Regulation of c-SMAC formation and AKT-mTOR signaling by the TSG101-IFT20 axis in CD4^(+)T cells

CD4^(+)T cells play major roles in the adaptive immune system,which requires antigen recognition,costimulation,and cytokines for its elaborate orchestration.Recent studies have provided new insight into the importance of the supramolecular activation cluster(SMAC),which comprises concentric circles and is involved in the amplification of CD4^(+)T cell activation.However,the underlying mechanism of SMAC formation remains poorly understood.Here,we performed single-cell RNA sequencing of CD4^(+)T cells left unstimulated and stimulated with anti-CD3 and anti-CD28 antibodies to identify novel proteins involved in their regulation.We found that intraflagellar transport 20(IFT20),previously known as cilia-forming protein,was upregulated in antibody-stimulated CD4^(+)T cells compared to unstimulated CD4^(+)T cells.We also found that IFT20 interacted with tumor susceptibility gene 101(TSG101),a protein that endocytoses ubiquitinated T-cell receptors.The interaction between IFT20 and TSG101 promoted SMAC formation,which led to amplification of AKT-mTOR signaling.However,IFT20-deficient CD4^(+)T cells showed SMAC malformation,resulting in reduced CD4^(+)T cell proliferation,aerobic glycolysis,and cellular respiration.Finally,mice with T-cell-specific IFT20 deficiency exhibited reduced allergen-induced airway inflammation.Thus,our data suggest that the IFT20-TSG101 axis regulates AKT-mTOR signaling via SMAC formation.

Gram-negative bacteria and their lipopolysaccharides in Alzheimer’s disease:pathologic roles and therapeutic implications

Alzheimer's disease(AD)is the most serious age-related neurodegenerative disease and causes destructive and irreversible cognitive decline.Failures in the development of therapeutics targeting amyloid-β(Aβ)and tau;principal proteins inducing pathology in AD,suggest a paradigm shift towards the development of new therapeutic targets.The gram-negative bacteria and lipopolysaccharides(LPS)are attractive new targets for AD treatment.Surprisingly,an altered distribution of gram-negative bacteria and their LPS has been reported in AD patients.Moreover,gram-negative bacteria and their LPS have been shown to affect a variety of AD-related pathologies,such as Aβ homeostasis,tau pathology,neuroinflammation,and neurodegeneration.Moreover,therapeutic approaches targeting gram-negative bacteria or gram-negative bacterial molecules have significantly alleviated AD-related pathology and cognitive dysfunction.Despite multiple evidence showing that the gram-negative bacteria and their LPS play a crucial role in AD pathogenesis,the pathogenic mechanisms of gram-negative bacteria and their LPS have not been clarified.Here,we summarize the roles and pathomechanisms of gram-negative bacteria and LPS in AD.Furthermore,we discuss the possibility of using gram-negative bacteria and gram-negative bacterial molecules as novel therapeutic targets and new pathological characteristics for AD.