Deficiency of lysophosphatidic acid receptor 3 decreases the erythropoietin production in hypoxic mouse kidney

As a simple lipid mediator, Lysophosphatidic acid (LPA) exerts its function by binding to 6 GPCRs (LPAR1-6) on the cell membrane. Among the 6 LPA receptors, LPAR3 is highly expressed in mouse kidney, where it has only been found to play a harmful role in kidney ischemia-reperfusion injury and diabetic nephropathy. Our previous research and other researchers found the correlation between the ATX-LPA-LPAR axis and hypoxia-related biological processes. The kidney is one of the most susceptible organs to hypoxia. It is therefore interesting to identify the function of LPAR3 in hypoxic mice kidneys. In this study, the wild-type (WT) and Lpar3-/- mice were put into a normobaric hypoxic installation and RNA sequencing analysis showed that Lpar3-/- mice showed a significant decrease in hypoxia-induced EPO expression in the kidney compared with WT mice. The impaired EPO gene expression resulted in reduced plasma EPO levels and lower hematocrit and hemoglobin levels. The KEGG enrichment analysis revealed the reduced accumulation of HIF-2α caused by LPAR3 deficiency may be the reason for insufficient hypoxic renal EPO production. In in-vitro hypoxic cell models (Hep3B cells and HK2 cells), targeting LPAR3 can also regulate HIF-2α and EPO expression. KEGG analysis revealed that the PI3K/Akt signaling pathway was involved in the regulation of LPAR3 on HIF-2α-EPO, which was validated at the tissue level and cell level. Taken together, this study demonstrates that the murine renal LPAR3 promotes HIF-2α accumulation to maintain renal EPO production by activating the downstream PI3K/Akt pathway, ensuring the generation of red blood cells in mice and plays an important role in the body's adaptation to hypoxia.