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Identification of dual specificity phosphatases induced by olfactory bulbectomy in rat olfactory neuroepithelium
T Ishibashi1, M Shinogami, S Ishimoto
1Department of Otolaryngology, Social Insurance Central General Hospital, 3-22-1, Hyakunincho, Shinnjuku-ku, 169-0073, Tokyo, Japan. tisibasi-oto@umin.ac.jp
Abstract:
Dual specificity protein tyrosine phosphatases (dsPTPs) are a subfamily of protein tyrosine phosphatases implicated in the regulation of extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase/stress-activated protein kinase (JNK/SAPK), and p38 mitogen-activated protein kinases (MAPKs) which are target enzymes activated by a wide range of cell-surface stimuli. Like these kinases, a class of dsPTP has been implicated in cell differentiation, regeneration, and apoptosis. In order to isolate dsPTPs which might play an important role in neuronal regeneration and apoptosis in olfactory neuroepithelium, we subcloned DNA fragments amplified by reverse transcription-polymerase chain reaction (RT-PCR), using degenerate oligonucleotide primers based on the conserved amino acid regions within the catalytic domain of dsPTPs, from rat olfactory epithelial RNA 1 and 4 h after an olfactory bulbectomy. The PCR products were subcloned into the pCRII vector, and 23 clones were chosen for further characterization. The sequence of these 23 individual clones revealed that two clones were identical to the rat dsPTP, MKP-3, and the other 21 clones were identical to the rat dsPTP, MKP-1. By Northern analysis, the MKP-1 transcript was induced and peaked 4 h following a bulbectomy. Similar results were obtained with the MKP-3 transcript. These results suggest that MKP-1 and MKP-3 may be involved in the early steps of apoptosis in vivo in rat olfactory neuroepithelium.
Insights
Dual specificity protein tyrosine phosphatases (dsPTPs), specifically MKP-1 and MKP-3, were identified in rat olfactory neuroepithelium following bulbectomy. These phosphatases show increased expression, suggesting a role in neuronal apoptosis.
Area of Science:
- Molecular Biology
- Neuroscience
- Cell Biology
Background:
- Dual specificity protein tyrosine phosphatases (dsPTPs) regulate mitogen-activated protein kinases (MAPKs) like ERK, JNK, and p38.
- dsPTPs are involved in cellular processes including differentiation, regeneration, and apoptosis.
- Olfactory neuroepithelium regeneration and apoptosis are critical areas of neurological research.
Purpose of the Study:
- To identify dsPTPs involved in neuronal regeneration and apoptosis in the rat olfactory neuroepithelium.
- To investigate the expression patterns of dsPTPs after olfactory bulbectomy.
Main Methods:
- Reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify dsPTP DNA fragments from rat olfactory epithelial RNA.
- Degenerate oligonucleotide primers targeting conserved dsPTP catalytic domains were employed.
- PCR products were subcloned, sequenced, and analyzed using Northern blot analysis.
Main Results:
- Twenty-three dsPTP clones were isolated, with 21 identified as rat dsPTP MKP-1 and two as rat dsPTP MKP-3.
- Northern analysis revealed that MKP-1 transcript levels were induced and peaked 4 hours post-bulbectomy.
- MKP-3 transcript levels showed a similar induction pattern after olfactory bulbectomy.
Conclusions:
- MKP-1 and MKP-3 are expressed in the rat olfactory neuroepithelium.
- The expression of MKP-1 and MKP-3 is upregulated following olfactory bulbectomy.
- These findings suggest that MKP-1 and MKP-3 play a role in the early stages of apoptosis in the olfactory neuroepithelium in vivo.