NLRP7 is expressed in the ovine ovary and associated with in vitro pre-implantation embryo development.

Guangdong Li,Zhenzhen Zhang,Yingjie Wu,Lu Zhang,Pengyun Ji,Jing Wang,Guoshi Liu,Dongying Lv,Teng Ma,Minghui Yang,Hao Wu,Xiuzhi Tian,Wei Cui,Zhengxing Lian,Jingli Tao

doi:10.1530/rep-19-0081

Abstract

NLRP (NACHT, LRR and PYD domain-containing proteins) family plays pivotal roles in mammalian reproduction. Mutation of NLRP7 is often associated with human recurrent hydatidiform moles. Few studies regarding the functions of NLRP7 have been performed in other mammalian species rather than humans. In the current study, for the first time, the function of NLRP7 has been explored in ovine ovary. NLRP7 protein was mainly located in ovarian follicles and in in vitro pre-implantation embryos. To identify its origin, 763 bp partial CDS of NLRP7 deriving from sheep cumulus oocyte complexes (COCs) was cloned, it showed a great homology with Homo sapiens. The high levels of mRNA and protein of NLRP7 were steadily expressed in oocytes, parthenogenetic embryos or IVF embryos. NLRP7 knockdown by the combination of siRNA and shRNA jeopardized both the parthenogenetic and IVF embryo development. These results strongly suggest that NLRP7 plays an important role in ovine reproduction. The potential mechanisms of NLRP7 will be fully investigated in the future.

Highlights

NLRs (nucleotide-binding and oligomerization domain (NOD)-like receptors), called CATERPILLER, serve as the intracellular guards to coordinate the innate immunity and inflammatory responses after perception of adverse signals within the cell (Barbé et al 2014, Meunier & Broz 2017)
Current study indicated that NLRP7 is mainly expressed in sheep ovaries and its expression pattern differed from that in human (Kinoshita et al 2005)
The expression pattern of NLRP7 in sheep was similar to its paralog of Nlrp2 in the mouse which was only detected in ovaries, but not in other tested tissues, even the testes (Peng et al 2012)

Summary

Introduction

NLRs (nucleotide-binding and oligomerization domain (NOD)-like receptors), called CATERPILLER (caspase recruitment domain, transcription enhancer, purine binding, pyrin, lots of leucine repeats), serve as the intracellular guards to coordinate the innate immunity and inflammatory responses after perception of adverse signals within the cell (Barbé et al 2014, Meunier & Broz 2017). A subset of phylogenetically related NLRs represents a new category of maternal genes which are highly expressed in oocytes and preimplantation embryos. Mutations of these genes might lead to hereditary reproductive defects and imprinting diseases (Van Gorp et al 2014). Four subfamilies of NLRs are classified based on different N-terminal effector domain: NLRA, NLRB, NLRC and NLRP. The NLRP family contains a pyrin domain (PYD) (Ting et al 2008). Fourteen members of NLRP family are found in Macaca mulatta and Homo sapiens and 20 members are present in Mus musculus (Zhang et al 2008, McDaniel & Wu 2009). In humans, nine NLRP proteins (NLRP2, 4, 5, 7, 8, 9, 11, 13 and 14) are reproduction related and play the crucial roles in the reproductive system (Tian et al 2009)

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