FIGURE 1.

Identification, organization, and expression of the mpiR gene. (A) BLAST search of mouse ESTs using the last 70 nt of the 3′-UTR of mouse ALF mRNA reveal a class of antisense-oriented testis-specific ESTs. (B) The mpiR locus from which the antisense ESTs are derived is located between the Perp, EG237300, and KIAA1244 genes on mouse chromosome 10A2/A3. Sequencing of RT-PCR products derived with multiple primer sets revealed over 13 distinct splicing products (v.1 to v.11 from testis; v.4, v.12, and v.13 from liver) originate from the mpiR locus. The 12 unique exons are noted along with the location of the ALF antisense region. (C) Northern analysis of mpiR expression revealed a variety of transcript isoforms in different tissues whose detection depended on the exon used as the probe. The results reveal complex tissue-specific splicing of the mpiR gene. (D) Developmental Northern blot of mpiR expression shows up-regulation of the 0.7- and 2.0-kb mpiR transcripts in pre-pubertal mice at about day 14, a time that corresponds to the pachytene stage of meiosis I. (E) Bisulfite methylation analysis of the mpiR promoter region demonstrates hypomethylation in testis compared to brain and liver.