Premium
A novel untranslated ‘exon H’ of the human choline acetyltransferase gene in placenta
Author(s) -
Robert Isabelle,
QuirinStricker Christiane
Publication year - 2001
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.2001.00508.x
Subject(s) - microbiology and biotechnology , biology , exon , messenger rna , placenta , untranslated region , gene isoform , choline acetyltransferase , gene , genetics , endocrinology , fetus , pregnancy , cholinergic
To investigate the existence of 5′‐region(s) of human choline acetyltransferase (hChAT) mRNA in placenta we analyzed the presence or absence of ChAT 5′‐untranslated regions (UTR) in human neuronal and non‐neuronal cells. Total RNA from human spinal cord, placenta, cultured choriocarcinoma JEG‐3 and neuroblastoma CHP126 and MC‐IXC cells was reverse transcribed and used for polymerase chain reaction amplification (RT‐PCR). We used a sense primer located in the 5′‐flanking region, in the previously defined intronic sequence and an anti‐sense primer located in the common coding exon 2 of the hChAT gene. An amplified product of 567 bp in size was obtained only in human placenta and in JEG‐3 cells whereas it was absent in spinal cord, CHP126 and MC‐IXC cells. It was designated ‘H‐type’ of ChAT mRNA. Whereas CHP126 produced the R‐ and N‐type of ChAT mRNAs, no transcript of the N‐and R‐type was detected in JEG‐3 and human placenta. In addition, CHP126 and JEG‐3 cells and placenta showed the expression of the M‐type of ChAT mRNA. The idendity of the amplified 567 bp product (H‐type) was confirmed by Southern hybridization and sequencing. The nucleotide sequence of the amplified fragment in placenta revealed the existence of a previously unknown type of ChAT mRNA produced by alternative splicing. Using primer extension we further determined the transcription initiation site of the H‐type hChAT mRNA in placenta. These results demonstrate the expression of a novel ChAT mRNA isoform in human placenta in addition to the M‐type. These data may be possibly explained by the presence of a placenta specific promoter in the ChAT gene, which might be the proximal promoter P1.