Oxidant-Induced Alterations in the Adipocyte Transcriptome: Role of the Na,K-ATPase Oxidant Amplification Loop.

Komal Sodhi,James Denvir,Zijian Xie,Nader Abraham,Juan Sanabria,Yiliang Chen,Joseph Shapiro,Roy Silverstein,Jiang Liu

doi:10.3390/ijms21165923

Abstract

(1) Background: Recently we have noted that adipocyte specific expression of the peptide, NaKtide, which was developed to attenuate the Na,K-ATPase oxidant amplification loop, could ameliorate the phenotypical features of uremic cardiomyopathy. We performed this study to better characterize the cellular transcriptomes that are involved in various biological pathways associated with adipocyte function occurring with renal failure. (2) Methods: RNAseq was performed on the visceral adipose tissue of animals subjected to partial nephrectomy. Specific expression of NaKtide in adipocytes was achieved using an adiponectin promoter. To better understand the cause of gene expression changes in vivo, 3T3L1 adipocytes were exposed to indoxyl sulfate (IS) or oxidized low density lipoprotein (oxLDL), with and without pNaKtide (the cell permeant form of NaKtide). RNAseq was also performed on these samples. (3) Results: We noted a large number of adipocyte genes were altered in experimental renal failure. Adipocyte specific NaKtide expression reversed most of these abnormalities. High correlation with some cardiac specific phenotypical features was noted amongst groups of these genes. In the murine adipocytes, both IS and oxLDL induced similar pathway changes as were noted in vivo, and pNaKtide appeared to reverse these changes. Network analysis demonstrated tremendous similarities between the network revealed by gene expression analysis with IS compared with oxLDL, and the combined in vitro dataset was noted to also have considerable similarity to that seen in vivo with experimental renal failure. (4) Conclusions: This study suggests that the myriad of phenotypical features seen with experimental renal failure may be fundamentally linked to oxidant stress within adipocytes.

Highlights

Oxidant stress plays a key role in the development of renal-failure-associated cardiomyopathy, both experimentally and clinically [1]
To better understand the molecular phenotypical changes that occur within adipocytes subjected to oxidant stress, in the present work we examined transcriptomic changes (RNAseq data analysis) in adipocytes derived from in vivo adipose tissues obtained in the context of experimental renal failure, with and without treatment with adipocyte specific expression of the NaKtide peptide known to ameliorate oxidant stress
We have recently reported that adipocyte-specific expression of NaKtide can ameliorate many aspects of experimental uremia including systemic oxidant stress, systemic and local cytokine elevations as well as the morphological, biochemical and functional alterations that are characteristic of uremic cardiomyopathy

Summary

Introduction

Oxidant stress plays a key role in the development of renal-failure-associated cardiomyopathy ( known as uremic cardiomyopathy), both experimentally and clinically [1]. Our previously published in vivo studies have demonstrated increased α1 subunit protein carbonylation in visceral adipose tissue, under increased oxidative stress, which was accompanied by increased Na,K-ATPase signaling transduction and phosphorylation of Src and ERK expression [4,12,13]. ROS are generated from the Na,K-ATPase signaling cascade, and promote it, creating a feed-forward oxidant amplification loop [14,15] This observation led to the development of a peptide, NaKtide, derived from the α1 subunit of Na,K-ATPase, which interacts with the kinase domain of Src, inhibiting Na,K-ATPase signaling [4,9,10,13,16,17,18]. Our data indicated that the activation of adipocyte Na,K-ATPase signaling in this murine model of experimental uremic cardiomyopathy altered the adipocyte phenotype, induced mitochondrial dysfunction, and altered the systemic metabolic profile and cardiac phenotype [13]

Methods

Results

Conclusion