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FAK + and PYK2/CAKβ, two related tyrosine kinases highly expressed in the central nervous system: similarities and differences in the expression pattern
Author(s) -
Menegon Andrea,
Burgaya Ferran,
Baudot Pierre,
Dunlap David D.,
Girault JeanAntoine,
Valtorta Flavia
Publication year - 1999
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1046/j.1460-9568.1999.00798.x
Subject(s) - focal adhesion , biology , microbiology and biotechnology , growth cone , ptk2 , hippocampal formation , tyrosine kinase , neurite , kinase , receptor tyrosine kinase , neural cell adhesion molecule , axon , neuroscience , signal transduction , cell adhesion , cell , in vitro , biochemistry , protein kinase c , mitogen activated protein kinase kinase
Focal adhesion kinase (FAK) and proline‐rich tyrosine kinase 2/cell adhesion kinase β (PYK2/CAKβ) are related, non‐receptor, cytoplasmic tyrosine kinases, highly expressed in the central nervous system (CNS). In addition, FAK + is a splice isoform of FAK containing a 3‐amino acid insertion in the carboxy‐terminal region. In rat hippocampal slices, FAK + and PYK2/CAKβ are differentially regulated by neurotransmitters and depolarization. We have studied the regional and cellular distribution of these kinases in adult rat brain and during development. Whereas PYK2/CAKβ expression increased with postnatal age and was maximal in the adult, FAK + levels were stable. PYK2/CAKβ mRNAs, detected by in situ hybridization, were expressed at low levels in the embryonic brain, and became very abundant in the adult forebrain. Immunocytochemistry of the adult brain showed a widespread neuronal distribution of FAK + and PYK2/CAKβ immunoreactivities (ir). PYK2/CAKβ appeared to be particularly abundant in the hippocampus. In hippocampal neurons in culture at early stages of development, FAK + and PYK2/CAKβ were enriched in the perikarya and growth cones. FAK + extended to the periphery of the growth cones tips, whereas PYK2/CAKβ appeared to be excluded from the lamellipodia. During the establishment of polarity, a proximal‐distal gradient of increasing PYK2/CAKβ‐ir could be observed in the growing axon. In most older neurons, FAK + ‐ir was confined to the cell bodies, whereas PYK2/CAKβ‐ir was also present in the processes. In vitro and in vivo, a subpopulation of neurons displayed neurites with intense FAK + ‐ir. Thus, FAK + and PYK2/CAKβ are differentially regulated during development yet they are both abundantly expressed in the adult brain, with distinctive but overlapping distributions.