Intestinal Salmonella typhimurium Infection Leads to miR-29a Induced Caveolin 2 Regulation

Abstract

Background Salmonella are able to modulate host cell functions facilitating both uptake and resistance to cellular host defence mechanisms. While interactions between bacterial modulators and cellular proteins have been the main focus of Salmonella research, relatively little is known about mammalian gene regulation in response to Salmonella infection. A major class of mammalian gene modulators consists of microRNAs. For our study we examined interactions of microRNAs and regulated mRNAs in mammalian intestinal Salmonella infections using a piglet model.Methodology/Principal FindingsAfter performing microRNA as well as mRNA specific microarray analysis of ileal samples from Salmonella infected as well as control piglets, we integrated expression analysis with target prediction identifying microRNAs that mainly regulate focal adhesion as well as actin cytoskeleton pathways. Particular attention was given to miR-29a, which was involved in most interactions including Caveolin 2. RT-qPCR experiments verified up-regulation of miR-29a after infection while its predicted target Caveolin 2 was significantly down-regulated as examined by transcript and protein detection. Reporter gene assays as well as RNAi experiments confirmed Caveolin 2 to be a miR-29a target. Knock-down of Caveolin 2 in intestinal epithelial cells resulted in retarded proliferation as well as increased bacterial uptake. In addition, our experiments showed that Caveolin 2 regulates the activation of the small Rho GTPase CDC42 but apparently not RAC1 in human intestinal cells.Conclusions/SignificanceOur study outlines for the first time important regulation pathways in intestinal Salmonella infection pointing out that focal adhesion and organisation of actin cytoskeleton are regulated by microRNAs. Functional relevance is shown by miR-29a mediated Caveolin 2 regulation, modulating the activation state of CDC42. Further analysis of examined interactions may support the discovery of novel strategies impairing the uptake of intracellular pathogens.

The two faces of miR-29

“…87 The same authors pointed to miR-29b as a ‘female-predominant’ miRNA. Another group of miR-29 targets includes genes involved in metabolism and metabolic disorders, specifically those involved in glucose transport, 88 such as the transmembrane protein insulin-induced gene 1, 43 CAV2 , 89 monocarboxylate transporter 1 ( SLC16A1 , also known as MCT1 ), 90 and PIK3R1 , 91 which further confirm its critical role in diabetes mellitus.…”

Lipid rafts in immune signalling: current progress and future perspective

“…Furthermore, loss of function by antagonizing miR‐103/107 levels leads to the up‐regulation of caveolin‐1, which in turn stabilizes the insulin receptor and enhanced insulin signalling. In an independent study, Hoeke et al . observed that miR‐29a regulates cellular uptake of pathogens during intestinal salmonella infection by way of caveolin‐2‐mediated targeting of focal adhesion and the actin cytoskeleton pathway.…”

A Long Journey Ahead: Long Non-coding RNAs in Bacterial Infections

“…Intracellular bacterial pathogens have been shown to interfere with expression of small non-coding, regulatory RNAs like microRNAs (miRNA) affecting host cell response signaling pathways such as apoptosis and autophagy (Rodriguez et al, 2007; Schulte et al, 2011; Sharbati et al, 2011, 2012; Hoeke et al, 2013; Pawar et al, 2016b; zur Bruegge et al, 2016). While the role of miRNAs in bacterial infections has been extensively studied and excellently reviewed in previous years (Eulalio et al, 2012; Das et al, 2016; Kim et al, 2017), we are beginning to realize the pivotal role of another class of regulatory RNA molecules, which are collectively referred to as long non-coding RNAs (lncRNAs).…”