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Oriented smooth muscle layers in the intestine contract rhythmically due to the action of interstitial cells of Cajal (ICC) that serve as pacemakers of the intestine. Disruption of ICC networks has been reported in various intestinal motility disorders, which limit the quality and expectancy of life. A significant challenge in intestinal smooth muscle engineering is the rapid loss of function in cultured ICC and smooth muscle cells (SMC). Here we demonstrate a novel approach to maintain the function of both ICC and SMC in vitro. Primary intestinal SMC mixtures cultured on feeder cells seeded electrospun poly(3-caprolactone) scaffolds exhibited rhythmic contractions with directionality for over 10 weeks in vitro. The simplicity of this system should allow for wide usage in research on intestinal motility disorders and tissue engineering, and may prove to be a versatile platform for generating other types of functional SMC in vitro.

Neuronal necrosis occurs during early phase of ischemic insult. However, our knowledge of neuronal necrosis is still inadequate. To study the mechanism of neuronal necrosis, we previously established a Drosophila genetic model of neuronal necrosis by calcium overloading through expression of a constitutively opened cation channel mutant. Here, we performed further genetic screens and identified a suppressor of neuronal necrosis, CG17259, which encodes a seryl-tRNA synthetase. We found that loss-of-function (LOF) CG17259 activated eIF2α phosphorylation and subsequent up-regulation of chaperons (Hsp26 and Hsp27) and autophagy. Genetically, down-regulation of eIF2α phosphorylation, Hsp26/Hsp27 or autophagy reduced the protective effect of LOF CG17259, indicating they function downstream of CG17259. The protective effect of these protein degradation pathways indicated activation of a toxic protein during neuronal necrosis. Our data indicated that p53 was likely one such protein, because p53 was accumulated in the necrotic neurons and down-regulation of p53 rescued necrosis. In the SH-SY5Y human cells, tunicamycin (TM), a PERK activator, promoted transcription of hsp27; and necrosis induced by glutamate could be rescued by TM, associated with reduced p53 accumulation. In an ischemic stroke model in rats, p53 protein was also increased, and TM treatment could reduce the p53 accumulation and brain damage.

The main roles of equilibrative nucleoside transporters (ENTs) and concentrative nucleoside transporters (CNTs) are to transfer single nucleosides and analogues for the nucleic acid salvage pathway. Oligodeoxyribonucleotides (ODNs) can be transported into the cytoplasm or nucleus of cells under certain conditions. Among ODNs composed of a single type of nucleotide, the transport efficiency differs with the length and nucleotide composition of the ODNs and varies in different types of leukaemia cells; among the 5 tested random sequence ODNs and 3 aptamers with varying sequences, the data showed that some sequences were associated with significantly higher transport efficiency than others. The transport of ODNs was sodium, energy, and pH-independent, membrane protein-dependent, substrate nonspecific for ODNs and 4-nitrobenzylthioinosine (NBMPR)-insensitive, but it showed a low sensitivity to dipyridamole (IC50 = 35.44 µmol/L), distinguishing it from ENT1-4 and CNTs. The delivery efficiency of ODNs was superior to that of Lipofection and Nucleofection, demonstrating its potential applications in research or therapeutics. Moreover, this process was associated with p38 mitogen activated protein kinase (p38MAPK) instead of c-Jun N-terminal kinase (JNK) signalling pathways. We have denoted ODN transmembrane transport as equilibrative nucleic acid transport (ENAT). Overall, these findings indicate a new approach and mechanism for transmembrane transport of ODNs.