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A single cyclin A gene and multiple cyclin B1-related sequences are dispersed in the mouse genome
1Mammalian Genetics Laboratory, ABL-Basic Research Program, NCI-Frederick Cancer Research and Development Center, Maryland 21702.
Abstract:
Cyclin activation of protein serine/threonine kinases plays a pivotal role in regulating the cell cycle. Multiple cyclins that fall into at least five classes, A, B, C, D, and E, have been identified. In some organisms, more than one member of a single cyclin class has been observed. To gain insight into the function of cyclin multiplicity, we determined the number of cyclin A- and B1-related sequences present in the mouse genome, the relationship between these cyclin-related sequences and previously described mutations in the mouse, and cyclin A and B1 mRNA expression in mouse embryos. By genetic mapping using human cyclin A and B1 probes, we identified 1 cyclin A gene located on chromosome 3 and 10 cyclin B1-related sequences located on chromosomes 4, 5, 7, 8, 13, 14, 15, and 17. Cyclin B1-related sequences map in the vicinity of the metaphase-arrest mutation oligosyndactyly (Os) and embryonic lethal mutations associated with the albino (c) locus and the t-complex. In Northern analysis, two cyclin A-related transcripts of 2.1 and 3.4 kb and three cyclin B1-related transcripts of 1.7, 2.1, and 2.7 kb were detected in embryonic stem cells and postimplantation embryos from Day 9.5 to 15.5 of development. Identification of multiple cyclin B1-related sequences in the mouse genome and multiple cyclin B1 mRNAs raises the possibility that seemingly redundant cyclin B genes might have developmental- and/or cell-type-specific functions.
Insights
Researchers investigated mouse cyclin A and B1 genes to understand cyclin multiplicity. They identified one cyclin A gene and ten cyclin B1-related sequences, with varying mRNA expression, suggesting specific developmental roles.
Area of Science:
- Molecular Biology
- Genetics
- Developmental Biology
Background:
- Cyclin-dependent kinases regulate the cell cycle through cyclin activation.
- Multiple cyclin classes (A, B, C, D, E) exist, with some organisms having multiple members within a single class.
- The functional significance of cyclin multiplicity remains largely unexplored.
Purpose of the Study:
- To determine the number of cyclin A and B1 related sequences in the mouse genome.
- To investigate the relationship between these sequences and known mouse mutations.
- To analyze cyclin A and B1 mRNA expression patterns during mouse embryonic development.
Main Methods:
- Genetic mapping using human cyclin A and B1 probes.
- Analysis of cyclin-related sequence proximity to known mouse mutations (oligosyndactyly, albino, t-complex).
- Northern blot analysis to detect cyclin A and B1 mRNA transcripts in mouse embryos.
Main Results:
- One cyclin A gene was mapped to chromosome 3.
- Ten cyclin B1-related sequences were identified on multiple chromosomes (4, 5, 7, 8, 13, 14, 15, 17).
- Multiple cyclin A (2.1, 3.4 kb) and cyclin B1 (1.7, 2.1, 2.7 kb) mRNA transcripts were detected in developing mouse embryos.
Conclusions:
- The mouse genome contains a single cyclin A gene and multiple cyclin B1-related sequences.
- Cyclin B1-related sequences are located near genes associated with developmental mutations.
- The existence of multiple cyclin B1 genes and mRNAs suggests potential cell-type- or developmental-stage-specific functions.