Proteomic analysis of Nrk gene-disrupted placental tissue cells explains physiological significance of NRK

Abstract

Objective: NRK is a unique X chromosome-linked protein kinase expressed predominantly in placenta. The gene knockout causes placental overgrowth and delayed labor of Nrk-null fetuses from dams in mouse. To clarify unknown mechanisms behind the Nrk-null phenotypes, protein expression profiles were analyzed in the Nrk-null placenta using a high-performance two-dimensional electrophoresis methodology.

Results: Among around 1800 spots detected, we characterized a dozen protein spots whose expression levels were significantly altered in the Nrk-null placenta compared to wild-type. Analyzing these data sets is expected to reflect the difference physiologically in the presence or absence of NRK, facilitating the development of therapeutic strategies.

Keywords: Breast tumor; Dystocia; Placenta; Placentomegaly; Protein kinase.

Fig. 1

2DE map of the Nrk^−/− mouse placenta. Representative 2DE protein profiles with the protein spots marked as differentially regulated on Nrk^−/− placentas at embryonic day 18.5 (E18.5). We performed proteomics in over triplicate experiments and presented herein the dataset for late-pregnancy placental tissues disrupted for the tumor suppressor gene Nrk. Pairs of WT/KO gel images were compared to identify 18 protein spots (from approximately 1800 detected spots) that differed significantly in the 2DE images. The identities of the spots, as determined by LC–ESI–MS/MS, are presented in Table 1. Total protein fractions were separated by isoelectric focusing on a Multiphor II system (GE Healthcare Ltd., UK) and SDS-PAGE using a NuPAGE 4–12% Bis–Tris Z00m Gel (Thermo Fisher Scientific). SYPRO Ruby-stained gels were scanned using the Typhoon Imaging System (GE Healthcare Ltd., UK) and analyzed using Image Master 2D Platinum 7.0 software (GE Healthcare Ltd., UK). Spots corresponding to differentially expressed proteins are labeled with numbers