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Anaplastic lymphoma kinase is dynamically expressed on subsets of motor neurons and in the peripheral nervous system
Shawn P Hurley1, Douglas O Clary, Valerie Copie
1Department of Cell Biology and Neuroscience, Montana State University, Bozeman, Montana 59717, USA.
Abstract:
During embryonic development, complex events, such as cellular proliferation, differentiation, survival, and guidance of axons, are orchestrated and regulated by a variety of extracellular signals. Receptor tyrosine kinases mediate many of these events, with several playing critical roles in neuronal survival and axonal guidance. It is evident that not all the receptor tyrosine kinases that play key roles in regulating neuronal development have been identified. In this study, we have characterized the spatial-temporal expression profile of a recently identified receptor tyrosine kinase, anaplastic lymphoma kinase (ALK), in embryonic chick by means of whole-mount in situ hybridization in conjunction with immunohistochemistry. Our findings reveal that Alk is expressed in sympathetic and dorsal root ganglia as early as stage 19. In addition, mRNA is expressed from stage 23/24 (E4) to stage 39 (E13) in discrete motor neuron subsets of chick spinal cord along with a select group of muscles that are innervated by one of these particular motor neuron clusters. Expression within the spinal cord is coincident with the onset and duration of motor neuron programmed cell death and during the period of musculature innervation and synapse formation. Hence, the data presented here identify ALK as a novel candidate receptor for regulating critical events in the development of neurons in both the central and the peripheral nervous systems.
Insights
Anaplastic Lymphoma Kinase (ALK) is newly identified as a key regulator in embryonic chick nervous system development. Its expression in motor neurons and muscles suggests a role in neuronal survival and innervation.
Area of Science:
- Neuroscience
- Developmental Biology
- Molecular Biology
Background:
- Receptor tyrosine kinases (RTKs) are crucial for embryonic development, mediating cellular proliferation, differentiation, survival, and axon guidance.
- Several RTKs are critical for neuronal survival and axon guidance, but not all have been identified.
- Anaplastic Lymphoma Kinase (ALK) is a recently identified RTK with potential roles in neuronal development.
Purpose of the Study:
- To characterize the spatial-temporal expression profile of Anaplastic Lymphoma Kinase (ALK) in the embryonic chick.
- To investigate the potential role of ALK in the development of the central and peripheral nervous systems.
Main Methods:
- Whole-mount in situ hybridization was used to examine ALK mRNA expression.
- Immunohistochemistry was employed to confirm protein localization.
- Expression patterns were analyzed across different developmental stages (E4-E13) in the embryonic chick.
Main Results:
- ALK expression was detected in sympathetic and dorsal root ganglia starting at stage 19.
- mRNA expression was observed in specific motor neuron subsets and their innervated muscles from stage 23/24 (E4) to stage 39 (E13).
- Spinal cord expression of ALK coincided with motor neuron programmed cell death and muscle innervation/synapse formation.
Conclusions:
- Anaplastic Lymphoma Kinase (ALK) is expressed in key neuronal populations during critical developmental periods.
- ALK is identified as a novel candidate receptor regulating neuronal development in both the central and peripheral nervous systems.
- These findings highlight ALK's potential role in neuronal survival, axon guidance, and synapse formation during embryogenesis.
