No abstract

Osteoprotegerin (OPG) is a secreted glycoprotein that regulates bone resorption by inhibiting differentiation and activation of osteoclast, thereby potentially useful for the treatment of many bone diseases associated with increased bone loss. In this study, we designed a novel cDNA expression cassette by modifying the potent and mammary gland-specific goat β-casein/hGH hybrid gene construct and examined human OPG (hOPG) cDNA expression in transgenic mice. Six transgenic mice all successfully expressed hOPG in their milk at the level of 0.06-2,000 µg/ml. An estimated molecular weight of the milk hOPG was 55 kDa in SDS-PAGE, which is the same as a naturally glycosylated monomer. This hOPG expression was highly specific to the mammary glands of transgenic mice. hOPG mRNA was not detected in any organs analyzed except mammary gland. Functional integrity of milk hOPG was evaluated by TRAP (tartrate-resistant acid phosphatase) activity assay in bone marrow cell cultures. OPG ligand (OPG-L) treatment increased TRAP activity by two fold but it was completely abolished by co-treatment with transgenic milk containing hOPG. Taken together, our novel cDNA expression cassette could direct an efficient expression of biologically active hOPG, a potential candidate pharmaceutical for bone diseases, only in the mammary gland of transgenic mice.

We identified four new bovine tri-nucleotide microsatellite loci and analyzed their sequence structures and genetic parameters in 105 randomly selected Korean cattle (Hanwoo). Allele numbers of the loci B17S0808, B15S6253, B8S7996, and B17S4998 were 10, 11, 12, and 29, respectively. These alleles contained a simple or compound repeat sequences with some variations. Allele distributions of all these loci were in Hardy-Weinberg equilibrium (P > 0.05). Observed heterozygosity and expected heterozygosity ranged from 0.54 (B15S6253) to 0.92 (B17S4998) and from 0.599 (B15S6253) to 0.968 (B17S4998), respectively, and two measures of heterozygosity at each locus were highly correlated. Polymorphism information content (PIC) for these 4 loci ranged from 0.551 (B15S6253) to 0.932 (B17S4998), which means that all these loci are highly informative (PIC > 0.5). Other genetic parameters, power of discrimination (PD) and probability of exclusion (PE) ranged from 0.783 (B15S6253) to 0.984 (B17S4998) and from 0.210 (B15S6253) to 0.782 (B17S4998), respectively. Their combined PD and PE values were 0.9999968 and 0.98005176, respectively. Capillary electrophoresis revealed that average peak height ratio for a stutter was 13.89% at B17S0808, 26.67% at B15S6253, 9.09% at B8S7996, and 43.75% at B17S4998. Although the degree of genetic variability of the locus B15S6253 was relatively low among these four microsatellite markers, their favorable parameters and low peak height ratios for stutters indicate that these four new tri-nucleotide microsatellite loci could be useful multiplex PCR markers for the forensic and population genetic studies in cattle including Korean native breed.