Interferon-inducible Stat2 activation of JUND and CLDN4: mediators of IFN responses

Claudins and alveolar epithelial barrier function in the lung

The alveolar epithelium of the lung constitutes a unique interface with the outside environment. This thin barrier must maintain a surface for gas transfer while being continuously exposed to potentially hazardous environmental stimuli. Small differences in alveolar epithelial barrier properties could therefore have a large impact on disease susceptibility or outcome. Moreover, recent work has focused attention on the alveolar epithelium as central to several lung diseases, including acute lung injury and idiopathic pulmonary fibrosis. Although relatively little is known about the function and regulation of claudin tight junction proteins in the lung, new evidence suggests that environmental stimuli can influence claudin expression and alveolar barrier function in human disease. This review considers recent advances in the understanding of the role of claudins in the breakdown of the alveolar epithelial barrier in disease and in epithelial repair.

The yin and yang of viruses and interferons

Interferons (IFNs)-α/β are critical effectors of the innate immune response to virus infections. Through activation of the IFN-α/β receptor (IFNAR), they induce expression of IFN-stimulated genes (ISGs) that encode antiviral proteins capable of suppressing viral replication and promoting viral clearance. Many highly pathogenic viruses have evolved mechanisms to evade an IFN response and the balance between the robustness of the host immune response and viral antagonistic mechanisms determines whether or not the virus is cleared. Here, we discuss IFNs as broad-spectrum antivirals for treatment of acute virus infections. In particular, they are useful for treatment of re-emerging virus infections, where direct-acting antivirals (DAAs) have limited utility due to DAA-resistant mutations, and for newly emerging virus strains in which the time to vaccine availability precludes vaccination at the onset of an outbreak.

The role of signal transducer and activator of transcription-2 in the interferon response

The signal transducer and activator of transcription-2 (STAT2) was discovered as a cellular component of the DNA binding complex known as interferon (IFN) stimulated gene factor-3. Numerous studies have confirmed that STAT2 operates as a positive regulator in the transcriptional activation response elicited by IFNs. In this article, we highlight the progress made in elucidating the pivotal role of STAT2 in driving the expression of IFN-induced genes, innate antiviral immunity, apoptosis, and cancer. A better understanding of the functional role of STAT2 in the IFN response and how STAT2 is regulated will uncover new clues to its role in diseases.