Thy-1 inhibits mitogen-induced Ca2+ oscillation in ras-transformed mouse fibroblasts.

Cell surface glycoprotein Thy-1 functions as a transformation suppressor in v-ras-transformed NIH/3T3 cells [Sugimoto et al., (1991) Cancer Res. 51, 99-104.]. In order to understand the mechanism of action of Thy-1, we examined the effect of Thy-1 expression on mitogen-induced Ca2+ oscillation which was correlated with v-ras-transformation [Fu et al., (1991) FEBS Lett. 281, 263-266.]. Forced expression of Thy-1 in v-ras-transformed cells inhibited mitogen-induced Ca2+ oscillation. Although v-Ras-free, Thy-1-positive NIH/3T3 cells (major population) did not show Ca2+ oscillation, whereas in Thy-1-negative NIH/3T3 cells (less than 1% of the population) Ca2+ oscillation was observed. Finally, replacement of the carboxyl-half of Thy-1 with that of CD4 abolished the inhibitory effect of Thy-1. These results suggest that Thy-1 directly or indirectly participates in the negative regulation of Ca2+ response by inhibiting Ca2+ oscillation.     

Characterization of Cre recombinase mouse lines enabling cell type-specific targeting of postnatal intervertebral discs

Cre/loxP technology is an important tool for studying cell type-specific gene functions. Cre recombinase mouse lines, including Agc1-CreER^T2, Col2a1-Cre; Col2a1-CreER^T2, Shh-Cre, Shh-CreER^T2, and Osx-Cre, have been proven to be valuable tools to elucidate the biology of long bones, yet the information for their activity in postnatal intervertebral disc (IVD) tissues was very limited. In this study, we used R26-mTmG fluorescent reporter to systematically analyze cell specificity and targeting efficiency of these six mouse lines in IVD tissues at postnatal growing and adult stages. We found that Agc1-CreER^T2 is effective to direct recombination in all components of IVDs, including annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplate (CEP), upon tamoxifen induction at either 2 weeks or 2 months of ages. Moreover, Col2a1-Cre targets most of the cells in IVDs, except for some cells in the outer AF (OAF) and NP. In contrast, the activity of Col2a1-CreER^T2 is mainly limited to the IAF of IVD tissues at either stage of tamoxifen injection. Similarly, Shh-Cre directs recombination specifically in all NP cells, whereas Shh-CreER^T2 is active only in a few NP cells when tamoxifen is administered at either stage. Finally, Osx-Cre targets cells in the CEP, but not in the NP or AF of IVDs tissues at these two stages. Thus, our data demonstrated that all these Cre lines can direct recombination in IVD tissues at postnatal stages with different cell type specificity and/or targeting efficiency, and can, therefore, serve as valuable tools to dissect cell type-specific gene functions in IVD development and homeostasis.     

Design and activity detection of BH3-mimetic peptide based on Bcl-XL binding potency

Communicated by Ramaswamy H. Sarma     

Imputation of missing genotypes from low‐ to high‐density SNP panel in different population designs

Imputation of missing genotypes, in particular from low density to high density, is an important issue in genomic selection and genome‐wide association studies. Given the marker densities, the most important factors affecting imputation accuracy are the size of the reference population and the relationship between individuals in the reference (genotyped with high‐density panel) and study (genotyped with low‐density panel) populations. In this study, we investigated the imputation accuracies when the reference population (genotyped with Illumina BovineSNP50 SNP panel) contained sires, halfsibs, or both sires and halfsibs of the individuals in the study population (genotyped with Illumina BovineLD SNP panel) using three imputation programs (fimpute v2.2, findhap v2, and beagle v3.3.2). Two criteria, correlation between true and imputed genotypes and missing rate after imputation, were used to evaluate the performance of the three programs in different scenarios. Our results showed that fimpute performed the best in all cases, with correlations from 0.921 to 0.978 when imputing from sires to their daughters or between halfsibs. In general, the accuracies of imputing between halfsibs or from sires to their daughters were higher than were those imputing between non‐halfsibs or from sires to non‐daughters. Including both sires and halfsibs in the reference population did not improve the imputation performance in comparison with when only including halfsibs in the reference population for all the three programs.