Knockdown effect of CDK8 and CDK19 in HeLa S3 cell

Mediator complex has been known as pivotal regulator of RNA polymerase II. Mediator complex has two CDK subunits in vertebrates, named CDK8 and CDK19. To elucidate functional difference between CDK8 and CDK19 in human cell, we employ siRNA mediate knockdown assay using HeLa S3 cell line. According to this assay these CDKs possess highly redundancy in HeLa S3 cell transcription regulation mechanism but in several genes, each CDK shows gene specific regulatory function. HeLa S3 cells were seeded on 6-well plate at 4 x 104 cells per well in 2ml antibiotic free DMEM medium before 24hr transfection. We transfect siRNA using Lipofectamine 2000 (invitrogen) according to its manual and siRNA final concentration in the medium was 20nM. After culturing for 48hr, transfection medium was changed to fresh antibiotic containing medium. Then the cells were incubated for additional 12hr and then RNA was prepared using RNeazy column (QIAGEN). Five μg of prepared RNA was subjected to the gene expression analysis using Human Genome U133 Plus 2.0 (Affymetrix) followed by characterizations with GeneSpring software (Agilent) and Pathway Analysis software (Ingenuity). In this analysis we employ two individual siRNA against each CDK and three replicates in each condition.