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BCL2L12 has been reported to be involved in post-mitochondrial apoptotic events in glioblastoma, but the role of BCL2L12A, a splicing variant of BCL2L12, remains unknown. In this study, we showed that BCL2L12 and BCL2L12A were overexpressed in glioblastoma multiforme (GBM). Large-scale yeast two-hybrid screening showed that BCL2L12 was a GSK3b binding partner in a testis cDNA library. Our data demonstrated that GSK3b interacts with BCL2L12 but not BCL2L12A, whose C terminus lacks a binding region. We found that a BCL2L12(153-191) fragment located outside of the C-terminal BH2 motif is responsible for GSK3b binding. In contrast, no interaction was detected between BCL2L12A and GSK3b. In vitro kinase and l-phosphatase assays showed that GSK3b phosphorylates BCL2L12 at S156, while this site is absent on BCL2L12A. Moreover, our data also showed that the BCL2L12(153-191) fragment directly interrupted GSK3bmediated Tau phosphorylation in a dose-dependent manner. Ectopic expression of GFP-fused BCL2L12 or BCL2L12A in U87MG cells leads to repression of apoptotic markers and protects against staurosporine (STS) insults, indicating an antiapoptotic role for both BCL2L12 and BCL2L12A. In contrast, no anti-apoptotic ability was seen in BCL2L12(S156A). When BCL2L12-expressing U87MG cells were co-administrated with STS and LiCl, cells underwent apoptosis. This effect could be reversed by LiCl. In short, we established a model to demonstrate that GSK3b interacts with and phosphorylates BCL2L12 and might also affect BCL2L12A to modulate the apoptosis signaling pathway in glioblastoma. These findings suggest that LiCl may be a prospective therapeutic agent against GBM.

The functions of centrosomal protein ninein may be involved in microtubule minus end capping, centriole positioning, protein anchoring and microtubule nucleation, but the true physiological function of various human hNinein isoforms remains to be determined. Here we describe the identification of four diverse CCII-termini of human hNinein isoforms, including a novel isoform 6, by differential expression in a tissue-specific manner. These hNinein isoforms exhibit centrosomal (concentrated) and noncentrosomal (aggregated) localization when GFP-tagged fusion proteins are expressed transiently in mammalian cells. In a kinase assay, we show that the CCII region of hNinein provides a differential phosphorylation site by GSK3beta. In addition, our data indicate that either N-terminal or CCIIZ domain disruption may cause hNinein conformational change which recruits gamma-tubulin to centrosomal or noncentrosomal hNinein-containing sites, implying that the gamma-tubulin localization may be hNinein-dependent. Further, our RNA interference experiment against all hNinein isoforms caused a significant decrease in the gamma-tubulin signal in the centrosome. In domain swapping, we clearly show that the CCIIX-CCIIY region provides docking sites for gamma-tubulin. Moreover, our data also show that nucleation of microtubules from the centrosome is significantly affected by the presence of either the full -length hNinein or CCIIX-CCIIY region overexpression. Taken together, these results show that the centrosomal targeting signals of hNinein have a role not only in regulating hNinein conformation, resulting in localization change, but also provide docking sites to recruit gamma-tubulin at centrosomal and noncentrosomal sites.