IL-6 is increased in the cerebellum of autistic brain and alters neural cell adhesion, migration and synaptic formation

<p>Abstract</p> <p>Background</p> <p>Although the cellular mechanisms responsible for the pathogenesis of autism are not understood, a growing number of studies have suggested that localized inflammation of the central nervous system (CNS) may contribute to the development of autism. Recent evidence shows that IL-6 has a crucial role in the development and plasticity of CNS.</p> <p>Methods</p> <p>Immunohistochemistry studies were employed to detect the IL-6 expression in the cerebellum of study subjects. <it>In vitro </it>adenoviral gene delivery approach was used to over-express IL-6 in cultured cerebellar granule cells. Cell adhesion and migration assays, DiI labeling, TO-PRO-3 staining and immunofluorescence were used to examine cell adhesion and migration, dendritic spine morphology, cell apoptosis and synaptic protein expression respectively.</p> <p>Results</p> <p>In this study, we found that IL-6 was significantly increased in the cerebellum of autistic subjects. We investigated how IL-6 affects neural cell development and function by transfecting cultured mouse cerebellar granule cells with an IL-6 viral expression vector. We demonstrated that IL-6 over-expression in granule cells caused impairments in granule cell adhesion and migration but had little effect on the formation of dendritic spines or granule cell apoptosis. However, IL-6 over-expression stimulated the formation of granule cell excitatory synapses, without affecting inhibitory synapses.</p> <p>Conclusions</p> <p>Our results provide further evidence that aberrant IL-6 may be associated with autism. In addition, our results suggest that the elevated IL-6 in the autistic brain could alter neural cell adhesion, migration and also cause an imbalance of excitatory and inhibitory circuits. Thus, increased IL-6 expression may be partially responsible for the pathogenesis of autism.</p

The Therapeutic effect of Memantine through the Stimulation of Synapse Formation and Dendritic Spine Maturation in Autism and Fragile X Syndrome

Although the pathogenic mechanisms that underlie autism are not well understood, there is evidence showing that metabotropic and ionotropic glutamate receptors are hyper-stimulated and the GABAergic system is hypo-stimulated in autism. Memantine is an uncompetitive antagonist of NMDA receptors and is widely prescribed for treatment of Alzheimer's disease treatment. Recently, it has been shown to improve language function, social behavior, and self-stimulatory behaviors of some autistic subjects. However the mechanism by which memantine exerts its effect remains to be elucidated. In this study, we used cultured cerebellar granule cells (CGCs) from Fmr1 knockout (KO) mice, a mouse model for fragile X syndrome (FXS) and syndromic autism, to examine the effects of memantine on dendritic spine development and synapse formation. Our results show that the maturation of dendritic spines is delayed in Fmr1-KO CGCs. We also detected reduced excitatory synapse formation in Fmr1-KO CGCs. Memantine treatment of Fmr1-KO CGCs promoted cell adhesion properties. Memantine also stimulated the development of mushroom-shaped mature dendritic spines and restored dendritic spine to normal levels in Fmr1-KO CGCs. Furthermore, we demonstrated that memantine treatment promoted synapse formation and restored the excitatory synapses to a normal range in Fmr1-KO CGCs. These findings suggest that memantine may exert its therapeutic capacity through a stimulatory effect on dendritic spine maturation and excitatory synapse formation, as well as promoting adhesion of CGCs

Prediction and functional analysis of GGDEF/EAL domaincontaining proteins in Azorhizobium caulinodans ORS571

[Objective] c-di-GMP,an important second messenger regulating multiple functions of bacteria,is generally synthesized and hydrolysed by proteins containing GGDEF or EAL domain.In this study,we analyzed the genome-wide GGDEF/EAL domain-containing proteins of Azorhizobium caulinodans ORS571,and selected three GGDEF-EAL composite proteins (AZC_3085,AZC_3226 and AZC_4658) for functional analysis.[Methods] SMART and CLUSTALW were used for prediction and multi-alignment of GGDEF/EAL domain-containing proteins.Mutants were constructed by homologous recombination.Phenotypes including cell motility,exopolysaccharide (EPS) production,biofilm formation and nodulation with legume host were investigated.[Results] There were 37 GGDEF/EAL domain-containing proteins in A.caulinodans ORS571.Mutant Delta4658 showed deficiency in cell motility,while its EPS production and biofilm formation were higher than that of wild type.Mutant Delta4658 showed stronger competitiveness than wild type in competitive nodulation assay.The loss of AZC_4658 led to the increase of intracellular c-di-GMP level.Mutants Delta3085 and Delta3226 did not show obvious difference in comparison with wild type.[Conclusion] The vast number of GGDEF/EAL domain-containing proteins suggested that c-di-GMP may play an important role in signal transduction of ORS571.The GGDEF-EAL composite protein AZC_4658 was involved in cell motility,EPS production,biofilm formation and nodulation of A.caulinodans ORS571.</p