Cell Adhesion Structures in Epithelial Cells Are Formed in Dynamic and Cooperative Ways

There are many morphologically distinct membrane structures with different functions at the surface of epithelial cells. Among these, adherens junctions (AJ) and tight junctions (TJ) are responsible for the mechanical linkage of epithelial cells and epithelial barrier function, respectively. In the process of new cell–cell adhesion formation between two epithelial cells, such as after wounding, AJ form first and then TJ form on the apical side of AJ. This process is very complicated because AJ formation triggers drastic changes in the organization of actin cytoskeleton, the activity of Rho family of small GTPases, and the lipid composition of the plasma membrane, all of which are required for subsequent TJ formation. In this review, the authors focus on the relationship between AJ and TJ as a representative example of specialization of plasma membrane regions and introduce recent findings on how AJ formation promotes the subsequent formation of TJ.     

Metabolic engineering to improve 1,5-diaminopentane production from cellobiose using β-glucosidase-secreting Corynebacterium glutamicum

Microbial production of 1,5-diaminopentane (DAP) from renewable feedstock is a promising and sustainable approach for the production of polyamides. In this study, we constructed a β-glucosidase (BGL)-secreting Corynebacterium glutamicum and successfully used this strain to produce DAP from cellobiose and glucose. First, C. glutamicum was metabolically engineered to produce l -lysine (a direct precursor of DAP), followed by the coexpression of l -lysine decarboxylase and BGL derived from Escherichia coli and Thermobifida fusca YX (Tfu0937), respectively. This new engineered C. glutamicum strain produced 27 g/L of DAP from cellobiose in CGXII minimal medium using fed-batch cultivation. The yield of DAP was 0.43 g/g glucose (1 g of cellobiose corresponds to 1.1 g of glucose), which is the highest yield reported to date. These results demonstrate the feasibility of DAP production from cellobiose or cellooligosaccharides using an engineered C. glutamicum strain.     

Existence and possible roles of independent non-CpG methylation in the mammalian brain

Methylated non-CpGs (mCpHs) in mammalian cells yield weak enrichment signals and colocalize with methylated CpGs (mCpGs), thus have been considered byproducts of hyperactive methyltransferases. However, mCpHs are cell type-specific and associated with epigenetic regulation, although their dependency on mCpGs remains to be elucidated. In this study, we demonstrated that mCpHs colocalize with mCpGs in pluripotent stem cells, but not in brain cells. In addition, profiling genome-wide methylation patterns using a hidden Markov model revealed abundant genomic regions in which CpGs and CpHs are differentially methylated in brain. These regions were frequently located in putative enhancers, and mCpHs within the enhancers increased in correlation with brain age. The enhancers with hypermethylated CpHs were associated with genes functionally enriched in immune responses, and some of the genes were related to neuroinflammation and degeneration. This study provides insight into the roles of non-CpG methylation as an epigenetic code in the mammalian brain genome.