Protein Lactylation and Metabolic Regulation of the Zoonotic Parasite Toxoplasma gondii

The biology of Toxoplasma gondii,the causative pathogen of one of the most widespread parasitic diseases(toxoplasmosis),remains poorly understood.Lactate,which is derived from glucose metabolism,is not only an energy source in a variety of organisms,including T.gondii,but also a regulatory molecule that participates in gene activation and protein function.Lysine lactylation(Kla)is a type of post-translational modifications(PTMs)that has been recently associated with chromatin remodeling;however,Kla of histone and non-histone proteins has not yet been studied in T.gondii.To examine the prevalence and function of lactylation in T.gondii parasites,we mapped the lactylome of proliferating tachyzoite cells and identified 1964 Kla sites on 955 proteins in the T.gondii RH strain.Lactylated proteins were distributed in multiple subcellular compartments and were closely related to a wide variety of biological processes,including mRNA splicing,glycolysis,aminoacyl-tRNA biosynthesis,RNA transport,and many signaling pathways.We also performed a chromatin immunoprecipitation sequencing(ChIP-seq)analysis using a lactylationspecific antibody and found that the histones H4K12la and H3K14la were enriched in the promoter and exon regions of T.gondii associated with microtubule-based movement and cell invasion.We further confirmed the delactylase activity of histone deacetylases TgHDAC2–4,and found that treatment with anti-histone acetyltransferase(TgMYST-A)antibodies profoundly reduced protein lactylation in T.gondii.This study offers the first dataset of the global lactylation proteome and provides a basis for further dissecting the functional biology of T.gondii.

Dihydroartemisinin regulates immune cell heterogeneity by triggering a cascade reaction of CDK and MAPK phosphorylation

Artemisinin(ART)and dihydroartemisinin(DHA),apart from their profound anti-malaria effect,can also beneficially modulate the host immune system;however,the underlying molecular mechanisms remain unclear.Here,we report that DHA selectively induced T-cell activation,with an increased proportion of Ki67^(+)CD4^(+)T cells,CD25^(+)CD4^(+)T cells,interferon(IFN)-γ-producing CD8^(+)T cells,Brdu^(+)CD8^(+)T cells and neutrophils,which was found to enhance cellular immunity to experimental malaria and overcome immunosuppression in mice.We further revealed that DHA upregulated the expression of cell proliferation-associated proteins by promoting the phosphorylation of mitogen-activated protein kinase(MAPK),cyclin-dependent kinases(CDKs),and activator protein 1 in the spleen.This study is the first to provide robust evidence that DHA selectively induced the expansion of subsets of splenic T cells through phosphorylated CDKs and MAPK to enhance cellular immune responses under non-pathological or pathological conditions.The data significantly deepened our knowledge in the mechanism underlying DHA-mediated immunomodulation.

Dihydroartemisinin beneficially regulates splenic immune cell heterogeneity through the SOD3-JNK-AP-1 axis

The immunomodulatory potential of dihydroartemisinin(DHA) has recently been highlighted;however, the potential mechanism remains to be clarified. Single-cell RNA sequencing was explored in combination with cellular and biochemical approaches to elucidate the immunomodulatory mechanisms of DHA. In this study, we found that DHA induced both spleen enlargement and rearrangement of splenic immune cell subsets in mice. It was revealed that DHA promoted the reversible expansion of effective regulatory T cells and interferon-γ^(+)cytotoxic CD8^(+)T cells in the spleen via induction of superoxide dismutase 3(SOD3) expression and increased phosphorylation of c-Jun N-terminal kinases(JNK) and its downstream activator protein 1(AP-1) transcription factors. Further, SOD3 knockout mice were resistant to the regulatory effect of DHA. Thus, DHA,through the activation of the SOD3-JNK-AP-1 axis, beneficially regulated immune cell heterogeneity and splenic immune cell homeostasis to treat autoimmune diseases.