The human sex hormone-binding globulin gene contains exons for androgen-binding protein and two other testicular messenger RNAs

When a sex hormone-binding globulin (SHBG) cDNA was used to screen a human testicular cDNA library, three distinct cDNAs were isolated, one of which corresponds to the human SHBG cDNA sequence and probably represents testicular androgen-binding protein. The other two SHBG-related cDNAs each contain unique 5' regions that diverge from the SHBG cDNA sequence at the same position, and one of them (SHBGr-2) lacks a 208-base pair region within the SHBG cDNA. As a result, this cDNA could potentially encode for a truncated form of SHBG which lacks N-linked carbohydrates and part of the steroid-binding domain. Southern blots of human placental DNA and cloned genomic DNA fragments also indicate that SHBG and its related testicular cDNAs are the products of a single gene. Sequence analysis of the gene indicates that the complete coding region for the SHBG precursor is comprised of 8 exons, which are distributed over 3.2 kilobase (kb) of genomic DNA, and the unique 5' regions associated with the two SHBG-related testicular cDNAs were identified 1.9 kb upstream from the initiating codon for SHBG. In addition, the deletion within SHBGr-2 is due to the removal of exon 7, and an interesting feature of the gene is that differentially used exons are preceded by Alu repetitive DNA sequences. Although the relative abundance of the various SHBG-related mRNAs in the testis has not been established, Northern blot analysis indicates that they are similar in size (1.6 kb) to that of hepatic SHBG mRNA.     

Evaluation of p53 genotype on gene expression in the testis, liver, and heart from male C57BL/6 mice

Our laboratory is conducting experiments designed to characterize the role of p53 in gene expression in the TSG-p53? mouse model. In the study reported here, gene expression levels in tissue derived from the testis, liver, and heart of male, 8–9 week old, p53 wild-type (WT), heterozygous (HET) or knockout (KO) mice were determined utilizing a targeted qPCR 84-gene array. The heart, liver and testis were selected because of the unique function and rate of cell division of each tissue. The genes on the arrays were categorized into three Functional Gene Groups, Apoptosis, Cell-Cycle and DNA Repair. Differences in expression of the functional groups were determined by multivariate analysis of variance (MANOVA) and significant (P < 0.05) differences in their expression were found among the heart, liver and testis. Further, the expression of the Functional Gene Groups in each of these tissues was also significantly affected by p53 genotype. These data indicate that gene expression in unperturbed tissue is influenced by the status of p53 genotype, and relates, at least partially, to the function of the tissue.     

Molecular cloning and expression of bovine (Bos taurus) leptin receptor isoform mRNAs

We characterized Bos taurus leptin receptor (Ob-R) isoform mRNAs as well as their expression in different tissues, including some adipose depots (perirenal, subcutaneous and intermuscular adipose tissues). Based on the GenBank database sequences of the bovine partial Ob-R, primers were designed to amplify cDNAs of bovine Ob-R isoforms. The full-length cDNAs of bovine the Ob-R isoforms were cloned by combination with 3'-and 5'-RACE. Three bovine Ob-R isoform cDNAs were cloned and the sequence analyses revealed that these cDNAs were bovine Ob-R isoforms, i.e., the long form (Ob-Rb), the middle form (Ob-Ra) and the short form (Ob-Rc). The open reading frames of Ob-Ra, Ob-Rb and Ob-Rc gene were 2688, 3498 and 2673 bp, respectively. The deduced amino acid sequences suggested that the isoforms were single transmembrane proteins, and differed in the C-terminal amino acid sequences. The amino acid sequence of these bovine Ob-R isoforms showed 73-75% identity compared with the corresponding mouse isoforms. The tissue-specific expression of the bovine Ob-R isoforms were measured by semi-quantitative RT-PCR. Expression of Ob-Rb was highest in liver, heart, spleen and kidney, with lower expression in lung and testis, and slight expression in muscle. Ob-Ra was highly expressed in liver and spleen, whereas moderate expression was observed in heart, testis, and muscle, and its expression was the lowest in lung and kidney. Ob-Rc mRNA was expressed in the liver, heart, testis, kidney and muscle, but not in the lung and spleen. In adipose tissues, higher expression of Ob-Ra and Ob-Rb mRNA was observed in intermuscular adipose tissue than in subcutaneous or perirenal adipose tissues. Ob-Ra mRNA level was positively correlated with Ob-Rb mRNA level in the adipose tissues (r=0.81, P<0.05). The results demonstrated that each Ob-R isoform mRNA was differentially expressed in various tissues of cattle, which may be involved in the difference of peripheral actions for leptin.