Transport of cellular misfolded proteins to the cell surface by HLA-B27 free heavy chain

Ginsenoside Rk1 inhibits HeLa cell proliferation through an endoplasmic reticulum signaling pathway

Background

Changes to work-life balance has increased the incidence of cervical cancer among younger people. A minor ginseng saponin known as ginsenoside Rk1 can inhibit the growth and survival of human cancer cells; however, whether ginsenoside Rk1 inhibits HeLa cell proliferation is unknown.

Methods and results

Ginsenoside Rk1 blocked HeLa cells in the G0/G1 phase in a dose-dependent manner and inhibited cell division and proliferation. Ginsenoside Rk1 markedly also activated the apoptotic signaling pathway via caspase 3, PARP, and caspase 6. In addition, ginsenoside Rk1 increased LC3B protein expression, indicating the promotion of the autophagy signaling pathway. Protein processing in the endoplasmic reticulum signaling pathway was downregulated in Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses, consistent with teal-time quantitative PCR and western blotting that showed YOD1, HSPA4L, DNAJC3, and HSP90AA1 expression levels were dramatically decreased in HeLa cells treated with ginsenoside Rk1, with YOD1 was the most significantly inhibited by ginsenoside Rk1 treatment.

Conclusion

These findings indicate that the toxicity of ginsenoside Rk1 in HeLa cells can be explained by the inhibition of protein synthesis in the endoplasmic reticulum and enhanced apoptosis, with YOD1 acting as a potential target for cervical cancer treatment.

MHC: new insights from old molecules into the pathogenesis of autoimmunity

The major histocompatibility complex (MHC) is a central molecule in the immune system. The MHC is also a highly polymorphic gene that is strongly involved in susceptibility to many autoimmune diseases. Therefore, the elucidation of the mechanism by which specific MHCs are involved in disease pathogenesis is important to our understanding of the pathogenesis of autoimmune diseases. On the other hand, the production of autoantibodies is observed in many autoimmune diseases, but the mechanism underlying their production remains unclear. We have shown that MHC class II molecules exhibit a chaperone-like function to transport misfolded proteins in the endoplasmic reticulum to the outside of cells. Furthermore, misfolded proteins transported to the cell surface have been shown to be the targets of various autoantibodies produced in autoimmune diseases. In this article, I describe novel mechanisms underlying autoimmune diseases mediated by misfolded proteins complexes with MHC class II.

HLA transgenic mice: application in reproducing idiosyncratic drug toxicity

Various types of transgenic mice carrying either class I or II human leukocyte antigen (HLA) molecules are readily available, and reports describing their use in a variety of studies have been published for more than 30 years. Examples of their use include the discovery of HLA-specific antigens against viral infection as well as the reproduction of HLA-mediated autoimmune diseases for the development of therapeutic strategies. Recently, HLA transgenic mice have been used to reproduce HLA-mediated idiosyncratic drug toxicity (IDT), a rare and unpredictable adverse drug reaction that can result in death. For example, abacavir-induced IDT has successfully been reproduced in HLA-B*57:01 transgenic mice. Several reports using HLA transgenic mice for IDT have proven the utility of this concept for the evaluation of IDT using various HLA allele combinations and drugs. It has become apparent that such models may be a valuable tool to investigate the mechanisms underlying HLA-mediated IDT. This review summarizes the latest findings in the area of HLA transgenic mouse models and discusses the current challenges that must be overcome to maximize the potential of this unique animal model.