Transcriptional activity of acetylcholinesterase gene is regulated by DNA methylation during C2C12 myogenesis

DNA hydroxymethylation rate in the AChE and HoxC4 promoter associated with human sperm quality

The relationship of altered DNA 5'-hydroxymethylation in human spermatozoa with seminal parameters remains unclear. The aim of the study was to investigate the association between the 5'-hydroxymethylcytosine (5hmC) rate in the promoters of acetylcholinesterase (AChE) and homeobox C4 (HoxC4) genes and human sperm concentration/motility. The study population consisted of three groups: asthenozoospermia (AZ), oligoasthenozoospermia (OAZ) and normozoospermia (NZ). The 5hmC rate in the promoter was measured by CCGG loci-dependent MspI/HpaII restriction mapping of glycosylation-modified sperm DNA combined with a hydroxymethylation-specific real-time polymerase chain reaction assay. The 5hmC rate in the AChE promoter in group AZ and OAZ was higher than that in group NZ (p < .05). A weak inverse correlation between 5hmC rate of AChE and sperm motility was observed in all subjects (r = -.172, p < .05). The 5hmC rate in the HoxC4 promoter in group OAZ was lower than that in group NZ (p < .05). These results indicated that altered 5hmC rates of AChE and HoxC4 promoters are associated with low sperm motility and sperm concentration respectively.

Wnt3a induces the expression of acetylcholinesterase during osteoblast differentiation via the Runx2 transcription factor

Acetylcholinesterase (AChE) hydrolyzes acetylcholine to terminate cholinergic transmission in neurons. Apart from this AChE activity, emerging evidence suggests that AChE could also function in other, non-neuronal cells. For instance, in bone, AChE exists as a proline-rich membrane anchor (PRiMA)-linked globular form in osteoblasts, in which it is proposed to play a noncholinergic role in differentiation. However, this hypothesis is untested. Here, we found that in cultured rat osteoblasts, AChE expression was increased in parallel with osteoblastic differentiation. Because several lines of evidence indicate that AChE activity in osteoblast could be triggered by Wnt/β-catenin signaling, we added recombinant human Wnt3a to cultured osteoblasts and found that this addition induced expression of the ACHE gene and protein product. This Wnt3a-induced AChE expression was blocked by the Wnt-signaling inhibitor Dickkopf protein-1 (DKK-1). We hypothesized that the Runt-related transcription factor 2 (Runx2), a downstream transcription factor in Wnt/β-catenin signaling, is involved in AChE regulation in osteoblasts, confirmed by the identification of a Runx2-binding site in the ACHE gene promoter, further corroborated by ChIP. Of note, Runx2 overexpression in osteoblasts induced AChE expression and activity of the ACHE promoter tagged with the luciferase gene. Moreover, deletion of the Runx2-binding site in the ACHE promoter reduced its activity during osteoblastic differentiation, and addition of 5-azacytidine and trichostatin A to differentiating osteoblasts affected AChE expression, suggesting epigenetic regulation of the ACHE gene. We conclude that AChE plays a role in osteoblastic differentiation and is regulated by both Wnt3a and Runx2.

Chiral Orientation of Skeletal Muscle Cells Requires Rigid Substrate

Reconstitution of tissue morphology with inherent left–right (LR) asymmetry is essential for tissue/organ functions. For skeletal muscle, the largest tissue in mammalian organisms, successful myogenesis requires the regulation of the LR asymmetry to form the appropriate muscle alignment. However, the key factor for reproducing the LR asymmetry of skeletal tissues in a controllable, engineering context remains largely unknown. Recent reports indicate that cell chirality may underlie the LR development in tissue morphogenesis. Here, we report that a rigid substrate is required for the chirality of skeletal muscle cells. By using alternating micropatterned cell-adherent and cell-repellent stripes on a rigid substrate, we found that C2C12 skeletal muscle myoblasts exhibited a unidirectional tilted orientation with respect to the stripe boundary. Importantly, such chiral orientation was reduced when soft substrates were used instead. In addition, we demonstrated the key role of actin stress fibers in the formation of the chiral orientation. This study reveals that a rigid substrate is required for the chiral pattern of myoblasts, paving the way for reconstructing damaged muscle tissue with inherent LR asymmetry in the future.

New perspectives for multi-level regulations of neuronal acetylcholinesterase by dioxins

Acetylcholinesterase (AChE; EC 3.1.1.7) is a vital functional enzyme in cholinergic neurotransmission which can rapidly hydrolyze neurotransmitter, acetylcholine, in the central and peripheral nervous systems. Emerging evidence showed that in addition to classical environmental AChE inhibitors, e.g. organophosphate and carbamate pesticides, dioxins are a new type of xenobiotic causing impairment of AChE. Dioxin can transcriptionally or post-transcriptionally suppress AChE expression in human neuroblastoma cells or mouse immune cells via the aryl hydrocarbon receptor (AhR) pathway, respectively. Dioxins can affect gene expression through other mechanisms, such as cross-talk with other signaling cascades and epigenetic modulations. Therefore, in this review, by summarizing the known mechanisms of AChE regulation and dioxin-induced gene alteration, potential signaling cascades and epigenetic mechanisms are proposed for dioxin-mediated AChE regulation. Mitogen activated protein (MAP) kinase, 3', 5'-cyclic adenosine monophosphate (cAMP) and calcium-related singaling pathways, as well as potential epigenetic mechanisms, such as DNA methylation, and post-transcriptional regulation via microRNAs, including hsa-miR-132, hsa-miR-212 and hsa-miR-25-3p are discussed here. These proposed mechanisms may be invaluable not only to promote comprehensive understanding of the action mechanisms for dioxin, but to illustrate the molecular basis of dioxin-induced health impacts.