RhoGDI2-Mediated Rac1 Recruitment to Filamin A Enhances Rac1 Activity and Promotes Invasive Abilities of Gastric Cancer Cells

Assessing the Mechanism of Rac1b: An All-Atom Simulation Study of the Alternative Spliced Variant of Rac1 Small Rho GTPase

The Rho GTPase family plays a key role in cell migration, cytoskeletal dynamics, and intracellular signaling. Rac1 and its splice variant Rac1b, characterized by the insertion of an Extraloop, are frequently associated with cancer. These small GTPases switch between an active GTP-bound state and an inactive GDP-bound state, a process that is regulated by specific protein modulators. Among them, the Guanine nucleotide exchange factor (GEF) protein DOCK5 specifically targets Rho GTPases, promoting their activation by facilitating the exchange of GDP for GTP. In this study, we performed cumulative 10-μs-long all-atom molecular dynamics simulations of Rac1 and Rac1b, in isolation and in complex with DOCK5 and ELMO1, to investigate the impact of the Rac1b Extraloop. Our findings reveal that this Extraloop decreases the GDP residence time as compared to Rac1, mimicking the effect of accelerated GDP/GTP exchange induced by DOCK5. Furthermore, both Rac1b Extraloop and the ELMO1 protein stabilize the GTPase/DOCK5 complex, contributing to facilitate GDP dissociation. This shifts the balance between the GPT- and GDP-bound state of Rac1b toward the active GTP-bound state, sending a prooncogenic signal. Besides broadening our understanding of the biological functions of small Rho GTPases, this study provides key information to exploit a previously unexplored therapeutic niche to counter Rac1b-associated cancer.

Correlation analysis of serum Rac1 level with asthma control, airway inflammatory response and lung function in asthmatic children

OBJECTIVE

To investigate the correlation between serum Rac1 enzyme (Rac1) level with asthma control, airway inflammatory response and lung function in asthmatic children.

METHODS

A retrospective analysis was performed on 79 children with asthma who were diagnosed and treated in our hospital from June 2020 to January 2023. According to the severity of the disease, the children were divided into mild group (25 cases), moderate group (30 cases) and severe group (24 cases). 36 healthy children who underwent physical examination at the same period in our hospital were selected as the control group. The state of an illness, control level, serum mRNA Rac1, inflammatory factors, and lung function of the children in two groups were compared between the control group and the observation group.

RESULTS

The Rac1 mRNA levels, forced vital capacity (FVC), forced expiratory volume in one second/FVC (FEV1/FVC), peak expiratory flow (PEF), and maximum mid-expiratory flow (MMEF) in the observation group were significantly lower than these in the control group (P < 0.05). The tumor necrosis factor-alpha (TNF-α), interleukin-5 (IL-5), IL-6, and IL-33 in the observation group were markedly higher than these in the control group (P < 0.05). As the state of an illness worsened, the Rac1 mRNA levels, FVC, FEV1/FVC, PEF, and MMEF gradually reduced (P < 0.05), while the levels of TNF-α, IL-5, IL-6, and IL-33 increased (P < 0.05). As the degree of disease control improved, the Rac1 mRNA levels, FVC, FEV1/FVC, PEF, and MMEF gradually elevated (P < 0.05), and the levels of TNF- α, IL-5, IL-6, and IL-33 showed the opposite trend (P < 0.05). Rac1 was negatively related to the levels of TNF-α, IL-5, IL-6 and IL-33 (P < 0.05), and positively to the levels of FVC, FEV1/FVC, PEF and MMEF (P < 0.001). Rac1 mRNA levels, FVC, FEV1/FVC, PEF and MMEF were protective factors, while TNF-α, IL-5, IL-6 and IL-33 were risk factors for the prognosis of children with asthma (P < 0.05).

CONCLUSION

Children with asthma have obviously lower serum Rac1 mRNA levels, higher inflammatory factor levels and lower lung function. Serum Rac1 mRNA level may be associated with better asthma control, lower airway inflammatory response, better lung function and lower disease severity. It has important reference value for the evaluation of the state of an illness, efficacy and prognosis of children with bronchial asthma.

Molecular Insight into Gastric Cancer Invasion-Current Status and Future Directions

Gastric cancer (GC) is one of the most common malignancies worldwide. There has been no efficient therapy for stage IV GC patients due to this disease's heterogeneity and dissemination ability. Despite the rapid advancement of molecular targeted therapies, such as HER2 and immune checkpoint inhibitors, survival of GC patients is still unsatisfactory because the understanding of the mechanism of GC progression is still incomplete. Invasion is the most important feature of GC metastasis, which causes poor mortality in patients. Recently, genomic research has critically deepened our knowledge of which gene products are dysregulated in invasive GC. Furthermore, the study of the interaction of GC cells with the tumor microenvironment has emerged as a principal subject in driving invasion and metastasis. These results are expected to provide a profound knowledge of how biological molecules are implicated in GC development. This review summarizes the advances in our current understanding of the molecular mechanism of GC invasion. We also highlight the future directions of the invasion therapeutics of GC. Compared to conventional therapy using protease or molecular inhibitors alone, multi-therapy targeting invasion plasticity may seem to be an assuring direction for the progression of novel strategies.

Dahuang—Taoren, a botanical drug combination, ameliorates adenomyosis via inhibiting Rho GTPases

Introduction: Dahuang-Taoren (DT) is a classic combination of botanical drugs applied to treat pain-related diseases in ancient China. Today, DT is frequently applied for dysmenorrhea of adenomyosis (AM) in the clinic. Growing evidence indicates Rho GTPases may play an essential role in AM progression. However, the potential mechanism of DT on Rho GTPases in AM remains unclear.

Methods: The expressions of Rho GTPases in the patients with AM were evaluated. Further, pituitary transplantation-induced AM mice and the primary AM endometrial stromal cells (AMESCs) were subjected to DT intervention.

Results: The results revealed that the expressions of Rho GTPases were significantly upregulated in both AM patients and AM mice. The DT could reduce pathological infiltration, relieve hyperalgesia, and alleviate cytoskeleton remodeling in AM mice. Besides, the migration and invasion of AMESCs were markedly inhibited after exposure to DT.

Discussion: These effects may be linked to the decreased Rho GTPases expression. The results may offer a novel explanation of DT against AM.

The Dual Function of RhoGDI2 in Immunity and Cancer

RhoGDI2 is a guanine nucleotide dissociation inhibitor (GDI) specific for the Rho family of small GTPases. It is highly expressed in hematopoietic cells but is also present in a large array of other cell types. RhoGDI2 has been implicated in multiple human cancers and immunity regulation, where it can display a dual role. Despite its involvement in various biological processes, we still do not have a clear understanding of its mechanistic functions. This review sheds a light on the dual opposite role of RhoGDI2 in cancer, highlights its underappreciated role in immunity and proposes ways to explain its intricate regulatory functions.

Deficiency of filamin A in smooth muscle cells protects against hypoxia‑mediated pulmonary hypertension in mice

Filamin A (FLNA) is a high molecular weight cytoskeleton protein important for cell locomotion. A relationship between FLNA mutations and pulmonary arterial hypertension (PAH) has previously been reported; however, the detailed mechanism remains unclear. The present study aimed to explore the role of FLNA in vascular smooth muscle cells during the development of PAH. Smooth muscle cell (SMC)‑specific FLNA‑deficient mice were generated and the mice were then exposed to hypoxia for 28 days to build the mouse model of PAH. Human pulmonary arterial smooth muscle cells (PASMCs) were also cultured and transfected with FLNA small interfering RNA or overexpression plasmids to investigate the effects of FLNA on PASMC proliferation and migration. Notably, compared with control individuals, the expression levels of FLNA were increased in lung tissues from patients with PAH, and it was obviously expressed in the PASMCs of pulmonary arterioles. FLNA deficiency in SMCs attenuated hypoxia‑induced pulmonary hypertension and pulmonary vascular remodeling. In vitro studies suggested that absence of FLNA impaired PASMC proliferation and migration, and produced lower levels of phosphorylated (p)‑PAK‑1 and RAC1 activity. However, FLNA overexpression promoted PASMC proliferation and migration, and increased the expression levels of p‑PAK‑1 and RAC1 activity. The present study highlights the role of FLNA in pulmonary vascular remodeling; therefore, it could serve as a potential target for the treatment of PAH.

Comparison of Sodium-Glucose Cotransporter 2 Inhibitors vs Glucagonlike Peptide-1 Receptor Agonists and Incidence of Dry Eye Disease in Patients With Type 2 Diabetes in Taiwan

IMPORTANCE

Sodium-glucose cotransporter 2 (SGLT2) inhibitors have been found to improve low-grade systemic and tissue inflammation; however, the association between SGLT2 inhibitor use and the incidence of dry eye disease (DED) has not been explored.

OBJECTIVE

To investigate the association between SGLT2 inhibitor use and dry eye disease in patients with type 2 diabetes (T2D).

DESIGN, SETTING, AND PARTICIPANTS

A retrospective cohort analysis of the largest multi-institutional electronic medical records database in Taiwan was conducted to identify patients with T2D newly receiving SGLT2 inhibitors or glucagonlike peptide-1 receptor agonists (GLP-1 RAs) from 2016 to 2018. Data analysis was performed from March 1 to May 31, 2022. Propensity scores with inverse probability of treatment weighting were generated to enable homogeneous comparisons between the 2 groups.

EXPOSURES

Treatment with SGLT2 inhibitors or GLP-1 RAs.

MAIN OUTCOMES AND MEASURES

Incident dry eye disease, which was defined by clinical diagnoses, plus the related drug prescription. Cox proportional hazards regression models were used to estimate hazard ratios with 95% CIs for the risk of DED.

RESULTS

A total of 10 038 and 1077 T2D patients newly receiving SGLT2 inhibitors (mean [SD] age, 59.5 [12.1] years; 5689 [56.7%] men) or GLP-1 RAs (mean [SD] age, 58.5 [41.2] years; 587 [54.5%] men), respectively, were included in the analysis. The incidence of DED was lower in patients newly receiving SGLT2 inhibitors (9.0 events per 1000 person-years) compared with those receiving GLP-1 RAs (11.5 events per 1000 person-years), yielding a hazard ratio of 0.78 (95% CI, 0.68-0.89). Subgroup analyses indicated that the lowered DED risks associated with SGLT2 inhibitors in patients with T2D were similar across different age, sex, blood glucose level, and kidney function groups. Results from the sensitivity analyses (including the propensity score-matching approach, on-treatment analyses, and different follow-up periods of 1, 2, and 3 years) were similar to the main analyses.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that patients with T2D newly receiving SGLT2 inhibitors may have a lower risk for DED compared with those receiving GLP-1 RAs. Prospective studies are needed to analyze these results.