PERK x eIF2α

Jingfang Granules (JF) is a modified herbal compound preparation that is empirically used in clinical practice for the treatment of allergic diseases. Nevertheless, the role of JF in allergic rhinitis (AR) has yet to be demonstrated, and its potential mechanisms of action remain to be fully evaluated.

The objective of this research is to examine the underlying mechanisms by which JF can be used to treat AR. This will be achieved through the use of an ovalbumin (OVA)/aluminum hydroxide AR model in mice.

ICR mice were administered an intraperitoneal (i.p.) injection of OVA/aluminium hydroxide in order to permit the establishment of an AR model. Following the intragastric administration of JF to the mice, testing nose scratching and sneezing behavior in mice to determine modeling status, and stained transverse sections of the mouse nose using the Hematoxylin and Eosin (H&E) method were in vitro evaluated to assess the histological effects of JF on mice with AR. The regulatory network was subjected to proteomic and metabolomic investigation. The expression of serum cytokines as well as histamine (HIS) was detected using ELISA kits. Protein expression in nasal mucosal tissues was identified through the use of a Western blot.

JF demonstrated a notable reduction in nose-scratching and sneezing in AR mice. Concurrently, JF markedly reduced IgE, IL-4, IL-6, IL-13, TNF-α and HIS levels while elevating IFN-γ levels in the serum of AR mice. This was achieved by inhibiting the endoplasmic reticulum (ER) stress-related protein associated proteins including GADD and ATF4, p-eIF2α, p-IRE1α, XBP1s and p-PERK. Proteomics, metabolomics, Western blotting and Quantitative Real-time polymerase chain reaction (qPCR) results confirmed that JF inhibits the glycolysis/arginine biosynthesis pathway by suppressing the ER stress (ERs) signaling pathway, which in turn inhibits the inflammatory response.

Findings from the present study indicate that JF is an efficacious treatment for OVA/aluminum hydroxide-induced nasal mucosal injury and inflammation in mice. Furthermore, the study demonstrated that JF exhibited anti-AR clinic pharmacological effects by modulating the ERs signaling pathway and inhibiting glycolysis as well as arginine biosynthesis.

The ongoing Goose astrovirus (GoAstV) epidemic, which primarily infects goslings causing severe liver damage, has inflicted considerable damage on the poultry industry. Endoplasmic reticulum stress (ERS) is a significant modulator of several viral infections, while severe ERS may result in apoptosis. This study examined the roles and possible mechanisms of ERS and apoptosis in GoAstV-induced liver injury in goslings. Two hundred Xingguo gray geese were chosen and randomly separated into two groups (Con and Dis). The Dis group received a subcutaneous injection of GoAstV genotype 2 (GoAstV-2) JX01 (2 × 10⁶ TCID₅₀/0.2 mL), whereas the Con group received a subcutaneous injection of 0.2 mL physiological saline, both at 1 day of life. Subsequent analyses demonstrate that the levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) increased following GoAstV infection. Hematoxylin and eosin (HE) staining revealed swollen and ruptured hepatocytes, with significant inflammatory cell infiltration. Electron microscopy revealed expansion of the endoplasmic reticulum (ER) and aggregation of chromatin at the periphery. TUNEL testing further demonstrated an increase in the quantity of positive cells. RT-qPCR and Western blot analyses indicated that GoAstV infection enhanced the expression of ER Ca²⁺ release channels (IP3R and RYR) and calmodulin-dependent protein kinase II (CaMKII), while decreasing the expression of ER Ca²⁺ uptake channels (SERCA). Further, GoAstV infection activated ERS-related factors, including GRP78, IRE1α, PERK, ATF6, eIF2α, ATF4, CHOP, TRAF2, and JNK, induced the expression of pro-apoptotic factors (Caspase-3, Caspase-9, and Bax), and inhibited the mRNA and protein expression of the anti-apoptotic factor Bcl-2. Correlation analysis further revealed a potential relationship among ERS gene expression, apoptotic gene expression, and liver injury. In summary, GoAstV infection can lead to liver injury by interfering with ER Ca²⁺ homeostasis, exacerbating ERS and inducing hepatocyte apoptosis.

Conditions of endoplasmic reticulum (ER) stress reduce protein synthesis by provoking translation regulation, governed by the eIF2α kinase PERK. When PERK is inhibited during ER stress, retention of a selective subset of glycoproteins occurs, a phenomenon we termed selective ER retention (sERr). sERr clients are enriched with tyrosine kinase receptors (RTKs), which form large molecular weight disulfide bonded complexes in the ER. The protein disulfide isomerase ERp44 promotes sERr and increases the size of sERr complexes. Here we show that sERr is reversible upon washout. Pulse chase analyses show that upon recovery, only a small fraction of the sERr complexes disintegrates and contributes to the matured proteins, while most are newly synthesized. Sequential inductions of sERr and washouts demonstrate an accelerated recovery that is dependent on the unfolded protein response transducer IRE1. Since IRE1 regulates the expression level PDIA6, we analyzed its contribution to sERr. We found that PDIA6 and ERp44 constitutively interact by disulfides and have opposite effects on resumed recovery of trafficking following removal of sERr conditions. Deletion of ERp44 accelerates, while deletion of PDIA6 slows down recovery with a minimal effect on total protein synthesis. ERp44 is a primary interactor with sERr clients. When missing, PDIA6 partitions more into sERr complexes. Deletion of the tumor suppressor PTEN, which induces RTK signaling, promoted sERr formation kinetics, and accelerated the recovery, suggesting feedback between RTKs signaling and sERr. This study suggests that sERr, should develop physiologically or pathologically, is counteracted by adaptation responses that involve IRE1 and PDIA6.