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Localization and Developmental Changes of τ Protein Kinase I/Glycogen Synthase Kinase‐3β in Rat Brain
Author(s) -
Takahashi Miho,
Tomizawa Kayoko,
Kato Rika,
Sato Kazuki,
Uchida Tsuneko,
Fujita Shinobu C.,
Imahori Kazutomo
Publication year - 1994
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1046/j.1471-4159.1994.63010245.x
Subject(s) - biology , cerebellum , polyclonal antibodies , gsk 3 , developmental profile , kinase , glycogen synthase , glycogen , immunohistochemistry , enzyme , protein kinase a , phosphorylation , biochemistry , microbiology and biotechnology , endocrinology , medicine , antibody , immunology
τ protein kinase I (TPKI) purified from bovine brain extract has been shown to phosphorylate τ and to form paired helical filament (PHF) epitopes and was found recently to be identical to glycogen synthase kinase‐3β (GSK‐3β). Before elucidating a role of TPKI/GSK‐3β in PHF formation, it is necessary to investigate the normal function of the enzyme. To study the distribution and developmental changes of the enzyme, specific polyclonal antibodies were prepared against TPKI and GSK‐3α. Immunoblot analysis demonstrated that TPKI was nearly specifically localized in the brain of adult rats. The level of TPKI in the rat brain was high at gestational day 18, peaked on postnatal day 8, and then decreased rapidly to a low level, which was sustained up to 2 years. Immunohistochemistry indicated primarily neuronal localization of TPKI. Growing axons were stained most intensely in the developing cerebellum, but the immunoreactivity became restricted to the gray matter in the mature tissue. Parallel fibers had a high level of TPKI and also stained intensely for τ. These findings indicate that τ is one of the physiological substrates of TPKI and suggest that the enzyme plays an important role in the growth of axons during development of the brain.