The recent advancements in protein nanoparticles for immunotherapy.

In recent years, the advancement of nanoparticle-based immunotherapy has introduced an innovative strategy for combatting diseases. Compared with other types of nanoparticles, protein nanoparticles have obtained substantial attention owing to their remarkable biocompatibility, biodegradability, ease of modification, and finely designed spatial structures. Nature provides several protein nanoparticle platforms, including viral capsids, ferritin, and albumin, which hold significant potential for disease treatment. These naturally occurring protein nanoparticles not only serve as effective drug delivery platforms but also augment antigen delivery and targeting capabilities through techniques like genetic modification and covalent conjugation. Motivated by nature's originality and driven by progress in computational methodologies, scientists have crafted numerous protein nanoparticles with intricate assembly structures, showing significant potential in the development of multivalent vaccines. Consequently, both naturally occurring and de novo designed protein nanoparticles are anticipated to enhance the effectiveness of immunotherapy. This review consolidates the advancements in protein nanoparticles for immunotherapy across diseases including cancer and other diseases like influenza, pneumonia, and hepatitis.

Nuclear localization of mitochondrial TCA cycle enzymes modulates pluripotency via histone acetylation.

Pluripotent stem cells hold great promise in regenerative medicine and developmental biology studies. Mitochondrial metabolites, including tricarboxylic acid (TCA) cycle intermediates, have been reported to play critical roles in pluripotency. Here we show that TCA cycle enzymes including Pdha1, Pcb, Aco2, Cs, Idh3a, Ogdh, Sdha and Mdh2 are translocated to the nucleus during somatic cell reprogramming, primed-to-naive transition and totipotency acquisition. The nuclear-localized TCA cycle enzymes Pdha1, Pcb, Aco2, Cs, Idh3a promote somatic cell reprogramming and primed-to-naive transition. In addition, nuclear-localized TCA cycle enzymes, particularly nuclear-targeted Pdha1, facilitate the 2-cell program in pluripotent stem cells. Mechanistically, nuclear Pdha1 increases the acetyl-CoA and metabolite pool in the nucleus, leading to chromatin remodeling at pluripotency genes by enhancing histone H3 acetylation. Our results reveal an important role of mitochondrial TCA cycle enzymes in the epigenetic regulation of pluripotency that constitutes a mitochondria-to-nucleus retrograde signaling mode in different states of pluripotent acquisition.

A Combined Model of Human iPSC-Derived Liver Organoids and Hepatocytes Reveals Ferroptosis in DGUOK Mutant mtDNA Depletion Syndrome.

Mitochondrial DNA depletion syndrome (MDS) is a group of severe inherited disorders caused by mutations in genes, such as deoxyribonucleoside kinase (DGUOK). A great majority of DGUOK mutant MDS patients develop iron overload progressing to severe liver failure. However, the pathological mechanisms connecting iron overload and hepatic damage remains uncovered. Here, two patients' skin fibroblasts are reprogrammed to induced pluripotent stem cells (iPSCs) and then corrected by CRISPR/Cas9. Patient-specific iPSCs and corrected iPSCs-derived high purity hepatocyte organoids (iHep-Orgs) and hepatocyte-like cells (iHep) are generated as cellular models for studying hepatic pathology. DGUOK mutant iHep and iHep-Orgs, but not control and corrected one, are more sensitive to iron overload-induced ferroptosis, which can be rescued by N-Acetylcysteine (NAC). Mechanically, this ferroptosis is a process mediated by nuclear receptor co-activator 4 (NCOA4)-dependent degradation of ferritin in lysosome and cellular labile iron release. This study reveals the underlying pathological mechanisms and the viable therapeutic strategies of this syndrome, and is the first pure iHep-Orgs model in hereditary liver diseases.

Phospholipid remodeling is critical for stem cell pluripotency by facilitating mesenchymal-to-epithelial transition.

Metabolic reprogramming has emerged as a key regulator of cell fate decisions. Roles of glucose and amino acid metabolism have been extensively documented, whereas lipid metabolism in pluripotency remains largely unexplored. Using a high-coverage lipidomics approach, we reveal dynamic changes in phospholipids occurring during reprogramming and show that the CDP-ethanolamine (CDP-Etn) pathway for phosphatidylethanolamine (PE) synthesis is required at the early stage of reprogramming. Mechanistically, the CDP-Etn pathway inhibits NF-κB signaling and mesenchymal genes in a Pebp1-dependent manner, without affecting autophagy, resulting in accelerated mesenchymal-to-epithelial transition (MET) and enhanced reprogramming. Furthermore, PE binding to Pebp1 enhances the interaction of Pebp1 with IKKα/ß and reduces the phosphorylation of IKKα/ß. The CDP-Etn-Pebp1 axis is associated with EMT/MET in hepatocyte differentiation, indicating that Etn/PE is a broad-spectrum MET/EMT-regulating metabolite. Collectively, our study reveals an unforeseen connection between phospholipids, cell migration, and pluripotency and highlights the importance of phospholipids in cell fate transitions.

Short-Term Mitochondrial Permeability Transition Pore Opening Modulates Histone Lysine Methylation at the Early Phase of Somatic Cell Reprogramming.

Reprogramming of somatic cells to induced pluripotent stem cells reconfigures chromatin modifications. Whether and how this process is regulated by signals originating in the mitochondria remain unknown. Here we show that the mitochondrial permeability transition pore (mPTP), a key regulator of mitochondrial homeostasis, undergoes short-term opening during the early phase of reprogramming and that this transient activation enhances reprogramming. In mouse embryonic fibroblasts, greater mPTP opening correlates with higher reprogramming efficiency. The reprogramming-promoting function of mPTP opening is mediated by plant homeodomain finger protein 8 (PHF8) demethylation of H3K9me2 and H3K27me3, leading to reduction in their occupancies at the promoter regions of pluripotency genes. mPTP opening increases PHF8 protein levels downstream of mitochondrial reactive oxygen species production and miR-101c and simultaneously elevates levels of PHF8's cofactor, α-ketoglutarate. Our findings represent a novel mitochondria-to-nucleus pathway in cell fate determination by mPTP-mediated epigenetic regulation.

BNIP3L-dependent mitophagy accounts for mitochondrial clearance during 3 factors-induced somatic cell reprogramming.

Induced pluripotent stem cells (iPSCs) have fewer and immature mitochondria than somatic cells and mainly rely on glycolysis for energy source. During somatic cell reprogramming, somatic mitochondria and other organelles get remodeled. However, events of organelle remodeling and interaction during somatic cell reprogramming have not been extensively explored. We show that both SKP/SKO (Sox2, Klf4, Pou5f1/Oct4) and SKPM/SKOM (SKP/SKO plus Myc/c-Myc) reprogramming lead to decreased mitochondrial mass but with different kinetics and by divergent pathways. Rapid, MYC/c-MYC-induced cell proliferation may function as the main driver of mitochondrial decrease in SKPM/SKOM reprogramming. In SKP/SKO reprogramming, however, mitochondrial mass initially increases and subsequently decreases via mitophagy. This mitophagy is dependent on the mitochondrial outer membrane receptor BNIP3L/NIX but not on mitochondrial membrane potential (ΔΨm) dissipation, and this SKP/SKO-induced mitophagy functions in an important role during the reprogramming process. Furthermore, endosome-related RAB5 is involved in mitophagosome formation in SKP/SKO reprogramming. These results reveal a novel role of mitophagy in reprogramming that entails the interaction between mitochondria, macroautophagy/autophagy and endosomes.