Alu and L1 Retroelements Are Correlated with the Tissue Extent and Peak Rate of Gene Expression, Respectively

We exploited the serial analysis of gene expression (SAGE) libraries and human genome database in silico to correlate the breadth of expression (BOE; housekeeping versus tissue-specific genes) and peak rate of expression (PRE; high versus low expressed genes) with the density distribution of the retroelements. The BOE status is linearly associated with the density of the sense Alus along the 100 kb nucleotides region upstream of a gene, whereas the PRE status is inversely correlated with the density of antisense L1s within a gene and in the up- and downstream regions of the 0-10 kb nucleotides. The radial distance of intranuclear position, which is known to serve as the global domain for transcription regulation, is reciprocally correlated with the fractions of Alu (toward the nuclear center) and L1 (toward the nuclear edge) elements in each chromosome. We propose that the BOE and PRE statuses are related to the reciprocal distribution of Alu and L1 elements that formulate local and global expression domains.