Regulation of Cholinesterase Gene Expression Affects Neuronal Differentiation as Revealed by Transfection Studies on Reaggregating Embryonic Chicken Retinal Cells

Abstract

In the embryonic chicken neuroepithelium, butyrylcholinesterase (BChE) as a proliferation marker and then acetylcholinesterase (AChE) as a differentiation marker are expressed in a mutually exclusive manner. These and other data indicate a coregulation of cholinesterase expression, and also possible roles of cholinesterases during neurogenesis. Here, both aspects are investigated by two independent transfection protocols of dissociated retina cells of the 6-day-old chick embryo in reaggregation culture, both protocols leading to efficient overexpression of AChE protein. The effect of the overexpressed AChE protein on the re-establishment of retina-like three-dimensional networks (so-called retinospheroids) was studied. In a first approach, we transfected retinospheroids with a pSVK3 expression vector into which a cDNA construct encoding the entire rabbit AChE gene had been inserted in sense orientation. As detected at the mRNA level, rabbit AChE was heterologously overexpressed in chicken retinospheroids. Remarkably, this was accompanied by a strong increase in endogenous chicken AChE protein, while the total AChE activity was only slightly increased. This increase was due to chicken enzyme, as shown by species-specific inhibition studies using fasciculin. Clearly, total AChE activity is regulated post-translationally. As an alternative method of AChE overexpression, transfection of spheroids was performed with an antisense-5'-BChE vector, which not only resulted in the down-regulation of BChE expression, but also strongly increased chicken AChE transcripts, protein and enzyme activity. Histologically, a higher concentration of AChE protein (as a consequence of either AChE overexpression or BChE suppression) was associated with an advanced degree of tissue differentiation, as detected by immunostaining for the cytoskeletal protein vimentin.

Cholinesterase activity as biomarker of neurotoxicity: utility in the assessment of aquatic environment contamination

“…It is also shown that AChE and BChE modulate cell adhesion in human neuroblastoma cells (62). Antisense blocking of BChE has been shown to result in an inhibition of megakaryocytopoiesis and application of similar techniques in embryonic chick retinal cell resulted in an inhibition of proliferation (61,71). So we will read more about the relationship between BChE and tumorogenesis and the usage of specific BChE inhibitors used as chemothreapeutic agents in the future also.…”

Presenilin 1 Interacts with Acetylcholinesterase and Alters Its Enzymatic Activity and Glycosylation

“…Although transgenic mice expressing A246E-PS1 do not develop neuritic plaques, they show defects in hippocampal long-term potentiation (50) and neurogenesis (10), as well as alteration of distinct motor responses (33). Multiple lines of evidence point to the participation and/or modulation of these processes by AChE (48,62,73,81). Thus, AChE deficit in PS1-A246E transgenic mice may contribute to the described dysfunctions, similarly as cholinergic impairment contributes to cognitive and functional symptoms of AD.…”

Acetylcholinesterase antibody treatment results in neurite detachment and reduced outgrowth from cultured neurons: Further evidence for a cell adhesive role for neuronal acetylcholinesterase

“…Karpel et al (1996) have shown that over-expression of AChE in C6 rat glioma cells induced process extension and cell body enlargement in these otherwise low AChE-expressing cells. Likewise, over-expression of AChE in neuroblastoma cells (Koenigsberger et al, 1997), spinal neurons from transgenic Xenopus embryos (Sternberg et al, 1998), or retinal cells (Robitzki et al, 1997) resulted in increased outgrowth that paralleled the increase in AChE expression. Conversely, treatment with AChE antisense cDNA reduced outgrowth from two neural cell lines (Grifman et al, 1997;Koenigsberger et al, 1997).…”