Protein kinase R and other double-stranded RNA-sensing innate immune proteins (PKR and dsRNA sensors)

Protein kinase R (PKR) and other double-stranded RNA (dsRNA) sensors, including Toll-like receptor 3 (TLR3), Retinoic acid-inducible gene I (RIG-I), and Melanoma differentiation-associated protein 5 (MDA5), are essential components of the innate immune system that detect viral genetic material. PKR, also known as Eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2), is a serine/threonine kinase that undergoes autophosphorylation upon binding dsRNA, subsequently phosphorylating eIF2-alpha to inhibit protein synthesis and induce apoptosis (UniProt P19544). Other sensors like RIG-I and MDA5 are cytoplasmic helicases that signal through the Mitochondrial antiviral-signaling protein (MAVS) to induce Type I interferons, while TLR3 functions within endosomes to trigger the TRIF-dependent inflammatory pathway (PubMed: 31003775). These proteins are significant therapeutic targets in oncology, where agonists like Poly(I:C) and Rintatolimod are used to stimulate anti-tumor immunity by mimicking viral infection within the tumor microenvironment (PubMed: 28439030). Conversely, overactivation of these sensors is implicated in interferonopathies and autoimmune diseases, leading to the development of inhibitors to manage chronic inflammation (PubMed: 32103171).

Other names

Eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2)Toll-like receptor 3 (TLR3)Retinoic acid-inducible gene I (RIG-I)Melanoma differentiation-associated protein 5 (MDA5)2'-5'-oligoadenylate synthetase (OAS)Pattern recognition receptors (PRRs)

Agonists mimic viral dsRNA to activate sensors, inducing Type I interferon production and apoptosis in malignant or infected cells; inhibitors block sensor activation or downstream signaling to prevent chronic inflammation and pathological translation arrest.