MAP4K4 induces early blood-brain barrier damage in a murine subarachnoid hemorrhage model

Edaravone dexborneol attenuates oxidative stress in experimental subarachnoid hemorrhage via Keap1/Nrf2 signaling pathway

Background

Subarachnoid hemorrhage (SAH) serves as a disease characterized by high incidence rate, which is exceedingly prevalent and severe. Presently, there is no unambiguous or efficacious intervention for the neurological impairment following SAH. Administering multi-targeted neuroprotective agents to reduce oxidative stress (OS) and neuroinflammation caused by early brain injury (EBI) has been demonstrated to improve neurological function and prognosis following SAH. Edaravone dexborneol (EDB), a novel multi targeted neuroprotective medication, combines four parts edaravone (EDA) with 1 part (+)-borneol in proportion. Clinical trials conducted in China have revealed during 2 days of acute ischemic stroke (AIS), early administration of EDB leads to improved therapeutic outcomes compared to treatment in EDA monotherapy. Currently, there is no clear evidence that EDB can effectively treat SAH, therefore, our study aims to investigate its potential therapeutic effects and mechanisms on EBI after SAH.

Method

We used the intravascular threading method to establish a mouse model of SAH to explore whether EDA and EDB could produce anti-OS and anti-apoptosis effects. Behavioral assessment of mice was conducted using the balance beam experiment and the modified Garcia scoring system. Neuronal damage due to OS and Keap1/Nrf2 signaling pathway were detected through techniques of immunofluorescence, Western blotting, spectrophotometry. The group of EDA and EDB were injected intraperitoneally for 72 h after SAH.

Results

The experiment results indicated that EDB lead to remarkably positive results by significantly enhancing neurological function, reducing blood-brain barrier (BBB) injury, and effectively inhibiting neuronal apoptosis after SAH. Further examination indicated EDB significantly reduced the expression of Keap1 and increased the expression of Nrf2, and it inhibited MDA, and enhanced SOD activity after SAH. These outcomes surpassed the effectiveness observed in EDA monotherapy. However, the application of ML385 reversed the anti-OS effects of EDB and EDA.

Conclusion

Our experimental findings indicated that EDB could activate Keap1/Nrf2 signaling pathway to reduce OS damage, thereby protecting neurological function and enhancing behavioral abilities after SAH. These outcomes could facilitate the creation of new approaches for the clinical management of SAH.

A Carboxy-terminal Smarcb1 Point Mutation Induces Hydrocephalus Formation and Affects AP-1 and Neuronal Signalling Pathways in Mice

The BAF (BRG1/BRM-associated factor) chromatin remodelling complex is essential for the regulation of DNA accessibility and gene expression during neuronal differentiation. Mutations of its core subunit SMARCB1 result in a broad spectrum of pathologies, including aggressive rhabdoid tumours or neurodevelopmental disorders. Other mouse models have addressed the influence of a homo- or heterozygous loss of Smarcb1, yet the impact of specific non-truncating mutations remains poorly understood. Here, we have established a new mouse model for the carboxy-terminal Smarcb1 c.1148del point mutation, which leads to the synthesis of elongated SMARCB1 proteins. We have investigated its impact on brain development in mice using magnetic resonance imaging, histology, and single-cell RNA sequencing. During adolescence, Smarcb11148del/1148del mice demonstrated rather slow weight gain and frequently developed hydrocephalus including enlarged lateral ventricles. In embryonic and neonatal stages, mutant brains did not differ anatomically and histologically from wild-type controls. Single-cell RNA sequencing of brains from newborn mutant mice revealed that a complete brain including all cell types of a physiologic mouse brain is formed despite the SMARCB1 mutation. However, neuronal signalling appeared disturbed in newborn mice, since genes of the AP-1 transcription factor family and neurite outgrowth-related transcripts were downregulated. These findings support the important role of SMARCB1 in neurodevelopment and extend the knowledge of different Smarcb1 mutations and their associated phenotypes.

Nanotechnology meets glioblastoma multiforme: Emerging therapeutic strategies

Glioblastoma multiforme (GBM) represents the most common and fatal form of primary invasive brain tumors as it affects a great number of patients each year and has a median overall survival of approximately 14.6 months after diagnosis. Despite intensive treatment, almost all patients with GBM experience recurrence, and their 5-year survival rate is approximately 5%. At present, the main clinical treatment strategy includes surgical resection, radiotherapy, and chemotherapy. However, tumor heterogeneity, blood-brain barrier, glioma stem cells, and DNA damage repair mechanisms hinder efficient GBM treatment. The emergence of nanometer-scale diagnostic and therapeutic approaches in cancer medicine due to the establishment of nanotechnology provides novel and promising tools that will allow us to overcome these difficulties. This review summarizes the application and recent progress in nanotechnology-based monotherapies (e.g., chemotherapy) and combination cancer treatment strategies (chemotherapy-based combined cancer therapy) for GBM and describes the synergistic enhancement between these combination therapies as well as the current standard therapy for brain cancer and its deficiencies. These combination therapies that can reduce individual drug-related toxicities and significantly enhance therapeutic efficiency have recently undergone rapid development. The mechanisms underlying these different nanotechnology-based therapies as well as the application of nanotechnology in GBM (e.g., in photodynamic therapy and chemodynamic therapy) have been systematically summarized here in an attempt to review recent developments and to identify promising directions for future research. This review provides novel and clinically significant insights and directions for the treatment of GBM, which is of great clinical importance. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Diagnostic Tools > In Vivo Nanodiagnostics and Imaging.

The molecular basis of the dichotomous functionality of MAP4K4 in proliferation and cell motility control in cancer

The finely tuned integration of intra- and extracellular cues by components of the mitogen-activated protein kinase (MAPK) signaling pathways controls the mutually exclusive phenotypic manifestations of uncontrolled growth and tumor cell dissemination. The Ser/Thr kinase MAP4K4 is an upstream integrator of extracellular cues involved in both proliferation and cell motility control. Initially identified as an activator of the c-Jun N-terminal kinase (JNK), the discovery of diverse functions and additional effectors of MAP4K4 beyond JNK signaling has considerably broadened our understanding of this complex kinase. The implication of MAP4K4 in the regulation of cytoskeleton dynamics and cell motility provided essential insights into its role as a pro-metastatic kinase in cancer. However, the more recently revealed role of MAP4K4 as an activator of the Hippo tumor suppressor pathway has complicated the understanding of MAP4K4 as an oncogenic driver kinase. To develop a better understanding of the diverse functions of MAP4K4 and their potential significance in oncogenesis and tumor progression, we have collected and assessed the current evidence of MAP4K4 implication in molecular mechanisms that control proliferation and promote cell motility. A better understanding of these mechanisms is particularly relevant in the brain, where MAP4K4 is highly expressed and under pathological conditions either drives neuronal cell death in neurodegenerative diseases or cell dissemination in malignant tumors. We review established effectors and present novel interactors of MAP4K4, which offer mechanistic insights into MAP4K4 function and may inspire novel intervention strategies. We discuss possible implications of novel interactors in tumor growth and dissemination and evaluate potential therapeutic strategies to selectively repress pro-oncogenic functions of MAP4K4.

Intestinal epithelial cell-derived exosomes package microRNA-23a-3p alleviate gut damage after ischemia/reperfusion via targeting MAP4K4

Intestinal epithelial cells (IECs) contribute to regulation of gut injury after intestinal ischemia/reperfusion (II/R). Exosomes are well documented to deliver bioactive molecules to recipient cells for the purpose of modulating cell function. However, the role of IEC-derived exosomes in gut damage after II/R and the underlying mechanisms remain unclear. Here, we investigated the effects of exosomal miR-23a-3p on gut damage using primary IECs that underwent oxygen-glucose deprivation (OGD) as well as II/R rats. We observed that exosomes released by IECs attenuated damage in IECs that underwent OGD in vitro (P < 0.05) as well as the degree of gut injury after an II/R assault in vivo (P < 0.05). Injection of miR-23a-3p knockdown exosomes aggravated the II/R injury, whereas PF-6260933, a small-molecule inhibitor of MAP4K4, partly reversed the injury. Underlying mechanistic studies revealed that exosomal miR-23a-3p attenuated gut damage by regulating its downstream target, MAP4K4.

The blood-brain barrier and the neurovascular unit in subarachnoid hemorrhage: molecular events and potential treatments

The response of the blood-brain barrier (BBB) following a stroke, including subarachnoid hemorrhage (SAH), has been studied extensively. The main components of this reaction are endothelial cells, pericytes, and astrocytes that affect microglia, neurons, and vascular smooth muscle cells. SAH induces alterations in individual BBB cells, leading to brain homeostasis disruption. Recent experiments have uncovered many pathophysiological cascades affecting the BBB following SAH. Targeting some of these pathways is important for restoring brain function following SAH. BBB injury occurs immediately after SAH and has long-lasting consequences, but most changes in the pathophysiological cascades occur in the first few days following SAH. These changes determine the development of early brain injury as well as delayed cerebral ischemia. SAH-induced neuroprotection also plays an important role and weakens the negative impact of SAH. Supporting some of these beneficial cascades while attenuating the major pathophysiological pathways might be decisive in inhibiting the negative impact of bleeding in the subarachnoid space. In this review, we attempt a comprehensive overview of the current knowledge on the molecular and cellular changes in the BBB following SAH and their possible modulation by various drugs and substances.