The Expression and Significance of Neuronal Iconic Proteins in Podocytes

Growing evidence suggests that there are many common cell biological features shared by neurons and podocytes; however, the mechanism of podocyte foot process formation remains unclear. Comparing the mechanisms of process formation between two cell types should provide useful guidance from the progress of neuron research. Studies have shown that some mature proteins of podocytes, such as podocin, nephrin, and synaptopodin, were also expressed in neurons. In this study, using cell biological experiments and immunohistochemical techniques, we showed that some neuronal iconic molecules, such as Neuron-specific enolase, nestin and Neuron-specific nuclear protein, were also expressed in podocytes. We further inhibited the expression of Neuron-specific enolase, nestin, synaptopodin and Ubiquitin carboxy terminal hydrolase-1 by Small interfering RNA in cultured mouse podocytes and observed the significant morphological changes in treated podocytes. When podocytes were treated with Adriamycin, the protein expression of Neuron-specific enolase, nestin, synaptopodin and Ubiquitin carboxy terminal hydrolase-1 decreased over time. Meanwhile, the morphological changes in the podocytes were consistent with results of the Small interfering RNA treatment of these proteins. The data demonstrated that neuronal iconic proteins play important roles in maintaining and regulating the formation and function of podocyte processes.     

The structure of the epithelial surface of the gastrointestinal tract of Pikas (Ochotona pallasi and O. dauurica,Lagomorpha, Ochotonidae): Functional and species specificity

The macro- and microrelief of the surface of the digestive tract mucosa of two pika species—Pallas’s (Ochotona pallasi) and Daurian (O. dauurica)—were studied in detail using whole-mount preparations and scanning electron microscopy. The structural features of the intestinal mucosal surface specific of mammals, such as the formation of projections on the crest of the cecal spiral fold and microcells in the colonic ampulla, were studied. It was found that the colonic mucosa forms sparse large conical villi in pocket cavities and on the surface of muscle bands. Significant differences in the cecal mucosal relief were found between the species studied. The possible functional significance of the identified morphological features is discussed.     

Production of reactive oxygen species by monocyte-derived macrophages from blood of healthy donors and patients with ischemic heart disease

Production of reactive oxygen species (ROS) by macrophages derived from blood monocytes of healthy donors (MP_N) and patients with ischemic heart disease (IHD) (MP_IHD) before, during, and after their incubation with low-density lipoprotein (LDL) isolated from blood plasma of healthy donors (LDL_N) and patients with a high cholesterol level (LDL_H) was investigated by the method of luminol-dependent (spontaneous) and stimulated chemiluminescence (CL) using opsonized zymosan (OZ) or phorbol-12-myristate-13-acetate (PMA) as the CL stimulators. It was shown that proper, luminol-dependent, and zymosan-or PMA-stimulated chemiluminescence of MP_IHD was 1.4-, 1.8-, 2.7-, and 1.6-fold higher than the same types of chemiluminescence of MP_N, respectively, (p<0.05–0.01). Although the effect of OZ on MP_N and MP_IHD was more potent than that of PMA (by 4.3- and 3.2-fold, respectively), but it appeared in 2.5–3.0 times slower than that of PMA. LDL_N and LDL_H incubated with MP_N for the first 15 and 60 min caused the 1.4- and 2.5-increase of the luminol-dependent CL of MP_N; the same treatment of MP_IHD did not influence ROS production by these cells. Repeated increase in the OZ-stimulated CL of MP_N was also observed after preincubation for 15–180 min with LDL_N and LDL_H followed by LDL removal, subsequent MP_N washing and addition of Hanks solution and OZ; the repeated increase in OZ-stimulated CL of MP_N was only observed after incubation with LDL_H than with LDL_N. No increase of CL was observed in experiments with MP_IHD. Thus, more intensive chemiluminescence of macrophages obtained from blood of patients with IHD suggests their in vivo stimulation. LDL_N and LDL_H may cause both primary and secondary (after preincubation) stimulating effect on CL of MP_N but not of MP_IHD. Thus, the analysis of macrophage chemiluminescence is a sensitive test for evaluation the degree of macrophage stimulation; it may be effectively used for monitoring of effectiveness of medical treatment of patients.     

The putative propeptide of MycP1 in mycobacterial type VII secretion system does not inhibit protease activity but improves protein stability

Mycosin-1 protease (MycP1) is a serine protease anchored to the inner membrane of Mycobacterium tuberculosis, and is essential in virulence factor secretion through the ESX-1 type VII secretion system (T7SS). Bacterial physiology studies demonstrated that MycP1 plays a dual role in the regulation of ESX-1 secretion and virulence, primarily through cleavage of its secretion substrate EspB. MycP1 contains a putative N-terminal inhibitory propeptide and a catalytic triad of Asp-His-Ser, classic hallmarks of a subtilase family serine protease. The MycP1 propeptide was previously reported to be initially inactive and activated after prolonged incubation. In this study, we have determined crystal structures of MycP1 with (MycP1^24-422) and without (MycP1^63-422) the propeptide, and conducted EspB cleavage assays using the two proteins. Very high structural similarity was observed in the two crystal structures. Interestingly, protease assays demonstrated positive EspB cleavage for both proteins, indicating that the putative propeptide does not inhibit protease activity. Molecular dynamic simulations showed higher rigidity in regions guarding the entrance to the catalytic site in MycP1^24-422 than in MycP1^63-422, suggesting that the putative propeptide might contribute to the conformational stability of the active site cleft and surrounding regions.     

Identification of the active site of human mitochondrial malonyl‐coenzyme a decarboxylase: A combined computational study

Malonyl‐CoA decarboxylase (MCD) can control the level of malonyl‐CoA in cell through the decarboxylation of malonyl‐CoA to acetyl‐CoA, and plays an essential role in regulating fatty acid metabolism, thus it is a potential target for drug discovery. However, the interactions of MCD with CoA derivatives are not well understood owing to unavailable crystal structure with a complete occupancy in the active site. To identify the active site of MCD, molecular docking and molecular dynamics simulations were performed to explore the interactions of human mitochondrial MCD (HmMCD) and CoA derivatives. The findings reveal that the active site of HmMCD indeed resides in the prominent groove which resembles that of CurA. However, the binding modes are slightly different from the one observed in CurA due to the occupancy of the side chain of Lys183 from the N‐terminal helical domain instead of the adenine ring of CoA. The residues 300 ? 305 play an essential role in maintaining the stability of complex mainly through hydrogen bond interactions with the pyrophosphate moiety of acetyl‐CoA. Principle component analysis elucidates the conformational distribution and dominant concerted motions of HmMCD. MM_PBSA calculations present the crucial residues and the major driving force responsible for the binding of acetyl‐CoA. These results provide useful information for understanding the interactions of HmMCD with CoA derivatives. Proteins 2016; 84:792–802. © 2016 Wiley Periodicals, Inc.     

RBM10 inhibits cell proliferation of lung adenocarcinoma via RAP1/AKT/CREB signalling pathway

Initial functional studies have demonstrated that RNA‐binding motif protein 10 (RBM10) can promote apoptosis and suppress cell proliferation; however, the results of several studies suggest a tumour‐promoting role for RBM10. Herein, we assessed the involvement of RBM10 in lung adenocarcinoma cell proliferation and explored the potential molecular mechanism. We found that, both in vitro and in vivo, RBM10 overexpression suppresses lung adenocarcinoma cell proliferation, while its knockdown enhances cell proliferation. Using complementary DNA microarray analysis, we previously found that RBM10 overexpression induces significant down‐regulation of RAP1A expression. In this study, we have confirmed that RBM10 decreases the activation of RAP1 and found that EPAC stimulation and inhibition can abolish the effects of RBM10 knockdown and overexpression, respectively, and regulate cell growth. This effect of RBM10 on proliferation was independent of the MAPK/ERK and P38/MAPK signalling pathways. We found that RBM10 reduces the phosphorylation of CREB via the AKT signalling pathway, suggesting that RBM10 exhibits its effect on lung adenocarcinoma cell proliferation via the RAP1/AKT/CREB signalling pathway.