The β ₄ subunit of Ca _v 1.2 channels is required for an optimal interferon response in cardiac muscle cells

Abstract

The auxiliary β4subunit of the cardiac Cav1.2 channel plays a poorly understood role in gene transcription. Here, we characterized the regulatory effects of the β4subunit in H9c2 rat cardiac cells on the abundances ofIfnbmRNA [which encodes interferon-β (IFN-β)] and of the IFN-β–related genesDdx58,Ifitm3,Irf7,Stat2,Ifih1, andMx1, as well as on the abundances of the antiviral proteins DDX58, IRF7, STAT2, and IFITM3. Knocking down the β4subunit in H9c2 cells reduced the expression of IFN-β–stimulated genes. In response to inhibition of the kinase JAK1, the abundances of β4subunit mRNA and protein were decreased. β4subunit abundance was increased, and it translocated to the nucleus, in cells treated with IFN-β, infected with dengue virus (DENV), or transfected with poly(I:C), a synthetic analog of double-stranded RNA. Cells that surrounded the virus-infected cells showed translocation of β4subunit proteins to nuclei in response to spreading infection. We showed that the β4subunit interacted with the transcriptional regulator IRF7 and that the activity of anIrf7promoter–driven reporter was increased in cells overexpressing the β4subunit. Last, overexpressing β4in undifferentiated and differentiated H9c2 cells reduced DENV infection and decreased the abundance of the viral proteins NS1, NS3, and E-protein. DENV infection and poly(I:C) also increased the concentration of intracellular Ca2+in these cells. These findings suggest that the β4subunit plays a role in promoting the expression of IFN-related genes, thereby reducing viral infection.

Molecular and Cellular Response of the Myocardium (H9C2 Cells) Towards Hypoxia and HIF-1α Inhibition

“…To illustrate the Cocl2 and hypoxia-induced intracellular Ca 2+ levels in H9c2 cells in addition to mRNA and protein analysis, we also used the immunofluorescence staining technique for Cav1.1 (1:200), Cav1.2 (1:200), and Cav1.3 (1:200) proteins, by following previous reports with slight modification ( 28 ). Briefly, H9c2 cells were cultured and maintained as described above in 8- chambered cell culture slides (Falcon #08-774-208, Fisher Scientific).…”

Could Lower Testosterone in Older Men Explain Higher COVID-19 Morbidity and Mortalities?

“…VDCC blockers have also been shown to effectively inhibit the infection of the West Nile virus (NWV) and severe fever with thrombocytopenia syndrome virus (SFTSV) by inhibiting the virus-cell fusion step [23,43,44]. The increase in [Ca 2+ ]i produced by certain viruses through VDCCs has also been demonstrated to be necessary for viral replication, and VDCC blockers have proven to be effective antiviral agents against Japanese encephalitis virus (JEV), ZIKV, DENV, and WNV [23,24,45]. It has been shown that Ca 2+ binds to the fusion protein (FP) of MERS-CoV and the 2 FP domains on the S protein of SARS-CoV during the entry stage of both virus types [27,46,47], nevertheless, this phenomenon still requires further investigation.…”

Identification of the Hub Genes and the Signaling Pathways in Human iPSC-Cardiomyocytes Infected by SARS-CoV-2

“…It is suggested that ISG15 may play a crucial role in cardiomyocytes infected by SARS-CoV-2. As for another hub gene (MX1), Eshwar et al have shown that the β 4 subunit of Cav1.2 channels can promote the expression of IFN-related genes (including MX1) in cardiomyocytes, thus alleviating viral infection (Tammineni et al 2018). IFIT1, IFIT2, IFIT3 and IFIT5 constitute the human IFIT gene family, which expressed very low in most cell types but can be significantly increased by interferon therapy, viral infection and pathogen-related molecular pattern (PAMP) (Pidugu et al 2019).…”