The JAK/STAT3 signaling pathway mediates inhibition of host cell apoptosis by Chlamydia psittaci infection

In vitro and in-vivo exploration of physostigmine analogues to understand the mechanistic crosstalk between Klotho and targets for epilepsy

Background

Epilepsy and seizures are characterized by neuronal hyperexcitability and damage, influenced by metabolic dysregulation, neuroinflammation, and oxidative stress. Despite available treatments, many patients remain resistant to therapy, necessitating novel therapeutic strategies. Klotho, a neuroprotective, anti-inflammatory, and antioxidative protein has emerged as a potential modulator of epilepsy-related pathways.

Objective

This study investigates the therapeutic potential of novel physostigmine analogues in regulating Klotho expression and its downstream targets in epilepsy.

Methods

An integrative in vitro and in vivo approach was employed in PTZ-induced kindled mice. Behavioral assessments, including the Morris Water Maze (MWM), Rota Rod, Black and White Box, and Tail Suspension tests were conducted. Biochemical analyses quantified serum glucose, lipid profiles, pro-inflammatory cytokines (TNF-α, FOXO1), and apoptotic proteins (caspase-3). Quantitative real-time PCR (qRT-PCR) was performed to assess Klotho and epilepsy-associated gene expression (STAT3, Bax, Bcl2).

Results

The synthesized physostigmine analogues exhibited varying inhibitory effects on Klotho transcriptional activators, with Compound C (1,8-bis(phenylsulfonyl)-1,8-dihydropyrrolo [2,3-b] indole) showing the weakest inhibition (IC50 = 1.31 µM). In vivo, Compound C demonstrated anticonvulsant (p < 0.05), neuroprotective (5 mg/kg, p < 0.05, 10 mg/kg, p < 0.01, 20 mg/kg p < 0.0001), antidepressant (p < 0.05), and anti-inflammatory (p < 0.05) effects in PTZ-induced seizure models, improving motor function (p < 0.001), cognitive performance (p < 0.01), and reducing neuroinflammatory/metabolic markers (p < 0.05), while modulating STAT3 (p < 0.001), BAX (p < 0.001), Bcl2 (p < 0.05), and Klotho (p < 0.05) gene expression.

Conclusion

The therapeutic potential of 1,8-bis(phenylsulfonyl)-1,8-dihydropyrrolo [2,3-b] indole in epilepsy via Klotho modulation was observed. Targeting metabolic, inflammatory, and apoptotic pathways presents a promising strategy for epilepsy management. Further research is required to optimize clinical translation and ensure long-term efficacy and safety.

Chlamydia trachomatis induces the transcriptional activity of host YAP in a Hippo-independent fashion

Introduction

The obligate intracellular pathogen Chlamydia trachomatis is the causative agent of the most common bacterial sexually transmitted disease worldwide. While the host response to infection by this pathogen has been well characterized, it remains unclear to what extent host gene expression during infection is the product of Chlamydia-directed modulation of host transcription factors.

Methods

To identify transcription factors potentially modulated by Chlamydia during infection, we infected immortalized endocervical epithelial cells (End1/E6E7) with the anogenital C. trachomatis serovar L2, harvesting polyadenylated RNA for bulk RNA-sequencing. Subsequent experiments elucidating the mechanism of infection-mediated YAP activation assayed YAP target gene expression via qRT-PCR, YAP nuclear translocation via quantitative immunofluorescence, and YAP phosphorylation via Western blotting.

Results

RNA sequencing of Chlamydia-infected endocervical epithelial cells revealed gene expression consistent with activity of YAP, a transcriptional coactivator implicated in cell proliferation, wound healing, and fibrosis. After confirming induction of YAP target genes during infection, we observed an infection-dependent increase in YAP nuclear translocation sensitive to inhibition of bacterial protein synthesis. While Hippo-mediated phosphoinhibition of YAP at S127 was unaffected by C. trachomatis infection, Hippo-independent phosphorylation at Y357 was increased. Infection did not enhance nuclear translocation of Y357F mutant YAP, illustrating a requirement for phosphorylation at this residue. Pharmacological inhibition of host Src-family kinase activity attenuated YAP Y357 phosphorylation, but not nuclear translocation - which was instead sensitive to inhibition of Abl.

Discussion

Our results define a transcriptome-altering mechanism of pathogen-directed YAP activation that bypasses canonical inhibition by the Hippo kinase cascade, with a potential link to chlamydial fibrosis and other advanced disease sequelae. Additional study is required to determine the specific role of infection-associated Y357 phosphorylation and Abl activity in chlamydial induction of YAP.

Anti-neoplastic pharmacophore benzophenone-1 coumarin (BP-1C) targets JAK2 to induce apoptosis in lung cancer

Reigning of the abnormal gene activation associated with survival signalling in lung cancer leads to the anomalous growth and therapeutic failure. Targeting specific cell survival signalling like JAK2/STAT3 nexus has become a major focus of investigation to establish a target specific treatment. The 2-bromobenzoyl-4-methylphenoxy-acetyl hydra acetyl Coumarin (BP-1C), is new anti-neoplastic agent with apoptosis inducing capacity. The current study was aimed to develop antitumor phramacophore, BP-1C as JAK2 specific inhibitor against lung neoplastic progression. The study validates and identifies the molecular targets of BP-1C induced cell death. Cell based screening against multiple cancer cell lines identified, lung adenocarcinoma as its specific target through promotion of apoptosis. The BP-1C is able to induce, specific hall marks of apoptosis and there by conferring anti-neoplastic activity. Validation of its molecular mechanism, identified, BP-1C specifically targets JAK2^Tyr1007/1008 phosphorylation, and inhibits its downstream STAT3^Tyr705 signalling pathway to induce cell death. As a consequence, modulation in Akt/Src survival signal and altered expression of interwoven apoptotic genes were evident. The results were reproducible in an in-vivo LLC tumor model and in-ovo xenograft studies. The computational approaches viz, drug finger printing confers, BP-1C as novel class JAK2 inhibitor and molecular simulations studies assures its efficiency in binding with JAK2. Overall, BP-1C is a novel JAK2 inhibitor with experimental evidence and could be effectively developed into a promising drug for lung cancer treatment.

Host cell death during infection with Chlamydia: a double-edged sword

The phylum Chlamydiae constitutes a group of obligate intracellular bacteria that infect a remarkably diverse range of host species. Some representatives are significant pathogens of clinical or veterinary importance. For instance, Chlamydia trachomatis is the leading infectious cause of blindness and the most common bacterial agent of sexually transmitted diseases. Chlamydiae are exceptionally dependent on their eukaryotic host cells as a consequence of their developmental biology. At the same time, host cell death is an integral part of the chlamydial infection cycle. It is therefore not surprising that the bacteria have evolved exquisite and versatile strategies to modulate host cell survival and death programs to their advantage. The recent introduction of tools for genetic modification of Chlamydia spp., in combination with our increasing awareness of the complexity of regulated cell death in eukaryotic cells, and in particular of its connections to cell-intrinsic immunity, has revived the interest in this virulence trait. However, recent advances also challenged long-standing assumptions and highlighted major knowledge gaps. This review summarizes current knowledge in the field and discusses possible directions for future research, which could lead us to a deeper understanding of Chlamydia's virulence strategies and may even inspire novel therapeutic approaches.

KDM4B Overexpression Promotes the Growth, Migration, and Invasion of Rheumatoid Arthritis Fibroblast-Like Synoviocytes by Activating STAT3 Pathway

In rheumatoid arthritis (RA), fibroblast-like synoviocytes (FLS) present a unique aggressive phenotype and have a passive response to the inflammatory microenvironment, which are critical for the disease’s progression. KDM4B, as a histone demethylase, functions as an oncogenic factor in many cancers and is implicated in osteoclastogenesis as well as pro-inflammatory cytokine release in inflammatory diseases. However, the effects of KDM4B on RA FLS have not been reported. To investigate this issue, our study determined the expression of KDM4B in RA FLS using RT-qPCR and western blot. The effects of KDM4B on RA FLS viability, apoptosis, migration, and invasion were detected by MTT, flow cytometry, transwell migration, and invasion assays. Furthermore, the interaction of KDM4B with STAT3 signaling was studied by western blot, MTT, flow cytometry, transwell migration, and invasion assays. The experimental results showed that KDM4B expression was upregulated in RA synovial tissues and FLS as compared to healthy control tissues and normal FLS. Knockdown of KDM4B obviously suppressed RA FLS viability, migration and invasion, and induced apoptosis. In addition, knockdown of KDM4B in RA FLS decreased the expression of p-STAT3 and MMP-9 but increased cleaved caspase-3 expression compared with the control group. Moreover, KDM4B overexpression could promote cell growth, migration and invasion, and suppress apoptosis in RA FLS by activating STAT3 signaling. Therefore, these findings provide new insight for understanding the pathogenesis of RA and indicate that KDM4B may have a potential to be an effective therapeutic target for RA.

The Hypothetical Inclusion Membrane Protein CPSIT_0846 Regulates Mitochondrial-Mediated Host Cell Apoptosis via the ERK/JNK Signaling Pathway

Chlamydia psittaci is an important zoonotic factor associated with human and animal atypical pneumonia. Resisting host cell apoptosis is central to sustaining Chlamydia infection in vivo. Chlamydia can secrete inclusion membrane proteins (Incs) that play important roles in their development cycle and pathogenesis. CPSIT_0846 is an Inc protein in C. psittaci identified by our team in previous work. In the current study, we investigated the regulatory role of CPSIT_0846 in HeLa cell apoptosis, and explored potential mechanisms. The results showed that HeLa cells treated with CPSIT_0846 contained fewer apoptotic bodies and exhibited a lower apoptotic rate than untreated cells either with Hoechst 33258 fluorescence staining or flow cytometry with or without induction by staurosporine (STS). CPSIT_0846 could increase the phosphorylation of the extracellular signal-regulated kinases 1/2 (ERK1/2) or stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathways, and the Bcl-2 associated X protein (Bax)/B cell lymphoma 2 (Bcl-2) ratio, levels of cleaved caspase-3/9 and cleaved Poly-ADP-ribose polymerase (PARP) were significantly up-regulated following inhibition of ERK1/2 or SAPK/JNK pathways with U0126 or SP600125. After carbonyl cyanide 3-chlorophenylhydrazone (CCCP) treatment, the mitochondrial membrane potential (MMP) of cells was significantly decreased in control group, but stable in the CPSIT_0846 treated one, and less cytochrome c (Cyt.c) was released into the cytoplasm. Inhibition of the ERK1/2 or SAPK/JNK pathway significantly decreased the JC-1 red-green fluorescence signal, and promoted Cyt.c discharge into the cytoplasm in HeLa cells treated with CPSIT_0846. In conclusion, CPSIT_0846 can regulate mitochondrial pathway-mediated apoptosis in HeLa cells by activating the ERK/JNK signaling pathway.

Downregulation of RPN2 induces apoptosis and inhibits migration and invasion in colon carcinoma

The morbidity of colorectal cancer (CRC) increases annualy, which accounts to higher mortality worldwide. Therefore, it is important to study the pathogenesis of colon cancer. Ribophorin II (RPN2), part of the N-oligosaccharyltransferase complex, is highly expressed in CRC. In the present study, we investigated whether RPN2 can regulate apoptosis, migration and invasion by RNA interference in CRC and sought to clarify the molecular mechanism involved. Based on previous research, an abnormal high expression of RPN2 was observed in CRC tissues and cell lines by real-time (RT)-PCR, immunohistochemistry (IHC) and western blot analysis. RPN2 knockdown via small RNA interference (siRNA) strategy attenuated the expression of RPN2 at the mRNA and protein levels in vivo, leading to decreased cell viability and increased cell apoptosis. In addition, RNAi-RPN2 effectively arrested the cell cycle at the G0/G1-phase in SW1116 and SW480 cells. Furthermore, the Transwell assay demonstrated that cell migration and invasion abilities were significantly inhibited after cell transfection with RPN2 interference plasmid. The apoptosis-related protein (caspase-3) expression was increased and the cell cycle-related protein (cyclin D1) expression was decreased in the siRNA-RPN2 group. RT-PCR and western blot analysis results indicated that migration- and invasion-related proteins including E-cadherin, matrix metalloproteinases (MMP)-2 and TIMP-2 were markedly regulated by RPN2 siRNA. Phosphorylation levels of signal transducer and activator of transcription (STAT)3 and Janus kinase (JAK)2 were inhibited by RPN2 siRNA. These findings indicated a novel pathway of tumor-promoting activity by RPN2 in CRC, with significant implications for unraveling the tumorigenesis of CRC.