Smad anchor for receptor activation contributes to seizures in temporal lobe epilepsy

HAT- and HDAC-Targeted Protein Acetylation in the Occurrence and Treatment of Epilepsy

Epilepsy is a common and severe chronic neurological disorder. Recently, post-translational modification (PTM) mechanisms, especially protein acetylation modifications, have been widely studied in various epilepsy models or patients. Acetylation is regulated by two classes of enzymes, histone acetyltransferases (HATs) and histone deacetylases (HDACs). HATs catalyze the transfer of the acetyl group to a lysine residue, while HDACs catalyze acetyl group removal. The expression of many genes related to epilepsy is regulated by histone acetylation and deacetylation. Moreover, the acetylation modification of some non-histone substrates is also associated with epilepsy. Various molecules have been developed as HDAC inhibitors (HDACi), which have become potential antiepileptic drugs for epilepsy treatment. In this review, we summarize the changes in acetylation modification in epileptogenesis and the applications of HDACi in the treatment of epilepsy as well as the mechanisms involved. As most of the published research has focused on the differential expression of proteins that are known to be acetylated and the knowledge of whole acetylome changes in epilepsy is still minimal, a further understanding of acetylation regulation will help us explore the pathological mechanism of epilepsy and provide novel ideas for treating epilepsy.

MiR-203a-3p regulates TGF-β1-induced epithelial-mesenchymal transition (EMT) in asthma by regulating Smad3 pathway through SIX1

Asthma is a common chronic airway disease with increasing prevalence. MicroRNAs act as vital regulators in cell progressions and have been identified to play crucial roles in asthma. The objective of the present study is to clarify the molecular mechanism of miR-203a-3p in the development of asthma. The expression of miR-203a-3p and Sine oculis homeobox homolog 1 (SIX1) were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The protein levels of SIX1, fibronectin, E-cadherin, vimentin, phosphorylated-drosophila mothers against decapentaplegic 3 (p-Smad3) and Smad3 were measured by Western blot. The interaction between miR-203a-3p and SIX1 was confirmed by dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay. MiR-203a-3p was down-regulated and SIX1 was up-regulated in asthma serums, respectively. Transforming growth factor-β1 (TGF-β1) treatment induced the reduction of miR-203a-3p and the enhancement of SIX1 in BEAS-2B and 16HBE cells in a time-dependent manner. Subsequently, functional experiments showed the promotion of epithelial–mesenchymal transition (EMT) induced by TGF-β1 treatment could be reversed by miR-203a-3p re-expression or SIX1 deletion in BEAS-2B and 16HBE cells. SIX1 was identified as a target of miR-203a-3p and negatively regulated by miR-203a-3p. Then rescue assay indicated that overexpressed miR-203a-3p ameliorated TGF-β1 induced EMT by regulating SIX1 in BEAS-2B and 16HBE cells. Moreover, miR-203a-3p/SIX1 axis regulated TGF-β1 mediated EMT process in bronchial epithelial cells through phosphorylating Smad3. These results demonstrated that MiR-203a-3p modulated TGF-β1-induced EMT in asthma by regulating Smad3 pathway through targeting SIX1.

Inflammatory and immune mechanisms underlying epileptogenesis and epilepsy: From pathogenesis to treatment target

Epilepsy is a brain disease associated with epileptic seizures as well as with neurobehavioral outcomes of this condition. In the last century, inflammation emerged as a crucial factor in epilepsy etiology. Various brain insults through activation of neuronal and non-neuronal brain cells initiate a series of inflammatory events. Growing observations strongly suggest that abnormal activation of critical inflammatory processes contributes to epileptogenesis, a gradual process by which a normal brain transforms into the epileptic brain. Increased knowledge of inflammatory pathways in epileptogenesis has unveiled mechanistic targets for novel antiepileptic therapies. Molecules specifically targeting the pivotal inflammatory pathways may serve as promising candidates to halt the development of epilepsy. The present paper reviews the pieces of evidence conceptually supporting the potential role of inflammatory mechanisms and the relevant blood-brain barrier (BBB) disruption in epileptogenesis. Also, it discusses the mechanisms underlying inflammation-induced neuronal-glial network impairment and highlights innovative neuroregulatory actions of typical inflammatory molecules. Finally, it presents a brief analysis of observations supporting the therapeutic role of inflammation-targeting tiny molecules in epileptic seizures.

Role of Elevated Thrombospondin-1 in Kainic Acid-Induced Status Epilepticus

Previous studies have suggested that thrombospondin-1 (TSP-1) regulates the transforming growth factor beta 1 (TGF-β1)/phosphorylated Smad2/3 (pSmad2/3) pathway. Moreover, TSP-1 is closely associated with epilepsy. However, the role of the TSP-1-regulated TGF-β1/pSmad2/3 pathway in seizures remains unclear. In this study, changes in this pathway were assessed following kainic acid (KA)-induced status epilepticus (SE) in rats. The results showed that increases in the TSP-1/TGF-β1/pSmad2/3 levels spatially and temporally matched the increases in glial fibrillary acidic protein (GFAP)/chondroitin sulfate (CS56) levels following KA administration. Inhibition of TSP-1 expression by small interfering RNA or inhibition of TGF-β1 activation with a Leu-Ser-Lys-Leu peptide significantly reduced the severity of KA-induced acute seizures. These anti-seizure effects were accompanied by decreased GFAP/CS56 expression and Smad2/3 phosphorylation. Moreover, inhibiting Smad2/3 phosphorylation with ponatinib or SIS3 also significantly reduced seizure severity, alongside reducing GFAP/CS56 immunoreactivity. These results suggest that the TSP-1-regulated TGF-β1/pSmad2/3 pathway plays a key role in KA-induced SE and astrogliosis, and that inhibiting this pathway may be a potential anti-seizure strategy.

Smad Anchor for Receptor Activation and Phospho-Smad3 Were Upregulated in Patients with Temporal Lobe Epilepsy

Smad anchor for receptor activation (SARA) is an important regulator of transforming growth factor β (TGF-β) signaling by recruiting Smad2/3 to TGF-β receptors. We recently demonstrated that the expressions of SARA and level of downstream phospho-Smad3 (p-Smad3) were upregulated in the brain in the epileptic rat model, but were never examined in patients with temporal lobe epilepsy (TLE). In this study, we examined the expressions of SARA and level of p-Smad3 in brain tissues of TLE patients using immunohistochemistry and western blot to demonstrate that SARA activation in neurons is sufficient to facilitate TGF- β pathway in patients to regulate epilepsy. We found that the expressions of SARA and level of p-Smad3 were significantly upregulated in neurons of the temporal cortex of TLE patients compared to controls. Moreover, SARA and p-Smad3 were strongly stained in the cytoplasm in the temporal cortex of TLE patients. Our results indicate that upregulation of SARA and p-Smad3 in cortex neurons might be involved in the development of intractable temporal lobe epilepsy.

New Player in Endosomal Trafficking: Differential Roles of Smad Anchor for Receptor Activation (SARA) Protein

The development and maintenance of multicellular organisms require specialized coordination between external cellular signals and the proteins receiving stimuli and regulating responses. A critical role in the proper functioning of these processes is played by endosomal trafficking, which enables the transport of proteins to targeted sites as well as their return to the plasma membrane through its essential components, the endosomes. During this trafficking, signaling pathways controlling functions related to the endosomal system are activated both directly and indirectly. Although there are a considerable number of molecules participating in these processes, some are more known than others for their specific functions. Toward the end of the 1990s, Smad anchor for receptor activation (SARA) protein was described to be controlling and to facilitate the localization of Smads to transforming growth factor β (TGF-β) receptors during TGF-β signaling activation, and, strikingly, SARA was also identified to be one of the proteins that bind to early endosomes (EEs) participating in membrane trafficking in several cell models. The purpose of this review is to analyze the state of the art of the contribution of SARA in different cell types and cellular contexts, focusing on the biological role of SARA in two main processes, trafficking and cellular signaling, both of which are necessary for intercellular coordination, communication, and development.