Clinical significance of expression of RGS4 in pediatric nephroblastoma tissue / 天津医药

Objective To investigate the expression levels of regulator of G-protein signaling 4 (RGS4) in pediatric nephroblastoma and pericancerous tissues, and explore the relationship between RGS4 and the occurrence and development of pediatric nephroblastoma. Methods Thirty-seven samples of pediatric nephroblastoma tissues and 8 samples of pericancerous tissues were collected after surgery to detect the expression of RGS4 protein by immunohistochemistry. Another 8 samples of fresh cancer tissues and corresponding pericancerous tissues were collected to detect the mRNA and protein levels of RGS4 by qRT-PCR and Western blot assay, respectively. Results Immunohistochemistry results showed that RGS4 protein was positively expressed both in pediatric nephroblastoma and pericancerous tissues, and its high expression rate was lower in pediatric nephroblastoma than that in pericancerous tissues [(37.83%(14/37) vs. 87.5%(7/8),χ2=4.675, P<0.05]. The expression level of RGS4 mRNA was significantly lower in pediatric nephroblastoma than that in pericancerous tissues (1.064 ± 0.549 vs. 5.374 ± 0.735, t=13.290, n=8, P < 0.01). Western blot results showed that the expression level of RGS4 protein was lower in pediatric nephroblastoma than that of pericancerous tissues (0.301±0.092 vs. 0.779 ± 0.041, t=13.424, n=8, P < 0.01). Conclusion The expression level of RGS4 is down-regulated in pediatric nephroblastoma, which may be related to the occurrence and development of pediatric nephroblastoma.

G protein signaling in the parasite Entamoeba histolytica

The parasite Entamoeba histolytica causes amebic colitis and systemic amebiasis. Among the known amebic factors contributing to pathogenesis are signaling pathways involving heterotrimeric and Ras superfamily G proteins. Here, we review the current knowledge of the roles of heterotrimeric G protein subunits, Ras, Rho and Rab GTPase families in E. histolytica pathogenesis, as well as of their downstream signaling effectors and nucleotide cycle regulators. Heterotrimeric G protein signaling likely modulates amebic motility and attachment to and killing of host cells, in part through activation of an RGS-RhoGEF (regulator of G protein signaling-Rho guanine nucleotide exchange factor) effector. Rho family GTPases, as well as RhoGEFs and Rho effectors (formins and p21-activated kinases) regulate the dynamic actin cytoskeleton of E. histolytica and associated pathogenesis-related cellular processes, such as migration, invasion, phagocytosis and evasion of the host immune response by surface receptor capping. A remarkably large family of 91 Rab GTPases has multiple roles in a complex amebic vesicular trafficking system required for phagocytosis and pinocytosis and secretion of known virulence factors, such as amebapores and cysteine proteases. Although much remains to be discovered, recent studies of G protein signaling in E. histolytica have enhanced our understanding of parasitic pathogenesis and have also highlighted possible targets for pharmacological manipulation.

Receptor-specific Ca2+ signaling in polarized cells

No abstract available.