Current advances in biomolecular technology allow precise genetic fingerprinting of specific cells responsible for the pathogenesis of human diseases. This study demonstrates the feasibility of enerating target samples from laser capture microdissection (LCM) tissues suitable for hybridization of high-density oligonucleotide arrays for gene expression profiling. RNA was successfully isolated by LCM from three paired specimens of oral cancer and linearly amplified using T7 RNA polymerase. Evaluation of the cDNA revealed that five of five cellular maintenance transcripts are detected. Biotinylated cRNA was generated and hybridized to the human Test 1 GeneChip "probe arrays, which demonstrated that the RNA is of sufficient quality and integrity to warrant further analysis. Subsequent hybridization of the samples to the HuGenFL GeneChip probe arrays revealed that 26.5%-33.0% of the approximately 7000 represented genes are expressed in each of the six samples. These results demonstrate that LCM-generated tissues can generate sufficient quality cRNA for high-density oligonucleotide microarray analysis, an important step in determining comprehensive gene expression profiling using this high-throughput technology.hybridization of LCM-generated RNA to cDNA-based expression microarrays, no report has yet shown the successful hybridization to high-density oligonucleotide mircoarrays. The limited quantity and quality of RNA isolated using LCM continues to be a technical obstacle for in vivo analysis of gene expression using microarrays. While RNA isolated from LCM-harvested tissue can be converted into cDNA libraries, it is generally agreed that the most accurate representation of gene expression for DNA chips is achieved by making the target sample directly from the RNA or by a T7-based linear RNA amplification (2,4,5). Comprehensive gene expression analysis of LCM-isolated pure cell populations will represent a major biomedical advance in our understanding of the pathogenesis of human disease (7). A major challenge in this line of investigation is the ability to generate a sufficient amount and quality of the desireddesired macromolecule from biopsied material. The GeneChip"probe arrays (Affymetrix, Santa Clara, CA, USA) allow the generation of accurate and reproducible mRNA transcript-level data (3,6,9). The HuGeneFL probe array contains probes representing approximately 7000 full-length human genes. The ability to generate target samples from LCM-based cells and tissues for hybridization to DNA chips represents an important advance that demonstrates the feasibility of using this method of sample collection for gene expression analysis on DNA chips.

Human DOC-1/CDK2AP1 gene encodes a growth suppressor protein of 12kDa (p12DOC-1=CDK2AP1). Recently, p12DOC-1=CDK2AP1 has been shown to associate with cell cycle proteins including CDK2 and DNA olymerase a/primase. It negatively regulates CDK2 activities and suppressesDNAreplication. Therefore, identification of other p12DOC-1=CDK2AP1 interacting proteins might clarify its role in the cell cycle regulation and carcinogenesis. The purpose of this study was to identify additional p12DOC-1=CDK2AP1 interacting proteins using the yeast two-hybrid system. Using human p12DOC-1=CDK2AP1 as a bait in a liver cDNA library screening, cDNA clones identical to human DOC-1R transcript were identified. The interaction between p12DOC-1=CDK2AP1 and p14DOC-1R was verified in vitro and in cells. GST pull-down assay and immunoprecipitation experiments confirmed the interaction between the two proteins. The ritical region for p12DOC-1=CDK2AP1's interaction with p14DOC-1R was defined to amino acids 20-25 by using a series of deletion mutants as baits in the yeast two-hybrid system. Our data indicated that p12DOC-1=CDK2AP1 could associate with its homologous protein, p14DOC-1R.

Large scale gene expression pro

Regulated cyclin-dependent kinase (CDK) levels and activities are critical for the proper progression of the cell division cycle. p12DOC-1 is a growth suppressor isolated from normal keratinocytes. We report that p12DOC-1 associates with CDK2. More specifically, p12DOC-1 associates with the monomeric nonphosphorylated form of CDK2 (p33CDK2). Ectopic expression of p12DOC-1 resulted in decreased cellular CDK2 and reduced CDK2-associated kinase activities and was accompanied by a shift in the cell cycle positions of p12DOC-1 transfectants (1G1 and2S). The p12DOC-1-mediated decrease of CDK2 was prevented if the p12DOC-1 transfectants were grown in the presence of the proteosome inhibitor clasto-lactacystin b-lactone, suggesting that p12DOC-1 may target CDK2 for proteolysis. A CDK2 binding mutant was created and was found to revert p12DOC-1-mediated, CDK2-associated cell cycle phenotypes. These data support p12DOC-1 as a specific CDK2-associated protein that negatively regulates CDK2 activities by sequestering the monomeric pool of CDK2 and/or targets CDK2 for proteolysis, reducing the active pool of CDK2.