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High ß-Galactosidase and Ganglioside GM1 Levels in the Human Parotid Gland
Nakisa Nowroozi, PhD;
Toshitsugu Kawata, DDS, PhD;
Peixin Liu, PhD;
Dale Rice, MD;
Joseph H. Zernik, DMD, PhD
Arch Otolaryngol Head Neck Surg. 2001;127:1381-1384.
Background Ganglioside GM1 is a membrane glycolipid typical of nerve
cell membranes, where it partakes in neurotransmitter release and is catabolized
by the lysosomal ß-galactosidase (GM1ase) (EC 3.2.1.23). After demonstrating
a novel degenerative disease of the parotid gland in mice deficient in GM1ase,
mimicking the human storage disease GM1 gangliosidosis, we studied
GM1ase and ganglioside GM1 content in the human parotid glands.
Study Design Levels of GM1ase and ganglioside GM1 were determined in samples
of parotid tissues and neighboring muscle (as a negative control) for 3 subjects.
Tissues were also processed for histochemical demonstration of GM1ase.
Results The mean specific activity of GM1ase was more than 6-fold higher in
the healthy human parotid tissues (1.4 ± 0.5 nmol of 4-methylumbelliferone
per minute per milligram of protein) relative to the neighboring muscle tissue
(0.23 ± 0.07 nmol of 4-methylumbelliferone per minute per milligram
of protein). Activity of GM1ase was histochemically localized mainly to striated
duct and acinar cells of the parotid gland. Ganglioside GM1 content
in the parotid gland was on average 30-fold higher relative to muscle.
Conclusions Our results are consistent with previous findings reported in the mouse
and the rabbit, and probably reflect a general property of the mammalian parotid
glands. The novel mechanism we previously proposed for the mouse parotid saliva
secretion, mimicking neurotransmitter release in ganglioside GM1–containing
nerve cells, is probably applicable also to the human parotid gland. Similarly,
the human parotid gland is probably also severely affected in GM1
gangliosidosis.
From the Departments of Orthodontics and Basic Sciences, School of
Dentistry, University of Southern California, Los Angeles (Drs Nowroozi, Liu,
and Zernik); the Department of Orthodontics, Hiroshima University School of
Dentistry, Hiroshima, Japan (Dr Kawata); and the Department of Otolaryngology,
University of Southern California General Hospital (Dr Rice).
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Arch Otolaryngol Head Neck Surg. 2001;127(11):1403-1405.
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