Journal Article

Cloning of the cDNA and Gene Encoding Mouse Lysosomal Sialidase and Correction of Sialidase Deficiency in Human Sialidosis and Mouse SM/J Fibroblasts

Suleiman A. Igdoura, Christopher Gafuik, Carmen Mertineit, Farzad Saberi, Alex V. Pshezhetsky, Michel Potier, Jacquetta M. Trasler and Roy A. Gravel

in Human Molecular Genetics

Volume 7, issue 1, pages 115-120
Published in print January 1998 | ISSN: 0964-6906
Published online January 1998 | e-ISSN: 1460-2083 | DOI: http://dx.doi.org/10.1093/hmg/7.1.115
Cloning of the cDNA and Gene Encoding Mouse Lysosomal Sialidase and Correction of Sialidase Deficiency in Human Sialidosis and Mouse SM/J Fibroblasts

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Lysosomal sialidase occurs in a multienzyme complex that also contains β-galactosidase and cathepsin A. We previously cloned the human lysosomal sialidase cDNA and characterized mutations in human sialidosis patients. Here, we report the cloning and expression of the mouse lysosomal sialidase cDNA and gene. The 1.77 kb cDNA encodes an open reading frame of 408 amino acids which shows high homology to the human lysosomal sialidase (80%), the rat cytosolic sialidase (65%) and viral and bacterial sialidases (50–55%). The sialidase gene is ∼4 kb long and contains six exons. The five in-trons range in size from 96 to 1200 bp. Northern blot analysis revealed high expression of multiple sialidase transcripts in kidney and epididymis, moderate levels in brain and spinal cord, and low levels in adrenal, heart, liver, lung and spleen. Transient expression of the cDNA clone in sialidase-deficient SM/J mouse fibroblasts and human sialidosis fibroblasts restored normal levels of sialidase activities in both cell types. Immunocytochemically expressed sialidase co-localized with a lysosomal marker, LAMP2, confirming its lysosomal nature. Since sialidase activity requires its association with β-galactosidase and cathepsin A, the expression of mouse sialidase within human sialidosis cells underlines the structural similarity between mouse and human enzymes and suggests that the mechanism for complex formation and function is highly conserved.

Journal Article.  3102 words.  Illustrated.

Subjects: Genetics and Genomics

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