NLRP14 Safeguards Calcium Homeostasis via Regulating the K27 Ubiquitination of Nclx in Oocyte-to-Embryo Transition.

Abstract

Sperm-induced Ca2+ rise is critical for driving oocyte activation and subsequent embryonic development, but little is known about how lasting Ca2+ oscillations are regulated. Here it is shown that NLRP14, a maternal effect factor, is essential for keeping Ca2+ oscillations and early embryonic development. Few embryos lacking maternal NLRP14 can develop beyond the 2-cell stage. The impaired developmental potential of Nlrp14-deficient oocytes is mainly caused by disrupted cytoplasmic function and calcium homeostasis due to altered mitochondrial distribution, morphology, and activity since the calcium oscillations and development of Nlrp14-deficient oocytes can be rescued by substitution of whole cytoplasm by spindle transfer. Proteomics analysis reveal that cytoplasmic UHRF1 (ubiquitin-like, containing PHD and RING finger domains 1) is significantly decreased in Nlrp14-deficient oocytes, and Uhrf1-deficient oocytes also show disrupted calcium homeostasis and developmental arrest. Strikingly, it is found that the mitochondrial Na+ /Ca2+ exchanger (NCLX) encoded by Slc8b1 is significantly decreased in the Nlrp14mNull oocyte. Mechanistically, NLRP14 interacts with the NCLX intrinsically disordered regions (IDRs)domain and maintain its stability by regulating the K27-linked ubiquitination. Thus, the study reveals NLRP14 as a crucial player in calcium homeostasis that is important for early embryonic development.