␣-Actinin is an abundant actin-bundling and adhesion protein that directly links actin filaments to integrin receptors. Previously, in platelet-derived growth factortreated fibroblasts, we demonstrated that phosphoinositides bind to ␣-actinin, regulating its localization (Greenwood, J. A., Theibert, A. B., Prestwich, G. D., and Murphy-Ullrich, J. E. (2000) J. Cell Biol. 150, 627-642). In this study, phosphoinositide binding and regulation of ␣-actinin function is further characterized. Phosphoinositide binding specificity, determined using a protein-lipid overlay procedure, suggests that ␣-actinin interacts with phosphates on the 4th and 5th position of the inositol head group. Binding assays and mutational analyses demonstrate that phosphoinositides bind to the calponin homology domain 2 of ␣-actinin. Phosphoinositide binding inhibited the bundling activity of ␣-actinin by blocking the interaction of the actin-binding domain with actin filaments. Consistent with these results, excessive bundling of actin filaments was observed in fibroblasts expressing an ␣-actinin mutant with decreased phosphoinositide affinity. We conclude that the interaction of ␣-actinin with phosphoinositides regulates actin stress fibers in the cell by controlling the extent to which microfilaments are bundled.

Cyclic adenosine monophosphate (cAMP)-dependent protein kinase A (PKA) is an important mediator of signal transduction in eukaryotic cells. Thus, identifying its function is necessary to understand the cAMP signaling network. StPKA-c, the PKA catalytic subunit gene in Setosphaeria turcica, was investigated by RNA interference technology. Transformant strains M3, M5, and M9 with diverse StPKA-c silencing efficiency were confirmed by reverse transcription polymerase chain reaction and Northern blot. Compared with the wild-type strain 01-23, the transformant strains exhibited increased growth rate and significantly decreased conidium production. In addition, the ratios of spore germination and appressorium formation and penetration were slightly reduced. Relative to the wild-type strain, the transformants demonstrated different colony color, greatly reduced pathogenicity, and similar HT-toxin activity. Further studies showed that the content of intracellular melanin in the transformants significantly decreased, and the transcription of transcriptional factor StMR was down-regulated correspondingly. The transcription and enzyme activity of xylanase was also impaired. Thus, we proposed that StPKA-c was mainly involved in the mycelium growth, conidiation, and pathogenesis of S. turcica. Furthermore, it was positively correlated with the biosyntheses of melanin and xylanase but dispensable for the activity of HT-toxin.

Spinal cord injury (SCI) is a devastating event resulting in neuron degeneration and permanent paralysis through inflammatory cytokine overproduction and glial scar formation. Presently, the endogenous molecular mechanisms coordinating glial scar formation in the injured spinal cord remain elusive. Signal transducer and activator of transcription 3 (STAT3) is a well-known transcription factor particularly involving in cell proliferation and inflammation in the lesion site following SCI. Meanwhile, CAP-Gly domain containing linker protein 3(CLIP3), a vital cytoplasmic protein, has been confirmed to providing an optimal conduit for intracellular signal transduction and interacting with STAT3 with mass spectrometry analysis. In this study, we aimed to identify the expression of CLIP3 in the spinal cord as well as its role in mediating astrocyte activation and glial scar formation after SCI by establishing an acute traumatic SCI model in male adult rats. Western blot analysis revealed that CLIP3 increased gradually after injury, reached a peak at day 3. The immunohistochemistry staining showed the same result in white matter. With double immunofluorescence staining, we found that CLIP3 was expressed in glial cells and significant changes of CLIP3 expression occurred in astrocytes during the pathological process. Statistical analysis demonstrated there was a correlation between the number of positive cells stained by CLIP3 and STAT3 in the spinal cord after SCI. Co-immunoprecipitation further indicated that CLIP3 interacted with STAT3 in the injured spinal cord. Taken together, our study clearly suggested that CLIP3 played an essential role in astrocyte activation, associating with the STAT3 pathway activation induced by SCI.

Background: MMPs/TIMPs system is well known to play important roles in pressure overload-induced cardiac remodeling, and Amlodipine and Atorvastatin have been showed to exert favourable protective effects on cardiovascular disease, however, it is not clear whether Amlodipine and Atorvastatin can improve hypertensive cardiac remodeling and whether the MMPs/TIMPs system is involved. The present study aims to answer these questions. Methods: 36 weeks old male spontaneous hypertension (SHR) rats were randomly divided into four groups: 1). SHR control group, 2). Amlodipine alone (10 mg/kg/d) group, 3). Atorvastatin alone (10 mg/kg/d) group, 4).Combination of Amlodipine and Atorvastatin (10 mg/kg/d for each) group. Same gender, weight and age of Wistar-Kyoto (WKY) rats with normal blood pressure were used as normal control. Drugs were administered by oral gavage over 12 weeks. The blood pressure and left ventricle mass index were measured. Enzyme activity of MMP-2 and MMP-9 was assessed with Gelatin zymography. MMP-2, MMP-9, TIMP-1 and TIMP-2 mRNA and protein expression was studied by RT-PCR and Western blot. Single factor ANOVA and LSD-t test were used in statistical analysis. Results: Treatment with Amlodipine alone or combination with atorvastatin significantly decreased blood pressure, left ventricle mass index in SHR rats (P < 0.05 for both). Compared with WKY rats, the myocardial levels of MMP-2, MMP-9 mRNA, protein and enzyme activity were significantly increased (P<0.05). Amlodipine alone, Atorvastatin alone, and combination of the two all reduced MMP-2 and MMP-9 mRNA, protein and enzyme activity, with the best effects seen in the combination. Compared with WKY rats, the myocardial levels of TIMP-1 mRNA and protein were significantly increased (P<0.05), however, there was no difference in levels of TIMP-2. Neither Amlodipine alone, Atorvastatin alone, nor combination of the two drugs significantly affect the expression of TIMP-1 or TIMP-2. Conclusion: Amlodipine and Atorvastatin could improve ventricular remodeling in SHR rats through intervention with the imbalance of MMP-2/TIMP-2 and MMP-9/TIMP-1 system.

No abstract