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Developmental changes in distribution of death-associated protein kinase mRNAs
M Yamamoto1, H Takahashi, T Nakamura
1Pharmaceuticals Discovery Laboratory, Yokohama Research Center, Mitsubishi Chemical Corporation, Aoba-ku, Yokohama, Japan.
Abstract:
Death-associated protein kinase (DAP-kinase) is Ca(2+)/calmodulin-dependent serine/threonine kinase that contains ankyrin repeats and the death domain. It has been isolated as a positive mediator of interferon-gamma-induced apoptotic cell death of HeLa cells. In order to reveal the physiological role of DAP-kinase, the tissue distribution and developmental changes in mRNA expression of DAP-kinase were investigated by Northern blot and in situ hybridization analyses. DAP-kinase mRNA was predominantly expressed in brain and lung. In brain, DAP-kinase mRNA had already appeared at embryonic day 13 (E13) and was, thereafter, detected throughout the entire embryonic period. High levels of expression were detected in proliferative and postmitotic regions within cerebral cortex, hippocampus, and cerebellar Purkinje cells. These findings suggest that DAP-kinase may play an important role in neurogenesis where a physiological type of cell death takes place. The overall expression of DAP-kinase mRNA in the brain gradually declined at postnatal stages, and the expression became restricted to hippocampus, in which different expression patterns were observed among rostral, central, and caudal coronal sections, suggesting that DAP-kinase may be implicated in some neuronal functions. Furthermore, it was found that the expression of DAP-kinase mRNA was increased prior to a certain cell death induced by transient forebrain ischemia, indicating a possible relationship between DAP-kinase and neuronal cell death.
Insights
Death-associated protein kinase (DAP-kinase) is crucial for neurogenesis and neuronal function. Its mRNA expression is prominent in the brain during development and in specific regions postnatally, suggesting roles in cell death and neuronal processes.
Area of Science:
- Molecular Biology
- Neuroscience
- Cell Biology
Background:
- Death-associated protein kinase (DAP-kinase) is a Ca(2+)/calmodulin-dependent serine/threonine kinase.
- DAP-kinase was previously identified as a mediator of interferon-gamma-induced apoptosis in HeLa cells.
Purpose of the Study:
- To investigate the physiological role of DAP-kinase by examining its tissue distribution and developmental mRNA expression patterns.
- To explore the potential involvement of DAP-kinase in neurogenesis and neuronal cell death.
Main Methods:
- Northern blot analysis to determine DAP-kinase mRNA expression levels.
- In situ hybridization to analyze the spatial and temporal distribution of DAP-kinase mRNA in developing and adult brain tissue.
Main Results:
- DAP-kinase mRNA was predominantly expressed in the brain and lung, with significant expression detected in the brain from embryonic day 13 onwards.
- High expression levels were observed in proliferative and postmitotic regions of the cerebral cortex, hippocampus, and cerebellar Purkinje cells during embryonic development.
- Postnatal expression in the brain declined but remained restricted to the hippocampus, with varied patterns in different coronal sections. Expression increased prior to cell death induced by forebrain ischemia.
Conclusions:
- DAP-kinase likely plays a significant role in neurogenesis, a process involving physiological cell death.
- The specific expression patterns in the postnatal hippocampus suggest a role for DAP-kinase in mature neuronal functions.
- DAP-kinase may be implicated in neuronal cell death, particularly in response to ischemic injury.