Molecular cloning of acid α-glucosidase cDNA of Japanese quail ( Coturnix coturnix japonica) and the lack of its mRNA in acid maltase deficient quails

• Published in: Biochimica et biophysica acta Vol. 1362; no. 2; pp. 269 - 278
• Main Authors: Kunita, Ryota, Nakabayashi, Osamu, Wu, Jer-Yuarn, Hagiwara, Yasuko, Mizutani, Makoto, Pennybacker, Mark, Chen, Yuan-Tsong, Kikuchi, Tateki
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 31.12.1997
• Subjects: Acid maltase deficiency; Acid α-glucosidase; alpha-Glucosidases - genetics; Amino Acid Sequence; Animal model; Animals; Base Sequence; cDNA cloning; Cloning, Molecular; Coturnix - genetics; DNA, Complementary - genetics; Gene Expression Regulation, Enzymologic; Glucan 1,4-alpha-Glucosidase - deficiency; Humans; Isoenzymes - genetics; Japanese quail; Liver - enzymology; Molecular Sequence Data; mRNA deficiency; Muscle, Skeletal - enzymology; Myocardium - enzymology; Polymerase Chain Reaction; RNA, Messenger - genetics; Sequence Alignment; Sequence Homology, Amino Acid; Transfection; mRNA deficiency; SSC, 0.15 M NaCl/0.015 M sodium citrate; Animal model; kb, kilobase; Acid α-glucosidase; Japanese quail; GAA, acid α-glucosidase (EC 3.2.1.20); SDS, sodium dodecyl sulfate; cDNA cloning; bp, base pair; 4-MU, 4-methyl-umbeliferyl- α-glucopyranoside; AMD, acid maltase deficiency; Acid maltase deficiency
• ISSN: 0925-4439; 0006-3002; 1879-260X; 1878-2434
• DOI: 10.1016/S0925-4439(97)00092-6

Acid α-glucosidase (GAA) hydrolyzes α-1, 4 and α-1, 6 glucosidic linkages of oligosaccharides and degrades glycogen in the lysosomes. The full-length GAA I cDNA, pQAM8, was isolated from a cDNA library derived from Japanese quail liver. The cDNA is 3569 base pairs long and has an open reading frame capable of coding 932 amino acids. The deduced amino acid sequence shares 52% identity with human GAA. Transfection of expression vector pETAM8 into COS-7 cells or acid maltase deficient (AMD) quail embryonic fibroblasts increased the level of GAA 20–50-fold. Compared to normal quail, the levels of GAA I mRNA were significantly reduced in the muscle, liver, heart, and brain of AMD quails, suggesting the GAA deficiency in AMD quail is due to a lack of GAA I mRNA. A second GAA II cDNA was identified after probing the cDNA library from the ovarian large follicles of quails with a PCR product derived from cultured quail skin fibroblasts. This clone having 3.1 kb insert, has GAA activity as well (3 to 10 fold increase). This cDNA, designated GAA II, predicted an 873 amino acid polypeptide showing 63% identity to human GAA and 51% identity to the GAA I. The RT–PCR analysis demonstrated that GAA II mRNAs were barely detectable in normal tissues, while they were enhanced to higher levels in AMD tissues. These results suggest that GAA II expression is up-regulated at the transcription levels, and quail GAA gene redundancy performs the same function of satisfying GAA demand at the two different phases represented by normal and AMD.