Genomic organization and tissue expression of the mouse proteasome gene Lmp-7

Abstract

LMP7 is one of the two proteasome subunits encoded in the major histocompatibility complex and is speculated to play a role in the generation of endogenous peptides for presentation by class I molecules to cytotoxic T cells. Here we report the genomic organization of the mouse Lmp-7 gene and the tissue distribution of its messenger RNA. In contrast to human LMP7 which is composed of seven exons and six introns, the mouse Lmp-7 gene is organized in six exons and five introns. Interestingly, the region corresponding to the first exon of human LMP7 is highly modified by numerous insertions and deletions and contains two in frame stop codons. Consequently, the mouse Lmp-7 gene does not allow the alternative exon usage described in humans and most likely encodes for only one LMP7 protein. Thus, the Tap-1 3' end gene region and the Lmp-7 initial translation codon are separated by an 1182 nucleotide region which contains a TATA-box, a cAMP regulatory element, two SP1 sites, and two G-C-rich regions. Expression of the Lmp-7 messenger RNA was analyzed on different tissues from unstimulated mice. Lmp-7 messenger RNA is expressed in spleen, thymus, lung, liver, heart, and, at a very low level, in kidney but not in brain and testis. The possible role of Lmp genes in antigen processing is discussed.

Organization and Functional Analysis of the Mouse Transporter Associated with Antigen Processing 2 Promoter

“…8C) shows that the only common element shared by mouse TAP2, LMP2, LMP7, as well as by mouse and human LMP genes, is the CREB site (18). Cumulatively, these observations suggest that this element might have an important function in the regulation of genes associated with peptide production and transport.…”

“…These nucleotide differences determine the binding affinities of the relevant factors and, consequently, the contribution of these elements to promoter transactivation (16,17). The mouse and human LMP7 promoters as well as the mouse TAP1/LMP2 bidirectional promoter have not been fully functionally analyzed (18,19). Despite the coordinate regulation of human TAP1 and LMP2 genes observed in several cell lines (20 -22), it appears that binding of IRF1 or Stat1 to ICS2/GAS is sufficient to regulate transcription of the TAP1 gene, but binding of both factors is required for transcription of the LMP2 gene (23).…”

DNA Sequence, Chromosomal Localization, and Tissue Expression of the Mouse Proteasome SubunitLmp10(Psmb10) Gene

“…Northern blot analysis has shown that Lmp2 and Lmp7 are highly expressed in lung, thymus, and spleen, less so in liver, kidney, and heart, but not in brain, skeletal muscle, or testis (7,31). Thus, tissue- tissues revealed a similar pattern of Lmp10 expression the same element is found upstream of the genes for human (E2 when compared with Lmp2 and Lmp7 (Fig.…”

“…slightly more basic than is observed by 2D-NEPHGE-Homologous sequences are also conserved in the 5 re-PAGE (19), for reasons that are unclear at present. gion of the human (E2 form) and murine Lmp7 genes However, the pI observed for the processed (mature) (8,17,31) and in the bidirectional promoter of the LMP10 subunit in 2D-NEPHGE-PAGE (19) agrees pre-Lmp2 and Tap1 genes (Fig. 6) (8, 12, 30).…”

Characterization and mapping of the gene encoding mouse proteasome subunit DELTA (Lmp19)

“…Interestingly, the mature protein sequence of both LMP2 and DELTA begins precisely at the beginning of the exon 2 sequence. Like the mouse Lmp2 gene and proteasome genes encoding members of the a and [~ family in Drosophila (Frentzel et al 1992;Seelig et al 1993), but unlike the mouse Lmp7 gene, the Lmp19 gene does not appear to have a TATA box Zanelli et al 1993). Lack of a TATA box is characteristic of genes involved in housekeeping functions.…”