Jumonji (JmjC) domain proteins influence gene expression and chromatin
organization by way of histone demethylation, which provides a means to
regulate the activity of genes across the genome. JmjC proteins have been
associated with many human diseases including various cancers, developmental
and neurological disorders, however, the shared biology and possible common
contribution to organismal development and tissue homeostasis of all JmjC
proteins remains unclear. Here, we systematically tested the function of all
13 Drosophila JmjC genes. Generation of molecularly defined null mutants
revealed that loss of 8 out of 13 JmjC genes modify position effect
variegation (PEV) phenotypes, consistent with their ascribed role in
regulating chromatin organization. However, most JmjC genes do not critically
regulate development, as 10 members are viable and fertile with no obvious
developmental defects. Rather, we find that different JmjC mutants
specifically alter the phenotypic outcomes in various sensitized genetic
backgrounds. Our data demonstrate that, rather than controlling essential gene
expression programs, Drosophila JmjC proteins generally act to “fine-tune”
different biological processes
