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Characterization of the apoptosis-associated tyrosine kinase (AATYK) expressed in the CNS

M Tomomura1, A Fernandez-Gonzales, R Yano

  • 1Department of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, Tennessee, TN 38105-2794, USA.

Oncogene
|April 21, 2001
PubMed

Insights

Apoptosis-associated tyrosine kinase (AATYK) is a protein crucial for programmed cell death in mature neurons. Its tyrosine kinase activity promotes neuronal apoptosis, particularly in cerebellar granule cells.

Area of Science:

  • Neuroscience
  • Molecular Biology
  • Cell Biology

Background:

  • Apoptosis-associated tyrosine kinase (AATYK) gene expression increases in myeloid cells during growth arrest or apoptosis.
  • AATYK mRNA is detected at low levels in adult mouse brains but absent in embryos.
  • Widespread expression of AATYK mRNA is confirmed in adult mouse neurons via in situ hybridization.

Purpose of the Study:

  • To investigate the role of AATYK in neuronal apoptosis.
  • To characterize the tyrosine kinase activity of AATYK.
  • To determine AATYK's involvement in the apoptosis of mature neurons.

Main Methods:

  • Isolation of cDNA clones from a mouse cerebellar library.
  • Expression of AATYK in 293 cells to assess tyrosine kinase activity and autophosphorylation.
  • Induction of apoptosis in cultured cerebellar granule cells using low KCl concentrations.
  • Analysis of AATYK protein levels, molecular weight, and phosphorylation during apoptosis.
  • Comparison of apoptosis rates in cells overexpressing wild-type versus mutant AATYK.

Main Results:

  • AATYK exhibits tyrosine kinase activity and autophosphorylation.
  • AATYK mRNA expression is rapidly induced in cerebellar granule cells during KCl-induced apoptosis.
  • Apoptosis is associated with a slight increase in AATYK protein levels and a higher molecular weight, partly due to tyrosine phosphorylation.
  • Overexpression of wild-type AATYK significantly increases the number of apoptotic granule cells compared to a kinase-inactive mutant.

Conclusions:

  • AATYK plays a role in the apoptosis of mature neurons.
  • The tyrosine kinase activity of AATYK is essential for its function in promoting neuronal apoptosis.
  • AATYK is a key regulator of programmed cell death in the adult brain.

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