A novel kinase, AATYK induces and promotes neuronal differentiation in a human neuroblastoma (SH-SY5Y) cell line.
Apoptosis Associated Tyrosine Kinase (AATYK), a novel protein recently isolated from differentiating 32D mouse myeloid cells, contains a putative tyrosine kinase domain and several binding motifs for src homology 2 (SH-2) and src homology 3 (SH-3) domain containing proteins. We observed that AATYK is expressed in different regions of the brain. Although it might play a role in normal nervous system development by modulating apoptosis, little is known regarding its function in the brain or its intracellular localization and kinase activity. Recognizing its homology with Insulin like growth factor-I (IGF-I) receptor (IGF-IR) and the critical role of IGF-I in neuronal survival, we hypothesized that AATYK plays an important role in neuronal differentiation/apoptosis. To test this hypothesis, we transfected the human adrenergic neuroblastoma (NB):SH-SY5Y cells with AATYK cDNA under a tetracycline-repressible promoter and established stable cell lines that readily express AATYK on removal of tetracycline. AATYK immunoprecipitated from these cell lysates is an active kinase. Indirect immunofluorescent staining of the clones revealed AATYK to be localized in the cytoplasm. By itself, AATYK overexpression for short duration (2-3 days) did not induce differentiation in the stable SH-SY5Y clones. On the other hand, overexpression for longer periods (7-8 days) per se, significantly (P<0.05-0.001) increased the percent of differentiated cells as well as the neurite length. AATYK-induced differentiation was in the same range as the differentiation induced by agents like all-trans retinoic acid (RA), 12-O-Tetradecanoyl phorbol 13-acetate (TPA) and IGF-I. In addition, AATYK significantly promoted the neuronal differentiation induced by these agents. Our results demonstrate for the first time that AATYK is an active, non-receptor, cytosolic kinase which induces neuronal differentiation and also promotes differentiation induced by other agents in the SH-SY5Y cells.
Raghunath
M
M
Division of Neuro-Oncology, Children's Hospital of Philadelphia, Philadelphia, PA, 19104 USA.
Patti
R
R
Bannerman
P
P
Lee
C M
CM
Baker
S
S
Sutton
L N
LN
Phillips
P C
PC
Damodar Reddy
C
C
D000818:Animals; D051017:Apoptosis Regulatory Proteins; D001921:Brain / Q000166:cytology / Q000187:drug effects / Q000201:enzymology; D002454:Cell Differentiation / Q000187:drug effects; D048429:Cell Size / Q000187:drug effects; D003593:Cytoplasm / Q000201:enzymology; D004790:Enzyme Induction / Q000187:drug effects; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology; D051379:Mice; D016501:Neurites / Q000187:drug effects / Q000201:enzymology; D009447:Neuroblastoma; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology*; D009685:Nuclear Envelope / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D014162:Transfection; D014212:Tretinoin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D051017:Apoptosis Regulatory Proteins; D012333:RNA, Messenger; D014212:Tretinoin; D007334:Insulin-Like Growth Factor I; C118137:AATK protein, human; C485554:Aatk protein, mouse; D011505:Protein-Tyrosine Kinases; D013755:Tetradecanoylphorbol Acetate