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Oncogene- and tumor-suppressor gene-related proteins in plants and fungi
Abstract:
Protooncogene- and tumor-suppressor gene proteins serve essential functions in the regulation of proliferation and differentiation of cells. Abnormal regulation or mutation of these genes, or transformation with retroviral homologs, may lead to tumor development in animals. In contrast to vertebrates, only few data on these genes exist in plants and fungi. Plant nuclear protooncogene homologs, such as myb and myc have multiple regulatory functions in metabolic pathways not existing in mammalian cells; they are involved in the complex regulation of anthocyanin (purple pigment) and phlobaphene (red pigment) biosynthesis, lignin production, trichome differentiation, dehydration stress gene expression and seed development. Apart from these well-characterized roles in plant-specific pathways, few experimental data have been reported on a functional significance in growth and development. A screening for nuclear protooncogene- and tumor-suppressor gene-related proteins in the myxomycete Physarum polycephalum revealed the existence of homologs of vertebrate c-myc, c-fos, c-jun, p53, and retinoblastoma proteins during the synchronous cell cycle or sclerotization. The p53 homologs of Physarum and Zea mays were shown to be specific for quiescent stages of their life cycles. Plants and lower eukaryotes, such as fungi, may be useful experimental systems to elucidate novel functions of protooncogene- and tumor-suppressor proteins in cell cycle regulation and development, or to reveal target genes that might be difficult to identify in complex mammalian systems. Recent data indicate that oncogenes and tumor suppressors in animals have more cellular targets than originally proposed; some of these might be as unexpected as in plant secondary metabolism.
Insights
Protooncogene and tumor suppressor gene homologs are found in diverse organisms, including plants and fungi. These genes play crucial roles in cell cycle regulation and development, offering new insights beyond animal systems.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Protooncogene and tumor suppressor proteins regulate cell proliferation and differentiation in vertebrates.
- Limited data exists on these genes in plants and fungi, despite their potential roles in unique metabolic pathways and development.
- Plant protooncogene homologs (e.g., myb, myc) regulate diverse pathways like pigment biosynthesis and stress response.
Purpose of the Study:
- To investigate the presence and function of protooncogene and tumor suppressor gene homologs in lower eukaryotes.
- To explore novel roles of these conserved genes in cell cycle regulation and development outside of vertebrate systems.
Main Methods:
- Screening for nuclear protooncogene- and tumor-suppressor gene-related proteins in the myxomycete Physarum polycephalum.
- Identification of homologs for vertebrate proteins like c-myc, c-fos, c-jun, p53, and retinoblastoma proteins.
Main Results:
- Homologs of vertebrate c-myc, c-fos, c-jun, p53, and retinoblastoma proteins were identified in Physarum polycephalum during its cell cycle and sclerotization.
- Physarum and Zea mays p53 homologs were found to be specific to quiescent life cycle stages.
- Plant and lower eukaryote systems may reveal novel functions and target genes for oncogenes and tumor suppressors.
Conclusions:
- Lower eukaryotes like Physarum and plants are valuable models for uncovering new functions of protooncogene and tumor suppressor proteins.
- These systems can help identify conserved and novel target genes, potentially revealing unexpected roles in cellular processes and development.