Mh. Van Maanen et al., Characterization of the human glycogenin-1 gene: Identification of a muscle-specific regulatory domain, GENE, 234(2), 1999, pp. 217-226
The de-novo synthesis of glycogen is now known to involve a novel class of
self-glucosylating protein primers. In mammalian skeletal muscle, glycogeni
n-l is the protein responsible for this initiation step. Northern blot anal
ysis revealed that glycogenin-l gene transcription is differentially regula
ted in the C2C12 mouse muscle cell line. To define the regulatory elements
that control expression of the glycogenin-l gene, we have cloned and charac
terized the genomic structure of the human glycogenin-l gene and its promot
er region. This gene consists of seven exons and six introns, and spans ove
r 13 kb. Transcription of human glycogenin-l is initiated at two major site
s, XO and 86 bp upstream from the initiation of translation codon. Nucleoti
de sequence analysis of 2.1 kb of the 5'-flanking region revealed the proxi
mal promoter contains both a TATA box and two putative Spl binding sites lo
cated in a CpG island. There are numerous binding sites for developmental a
nd cell-type-specific transcription factors, including AP-1, AP-2, GATA, an
d several potential Oct 1 binding domains. There are also nine consensus E-
boxes that bind the basic helix-loop-helix family of muscle-specific transc
ription factors. The transcriptional activity of the glycogenin-l gene was
investigated by transient transfection of the 5'-flanking region in HepG2 c
ells and C2C12 myoblasts and myotubes. These results permitted the definiti
on of a minimal 232 bp promoter fragment that is responsible for basal leve
l transcription in a cell-type-independent manner. Furthermore, we have ide
ntified a regulatory region located between -2076 and -1736 of the 5'-flank
ing region of the human glycogenin-l gene that allows myotube-specific expr
ession in C2C12 cells. (C) 1999 Elsevier Science B.V. All rights reserved.