RECQL4 is a gene that encodes a 1208 amino acid protein. RECQL4 protein is required during
DNA replication initiation and DNA end resection. A lack of RECQL4 is therefore associated
with a decrease in DNA damage repair. There are three unrelated autosomal recessive
diseases that are linked with mutations in RECQL4. Rothmund Thomson Syndrome is rare
disorder which has documented mutations within RECQL4 which has been linked to an
increased tendency to develop osteosarcomas.
To study the effect of RECQL4 depletion, shRNA knockdowns, ASC52Telo cells, osteodifferentiated cells and osteo-differentiated cells in long term PHA-767491 treatment were
subjected to a series of experiments. The trilineage differentiation capability, growth
characteristics, expression of cell proliferation and bone formation markers, drug sensitivity
and chromosomal instability was tested for each of the cell lines. These results could be used
to identify any differences in expressions and behaviours between the RECQL4 depleted cells
and the control cells.
All the cell lines were able to differentiate into adipocytes and osteoblasts, with p44 pLK0.1
and p44 shRQ-9 having a decreased adipocyte differentiation in comparison to the others. No
significant difference was observed in the growth assay between the cells in which RECQL4
was depleted and their controls. The p44 shRQ-9 cells showed the lowest foci count when
tested for 53BP expression but the highest Ki67 expression. There were no significant results
between the RECQL4 depleted cells and their controls when looking at marker gene
expressions. The drug sensitivity assays also show no significant differences however p14
shRQ-10 and P44 shRQ-10 appear less sensitive in the mid-range concentrations. The
chromosomal analysis showed that OD+PHA, p44 shRQ-9 and p44 shRQ-10 have an increased
degree of aneuploidy and tetraploid cells
