An integrative single-cell multi-omics profiling of human pancreatic islets identifies T1D associated genes and regulatory signals.

Genome wide association studies (GWAS) have identified over 100 signals associated with type 1 diabetes (T1D). However, translating any given T1D GWAS signal into mechanistic insights, including putative causal variants and the context (cell type and cell state) in which they function, has been limited. Here, we present a comprehensive multi-omic integrative analysis of single-cell/nucleus resolution profiles of gene expression and chromatin accessibility in healthy and autoantibody (AAB+) human islets, as well as islets under multiple T1D stimulatory conditions.

Human and rat skeletal muscle single-nuclei multi-omic integrative analyses nominate causal cell types, regulatory elements, and SNPs for complex traits.

Skeletal muscle accounts for the largest proportion of human body mass, on average, and is a key tissue in complex diseases and mobility. It is composed of several different cell and muscle fiber types. Here, we optimize single-nucleus ATAC-seq (snATAC-seq) to map skeletal muscle cell-specific chromatin accessibility landscapes in frozen human and rat samples, and single-nucleus RNA-seq (snRNA-seq) to map cell-specific transcriptomes in human.

Molecular modelling and docking analysis of pleurocidin (an antimicrobial peptide) like peptides with enterotoxin H from Klebsilla pneumonia.

Enterotoxin H is a key molecular target for replication and establishment of Klebsilla pneumonia in the host. Therefore, it is of interest to study the interaction of enterotoxin H with pleurocidin like peptides using molecular modelling (template PDB ID: 1YCE), Lig-Plot (ligand construction) and docking tools for therapeutic consideration. The hydrophobic pocket and the active site residues (Val 13, Met 16, Gly 25, Ala 25, and Ile 28) were identified using Cast P, Molegro and Sitehound tools.

Disulfide Mispairing During Proinsulin Folding in the Endoplasmic Reticulum.

Proinsulin folding within the endoplasmic reticulum (ER) remains incompletely understood, but it is clear that in mutant INS gene-induced diabetes of youth (MIDY), progression of the (three) native disulfide bonds of proinsulin becomes derailed, causing insulin deficiency, β-cell ER stress, and onset of diabetes. Herein, we have undertaken a molecular dissection of proinsulin disulfide bond formation, using bioengineered proinsulins that can form only two (or even only one) of the native proinsulin disulfide bonds. In the absence of preexisting proinsulin disulfide pairing, Cys(B19)-Cys(A20) (a major determinant of ER stress response activation and proinsulin stability) preferentially initiates B-A chain disulfide bond formation, whereas Cys(B7)-Cys(A7) can initiate only under oxidizing conditions beyond that existing within the ER of β-cells.

Effects of tRNA modification on translational accuracy depend on intrinsic codon-anticodon strength.

Cellular health and growth requires protein synthesis to be both efficient to ensure sufficient production, and accurate to avoid producing defective or unstable proteins. The background of misreading error frequency by individual tRNAs is as low as 2 × 10(-6) per codon but is codon-specific with some error frequencies above 10(-3) per codon. Here we test the effect on error frequency of blocking post-transcriptional modifications of the anticodon loops of four tRNAs in Escherichia coli.

PDI reductase acts on Akita mutant proinsulin to initiate retrotranslocation along the Hrd1/Sel1L-p97 axis.

In mutant INS gene-induced diabetes of youth (MIDY), characterized by insulin deficiency, MIDY proinsulin mutants misfold and fail to exit the endoplasmic reticulum (ER). Moreover, these mutants bind and block ER exit of wild-type (WT) proinsulin, inhibiting insulin production. The ultimate fate of ER-entrapped MIDY mutants is unclear, but previous studies implicated ER-associated degradation (ERAD), a pathway that retrotranslocates misfolded ER proteins to the cytosol for proteasomal degradation.

Studies of translational misreading in vivo show that the ribosome very efficiently discriminates against most potential errors.

Protein synthesis must rapidly and repeatedly discriminate between a single correct and many incorrect aminoacyl-tRNAs. We have attempted to measure the frequencies of all possible missense errors by tRNA , tRNA and tRNA . The most frequent errors involve three types of mismatched nucleotide pairs, U•U, U•C, or U•G, all of which can form a noncanonical base pair with geometry similar to that of the canonical U•A or C•G Watson-Crick pairs.