Downregulated Rac1 promotes apoptosis and inhibits the clearance of apoptotic cells in airway epithelial cells, which may be associated with airway hyper-responsiveness in asthma

Rac1 promotes the lipopolysaccharide-induced inflammatory response and contraction-associated proteins (CAPs) expression in mouse uterine smooth muscle cells

Activation of the maternal immune system leads to a downstream cascade of proinflammatory events that culminate in the activation of spontaneous uterine contractions, which is associated with preterm birth. Ras-related C3 botulinum toxin substrate 1 (Rac1) is a crucial protein related to cell contraction and inflammation. The main purpose of this study was to explore the role and function of Rac1's regulation of inflammation through in- vivo and in-vitro experiments. Rac1 inhibitor was used in animal model of preterm birth and cells isolated from the uterine tissues of pregnant mice on gestational day 16 were transfected with adenovirus to knockdown or overexpress Rac1 and treated with the Calcium-calmodulin-dependent protein kinase II (CaMKII) inhibitor KN93. The expression of Rac1, uterine contraction-associated proteins (CAPs) (COX-2 and Connexin43), and inflammatory cytokines, were assessed by Western blotting and RTPCR. LPS upregulated Rac1, COX-2 and Connexin43 expression in uterine smooth muscle cells (USMCs). The expression of inflammatory cytokines, COX-2, and Connexin43 was significantly decreased in shRac1-transfected cells compared with cells stimulated with LPS only. Rac1 overexpression led to an increase in the expression of inflammatory cytokines, COX-2, and Connexin43. Furthermore, after Rac1 overexpression, KN93 reduced the expression of uterine contraction-associated proteins and inflammatory cytokines. It is thought that the effect of Rac1 on inflammatory cytokine and contraction-associated protein expression in USMCs is mediated by CaMKII. Rac1 can modulate the expression of contraction-associated proteins and inflammatory cytokines through the CaMKII pathway. Rac1 could be an effective therapeutic target for improving the outcome of preterm birth.

Programmed Cell Death in Asthma: Apoptosis, Autophagy, Pyroptosis, Ferroptosis, and Necroptosis

Bronchial asthma is a complex heterogeneous airway disease, which has emerged as a global health issue. A comprehensive understanding of the different molecular mechanisms of bronchial asthma may be an efficient means to improve its clinical efficacy in the future. Increasing research evidence indicates that some types of programmed cell death (PCD), including apoptosis, autophagy, pyroptosis, ferroptosis, and necroptosis, contributed to asthma pathogenesis, and may become new targets for future asthma treatment. This review briefly discusses the molecular mechanism and signaling pathway of these forms of PCD focuses on summarizing their roles in the pathogenesis and treatment strategies of asthma and offers some efficient means to improve clinical efficacy of therapeutics for asthma in the near future.

MicroRNA-98-5p Inhibits IL-13-Induced Proliferation and Migration of Human Airway Smooth Muscle Cells by Targeting RAC1

The dysfunction of airway smooth muscle cells (ASMCs) is one of the key factors in the pathogenesis of asthma. How miR-98-5p works in asthma has not been completely elucidated. This work focused on how miR-98-5p functions in the proliferation and migration of human ASMCs treated with interleukin-13 (IL-13). MiR-98-5p expression in plasma of asthmatic patients and IL-13-stimulated ASMCs was probed by quantitative real-time polymerase chain reaction (qRT-PCR). RAS-relevant C3 botulinum toxin substrate 1 (RAC1) protein expression in ASMCs was assessed by Western blot. The growth of ASMCs was measured by cell counting kit-8 (CCK-8) assay and 5-ethynyl-2'-deoxyuridine (EdU) assay. The migration of ASMCs was examined by Transwell assay. Besides, the apoptosis of ASMCs was analyzed by flow cytometry. The targeting relationship between miR-98-5p and RAC1 3'-UTR was verified by a dual-luciferase reporter gene assay. MiR-98-5p expression was reduced in patients' plasma and IL-13-stimulated ASMCs, and RAC1 expression was upregulated in ASMCs treated with IL-13. MiR-98-5p overexpression inhibited IL-13-induced proliferation and migration of ASMCs while promoting the apoptosis. The opposite result was observed after inhibiting miR-98-5p expression. Besides, RAC1 was identified as a direct downstream target of miR-98-5p in ASMCs. The restoration of RAC1 expression counteracted the impacts of miR-98-5p overexpression on IL-13-stimulated proliferation, migration, and apoptosis of ASMCs. MiR-98-5p inhibits IL-13-induced proliferation and migration and accelerates the apoptosis of ASMCs by downregulating RAC1 expression.

Rac1, A Potential Target for Tumor Therapy

RAS-related C3 botulinum toxin substrate 1 (Rac.1) is one of the important members of Rho GTPases. It is well known that Rac1 is a cytoskeleton regulation protein that regulates cell adhesion, morphology, and movement. Rac1 is highly expressed in different types of tumors, which is related to poor prognosis. Studies have shown that Rac1 not only participates in the tumor cell cycle, apoptosis, proliferation, invasion, migration and angiogenesis, but also participates in the regulation of tumor stem cell, thus promoting the occurrence of tumors. Rac1 also plays a key role in anti-tumor therapy and participates in immune escape mediated by the tumor microenvironment. In addition, the good prospects of Rac1 inhibitors in cancer prevention and treatment are exciting. Therefore, Rac1 is considered as a potential target for the prevention and treatment of cancer. The necessity and importance of Rac1 are obvious, but it still needs further study.

Fructose-1,6-bisphosphatase aggravates oxidative stress-induced apoptosis in asthma by suppressing the Nrf2 pathway

Asthma is a chronic airway disease that causes excessive inflammation, oxidative stress, mucus production and bronchial epithelial cell apoptosis. Fructose‐1,6‐bisphosphatase (Fbp1) is one of the rate‐limiting enzymes in gluconeogenesis and plays a critical role in several cancers. However, its role in inflammatory diseases, such as asthma, is unclear. Here, we examined the expression, function and mechanism of action of Fbp1 in asthma. Gene Expression Omnibus (GEO) data sets revealed that Fbp1 was overexpressed in a murine model of asthma and in interleukin (IL)‐4‐ or IL‐13‐stimulated bronchial epithelial cells. We confirmed the findings in an animal model as well as Beas‐2B and 16HBE cells. In vitro investigations revealed that silencing of Fbp1 reduced apoptosis and the proportion of cells in the G2/M phase, whereas overexpression led to increases. Fbp1 knock‐down inhibited oxidative stress by activating the nuclear factor erythroid 2‐related factor 2 (Nrf2) pathway, whereas Fbp1 overexpression aggravated oxidative stress by suppressingthe Nrf2 pathway. Moreover, the Nrf2 pathway inhibitor ML385 reversed the changes caused by Fbp1 inhibition in Beas‐2B and 16HBE cells. Collectively, our data indicate that Fbp1 aggravates oxidative stress‐induced apoptosis by suppressing Nrf2 signalling, substantiating its potential as a novel therapeutic target in asthma.