Transcripts for the acetylcholine receptor and acetylcholine esterase show distribution differences in cultured chick muscle cells.

Abstract

Abstract. In situ hybridization of chick cultured muscle cells using exonic DNA probes for both AChR or-subunit and the catalytic subunit of AChE, revealed major differences in the distribution of label both over nuclei and in their surrounding cytoplasm, although some overlap in these distributions exists. For the AChR a-subunit there is a highly skewed distribution of labeled nuclei, with 35% of the nuclei being relatively inactive (<0.25 times the mean label) and ,o10% being very heavily labeled (>2.5 times the mean label). In contrast the nuclei labeled with the exonic probe for the AChE transcripts had a more Gaussian distribution, yet with some slight skewness in the direction of a few heavily labeled nuclei. There was also a difference in the cytoplasmic distribution of the label. The AChR a-subunit mRNA was mainly within 4 #m of labeled nuclei while the AChE mRNA was more widely distributed throughout the cytoplasm, possibly within a 10 #m rim around labeled nuclei. An intronic probe for the AChE gave the identical distribution of nuclear label to that of the exonic probe (but without any cytoplasmic label). In addition, calibration of the technique indicated that per myotube the AChE transcript is about sixfold more abundant than the AChR c~-subunit transcript.

Local Control of Acetylcholinesterase Gene Expression in Multinucleated Skeletal Muscle Fibers: Individual Nuclei Respond to Signals from the Overlying Plasma Membrane

“…8 A, B). This perinuclear localization of AChE mRNA around some but not all of the myonuclei has been described earlier for chicken muscle cultures (Tsim et al, 1992) as well as for human muscle cultures (Grubic et al, 1995). Previous studies from our lab using a quantitative PCR assay in adult avian muscle fibers (Jasmin et al, 1993) as well as studies in adult mammalian muscle (Legay et al, 1995;Michel et al, 1995) have also shown that predominantly specific populations of nuclei, the ones at the neuromuscular junction, express higher levels of AChE transcripts.…”

A Globular, Not Asymmetric, Form of Acetylcholinesterase Is Expressed in Chick Motor Neurons: Down‐Regulation Toward Maturity and After Denervation

“…Both the asymmetric forms and the globular forms of AChE are known to be produced by muscle cells; this has been shown in vitro in aneural cultures of rat muscle (Koenig and Vigny, 1978;De La Porte et al, 1986) and chicken muscle (Rotundo, 1990;Vallette and Massoulie, 1991;Tsim et al, 1992) and in vivo in rat or chick muscles (Jasmin et al, 1993). Motor nerve terminals are shown to synthesize and secrete AChE at the neuromuscular junctions.…”

Nuclear autonomy in multinucleate fungi

“…In contrast with the fungi discussed, which primarily form by nucleokinesis without cytokinesis, fusion of uninucleate myoblasts produces multinucleate muscle cells. Some phenotypic variability exhibited by the myoblasts is maintained by the nuclei after syncytium formation, suggesting that cytoplasmic fusion is insufficient to coordinate nuclear behavior in this system [48]. However, nuclei can respond to the local cytoplasmic environment and/or other nuclei.…”