| A highly conserved, nucleolar factor named nucleostemin had been proposed to be a critical link between nucleolar function and stem-cell specific processes. Researchers postulated that nucleostemin had a nucleolus-based activity in controlling proliferation independent of ribosome biogenesis that was specific to stem cells and/or highly proliferating cells. However, nucleostemin homologs in the unicellular organisms S. cerevisae and S. pombe have been shown to modulate proliferation and growth by functioning in ribosome biogenesis. The research presented here utilized an intermediate metazoan, the nematode C. elegans, to address an important unresolved question in the fields of both stem cell biology and regulation of ribosome biogenesis, that of the role of nucleostemin in regulating cell proliferation. Similar to all known orthologs of nucleostemin, loss of C. elegans nucleostemin (nst-1) results in proliferation defects in the soma and germ line. The research presented here supports a role for C. elegans nucleostemin in cell growth and proliferation by promoting ribosome biogenesis. Thus, this work provides the first data in a metazoan linking nucleostemin's control of proliferation to ribosome biogenesis (published in Kudron and Reinke 2008). This work has uncovered functional differences between C. elegans and mammalian nucleostemin which has shed light on the possibility that mammalian nucleostemin may have diverged to have a function that is specific to stem cells or highly proliferating cells. |
