17β-estradiol upregulates striatin protein levels via Akt pathway in human umbilical vein endothelial cells

The foam cell-derived exosomal miRNA Novel-3 drives neuroinflammation and ferroptosis during ischemic stroke

Large artery atherosclerosis (LAA) is a prevalent cause of acute ischemic stroke (AIS). Understanding the mechanisms linking atherosclerosis to stroke is essential for developing appropriate intervention strategies. Here, we found that the exosomal miRNA Novel-3 is selectively upregulated in the plasma of patients with LAA-AIS. Notably, Novel-3 was predominantly expressed in macrophage-derived foam cells, and its expression correlated with atherosclerotic plaque vulnerability in patients undergoing carotid endarterectomy. Exploring the function of Novel-3 in a mouse model of cerebral ischemia, we found that Novel-3 exacerbated ischemic injury and targeted microglia and macrophages expressing ionized calcium-binding adapter molecule 1 in peri-infarct regions. Mechanistically, Novel-3 increased ferroptosis and neuroinflammation by interacting with striatin (STRN) and downregulating the phosphoinositide 3-kinase-AKT-mechanistic target of rapamycin signaling pathway. Blocking Novel-3 activity or overexpressing STRN provided neuroprotection under ischemic conditions. Our findings suggest that exosomal Novel-3, which is primarily derived from macrophage-derived foam cells, targets microglia and macrophages in the brain to induce neuroinflammation and could serve as a potential therapeutic target for patients with stroke who have atherosclerosis.

Cellular Impacts of Striatins and the STRIPAK Complex and Their Roles in the Development and Metastasis in Clinical Cancers (Review)

Striatins (STRNs) are generally considered to be cytoplasmic proteins, with lower expression observed in the nucleus and at cell-cell contact regions. Together with protein phosphatase 2A (PP2A), STRNs form the core region of striatin-interacting phosphatase and kinase (STRIPAK) complexes through the coiled-coil region of STRN proteins, which is crucial for substrate recruitment. Over the past two decades, there has been an increasing amount of research into the biological and cellular functions of STRIPAK members. STRNs and the constituent members of the STRIPAK complex have been found to regulate several cellular functions, such as cell cycle control, cell growth, and motility. Dysregulation of these cellular events is associated with cancer development. Importantly, their roles in cancer cells and clinical cancers are becoming recognised, with several STRIPAK components found to have elevated expression in cancerous tissues compared to healthy tissues. These molecules exhibit significant diagnostic and prognostic value across different cancer types and in metastatic progression. The present review comprehensively summarises and discusses the current knowledge of STRNs and core STRIPAK members, in cancer malignancy, from both cellular and clinical perspectives.

Striatins and STRIPAK complex partners in clinical outcomes of patients with breast cancer and responses to drug treatment

Objective

Striatins (STRNs) family, which contains three multi-domain scaffolding proteins, are cornerstones of the striatins interacting phosphatase and kinase (STRIPAK) complex. Although the role of the STRIPAK complex in cancer has become recognized in recent years, its clinical significance in breast cancer has not been fully established.

Methods

Using a freshly frozen breast cancer tissue cohort containing both cancerous and adjacent normal mammary tissues, we quantitatively evaluated the transcript-level expression of all members within the STRIPAK complex along with some key interacting and regulatory proteins of STRNs. The expression profile of each molecule and the integrated pattern of the complex members were assessed against the clinical-pathological factors of the patients. The Cancer Genome Atlas (TCGA) dataset was used to evaluate the breast cancer patients' response to chemotherapies. Four human breast cancer cell lines, MDA-MB-231, MDA-MB-361, MCF-7, and SK-BR-3, were subsequently adopted for in vitro work.

Results

Here we found that high-level expressions of STRIP2, calmodulin, CCM3, MINK1 and SLMAP were respectively associated with shorter overall survival (OS) of patients. Although the similar pattern observed for STRN3, STRN4 and a contrary pattern observed for PPP2CA, PPP2CB and PPPR1A were not significant, the integrated expression profile of STRNs group and PPP2 group members constitutes a highly significant prognostic indicator for OS [P<0.001, hazard ratio (HR)=2.04, 95% confidence interval (95% CI), 1.36-3.07] and disease-free survival (DFS) (P=0.003, HR=1.40, 95% CI, 1.12-1.75). Reduced expression of STRN3 has an influence on the biological functions including adhesiveness and migration. In line with our clinical findings, the breast cancer cells responded to STRN3 knockdown with changes in their chemo-sensitivity, of which the response is also breast cancer subtype dependent.

Conclusions

Our results suggest a possible role of the STRIPAK complex in breast cancer development and prognosis. Among the members, the expression profile of STRN3 presents a valuable factor for assessing patients' responses to drug treatment.

Striatin family proteins: The neglected scaffolds

The Striatin family of proteins constitutes Striatin, SG2NA, and Zinedin. Members of this family of proteins act as a signaling scaffold due to the presence of multiple protein-protein interaction domains. At least two members of this family, namely Zinedin and SG2NA, have a proven role in cancer cell proliferation. SG2NA, the second member of this family, undergoes alternative splicing and gives rise to several isoforms which are differentially regulated in a tissue-dependent manner. SG2NA evolved earlier than the other two members of the family, and SG2NA undergoes not only alternative splicing but also other posttranscriptional gene regulation. Striatin also undergoes alternative splicing, and as a result, it gives rise to multiple isoforms. It has been shown that this family of proteins plays a significant role in estrogen signaling, neuroprotection, cancer as well as in cell cycle regulation. Members of the striatin family form a complex network of signaling hubs with different kinases and phosphatases, and other signaling proteins named STRIPAK. Here, in the present manuscript, we thoroughly reviewed the findings on striatin family members to elaborate on the overall structural and functional idea of this family of proteins. We also commented on the involvement of these proteins in STRIPAK complexes and their functional relevance.

Signalling mechanisms in the cardiovascular protective effects of estrogen: With a focus on rapid/membrane signalling

In modern society, cardiovascular disease remains the biggest single threat to life, being responsible for approximately one third of worldwide deaths. Male prevalence is significantly higher than that of women until after menopause, when the prevalence of CVD increases in females until it eventually exceeds that of men. Because of the coincidence of CVD prevalence increasing after menopause, the role of estrogen in the cardiovascular system has been intensively researched during the past two decades in vitro, in vivo and in observational studies. Most of these studies suggested that endogenous estrogen confers cardiovascular protective and anti-inflammatory effects. However, clinical studies of the cardioprotective effects of hormone replacement therapies (HRT) not only failed to produce proof of protective effects, but also revealed the potential harm estrogen could cause. The "critical window of hormone therapy" hypothesis affirms that the moment of its administration is essential for positive treatment outcomes, pre-menopause (3-5 years before menopause) and immediately post menopause being thought to be the most appropriate time for intervention. Since many of the cardioprotective effects of estrogen signaling are mediated by effects on the vasculature, this review aims to discuss the effects of estrogen on vascular smooth muscle cells (VSMCs) and endothelial cells (ECs) with a focus on the role of estrogen receptors (ERα, ERβ and GPER) in triggering the more recently discovered rapid, or membrane delimited (non-genomic), signaling cascades that are vital for regulating vascular tone, preventing hypertension and other cardiovascular diseases.

Aldosterone Rapidly Enhances Levels of the Striatin and Caveolin-1 Proteins in Rat Kidney: The Role of the Mineralocorticoid Receptor

BACKGROUND

Striatin and caveolin-1 (cav-1) are scaffolding/regulating proteins that are associated with salt-sensitive high blood pressure and promote renal sodium and water reabsorption, respectively. The mineralocorticoid receptor (MR) interacts with striatin and cav-1, while aldosterone increases striatin and cav-1 levels. However, no in vivo data have been reported for the levels of these proteins in the kidney.

METHODS

Male Wistar rats were intraperitoneally injected with normal saline solution, aldosterone alone (Aldo: 150 μg/kg body weight), or aldosterone after pretreatment with eplerenone, an MR blocker, 30 minutes before the aldosterone injection (eplerenone [Ep.]+Aldo). Thirty minutes after the aldosterone injection, the amount and localization of striatin and cav-1 were determined by Western blot analysis and immunohistochemistry, respectively.

RESULTS

Aldosterone increased striatin levels by 150% (P<0.05), and cav-1 levels by 200% (P<0.001). Eplerenone had no significant effect on striatin levels, but partially blocked the aldosterone-induced increase in cav-1 levels. Aldosterone stimulated striatin and cav-1 immunoreactivity in both the cortex and medulla. Eplerenone reduced cav-1 immunostaining in both areas; however, striatin intensity was reduced in the cortex, but increased in the medulla.

CONCLUSION

This is the first in vivo study demonstrating that aldosterone rapidly enhances renal levels of striatin and cav-1. Aldosterone increases striatin levels via an MR-independent pathway, whereas cav-1 is partially regulated through MR.

STRIPAK, a highly conserved signaling complex, controls multiple eukaryotic cellular and developmental processes and is linked with human diseases

The striatin-interacting phosphatases and kinases (STRIPAK) complex is evolutionary highly conserved and has been structurally and functionally described in diverse lower and higher eukaryotes. In recent years, this complex has been biochemically characterized better and further analyses in different model systems have shown that it is also involved in numerous cellular and developmental processes in eukaryotic organisms. Further recent results have shown that the STRIPAK complex functions as a macromolecular assembly communicating through physical interaction with other conserved signaling protein complexes to constitute larger dynamic protein networks. Here, we will provide a comprehensive and up-to-date overview of the architecture, function and regulation of the STRIPAK complex and discuss key issues and future perspectives, linked with human diseases, which may form the basis of further research endeavors in this area. In particular, the investigation of bi-directional interactions between STRIPAK and other signaling pathways should elucidate upstream regulators and downstream targets as fundamental parts of a complex cellular network.

Precise and systematic survey of the efficacy of multicomponent drugs against functional dyspepsia

Functional dyspepsia (FD) is one of the most prevalent functional gastrointestinal disorders, and more and more multicomponent drugs represented by traditional Chinese medicines have provided a favorable therapeutic effect in its treatment. However, their precise localization in the clinic, as well as corresponding mechanism, is ambiguous, thus hindering their widespread use. To meet this requirement, a precise and systematic approach based on a restriction of special disease-related molecules and the following network pharmacology analysis was developed and applied to a multicomponent conventional drug, XiaoErFuPi (XEFP) granules. Experimental verification of the results indicates that this approach can facilitate the prediction, and the precise and systematic efficacy of XEFP could be easily revealed, which shows that XEFP has an advantage over the positive control drug on lactate, gastrin, interleukin 4 and calcitonin gene-related peptide. Moreover, by the proteomics analysis, its superposition of multi-target effects was revealed and a new candidate target for the treatment of FD, striatin, was obtained and verified. This study provides a practicable precise approach for the investigation of the efficacy of multicomponent drugs against FD and offers a promising alternative for the systematical management of FD.