmic reticulum (ER)-resident protein [2]. It belongs to the stromal derived factor (SDFs) family. Sdf2 is involved in multiple biological processes such as the unfolded protein response (UPR) pathway when the ER is stressed due to misfolded protein accumulation [1,2,4,7]. It is also associated with protein quality control in the ER [5].

In rice, silencing of Sdf2 genes in the XA21 rice genetic background compromises resistance to Xanthomonas oryzae pv. oryzae (Xoo), indicating its importance in XA21-mediated immunity [3]. In endothelial cells, Sdf2 knockdown impairs agonist-stimulated NO synthesis and decreases the phosphorylation of eNOS at Ser(1177), while overexpression enhances NO synthesis, suggesting its role in Hsp90-dependent eNOS activation [6].

In conclusion, Sdf2 is crucial for processes like the UPR, protein quality control, plant immunity, and endothelial cell signal transduction. Its study in different models helps understand its role in various biological functions and disease-related processes, such as potential implications in pre-eclampsia which is associated with ER stress [1].

References:

1. Lorenzon-Ojea, Aline R, Yung, Hong Wa, Burton, Graham J, Bevilacqua, Estela. 2019. The potential contribution of stromal cell-derived factor 2 (SDF2) in endoplasmic reticulum stress response in severe preeclampsia and labor-onset. In Biochimica et biophysica acta. Molecular basis of disease, 1866, 165386. doi:10.1016/j.bbadis.2019.01.012. https://pubmed.ncbi.nlm.nih.gov/30776414/

2. Lorenzon-Ojea, Aline R, Caldeira, Waldir, Ribeiro, Alberto F, Guzzo, Cristiane R, Bevilacqua, Estela. 2014. Stromal cell derived factor-2 (Sdf2): a novel protein expressed in mouse. In The international journal of biochemistry & cell biology, 53, 262-70. doi:10.1016/j.biocel.2014.05.024. https://pubmed.ncbi.nlm.nih.gov/24878610/

3. Park, Chang-Jin, Sharma, Rita, Lefebvre, Benoit, Canlas, Patrick E, Ronald, Pamela C. 2013. The endoplasmic reticulum-quality control component SDF2 is essential for XA21-mediated immunity in rice. In Plant science : an international journal of experimental plant biology, 210, 53-60. doi:10.1016/j.plantsci.2013.05.003. https://pubmed.ncbi.nlm.nih.gov/23849113/

4. Schott, Andrea, Ravaud, Stéphanie, Keller, Sabrina, Sinning, Irmgard, Strahl, Sabine. 2010. Arabidopsis stromal-derived Factor2 (SDF2) is a crucial target of the unfolded protein response in the endoplasmic reticulum. In The Journal of biological chemistry, 285, 18113-21. doi:10.1074/jbc.M110.117176. https://pubmed.ncbi.nlm.nih.gov/20378538/

5. Fujimori, Tsutomu, Suno, Ryoji, Iemura, Shun-Ichiro, Wada, Ikuo, Hosokawa, Nobuko. 2017. Endoplasmic reticulum proteins SDF2 and SDF2L1 act as components of the BiP chaperone cycle to prevent protein aggregation. In Genes to cells : devoted to molecular & cellular mechanisms, 22, 684-698. doi:10.1111/gtc.12506. https://pubmed.ncbi.nlm.nih.gov/28597544/

6. Siragusa, Mauro, Fröhlich, Florian, Park, Eon Joo, Walther, Tobias C, Sessa, William C. 2015. Stromal cell-derived factor 2 is critical for Hsp90-dependent eNOS activation. In Science signaling, 8, ra81. doi:10.1126/scisignal.aaa2819. https://pubmed.ncbi.nlm.nih.gov/26286023/

7. Schott, Andrea, Strahl, Sabine. . Methods to study stromal-cell derived factor 2 in the context of ER stress and the unfolded protein response in Arabidopsis thaliana. In Methods in enzymology, 490, 295-319. doi:10.1016/B978-0-12-385114-7.00017-9. https://pubmed.ncbi.nlm.nih.gov/21266257/