Progress 09/01/07 to 08/31/10
Outputs
OUTPUTS: Experiments were conducted to establish how the expression of the maize A1 gene is affected by transposon insertions in its promoter. Several constructs were made and tested in transient expression experiments to demonstrate that the Mu1 (Mutator1) transposon insertion in the a1-mum2 allele negatively affected the expression of a reporter gene, and that this effect was largely mediated by the long terminal repeats. Inhibitors of histone acetylation and DNA methylation showed significant effects on the expression of a1-mum2 suggesting an important role of chromatin structure on the effect of the transposon. PARTICIPANTS: Dr. Erich Grotewold was responsible for overseeing all aspects of this project. Dr. Yongqin Wang (postdoc) carried out most of the experiments for this project with assistance from Dr. Kengo Morohashi (postdoc) and Antje Feller (Graduate Student first, then postdoc). Part of the materials used were obtained as part of a collaboration with Dr. Damon Lisch (UC Berkeley). TARGET AUDIENCES: The role of transposons on gene expression is of fundamental importance for plant breeding as well as human health. Concepts derived from these studies were used as part of classroom lectures (Plant Molecular Biology, PCMB 622) and other venues. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Our results contributed to highlight the important role of transposons on plant gene expression, while starting to identify novel mechanisms for how they affect chromatin structure and other aspects of gene regulation. The Mu1 and Spm insertions (in the a1-mum2 and a1-m2 alleles, respectively) provide an unique opportunity to explore the dynamics of the process, particularly with respect to alterations in chromatin architecture. The importance of our studies is at multiple levels. First, many agronomic traits are related to variations in gene expression as a consequence of transposable elements inserted in the gene promoters. Second, because transposon insertions are very important for human health, since about half of our gene promoters contain transposons. And finally, because transposons are central to epigenetic phenomena associated for example with small RNAs that significantly complicate breeding efforts and the analysis of quantitative trait loci.
Publications
- No publications reported this period
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Progress 09/01/08 to 08/31/09
Outputs
OUTPUTS: Activities: Experiments were conducted to determine how the insertion of transposons in the maize A1 gene altered A1 expression. Constructs were made to establish using transient expression experiments whether the tranposons could function by activating or repressing the expression of the A1 gene. Field crosses and new genetic stocks are being generated to determine whether the transposon insertions can make the expression of the A1 gene independent of the normal transcriptional regulators. Crosses to stocks lacking the mop1 gene encoding for an RNA-dependent RNA-polymerase were made to determine the participation of small RNAs on the control of the A1 gene by the transposon insertions. PARTICIPANTS: Erich Grotewold (PI), was responsible for overseeing all aspects of the project and performing genetic experiments in the field. Yongqin Wang (postdoc) carried out many of the other experiments related to this project, with some technical assistance from Kengo Morohashi (postdoc). A recent collaboration with Dr. Damon Lisch (UC Berkeley) was initiated. TARGET AUDIENCES: While interest on the effect of transposons on gene expression was only of interest to a small group of scientists in the past, the effect of transposon on chromatin structure and epigenetic phenomena has gained significance at multiple levels in agriculture and health. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The role of transposons as gene control elements is gaining more importance as the mechanisms continue to be uncovered, and small RNAs appear to be implicated in many instances. The Mu1 and Spm transposon insertions in the maize A1 gene provide a unique opportunity to understand how insertion affect the normal regulation of host gene expression. Our results are providing insights on how transposons control the expression of the maize A1 gene, particularly from the perspective of chromatin structure.
Publications
- No publications reported this period
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Progress 09/01/07 to 08/31/08
Outputs
OUTPUTS: Activities: Experiments were conducted to determine whether the insertion of transposons in the maize A1 gene altered nucleosome organization. Constructs were made to determine whether the tranposons could function activating or repressing the expression of the A1 gene. Field crosses and new genetic stocks were generated to determine whether the transposon insertions can make the expression of the A1 gene independent of the normal transcriptional regulators. Products: Protocols were developed to determine the sensitivity of the chromatin of various maize tissues and lines to nuclease treatments. PARTICIPANTS: Erich Grotewold (PI), was responsible for overseeing all aspects of the project and performing genetic experiments in the field. Yongqin Wang (postdoc) carried out many of the other experiments related to this project, with some technical assistance from Kengo Morohashi (postdoc). TARGET AUDIENCES: So far obtained results are probably of interest only to other scientists with interests in understanding control of plant gene expression, but broader findings derived from these studies will significantly impact breeders and geneticists involved in selecting important agronomic traits. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The presence of transposons (mobile elements) in the promoters of plant and animal genes is increasingly being recognized as a major component for gene expression. The Mu1 and Spm transposon insertions in the maize A1 gene provide a unique opportunity to understand how insertion affect the normal regulation of host gene expression. Our results are providing insights on how transposons control the expression of the maize A1 gene, particularly from the perspective of chromatin structure.
Publications
- No publications reported this period
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