Ae1/Sbe1 maize-derived high amylose improves gut barrier function and ameliorates type II diabetes in high-fat diet-fed mice by increasing Akkermansia.

Type II diabetes mellitus (T2DM) has its origins in chronic inflammation due to immune dysregulation. Improving chronic inflammation can significantly reduce the probability of T2DM and the rate of disease progression. Resistance to starch 2 (RSII) high-amylose maize starch (HAMS) has been widely implicated in the improvement and regulation of T2DM. However, its exact molecular mechanisms have not been fully discovered. Here, we used CRISPR/Cas9 technology to knock out two starch-branching enzyme genes, Ae1 and Sbe1, in maize to obtain mutants containing higher levels of HAMS. In experiments in which HAMS was fed to mice on a high-fat diet (HFD), we confirmed the function of HAMS in ameliorating hyperglycemia. Mechanistically, we found that HAMS improves the gut barrier function by increasing the Akkermansia abundance in the gut. This increase led to the alleviation of chronic inflammation in mice on a HFD, resulting in improved insulin sensitivity and a decrease in blood glucose.

Maize Dek44 Encodes Mitochondrial Ribosomal Protein L9 and Is Required for Seed Development.

Mitochondrial respiration depends on proteins encoded by the nuclear and mitochondrial genomes. Many respiratory chain-related proteins are encoded by the mitochondrial genome and undergo translation by mitochondrial ribosomes. The newly identified maize (Zea mays) defective kernel44 (dek44) mutant produces small kernels showing embryo-lethal phenotypes. We cloned Dek44 by isolating the Mutator tag that produced the mutation and identified it as encoding a putative 50S ribosomal protein L9. Subcellular fractionation by ultracentrifugation confirmed that DEK44 is a mitochondrial ribosomal protein. DEK44 is highly conserved in monocots and only accumulates in kernels. Transcriptome and reverse transcription quantitative PCR analyses revealed that loss of DEK44 function affects the expression of genes encoding respiratory chain-related proteins from the mitochondrial and nuclear genomes. Blue native-PAGE revealed significantly reduced assembly of respiratory chain complexes in dek44 mutant kernels. Transmission electron microscopy indicated that the biogenesis and morphology of mitochondria were strongly affected in dek44 mutant kernels. Furthermore, DEK44 might regulate cell growth and kernel development via cyclin/cyclin-dependent kinase-mediated activities. This study provides insight into the regulation of kernel development based on mitochondrial ribosomal protein function.

Similar biological characteristics of human embryonic stem cell lines with normal and abnormal karyotypes.

BACKGROUND: Human embryonic stem cell (hESC) lines derived from poor quality embryos usually have either normal or abnormal karyotypes. However, it is still unclear whether their biological characteristics are similar. METHODS: Seven new hESC lines were established using discarded embryos. Five cell lines had normal karyotype, one was with an unbalanced Robertsonian translocation and one had a triploid karyotype. Their biological characteristics, short tandem repeat loci, HLA typing, differentiation capability and imprinted gene, DNA methylation and X chromosome inactivation status were compared between different cell lines. RESULTS: All seven hESC lines had similar biological characteristics regardless of karyotype (five normal and two abnormal), such as expression of stage-specific embryonic antigen (SSEA)-4, tumor-rejection antigen (TRA)-1-81 and TRA-1-60 proteins, transcription factor octamer binding protein 4 mRNA, no detectable expression of SSEA-1 protein and high levels of alkaline phosphatase activity. All cell lines were able to undergo differentiation. Imprinted gene expression and DNA methylation were also similar among these cell lines. Non-random X chromosome inactivation patterns were found in XX cell lines. CONCLUSIONS: The present results suggest that hESC lines with abnormal karyotype are also useful experimental materials for cell therapy, developmental biology and genetic research.