Oncoprotein Stathmin Modulates Sensitivity to Apoptosis in Hepatocellular Carcinoma Cells During Hepatitis C Viral Replication

The Essential Role of Stathmin in Myoblast C2C12 for Vertical Vibration-Induced Myotube Formation

Vertical vibration (VV) is a type of whole body vibration, which induces muscle contraction through vibration to improve muscle strength and bone density. However, the mechanism of VV on muscle cell myotube formation is still unclear. In the current study, we aim to clarify the mechanism involved in VV's stimulation of myotube formation. In order to identify the molecules regulated by VV, we performed proteomics analysis including 2D electrophoresis combined with MALDI-TOF/TOF Mass. Stathmin was identified as a high potential molecule responding to VV stimulation, and we found that under VV stimulation, the expression of stathmin gene and protein increased in a time-dependent manner. In addition, we also confirmed that the increase of stathmin stimulated by VV is mediated through the PI3K/Akt pathway. Furthermore, stathmin siRNA significantly down-regulated the expression of myogenic regulatory factor (MRF) MyoD, decorin, and type I collagen (Col-I), and down-regulated the cellular process regulators such as FGF7, TGFBr1 and PAK3. Taken together, our results confirm that under the stimulation of VV, PI3K/Akt and stathmin would be activated, as well as the up-regulation of MRFs, such as FGF7, TGFBr1 and PAK3 to initiate myogenesis. It also showed that the response of MRF to VV stimulation was significantly related to stathmin expression, which also confirmed the importance of stathmin in the entire myotube formation process. This study may provide evidence of stathmin as a biological indicator of VV to increase muscle strength.

A Bioinformatics Analysis Identifies the Telomerase Inhibitor MST-312 for Treating High-STMN1-Expressing Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is a relatively chemo-resistant tumor. Several multi-kinase inhibitors have been approved for treating advanced HCC. However, most HCC patients are highly refractory to these drugs. Therefore, the development of more effective therapies for advanced HCC patients is urgently needed. Stathmin 1 (STMN1) is an oncoprotein that destabilizes microtubules and promotes cancer cell migration and invasion. In this study, cancer genomics data mining identified STMN1 as a prognosis biomarker and a therapeutic target for HCC. Co-expressed gene analysis indicated that STMN1 expression was positively associated with cell-cycle-related gene expression. Chemical sensitivity profiling of HCC cell lines suggested that High-STMN1-expressing HCC cells were the most sensitive to MST-312 (a telomerase inhibitor). Drug-gene connectivity mapping supported that MST-312 reversed the STMN1-co-expressed gene signature (especially BUB1B, MCM2/5/6, and TTK genes). In vitro experiments validated that MST-312 inhibited HCC cell viability and related protein expression (STMN1, BUB1B, and MCM5). In addition, overexpression of STMN1 enhanced the anticancer activity of MST-312 in HCC cells. Therefore, MST-312 can be used for treating STMN1-high expression HCC.

HIV-1 exposure promotes PKG1-mediated phosphorylation and degradation of stathmin to increase epithelial barrier permeability

Exposure of mucosal epithelial cells to the human immunodeficiency virus type 1 (HIV-1) envelope glycoprotein gp120 is known to disrupt epithelial cell junctions by impairing stathmin-mediated microtubule depolymerization. However, the pathological significance of this process and its underlying molecular mechanism remain unclear. Here we show that treatment of epithelial cells with pseudotyped HIV-1 viral particles or recombinant gp120 protein results in the activation of protein kinase G 1 (PKG1). Examination of epithelial cells by immunofluorescence microscopy reveals that PKG1 activation mediates the epithelial barrier damage upon HIV-1 exposure. Immunoprecipitation experiments show that PKG1 interacts with stathmin and phosphorylates stathmin at serine 63 in the presence of gp120. Immunoprecipitation and immunofluorescence microscopy further demonstrate that PKG1-mediated phosphorylation of stathmin promotes its autophagic degradation by enhancing the interaction between stathmin and the autophagy adaptor protein p62. Collectively, these results suggest that HIV-1 exposure exploits the PKG1/stathmin axis to affect the microtubule cytoskeleton and thereby perturbs epithelial cell junctions. Our findings reveal a novel molecular mechanism by which exposure to HIV-1 increases epithelial permeability, which has implications for the development of effective strategies to prevent mucosal HIV-1 transmission.