Activating transcription factor 6α deficiency exacerbates oligodendrocyte death and myelin damage in immune-mediated demyelinating diseases.

Endoplasmic reticulum (ER) stress and the unfolded protein response (UPR) play a critical role in immune-mediated demyelinating diseases, including multiple sclerosis (MS) and its animal model experimental autoimmune encephalomyelitis (EAE), by regulating the viability of oligodendrocytes. Our previous studies show that activation of the PERK branch of the UPR protects myelinating oligodendrocytes against ER stress in young, developing mice that express IFN-γ, a key pro-inflammatory cytokine in MS and EAE, in the CNS. Several studies also demonstrate that PERK activation preserves oligodendrocyte viability and function, protecting mice against EAE.

Synapse-specific astrocyte gating of amygdala-related behavior.

The amygdala plays key roles in fear and anxiety. Studies of the amygdala have largely focused on neuronal function and connectivity. Astrocytes functionally interact with neurons, but their role in the amygdala remains largely unknown.

NF-κB Activation Protects Oligodendrocytes against Inflammation.

NF-κB is a key player in inflammatory diseases, including multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). However, the effects of NF-κB activation on oligodendrocytes in MS and EAE remain unknown. We generated a mouse model that expresses IκBαΔN, a super-suppressor of NF-κB, specifically in oligodendrocytes and demonstrated that IκBαΔN expression had no effect on oligodendrocytes under normal conditions (both sexes).

Neuron-astrocyte signaling is preserved in the aging brain.

Astrocytes play crucial roles in brain homeostasis and are emerging as regulatory elements of neuronal and synaptic physiology by responding to neurotransmitters with Ca elevations and releasing gliotransmitters that activate neuronal receptors. Aging involves neuronal and astrocytic alterations, being considered risk factor for neurodegenerative diseases. Most evidence of the astrocyte-neuron signaling is derived from studies with young animals; however, the features of astrocyte-neuron signaling in adult and aging brain remain largely unknown.

Dual role of the integrated stress response in medulloblastoma tumorigenesis.

In response to endoplasmic reticulum (ER) stress, activation of pancreatic ER kinase (PERK) coordinates an adaptive program known as the integrated stress response (ISR) by phosphorylating translation initiation factor 2α (eIF2α). Phosphorylated eIF2α is quickly dephosphorylated by the protein phosphatase 1 and growth arrest and DNA damage 34 (GADD34) complex. Data indicate that the ISR can either promote or suppress tumor development.

PERK Activation Promotes Medulloblastoma Tumorigenesis by Attenuating Premalignant Granule Cell Precursor Apoptosis.

Evidence suggests that activation of pancreatic endoplasmic reticulum kinase (PERK) signaling in response to endoplasmic reticulum stress negatively or positively influences cell transformation by regulating apoptosis. Patched1 heterozygous deficient (Ptch1(+/-)) mice reproduce human Gorlin's syndrome and are regarded as the best animal model to study tumorigenesis of the sonic hedgehog subgroup of medulloblastomas. It is believed that medulloblastomas in Ptch1(+/-) mice results from the transformation of granule cell precursors (GCPs) in the developing cerebellum.

Pancreatic endoplasmic reticulum kinase activation promotes medulloblastoma cell migration and invasion through induction of vascular endothelial growth factor A.

Evidence is accumulating that activation of the pancreatic endoplasmic reticulum kinase (PERK) in response to endoplasmic reticulum (ER) stress adapts tumor cells to the tumor microenvironment and enhances tumor angiogenesis by inducing vascular endothelial growth factor A (VEGF-A). Recent studies suggest that VEGF-A can act directly on certain tumor cell types in an autocrine manner, via binding to VEGF receptor 2 (VEGFR2), to promote tumor cell migration and invasion. Although several reports show that PERK activation increases VEGF-A expression in medulloblastoma, the most common solid malignancy of childhood, the role that either PERK or VEGF-A plays in medulloblastoma remains elusive.

Impaired eukaryotic translation initiation factor 2B activity specifically in oligodendrocytes reproduces the pathology of vanishing white matter disease in mice.

Vanishing white matter disease (VWMD) is an inherited autosomal-recessive hypomyelinating disease caused by mutations in eukaryotic translation initiation factor 2B (eIF2B). eIF2B mutations predominantly affect the brain white matter, and the characteristic features of VWMD pathology include myelin loss and foamy oligodendrocytes. Activation of pancreatic endoplasmic reticulum kinase (PERK) has been observed in oligodendrocytes in VWMD.

PERK activation preserves the viability and function of remyelinating oligodendrocytes in immune-mediated demyelinating diseases.

Remyelination occurs in multiple sclerosis (MS) lesions but is generally considered to be insufficient. One of the major challenges in MS research is to understand the causes of remyelination failure and to identify therapeutic targets that promote remyelination. Activation of pancreatic endoplasmic reticulum kinase (PERK) signaling in response to endoplasmic reticulum stress modulates cell viability and function under stressful conditions.

Oligodendrocyte-specific activation of PERK signaling protects mice against experimental autoimmune encephalomyelitis.

There is compelling evidence that oligodendrocyte apoptosis, in response to CNS inflammation, contributes significantly to the development of the demyelinating disorder multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis (EAE). Therefore, approaches designed to protect oligodendrocytes would likely have therapeutic value. Activation of pancreatic endoplasmic reticulum kinase (PERK) signaling in response to endoplasmic reticulum (ER) stress increases cell survival under various cytotoxic conditions.

Interferon-γ activates nuclear factor-κ B in oligodendrocytes through a process mediated by the unfolded protein response.

Our previous studies have demonstrated that the effects of the immune cytokine interferon-γ (IFN-γ) in immune-mediated demyelinating diseases are mediated, at least in part, by the unfolded protein response (UPR) in oligodendrocytes. Data indicate that some biological effects of IFN-γ are elicited through activation of the transcription factor nuclear factor-κB (NF-κB). Interestingly, it has been shown that activation of the pancreatic endoplasmic reticulum kinase (PERK) branch of the UPR triggers NF-κB activation.

A deregulated integrated stress response promotes interferon-γ-induced medulloblastoma.

Endoplasmic reticulum (ER) stress activates pancreatic ER kinase (PERK), which coordinates an adaptive program known as the integrated stress response (ISR) by phosphorylating translation initiation factor 2α (eIF2α). There is evidence that the ISR is involved in tumor development. Recent studies also show that the ISR stimulates the expression of vascular endothelial growth factor A (VEGF-A), a master regulator of angiogenesis.