Gene expression profile of laminar flow–exposed HUVECs determined by cDNA array hybridization.

(A) The plot shows a log-log comparison of the 24-hour shear-stress–exposed versus static cultures of background corrected and normalized hybridization signals of all ∼18 000 cDNAs on the array. Diagonal lines represent the following: dashed line, unity line with equal expression in both conditions; +5/−5 and +10/−10 labeled lines, 5- and 10-fold up- and down-regulation. Gray boxes represent hybridization signals that are below the limits of significant expression (<5 × 10³). Clones more than 5-fold differentially expressed were picked, re-arrayed on a custom microarray, checked for reproducibility of induction (B-D), and sequence verified. (B-D) The kinetics of transcriptional regulation by steady laminar flow (25 dyne/cm²) for 0, 2, 6, and 24 hours were determined for the 12 highly shear-stress–responsive genes (Table1). (B) Late flow-responsive genes DIA4 (diaphorase),SAT (spermidine/spermine N¹-acetyltransferase),FTL (ferritin light polypeptide), TXNRD1(thioredoxin reductase 1), AF1Q (ALL1-fused gene from chromosome 1q), SLC7A11 (solute carrier family 7), and GenBank T80319 (hypothetical protein). (C) Immediate-early induced genes KLF2 (LKLF), CYP1B1 (cytochrome P450 1B1),CDKN1A (cyclin-dependent kinase inhibitor 1A [p21]), andGJA5 (connexin-40). (D) Down-regulated gene CLDN5(claudin-5). Hybridization signals shown are the mean ± SD of duplo spots and expressed as percentage of the GAPDH signal.