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Mycobacterium tuberculosis (Mtb) defends host-mediated killing by repressing the autophagolysosome machinery. For the first time, we report NCoR1 co-repressor as a crucial host factor, controlling Mtb growth in myeloid cells by regulating both autophagosome maturation and lysosome biogenesis. We found that the dynamic expression of NCoR1 is compromised in human peripheral blood mononuclear cells (PBMCs) during active Mtb infection, which is rescued upon prolonged anti-mycobacterial therapy. In addition, a loss of function in myeloid-specific NCoR1 considerably exacerbates the growth of M. tuberculosis in vitro in THP1 differentiated macrophages, ex vivo in bone marrow-derived macrophages (BMDMs), and in vivo in NCoR1MyeKO mice. We showed that NCoR1 depletion controls the AMPK-mTOR-TFEB signalling axis by fine-tuning cellular adenosine triphosphate (ATP) homeostasis, which in turn changes the expression of proteins involved in autophagy and lysosomal biogenesis. Moreover, we also showed that the treatment of NCoR1 depleted cells by Rapamycin, Antimycin-A, or Metformin rescued the TFEB activity and LC3 levels, resulting in enhanced Mtb clearance. Similarly, expressing NCoR1 exogenously rescued the AMPK-mTOR-TFEB signalling axis and Mtb killing. Overall, our data revealed a central role of NCoR1 in Mtb pathogenesis in myeloid cells. This is the first report depicting role of a Nuclear Receptor Co-repressor-1 (NCoR1) regulating autophagy induction and lysosomal biogenesis in myeloid cells by fine-tuning ATP homeostasis through AMPK-mTOR-TFEB signaling axis thereby controlling Mycobacterium tuberculosis pathogenesis. [ABSTRACT FROM AUTHOR]

Hsp16.3 plays a vital role in the slow growth of Mycobacterium tuberculosis via its chaperone function. Many secretory proteins, including Hsp16.3 undergo acetylation in vivo. Seven lysine (K) residues (K64, K78, K85, K114, K119, K132 and K136) in Hsp16.3 are acetylated inside pathogen. However, how lysine acetylation affects its structure, chaperone function and pathogen's growth is still elusive. We examined these aspects by executing in vitro chemical acetylation (acetic anhydride modification) and by utilizing a lysine acetylation mimic mutant (Hsp16.3-K64Q/K78Q/K85Q/K114Q/K119Q/K132Q/K136Q). Far- and near-UV CD measurements revealed that the chemically acetylated proteins(s) and acetylation mimic mutant has altered secondary and tertiary structure than unacetylated/wild-type protein. The chemical modification and acetylation mimic mutation also disrupted the oligomeric assembly, increased surface hydrophobicity and reduced stability of Hsp16.3, as revealed by GF-HPLC, 4,4′-dianilino-1,1′-binaphthyl-5,5′-disulfonic acid binding and urea denaturation experiments, respectively. These structural changes collectively led to an enhancement in chaperone function (aggregation and thermal inactivation prevention ability) of Hsp16.3. Moreover, when the H37Rv strain expressed the acetylation mimic mutant protein, its growth was slower in comparison to the strain expressing the wild-type/unacetylated Hsp16.3. Altogether, these findings indicated that lysine acetylation improves the chaperone function of Hsp16.3 which may influence pathogen's growth in host environment. • Lysine acetylation in Hsp16.3 perturbs its secondary, tertiary and quaternary structure. • This post-translational modification enhances the surface hydrophobicity of Hsp16.3. • The chaperone function of Hsp16.3 is enhanced upon lysine acetylation. • The improved chaperone function of Hsp16.3 influences the growth of H37Rv strain. [ABSTRACT FROM AUTHOR]

Tight control of gene regulation in dendritic cells (DCs) is important to mount pathogen specific immune responses. Apart from transcription factor binding, dynamic regulation of enhancer activity through global transcriptional repressors like Nuclear Receptor Co-repressor 1 (NCoR1) plays a major role in fine-tuning of DC responses. However, how NCoR1 regulates enhancer activity and gene expression in individual or multiple Toll-like receptor (TLR) activation in DCs is largely unknown. In this study, we did a comprehensive epigenomic analysis of murine conventional type-I DCs (cDC1) across different TLR ligation conditions. We profiled gene expression changes along with H3K27ac active enhancers and NCoR1 binding in the TLR9, TLR3 and combined TLR9 + TLR3 activated cDC1. We observed spatio-temporal activity of TLR9 and TLR3 specific enhancers regulating signal specific target genes. Interestingly, we found that NCoR1 differentially controls the TLR9 and TLR3-specific responses. NCoR1 depletion specifically enhanced TLR9 responses as evident from increased enhancer activity as well as TLR9-specific gene expression, whereas TLR3-mediated antiviral response genes were negatively regulated. We validated that NCoR1 KD cDC1 showed significantly decreased TLR3 specific antiviral responses through decreased IRF3 activation. In addition, decreased IRF3 binding was observed at selected ISGs leading to their decreased expression upon NCoR1 depletion. Consequently, the NCoR1 depleted cDC1 showed reduced Sendai Virus (SeV) clearance and cytotoxic potential of CD8+ T cells upon TLR3 activation. NCoR1 directly controls the majority of these TLR specific enhancer activity and the gene expression. Overall, for the first time, we revealed NCoR1 mediates transcriptional control towards TLR9 as compared to TLR3 in cDC1. [ABSTRACT FROM AUTHOR]

• Two biosurfactants (Taurocholic acid and Taurodeoxycholic acid) efficiently inhibit the primary fibrillation of insulin. • TDCA is also able to suppress the secondary fibrillation of insulin. • Both these bile acids attenuate insulin fibril-induced cellular toxicity. • They interact to the C-ter of insulin B-chain via hydrophobic & H-bond interactions. • Such interactions stabilize insulin secondary structure and reduce the aggregate size. Insulin-induced amyloidosis, a typical example of protein fibrillation, reduces the effectiveness of insulin treatment in type-II diabetic patients, which demands intense investigations to mitigate insulin fibrillation. Herein, the inhibitory effect of two taurine conjugated bile acids [taurocholic acid (TCA) and taurodeoxycholic acid (TDCA)] towards insulin fibrillation has been elucidated using various biophysical, imaging and computational tools. TCA delays lag time of fibrillation while TDCA targets fibril elongation step and thus impeding insulin primary fibrillation. TDCA also inhibits the secondary fibrillation of insulin efficiently. The greater inhibition of both fibrillation processes is evidenced once insulin is kept with TDCA under fibrillogenic conditions. In silico studies reveal that these two bile acids interact with several aggregation-prone residues (e.g. Tyr16, Phe24, Tyr26) present at the C-terminal portion of insulin B-chain. Such interactions stabilize the native insulin structure, reduce the surface hydrophobicity and aggregate size as well as modulate the fibril morphology. Both these molecules are non-toxic and attenuate insulin fibril-induced hemolysis of erythrocytes and cytotoxicity in HepG2 cells. Overall, our findings provide novel insights to the study of amyloidal protein fibrillation and lay foundation towards the utilization of these two taurine conjugated bile acids as inhibitors of insulin fibrillation and insulin-induced amyloidosis. [ABSTRACT FROM AUTHOR]

Highlights: [•] The Trypanosoma brucei telomerase RNA is a C/D snoRNA that is localized near the nucleolus. [•] TER silencing causes shortening of the chromosomes but no growth arrest. [•] pre-TER is trans-spliced linking trans-splicing to the processing of non-coding RNAs. [Copyright &y& Elsevier]