Molecular cloning of the murine JAK1 protein tyrosine kinase and its expression in the mouse central nervous system
Related Experiment Videos
1Department of Genetics, Harvard Medical School, Boston, Massachusetts 02115.
Abstract:
Degenerate oligonucleotide primers were employed in PCRs to clone protein tyrosine kinases that may play potential roles in the development of the mammalian CNS. Using one PCR clone to screen a mouse eye cDNA library, a full-length cDNA of a cytoplasmic tyrosine kinase, the homolog of human JAK1, was obtained. The murine JAK1 kinase belongs to a new family of cytoplasmic kinases that contain two tandem catalytic domains. Northern analyses indicated that murine JAK1 mRNA is expressed in a variety of tissues and cell lines. In the adult mouse eye, in situ hybridization and immunohistochemistry showed that JAK1 mRNA and protein were expressed in the retinal ganglion cell layer and the inner part of the inner nuclear layer, presumably in amacrine cells. JAK1 protein was also detected in horizontal cells and in the two synaptic layers of the adult retina. During retinal development, JAK1 protein was first detected in retinal ganglion cells and in their axons as early as embryonic day 14. Expression of JAK1 protein in amacrine cells and horizontal cells occurred only postnatally. This pattern of expression was also observed in the chick retina, suggesting an evolutionarily conserved function of JAK1 kinase in vertebrate retinal development and/or function. Immunohistochemical staining against JAK1 was detected in two areas of the adult mouse brain, the olfactory bulb and a group of cells in the hypothalamus. Together, these expression studies suggest a role for JAK1 kinase in the differentiation or function of a subset of CNS neurons.
Insights
Janus kinase 1 (JAK1) plays a role in the mammalian central nervous system (CNS). This study identifies JAK1 expression in the developing and adult retina, suggesting conserved functions in vertebrate retinal development.
Area of Science:
- Neuroscience
- Molecular Biology
- Genetics
Background:
- Protein tyrosine kinases are crucial for mammalian central nervous system (CNS) development.
- Janus kinase 1 (JAK1) is a cytoplasmic tyrosine kinase with potential roles in CNS development.
Purpose of the Study:
- To clone and characterize murine JAK1, a homolog of human JAK1.
- To investigate the expression pattern of JAK1 in the adult and developing mouse retina and brain.
- To explore the potential role of JAK1 in CNS neuron differentiation and function.
Main Methods:
- Polymerase chain reaction (PCR) with degenerate oligonucleotide primers was used to clone protein tyrosine kinases.
- A mouse eye cDNA library was screened using a PCR clone to obtain full-length murine JAK1 cDNA.
- Northern blot analysis, in situ hybridization, and immunohistochemistry were employed to determine JAK1 mRNA and protein expression patterns.
Main Results:
- Murine JAK1, a novel cytoplasmic kinase with two tandem catalytic domains, was cloned.
- JAK1 mRNA is expressed in various tissues and cell lines.
- In the adult mouse retina, JAK1 is expressed in ganglion cells, amacrine cells, horizontal cells, and synaptic layers.
- JAK1 protein appears in retinal ganglion cells and axons by embryonic day 14, with expression in amacrine and horizontal cells occurring postnatally.
- JAK1 is also detected in the olfactory bulb and hypothalamus of the adult mouse brain.
- Similar expression patterns were observed in the chick retina, indicating conserved function.
Conclusions:
- JAK1 kinase is expressed in specific neuronal populations within the developing and adult vertebrate retina and CNS.
- The expression pattern suggests a role for JAK1 in the differentiation or function of specific CNS neurons.
- JAK1 may have an evolutionarily conserved function in vertebrate retinal development and/or function.