The concluding remarks of this 2018 Chinese review were:

“Using heterochromatin as a model, we have reviewed here the mechanisms behind the establishment and maintenance of silent chromatin domains. We conclude that almost every component of the chromatin environment, including DNA elements, RNAs, histones and other chromatin proteins, plays a role in the process of shaping and maintaining epigenetic states.

Epigenetic mechanisms have evolved..to solve the problem of orchestrating the differentiation of cells with the same genome. Just as any stable system must preserve some degree of flexibility, crosstalk and feedback among all elements in the system are mechanistically required.

We emphasize that:

1. Epigenetic information is inherited [from parent cell to child cell] in a relatively stable but imprecise fashion;
2. Multiple cis and trans factors are involved in the maintenance of epigenetic information during mitosis; and
3. The maintenance of a repressive epigenetic state requires both recruitment and self-reinforcement mechanisms.”

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Studies I’ve curated in 2018 whose methodologies may have benefited from investigating multiple epigenetic mechanisms included:

Only DNA methylation:

• DNA methylation and childhood adversity
• The pain societies instill into children
• Cell senescence and DNA methylation

Only microRNAs:

• Maternal obesity causes fetal liver damage

A review of studies that investigated DNA methylation and microRNAs but not histone modifications:

• Make consequential measurements in epigenetic studies

https://link.springer.com/article/10.1007/s11427-018-9276-7 “Recruitment and reinforcement: maintaining epigenetic silencing” (not freely available)