Nonapoptotic caspases in neural development and in anesthesia-induced neurotoxicity

Death fuels growth: Emerging players bridging apoptosis and cell proliferation in Drosophila and beyond

Tissue homeostasis relies on a delicate balance between cell death and proliferation. Apoptosis plays a key role not only in removing damaged cells but also in promoting tissue recovery through a process known as apoptosis-induced proliferation (AiP). This review highlights how caspases, c-Jun N-terminal Kinase (JNK), and Reactive Oxygen Species (ROS) bridge cell death and proliferation, as revealed through studies using Drosophila as a model organism. We also compare these findings with advances in other model systems and discuss their broader implications for tissue regeneration and tumorigenesis.

Caspase family in autoimmune diseases

Programmed cell death (PCD) plays a crucial role in maintaining tissue homeostasis, with its primary forms including apoptosis, pyroptosis, and necroptosis. The caspase family is central to these processes, and its complex functions across different cell death pathways and other non-cell death roles have been closely linked to the pathogenesis of autoimmune diseases. This article provides a comprehensive review of the role of the caspase family in autoimmune diseases such as rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), type 1 diabetes (T1D), and multiple sclerosis (MS). It particularly emphasizes the intricate functions of caspases within various cell death pathways and their potential as therapeutic targets, thereby offering innovative insights and a thorough discussion in this field. In terms of therapy, strategies targeting caspases hold significant promise. We emphasize the importance of a holistic understanding of caspases in the overall concept of cell death, exploring their unique functions and interrelationships across multiple cell death pathways, including apoptosis, pyroptosis, necroptosis, and PANoptosis. This approach transcends the limitations of previous studies that focused on singular cell death pathways. Additionally, caspases play a key role in non-cell death functions, such as immune cell activation, cytokine processing, inflammation regulation, and tissue repair, thereby opening new avenues for the treatment of autoimmune diseases. Regulating caspase activity holds the potential to restore immune balance in autoimmune diseases. Potential therapeutic approaches include small molecule inhibitors (both reversible and irreversible), biological agents (such as monoclonal antibodies), and gene therapies. However, achieving specific modulation of caspases to avoid interference with normal physiological functions remains a major challenge. Future research must delve deeper into the regulatory mechanisms of caspases and their associated complexes linked to PANoptosis to facilitate precision medicine. In summary, this article offers a comprehensive and in-depth analysis, providing a novel perspective on the complex roles of caspases in autoimmune diseases, with the potential to catalyze breakthroughs in understanding disease mechanisms and developing therapeutic strategies.

Untargeted Metabolomics Reveals Metabolic Link Between Histone H3K27 Demethylase UTX and Neurodevelopment

Ubiquitously transcribed tetratricopeptide repeat on chromosome X (UTX) is a chromatin modifier responsible for regulating the demethylation of histone H3 lysine 27 trimethylation (H3K27me3), which is crucial for human neurodevelopment. To date, the impact of UTX on neurodevelopment remains elusive. Therefore, this study aimed to investigate the potential molecular mechanisms underlying the effects of UTX on neurodevelopment through untargeted metabolomics based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). We found that UTX knockout in neurones leads to cell death and apoptosis in the hippocampus and cortex, as well as induces impaired learning and memory functions in mice. Moreover, UTX deletion contributed to significant metabolic perturbations in brain tissues. A total of 223 differential metabolites were identified between wild-type (WT) and UTX cKO mice. Pathway analysis indicated that the metabolic pathways mainly affected by UTX deletion were alanine, aspartate, and glutamate metabolism, resulting in significant alterations in L-alanine, L-aspartate, D-aspartate, N-acetylaspartylglutamate, L-glutamate, and argininosuccinic acid. These data emphasised that UTX may exert a key effect in neurodevelopment and that the underlying mechanism may be related to the regulation of the alanine, aspartate, and glutamate metabolism pathways, especially the characteristic metabolites involved in this pathway.

Ciliopathy interacts with neonatal anesthesia to cause non-apoptotic caspase-mediated motor deficits

Increasing evidence suggests that anesthesia may induce developmental neurotoxicity, yet the influence of genetic predispositions associated with congenital anomalies on this toxicity remains largely unknown. Children with congenital heart disease often exhibit mutations in cilia-related genes and ciliary dysfunction, requiring sedation for their catheter or surgical interventions during the neonatal period. Here we demonstrate that briefly exposing ciliopathic neonatal mice to ketamine causes motor skill impairments, which are associated with a baseline deficit in neocortical layer V neuron apical spine density and their altered dynamics during motor learning.. These neuromorphological changes were linked to augmented non-apoptotic neuronal caspase activation. Neonatal caspase suppression rescued the spine density and motor deficits, confirming the requirement for sublethal caspase signaling in appropriate spine formation and motor learning. Our findings suggest that ciliopathy interacts with ketamine to induce motor impairments, which is reversible through caspase inhibition. Furthermore, they underscore the potential for ketamine- induced sublethal caspase responses in shaping neurodevelopmental outcomes.

The role of primary cilia in congenital heart defect-associated neurological impairments

Congenital heart disease (CHD) has, despite significant improvements in patient survival, increasingly become associated with neurological deficits during infancy that persist into adulthood. These impairments afflict a wide range of behavioral domains including executive function, motor learning and coordination, social interaction, and language acquisition, reflecting alterations in multiple brain areas. In the past few decades, it has become clear that CHD is highly genetically heterogeneous, with large chromosomal aneuploidies and copy number variants (CNVs) as well as single nucleotide polymorphisms (SNPs) being implicated in CHD pathogenesis. Intriguingly, many of the identified loss-of-function genetic variants occur in genes important for primary cilia integrity and function, hinting at a key role for primary cilia in CHD. Here we review the current evidence for CHD primary cilia associated genetic variants, their independent functions during cardiac and brain development and their influence on behavior. We also highlight the role of environmental exposures in CHD, including stressors such as surgical factors and anesthesia, and how they might interact with ciliary genetic predispositions to determine the final neurodevelopmental outcome. The multifactorial nature of CHD and neurological impairments linked with it will, on one hand, likely necessitate therapeutic targeting of molecular pathways and neurobehavioral deficits shared by disparate forms of CHD. On the other hand, strategies for better CHD patient stratification based on genomic data, gestational and surgical history, and CHD complexity would allow for more precise therapeutic targeting of comorbid neurological deficits.

Autism risk gene Cul3 alters neuronal morphology via caspase-3 activity in mouse hippocampal neurons

Autism Spectrum Disorders (ASDs) are neurodevelopmental disorders (NDDs) in which children display differences in social interaction/communication and repetitive stereotyped behaviors along with variable associated features. Cul3, a gene linked to ASD, encodes CUL3 (CULLIN-3), a protein that serves as a key component of a ubiquitin ligase complex with unclear function in neurons. Cul3 homozygous deletion in mice is embryonic lethal; thus, we examine the role of Cul3 deletion in early synapse development and neuronal morphology in hippocampal primary neuronal cultures. Homozygous deletion of Cul3 significantly decreased dendritic complexity and dendritic length, as well as axon formation. Synaptic spine density significantly increased, mainly in thin and stubby spines along with decreased average spine volume in Cul3 knockouts. Both heterozygous and homozygous knockout of Cul3 caused significant reductions in the density and colocalization of gephyrin/vGAT puncta, providing evidence of decreased inhibitory synapse number, while excitatory synaptic puncta vGulT1/PSD95 density remained unchanged. Based on previous studies implicating elevated caspase-3 after Cul3 deletion, we demonstrated increased caspase-3 in our neuronal cultures and decreased neuronal cell viability. We then examined the efficacy of the caspase-3 inhibitor Z-DEVD-FMK to rescue the decrease in neuronal cell viability, demonstrating reversal of the cell viability phenotype with caspase-3 inhibition. Studies have also implicated caspase-3 in neuronal morphological changes. We found that caspase-3 inhibition largely reversed the dendrite, axon, and spine morphological changes along with the inhibitory synaptic puncta changes. Overall, these data provide additional evidence that Cul3 regulates the formation or maintenance of cell morphology, GABAergic synaptic puncta, and neuronal viability in developing hippocampal neurons in culture.

Effects of the PAM of mGluR2, JNJ-46356479, on brain apoptotic protein levels in a mouse model of schizophrenia

Current treatment for schizophrenia (SZ) ameliorates the positive symptoms, but is inefficient in treating the negative and cognitive symptoms. The SZ glutamatergic dysfunction hypothesis has opened new avenues in the development of novel drugs targeting the glutamate storm, an inducer of progressive neuropathological changes. Positive allosteric modulators of metabotropic glutamate receptor 2 (mGluR2), such as JNJ-46356479 (JNJ), reduce the presynaptic release of glutamate, which has previously been demonstrated to attenuate glutamate- and dopamine-induced apoptosis in human neuroblastoma cell cultures. We hypothesised that JNJ treatment would modify the brain levels of apoptotic proteins in a mouse model of ketamine (KET)-induced schizophrenia. We analysed the levels of proapoptotic (caspase-3 and Bax) and antiapoptotic (Bcl-2) proteins by western blot in the prefrontal cortex and hippocampus of JNJ-treated mice. JNJ attenuated apoptosis in the brain by partially restoring the levels of the antiapoptotic Bcl-2 protein, which is significantly reduced in animals exposed to KET. Additionally, a significant inverse correlation was observed between proapoptotic protein levels and behavioural deficits in the mice. Our findings suggest that JNJ may attenuate brain apoptosis in vivo, as previously described in cell cultures, providing a link between neuropathological deficits and SZ symptomatology.

Trajectories of neurodevelopment and opportunities for intervention across the lifespan in congenital heart disease

Children with congenital heart disease (CHD) are at increased risk for neurodevelopmental challenges across the lifespan. These are associated with neurological changes and potential acquired brain injury, which occur across a developmental trajectory and which are influenced by an array of medical, sociodemographic, environmental, and personal factors. These alterations to brain development lead to an array of adverse neurodevelopmental outcomes, which impact a characteristic set of skills over the course of development. The current paper reviews existing knowledge of aberrant brain development and brain injury alongside associated neurodevelopmental challenges across the lifespan. These provide a framework for discussion of emerging and potential interventions to improve neurodevelopmental outcomes at each developmental stage.

Stress can affect mitochondrial energy metabolism and AMPK/SIRT1 signaling pathway in rats

OBJECTION

To investigate the potential link between aberrant mitochondrial energy metabolism mediated by the AMPK/SIRT1 pathway and the etiology of anxiety disorders.

METHODS

The anxiety rat model was established by uncertain empty water bottle（UEWB）stress. Rats were submitted behavioral tests on the seventh, fourteenth, and twenty-first days and had the prefrontal cortex and amygdala removed for biochemical tests. The morphological alterations of the mitochondria in the medial prefrontal cortex and amygdala were examined by using a transmission electron microscope. Expression levels of AMPK, SIRT1, PGC-1, NRF-1 and NRF-2 were tested by western-blot analysis. ATP, respiratory chain complex and caspase enzyme expressions were tested by neurochemical and biochemical assays.

RESULTS

Rats showed anxiety-like behavior after being exposed to the uncertain empty water bottle (UEWB) stress model. In model rats, mitochondrial structure is damaged, mitochondrial energy metabolism is decreased, and the expression of proteins associated with AMPK/SIRT1 pathway is significantly reduced in the brain.

CONCLUSION

The level of mitochondrial energy metabolism correlates with anxiety-like behavior. The main mechanism of anxiety disorder is a disturbance of mitochondrial energy metabolism, which might be related to AMPK/SIRT1 pathway.