Nuclear translocation of histone deacetylase 4 induces neuronal death in stroke.

Mounting evidence suggests that epigenetic modifications play critical roles in the survival/death of stressed neurons. Chief among these modifications is the deacetylation of histones within the chromatin by histone deacetylases (HDACs). HDAC4 is highly expressed in neurons and is usually trapped in cytosol.

Thyroid hormones and functional outcomes after ischemic stroke.

Background: Stroke is the fifth leading cause of death and the primary cause of long-term adult disability in the United States. Increasing evidence suggests that low T3 levels immediately following acute ischemic stroke are associated with greater stroke severity, higher mortality rates, and poorer functional outcomes. Prognosis is also poor in critically ill hospitalized patients who have non-thyroidal illness syndrome (NTIS), where T3 levels are low, but TSH is normal.

Inhibition of glycogen synthase kinase-3β enhances cognitive recovery after stroke: the role of TAK1.

Memory deficits are common among stroke survivors. Identifying neuroprotective agents that can prevent memory impairment or improve memory recovery is a vital area of research. Glycogen synthase kinase-3β (GSK-3β) is involved in several essential intracellular signaling pathways.

Sex differences in ischemic stroke sensitivity are influenced by gonadal hormones, not by sex chromosome complement.

Epidemiologic studies have shown sex differences in ischemic stroke. The four core genotype (FCG) mouse model, in which the testes determining gene, Sry, has been moved from Y chromosome to an autosome, was used to dissociate the effects of sex hormones from sex chromosome in ischemic stroke outcome. Middle cerebral artery occlusion (MCAO) in gonad intact FCG mice revealed that gonadal males (XXM and XYM) had significantly higher infarct volumes as compared with gonadal females (XXF and XYF).

Inhibition of mitogen-activated protein kinase phosphatase-1 (MKP-1) increases experimental stroke injury.

Background And Purpose: Activation of mitogen-activated protein kinases (MAPKs), particularly c-jun-N-terminal kinases (JNK) and p38 exacerbates stroke injury by provoking pro-apoptotic and pro-inflammatory cellular signaling. MAPK phosphatase-1 (MKP-1) restrains the over-activation of MAPKs via rapid de-phosphorylation of the MAPKs. We therefore examined the role of MKP-1 in stroke and studied its inhibitory effects on MAPKs after experimental stroke.

Inhibition of calcium/calmodulin-dependent protein kinase kinase β and calcium/calmodulin-dependent protein kinase IV is detrimental in cerebral ischemia.

Background And Purpose: Elevation of intracellular calcium was traditionally thought to be detrimental in stroke pathology. However, clinical trials testing treatments that block calcium signaling have failed to improve outcomes in ischemic stroke. Emerging data suggest that calcium may also trigger endogenous protective pathways after stroke.

Deletion of macrophage migration inhibitory factor worsens stroke outcome in female mice.

Sex is an important factor in the response to ischemic insults in both the laboratory and the clinic. Inflammation and cell death are points where sex-specific pathways diverge in stroke, and serum estrogen level status affect the response to inflammation. The cytokine macrophage migration inhibitory factor (MIF) is detrimental in experimental stroke models in male animals.

Protection from cerebral ischemia by inhibition of TGFβ-activated kinase.

Objective: Transforming growth factor-β-activated kinase (TAK1) is a member of the mitogen-activated protein kinase family that plays important roles in apoptosis and inflammatory signaling, both of which are critical components of stroke pathology. TAK1 has recently been identified as a major upstream kinase that phosphorylates and activates adenosine monophosphate-activated protein kinase (AMPK), a major mediator of neuronal injury after experimental cerebral ischemia. We studied the functional role of TAK1 and its mechanistic link with AMPK after stroke.

NF-κB contributes to the detrimental effects of social isolation after experimental stroke.

Social isolation (SI) is increasingly recognized as a risk factor for stroke. Individuals with lack of social support systems have an increased incidence of stroke, poorer recovery, and greater functional decline after injury compared to individuals with social support. Attesting to the importance of social factors in stroke outcome is that these same effects can be reproducibly demonstrated in animals; social interaction improves behavioral deficits and reduces damage after experimental stroke, whereas SI enhances injury.

miR-23a regulation of X-linked inhibitor of apoptosis (XIAP) contributes to sex differences in the response to cerebral ischemia.

It is increasingly recognized that the mechanisms underlying ischemic cell death are sexually dimorphic. Stroke-induced cell death in males is initiated by the mitochondrial release of apoptosis-inducing factor, resulting in caspase-independent cell death. In contrast, ischemic cell death in females is primarily triggered by mitochondrial cytochrome c release with subsequent caspase activation.

Post-stroke hypothermia provides neuroprotection through inhibition of AMP-activated protein kinase.

Hypothermia is robustly protective in pre-clinical models of both global and focal ischemia, as well as in patients after cardiac arrest. Although the mechanism for hypothermic neuroprotection remains unknown, reducing metabolic drive may play a role. Capitalizing on the beneficial effects of hypothermia while avoiding detrimental effects such as infection will be the key to moving this therapy forward as a treatment for stroke.

Age-related changes in AMP-activated protein kinase after stroke.

Adenosine monophosphate-activated protein kinase (AMPK) is an evolutionary conserved energy sensor sensitive to changes in cellular AMP/ATP ratio which is activated by phosphorylation (pAMPK). pAMPK levels decrease in peripheral tissues with age, but whether this also occurs in the aged brain, and how this contributes to the ability of the aged brain to cope with ischemic stress is unknown. This study investigated the activation of AMPK and the response to AMPK inhibition after induced stroke in both young and aged male mice.

Sex differences in the response to poly(ADP-ribose) polymerase-1 deletion and caspase inhibition after stroke.

Background And Purpose: Emerging data suggest that the molecular cell death pathways triggered by ischemic insults differ in the male and female brain. Cell death in males is initiated by poly(ADP-ribose) polymerase-1 (PARP-1) activation; however, manipulation of this pathway paradoxically increases ischemic damage in females. In contrast, females are exquisitely sensitive to caspase-mediated cell death.

Effects of metformin in experimental stroke.

Background And Purpose: Adenosine 5'-monophosphate-activated protein kinase (AMPK) is an important sensor of energy balance. Stroke-induced AMPK activation is deleterious because both pharmacological inhibition and genetic deletion of AMPK are neuroprotective. Metformin is a known AMPK activator but reduces stroke incidence in clinical populations.

Adenosine monophosphate activated protein kinase inhibition is protective in both sexes after experimental stroke.

Sex differences in clinical and experimental stroke are now well recognized. Adenosine monophosphate activated protein kinase (AMPK) is an important energy sensor that is activated in times of energy demand. Increasing AMPK is deleterious in experimental cerebral ischemia, at least in males.

Expression of Na-K-Cl cotransporter and edema formation are age dependent after ischemic stroke.

Age is the most important independent risk factor for stroke; however aging animals are rarely used in stroke studies. Previous work demonstrated that young male mice had more edema formation after an induced stroke than aging animals. An important contributor to cerebral edema formation is the Na-K-Cl cotransporter (NKCC).

Changes in experimental stroke outcome across the life span.

Acute ischemic stroke is a leading cause of mortality and disability in the elderly. Age is the most important nonmodifiable risk factor for stroke, yet many preclinical models continue to examine only young male animals. It remains unclear how experimental stroke outcomes change with aging and with biologic sex.

Redox-based control of the gamma heavy chain ATPase from Chlamydomonas outer arm dynein.

The outer dynein arm from Chlamydomonas flagella contains two redox-active thioredoxin-related light chains associated with the alpha and beta heavy chains; these proteins belong to a distinct subgroup within the thioredoxin family. This observation suggested that some aspect of dynein activity might be modulated through redox poise. To test this, we have examined the effect of sulfhydryl oxidation on the ATPase activity of isolated dynein and axonemes from wildtype and mutant strains lacking various heavy chain combinations.

A bipartite Ca2+-regulated nucleoside-diphosphate kinase system within the Chlamydomonas flagellum. The regulatory subunit p72.

Regulation of flagellar activity in Chlamydomonas involves both Ca(2+) and cAMP-mediated signaling pathways. However, Chlamydomonas and sea urchin sperm flagella also exhibit nucleoside-diphosphate kinase (NDK) activity, suggesting a requirement for GTP within this highly conserved organelle. In sea urchin sperm, the NDK catalytic subunit is an integral component of the outer dynein arm.