Ricerc@Sapienza

The expression of p57, a critical regulator of cell proliferation and differentiation, is precisely controlled by several epigenetic mechanisms including paternal imprinting. Kcnq1ot1, a LncRNA mapping to the p57 imprinting domain, is paternally expressed and participates in the cis-silencing of the near imprinted genes through chromatin-level regulation.
Unexpectedly, we found that paternal Kcnq1ot1 depletion boosts maternal p57 expression and that Kcnq1ot1 associates with chromatin at an intragenic p57 region (p57i) on the maternal allele, recruiting the repressive chromatin mark H3K27me3. Upon differentiation, the myogenic factor MyoD binds to p57i, interacts with Kcnq1ot1 and promotes H3K27me3 displacement.
In the present project, we plan to further investigate the Kcnq1ot1-dpendent regulation of p57 in muscle cells with the following objectives:
1) Understand how paternally expressed Kcnq1ot1 regulates maternal p57.
We hypothesize that paternally transcribed Kcnq1ot1, which is unlikely to act in trans as a diffusible product, interacts with and regulate maternal p57 through a mechanism involving allele proximity. This hypothesis will be verified through RNA/DNA FISH experiments.
2) Determine the role of the functional interaction between Kcnq1ot1 and DNMT1 in p57 control in muscle cells.
Maternal p57 promoter is hypermethylated and inaccessible to transcription factors in undifferentiated myoblasts. Since Kcnq1ot1 interacts with DNMT1 during imprinting, we suppose that Kcnq1ot1 also mediates DNA methylation at maternal p57. This hypothesis will be verified by analysing:
- the physical interaction between Kcnq1ot1 and DNMT1 during differentiation
- the DNMT1 binding to p57i
- the allele-specific methylation status of p57i during differentiation and after Kcnq1ot1 depletion.
The proposed research not only will elucidate a further mechanism for fine tuning p57 expression, but also will add new insights into the biology of Kcnq1ot1, a LncRNA still poorly known.