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Regulation of cellular functions by nucleoside diphosphate kinases in mammals
N Kimura1, N Shimada, M Fukuda
1Department of Gene Regulation and Protein Function, Tokyo Metropolitan Institute of Gerontology, Japan. nkimura@tmig.or.jp
Abstract:
The role of nucleoside diphosphate (NDP) kinases in cell growth, differentiation, and tumor metastasis in relation to signal transduction was investigated. The essential role of NDP kinase in cell growth was validated by coupling between reduced NDP kinase levels, induced by antisense oligonucleotides, and the suppression of proliferative activity of a cultured cell line. In addition, because NDP kinase levels are often enhanced with development and differentiation, as has been demonstrated in postmitotic cells and tissues, such as the heart and brain, we further examined this possibility using the bone tissue (osteoblasts) and a cultured cell line PC12D. The enhanced NDP kinase accumulation was demonstrated in the matured osteoblasts in vivo and in vitro by immunohistochemistry. In PC12D cells, neurite outgrowth took place in NDP kinase beta-transfected clones without differentiation inducers, which was accompanied by prolongation of doubling time. Neurite outgrowth, triggered by nerve growth factor and a cyclic AMP analog, was down-regulated upon forced expression of inactive mutant NDP kinase by virtue of a dominant negative effect. NDP kinase alpha-transfected rat mammary adenocarcinoma cells (MTLn3) and nm23-H2-transfected human oral squamous cell carcinoma cells (LMF4) manifested reduced metastatic potential and were associated with an altered sensitivity to environmental factors, such as motility and growth factors. NDP kinase alpha, compared to NDP kinase beta, was involved in a wide variety of the cellular phenomena examined. Taken together, NDP kinase isoforms appear to elicit both their own respective and common effects. They may have an ability to lead cells to both proliferative and differentiated states by modulating responsiveness to environmental factors, but their fate seems to depend on their surrounding milieu.
Insights
Nucleoside diphosphate (NDP) kinases are crucial for cell growth and differentiation. Manipulating NDP kinase levels impacts cell proliferation, differentiation, and tumor metastasis, suggesting a key role in signal transduction.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Nucleoside diphosphate (NDP) kinases are implicated in various cellular processes.
- Their role in cell growth, differentiation, and tumor metastasis requires further elucidation.
- NDP kinase expression is often elevated during development and differentiation.
Purpose of the Study:
- To investigate the role of NDP kinases in cell growth, differentiation, and tumor metastasis.
- To explore the relationship between NDP kinase activity and signal transduction pathways.
- To differentiate the specific roles of NDP kinase isoforms (alpha and beta).
Main Methods:
- Antisense oligonucleotides to reduce NDP kinase levels.
- Immunohistochemistry to assess NDP kinase accumulation in osteoblasts.
- Transfection of cell lines with NDP kinase alpha, beta, and mutant forms.
- Analysis of cell proliferation, differentiation, neurite outgrowth, and metastatic potential.
Main Results:
- Reduced NDP kinase levels suppressed cell proliferation.
- Enhanced NDP kinase accumulation observed in mature osteoblasts.
- NDP kinase beta transfection induced neurite outgrowth and slowed cell doubling.
- NDP kinase alpha and nm23-H2 transfection reduced metastatic potential in cancer cells.
- NDP kinase alpha exhibited broader cellular effects than NDP kinase beta.
Conclusions:
- NDP kinases play essential roles in regulating cell proliferation and differentiation.
- NDP kinase isoforms have distinct and overlapping functions.
- These enzymes modulate cellular responsiveness to environmental cues, influencing cell fate.
- NDP kinases are potential targets for cancer therapy, particularly in metastasis.