Galectin-3 (Gal-3) is a protein expressed by glia that belongs to an ancient family. Gal-3 recognises molecular patterns on pathogens due to the high degree of its binding specificity with carbohydrate recognition domains. Thus, in sponges as well as other invertebrates, galectins are an important component of the primitive innate immune system. Whereas Gal-3's function in driving mammalian inflammation is well known, its function in warding off bacterial and viral infections is not well appreciated. One route of brain infection is via the cerebrospinal fluid brain interface (CSFBI) which is primarily composed of ependymal cells (EC). ECs express high levels of Gal-3, and their motile cilia are compromised in Gal-3 KOs. In this mini-review, we discuss fundamentally important potential roles of Gal-3 in pathogen recognition at the CSFBI and suggest avenues of further study.

Glial glutamate uptake through sodium-dependent excitatory amino acid transporters (EAATs) is essential for synaptic homeostasis. Epigenetic modifications and neurotransmitter receptor signaling influence glial function although their interactive effects on glutamate transporter regulation remain poorly understood. To investigate how DNA methylation affects glutamate receptor-mediated regulation of its own removal, primary cultures from chick cerebellar Bergmann glial cells were used. Confluent monolayers were treated with a DNA methylation inhibitor. Glutamate transporter activity was assessed through radioactive uptake assays, while methylation levels within distinct regions of the chGLAST promoter were analyzed by methylated DNA immunoprecipitation (MeDIP)-PCR. The role of cytoskeletal dynamics and calcium signaling was evaluated using pharmacological modulators. DNA hypomethylation sensitizes glial cells to glutamate receptors stimulation. Kinetic analyses show a statistically significant increase in the Michaelis-Menten constant VMax and a non-significant change in KM, changes in VMax reflect alterations in plasma membrane transporter numberinity. Pharmacological analysis revealed the involvement of the phosphatidyl inositol 3 kinase (PI3K), the Ca2+/calmodulin-dependent kinase II (CaMKII) and the mammalian target of rapamycin (mTOR) pathways, suggesting coordinated regulation of glutamate transport. Importantly, short-term activation of AMPA receptors induced hypomethylation of the chglast promoter, suggesting the engagement of active demethylation pathways that sustain transporter expression during heightened excitatory activity. Together, these findings reveal a novel mechanism in which epigenetic flexibility and synaptic receptor activity converge to enhance glutamate uptake in glial cells. This synergy between DNA methylation and AMPA receptor signaling provide new insights into the mechanisms by which glial cells dynamically adapt to excitatory stress.

Parkinson’s disease is the second most prevalent neurodegenerative disorder and is characterized by the degeneration of dopaminergic neurons. Significant improvements in gait balance, particularly in step length and velocity, were observed with less invasive wireless cortical stimulation. Transcriptome sequencing was performed to demonstrate the cellular mechanism, specifically targeting the primary motor cortex, where stimulation was applied. Our findings indicated that 38 differentially expressed genes (DEGs), initially downregulated following Parkinson’s disease induction, were subsequently restored to normal levels after cortical stimulation. These 38 DEGs are potential targets for the treatment of motor disorders in Parkinson’s disease. These genes are implicated in crucial processes, such as astrocyte-mediated blood vessel development and microglia-mediated phagocytosis of damaged motor neurons, suggesting their significant roles in improving behavioral disorders. Moreover, these biomarkers not only facilitate the rapid and accurate diagnosis of Parkinson’s disease but also assist in precision medicine approaches.

Iron is a critical transition metal required to sustain a healthy central nervous system. Iron is involved in metabolic reactions, enzymatic activity, myelinogenesis, and oxygen transport. However, in several pathological conditions such as cancer, neurodegeneration, and neurotrauma iron becomes elevated. Excessive iron can have deleterious effects leading to reactive oxygen species (ROS) via the Fenton reaction. Iron-derived ROS are known to drive several mechanisms such as cell death pathways including ferroptosis, necroptosis, and pyroptosis. Excessive iron present in the post-traumatic brain could trigger these harmful pathways potentiating the high rates of morbidity and mortality. In the present review, we will discuss how iron plays an intricate role in initiating ferroptosis, necroptosis, and pyroptosis, examine their potential link to traumatic brain injury morbidity and mortality, and suggest therapeutic targets.

Although transferrin (Tf) is a glycoprotein best known for its role in iron delivery, iron-independent functions have also been reported. Here, we assessed apoTf (aTf) treatment effects on Neuro-2a (N2a) cells, a mouse neuroblastoma cell line which, once differentiated, shares many properties with neurons, including process outgrowth, expression of selective neuronal markers, and electrical activity. We first examined the binding of Tf to its receptor (TfR) in our model and verified that, like neurons, N2a cells can internalize Tf from the culture medium. Next, studies on neuronal developmental parameters showed that Tf increases N2a survival through a decrease in apoptosis. Additionally, Tf accelerated the morphological development of N2a cells by promoting neurite outgrowth. These pro-differentiating effects were also observed in primary cultures of mouse cortical neurons treated with aTf, as neurons matured at a higher rate than controls and showed a decrease in the expression of early neuronal markers. Further experiments in iron-enriched and iron-deficient media showed that Tf preserved its pro-differentiation properties in N2a cells, with results hinting at a modulatory role for iron. Moreover, N2a-microglia co-cultures revealed an increase in IL-10 upon aTf treatment, which may be thought to favor N2a differentiation. Taken together, these findings suggest that Tf reduces cell death and favors the neuronal differentiation process, thus making Tf a promising candidate to be used in regenerative strategies for neurodegenerative diseases.

Retinitis pigmentosa (RP) is an inherited disorder that results in vision impairment but general and mutation-independent therapeutic strategies are not available. However, it is widely regarded that the cGMP system, including cGMP and its interactor cGMP-dependent protein kinase (PKG), acts as a crucial effector during retinal degeneration. We have previously identified a list of cGMP-PKG-dependent genes in the context of RP, and in this study, we further validated one of these, namely pyruvate kinase 2 (PKM2), and investigated the potential role of PKM2 for the photoreceptors' well-being during RP. With the aid of organotypic retinal explant cultures, we pharmacologically manipulated the PKM2 activities in two different RP mouse models (rd2 and rd10) via the addition of TEPP-46 (a PKM2 activator) and found that activation of PKM2 alleviates the progress of photoreceptor death in the rd10 mouse model. We also noted that the expression of both PKM2 and one of its targets, glucose transporter-1 (Glut1), showed alterations depending on the degeneration state. The observations provide supportive evidence that PKM2 may serve as a novel potential molecular target in RP.

Neuronal migration and dendritogenesis are dependent on dynamic changes to the microtubule (MT) network. Among various factors that regulate MT dynamics and stability, post-translational modifications (PTMs) of MTs play a critical role in conferring specificity of regulatory protein binding to MTs. Thus, it is important to understand the regulation of PTMs during brain development as multiple developmental processes are dependent on MTs. In this study, we identified that carboxypeptidase E (CPE) changes tubulin polyglutamylation, a major PTM in the brain, and we examine the impact of CPE-mediated changes to polyglutamylation on cortical neuron migration and dendrite morphology. We show, for the first time, that overexpression of CPE increases the level of polyglutamylated α-tubulin while knockdown decreases the level of polyglutamylation. We also demonstrate that CPE-mediated changes to polyglutamylation are dependent on the CPE zinc-binding motif and that this motif is necessary for CPE action on p150Glued localization. However, overexpression of a CPE mutant that does not increase MT glutamylation mimics the effects of overexpression of wild type CPE on dendrite branching. Furthermore, although overexpression of wild type CPE does not alter cortical neuron migration, overexpression of the mutant may act in a dominant-negative manner as it decreases the number of neurons that reach the cortical plate (CP), as we previously reported for CPE knockdown. Overall, our data suggest that CPE changes MT glutamylation and redistribution of p150Glued and that this function of CPE is independent of its role in shaping dendrite development but plays a partial role in regulating cortical neuron migration.

Microglia are the resident tissue macrophages of the central nervous system (CNS). Recent findings point out that in the steady state the major role of microglia, is to instruct and regulate the correct function of the neuronal networks and different components of the neurovascular unit in the adult CNS, while providing immune surveillance. Paradoxically, during CNS infection immune activation of microglia generates an inflammatory milieu that contributes to the clearance of the pathogen but can, in the process, harm nearby cells of CNS. Most of the knowledge about the harmful effects of activated microglia on CNS has arisen from studies on neurodegenerative diseases. In this review we will focus on the beneficial role and detrimental functions of microglial cells on the neighboring cells of the CNS upon infection.