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A key role of antizyme in morphological and functional differentiation of pancreatic alpha cells
Author(s) -
Suzuki Junichiro,
Murakami Yasuko,
Samejima Keijiro,
Ohtani Masahiro,
Oka Takami
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.1194.1
Subject(s) - ornithine decarboxylase antizyme , alpha cell , glucagon , transfection , cellular differentiation , cell culture , microbiology and biotechnology , pancreas , enteroendocrine cell , biology , chemistry , endocrinology , biochemistry , beta cell , ornithine decarboxylase , islet , gene , enzyme , hormone , insulin , genetics , endocrine system
Pancreatic alpha cells produce and secrete glucagon. There is still much to be learned about mechanisms whereby alpha cell differentiation is regulated. We found that AsPC‐1 cells, a human pancreatic cell line, can be induced to differentiate into glucagon‐producing cells by trypsin treatment and subsequent culture in serum‐free medium. These cells expressed glucagon mRNA in response to reduction of glucose concentration in the medium. They also formed cell aggregates resembling the pancreatic islet. We used this system to identify regulatory molecules involved in alpha cell differentiation. Our present study focused on antizyme, a key protein that regulates the biosynthesis and transport of polyamine because antizyme and polyamine levels were high in the pancreas. Antizyme in AsPC‐1 cells was localized in the cytosol during differentiation whereas it was in the nucleus during cell proliferation. Antizyme mRNA and the concentration of spermidine increased when AsPC‐1 cells were induced to differentiate. Transfection of antizyme siRNA into AsPC‐1 cells resulted in specific suppression of antizyme expression and inhibited both morphological and functional differentiation including glucagon gene expression. However, the differentiated state was restored by subsequent transfection of a GFP‐antizyme construct. These results suggested that antizyme is needed for pancreatic alpha cell differentiation.