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PCNA-binding to DNA at the G1/S transition in proliferating cells of the developing cerebral wall
1Department of Neurology, Massachusetts General Hospital, Harvard Medical School, Boston 02114.
Insights
Proliferating cell nuclear antigen (PCNA) binds to DNA in the developing brain during late G1 and early S phases. This study reveals PCNA-DNA binding patterns in vivo, mirroring in vitro findings.
Area of Science:
- Developmental Biology
- Molecular Biology
- Neuroscience
Background:
- Proliferating cell nuclear antigen (PCNA) is crucial for DNA synthesis in eukaryotes.
- PCNA forms a complex that binds DNA at the start of S-phase.
- Understanding PCNA dynamics in vivo is essential for cell cycle research.
Purpose of the Study:
- To define the cell cycle interval of PCNA-DNA binding in the intact mammalian brain.
- To investigate PCNA-DNA binding patterns in the developing cerebral wall.
- To compare in vivo findings with established in vitro data.
Main Methods:
- Utilized the spatial alignment of cell cycle stages in the developing cerebral wall epithelium.
- Employed immunohistochemistry with ethanol fixation to detect PCNA-DNA binding.
- Correlated nuclear location within the epithelium with cell cycle stage.
Main Results:
- PCNA-DNA binding was initiated in the final 5% of G1-phase (26 min).
- Binding continued through the initial 35% of S-phase (1.3 h).
- Observed phasic pattern closely approximated in vitro characterized patterns.
Conclusions:
- PCNA-DNA binding in the intact cerebral wall occurs during late G1 and early S phases.
- The developing cerebral epithelium provides a suitable model for in vivo cell cycle studies.
- This research offers insights into molecular events of the cell cycle under histogenetic regulation.
Abstract:
Proliferating cell nuclear antigen is a nuclear protein essential to DNA synthesis in eukaryotic cells. It is known to form part of a multi-protein complex which binds to DNA from the outset of S-phase of the cell cycle. We define in this analysis the interval of proliferating cell nuclear antigen binding to DNA (strictly speaking, the interval through which proliferating cell nuclear antigen is stained immunohistochemically after ethanol fixation) with respect to the stages of the cell cycle in the intact mammalian brain. The epithelium of the developing cerebral wall is favourable for such an analysis because nuclei at the same stage of the cell division cycle are spatially aligned with each other at the same depth of the epithelium. Therefore spatial location of a nucleus within the epithelium is a reliable indicator of the stage of the cell cycle for that nucleus. Proliferating cell nuclear antigen-DNA binding in this epithelium is initiated in the final 5% (26 min) of G1-phase and continues through the initial 35% (1.3 h) of S-phase. This phasic pattern of proliferating cell nuclear antigen-DNA binding, as revealed for the first time in the intact cerebral wall, approximates closely the phasic pattern as it has been characterized until now only in vitro in vertebrate cell lines. This analysis illustrates the potential of the cerebral proliferative epithelium for study of the molecular events of the cell cycle under in vivo conditions of histogenetic regulation.