Discovery of novel cell proliferation-enhancing gene by random siRNA library based combinatorial screening.

Bone remodeling is tightly controlled by the actions of osteoblast and osteoclast. Impaired osteoblast proliferation and differentiation may disrupt the balance and lead to pathological symptom such as osteoporosis. To help understand the molecular mechanism of osteoblast proliferation, we performed a phenotype-driven high throughput screening with a random siRNA library, in search of novel genes that can accelerate murine preosteoblast MC3T3-E1 cell proliferation. Three siRNAs screened from the library were able to enhance MC3T3-E1 cell proliferation significantly. One of the proliferation-enhancing siRNAs (B7) was further subjected to expression profiling to pinpoint genes that putatively act down stream of it. A number of genes were regulated in response to proliferation-enhancing siRNA B7. Among these genes, Tmed2, which has never been reported yet in cell proliferation, was verified to be able to enhance MC3T3-E1 cell proliferation when over-expressed. Our screening process with random siRNA library provided an alternative strategy in addition to gene-specific siRNA library, in search of novel functional genes in genome scale.