UMP-CMP kinase 2 gene expression in macrophages is dependent on the IRF3-IFNAR signaling axis

Abstract

Toll-like receptors (TLRs) are highly-conserved pattern recognition receptors that mediate innate immune responses to invading pathogens and endogenous danger signals released from damaged and dying cells. Activation of TLRs trigger downstream signaling cascades, that culminate in the activation of interferon regulatory factors (IRFs), which subsequently leads to type I interferon (IFN) response. In the current study, we sought to expand the scope of gene expression changes in THP1-derived macrophages upon TLR4 activation and to identify interferon-stimulated genes. RNA-seq analysis led to the identification of several known and novel differentially expressed genes, including CMPK2, particularly in association with type I IFN signaling. We performed an in-depth characterization of CMPK2 expression, a nucleoside monophosphate kinase that supplies intracellular UTP/CTP for nucleic acid synthesis in response to type I IFN signaling in macrophages. CMPK2 was significantly induced at both RNA and protein levels upon stimulation with TLR4 ligand—LPS and TLR3 ligand—Poly (I:C). Confocal microscopy and subcellular fractionation indicated CMPK2 localization in both cytoplasm and mitochondria of THP-1 macrophages. Furthermore, neutralizing antibody-based inhibition of IFNAR receptor in THP-1 cells and BMDMs derived from IFNAR KO and IRF3 KO knockout mice further revealed that CMPK2 expression is dependent on LPS/Poly (I:C) mediated IRF3- type I interferon signaling. In summary, our findings suggest that CMPK2 is a potential interferon-stimulated gene in THP-1 macrophages and that CMPK2 may facilitate IRF3- type I IFN-dependent anti-bacterial and anti-viral roles.

A Role for the Chicken Interferon-Stimulated Gene CMPK2 in the Host Response Against Virus Infection

“…According to previous studies, the upregulation of CMPK2 mRNA can be induced by poly(I:C), LPS, and IFN-β in human and fish cells ( Collins et al, 2007 ; El-Diwany et al, 2018 ; Kim et al, 2021 ). In the present study, we found that the CMPK2 mRNA levels increased after poly(I:C) stimulation as well as upon virus infection, which was consistent with the increase of IFN-β levels ( Figures 4C , D , H ).…”

“…Though CMPK2 has been identified as an ISG in human, little is known about its regulatory pathway. A recent study revealed that CMPK2 expression is dependent on LPS/poly(I:C)-mediated IRF3 type I IFN signaling by inhibiting the IFN-α receptor (IFNAR) in THP-1 cells and bone marrow-derived macrophages (BMDMs) derived from IFNAR knockout and IRF3 knockout mice ( Kim et al, 2021 ). According to our results, IFNs are strong inducers of chCMPK2 expression, while IL had little influence on it.…”

“…As previously reported, CMPK2 localization showed differences between species and cell types. CMPK2 localized in the mitochondria of HeLa cells, whereas it was distributed in the cytoplasm and partially in the mitochondria of THP-1 cells ( Kim et al, 2021 ). In FHM cells, CMPK2 is localized in the cytoplasm and displays colocalization with mitochondria ( Chen et al, 2008 ; Xu et al, 2008 ).…”

“…In mammal, the expression of CMPK2 was ubiquitously distributed in different tissues, and significantly high levels were observed in the liver, pancreas, placenta, lung and heart and THP1 monocytic leukemia cells as well as human monocytes ( Chen et al, 2008 ). Human CMPK2, as a IRF3-type IFNAR dependent cytokine, induced explicitly by poly(I:C) and several viruses ( Kim et al, 2021 ). In term of virus infection, human CMPK2 was significantly increased after the infection of viruses, such as Hepatitis E virus (HEV) and Porcine reproductive and respiratory syndrome (PRRS) virus ( Zhang et al, 2014 ; Kommadath et al, 2017 ).…”

The mitochondrial gene CMPK2 functions as a rheostat for macrophage homeostasis in inflammation

“…One of the early and highly expressed ISG in macrophages following infection is the mitochondria associated kinase CMPK2. CMPK2 is actively induced in response to several viral infections like HEV(Zhang et al, 2014), HIV(El-Diwany et al, 2018), Dengue virus (DENV)(Lai et al, 2021b), Nipah virus(Hassan et al, 2019), SVCV(Liu et al, 2019) and in response to LPS and poly IC(Kim et al, 2021) in macrophages. A recent study has demonstrated the involvement of the fish homolog-3nCmpk2 in antibacterial response by controlling bacterial colonization and protecting the intestinal barrier (Feng et al, 2021).…”