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HuR deletion in IECs alters the regenerative potential of crypt progenitors. (A) Histograms depicting the labeling indices of cells at the S phase in resting (untreated) or S-phase descendants in the regenerating mucosa at different times (hours) in littermate (control) IEC-HuR −/− (IEC-KO) mice postirradiation as measured by BrdU detection. Values are shown as means ± SEM (n = 4). *p < 0.05. (B) Representative photomicrographs of paraffin-embedded small intestine. Sections stained with hematoxylin (blue) and anti-BrdU (brown). (C) Villus/crypt ratio of small intestinal mucosa postregeneration. Data were derived from 12 random villi and/or crypts from three mice per group/per time point; **p < 0.001 compared with littermates.
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Inhibition of growth of the intestinal epithelium, a rapidly self-renewing tissue, is commonly found in various critical disorders. The RNA-binding protein HuR is highly expressed in the gut mucosa and modulates the stability and translation of target mRNAs, but its exact biological function in the intestinal epithelium remains unclear. Here, we in...
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... investigate the in vivo function of HuR in intestinal epithelium, we generated intestinal epithelial-specific HuR deletion (IE-HuR −/− ) mice by crossing HuR fl/fl mice with mice carrying Villin-Cre (Supple- mental Figure S1A). As described previously ( Mosmann et al., 1983;Katasanou et al., 2009), HuR fl/fl mice were produced via standard gene-targeting procedures in embryonic stem cells and contained a Consistent with this finding, HuR mRNA and protein in the small intestinal and colonic mucosa were undetectable in IE-HuR −/− mice ( Figure 1B), whereas HuR expression levels in the intestinal mucosa of HuR fl/fl -Cre − and HuR fl/+ mice were normal. Immunohis- tochemical staining assays revealed that HuR levels almost completely disappeared in epithelial cells in the intestinal mucosa of IE-HuR −/− mouse, but its expression was un- affected in submucosal connective tissue ( Figure 1C). On the other hand, there were no changes in HuR expression levels in stomach mucosa, lung, liver, and pancreas in IE-HuR −/− mice compared with those ob- served in littermates (Supplemental Figure S1, B and C). These findings suggest that the IE-HuR −/− mouse is a suitable gene-tar- geting model of HuR deficiency in the intes- tinal epithelium. Generally, IE-HuR −/− mice looked normal; there were no significant differences in body weight (Figure 2A), gastrointestinal gross morphology ( Figure 2B), reproduction, and general appearances between IE-HuR −/− mice and littermate controls. Of interest, IE- HuR −/− mice exhibited significant mucosal atrophy in the small intestine, as indicated by a decrease in the lengths of villi and crypts ( Figure 2, C and D). The proliferating crypt cell population, marked by bromode- oxyuridine (BrdU; S phase), decreased re- markably in the small intestine of HuR −/− mice compared with those from littermates ( Figure 2E). Accordingly, the levels of cell proliferation marker proteins proliferating cell nuclear antigen (PCNA) and Ki67 were also decreased in the small intestinal mu- cosa of IE-HuR −/− mice ( Figure 2F). More- over, the loss of HuR in IECs inhibited the regenerative potential of crypt progenitors, since S-phase descendants in the villous re- gions decreased significantly in IE-HuR −/− mice compared with those observed in con- trol littermates after exposure to irradiation (Figure 3, A and B). Consistently, the villus/ crypt ratio in IE-HuR −/− mice also decreased when measured 10 h after irradiation ( Figure 3C). We also examined changes in colonic mucosal growth in IE-HuR −/− mice and found that epithelium-specific HuR de- letion did not alter mucosal growth in the colon. There were no significant decreases in the lengths of villi and crypts and BrdU- labeled cell proliferation in IE-HuR −/− mice compared with littermate controls (unpub- lished data). In addition, specific HuR deletion in IECs did not affect lineage dif- ferentiation in the intestine (Supplemental Figure S2, A and B), gut permeability (Sup- plemental Figure S2C), or crypt number per tissue area (Supplemental Figure S2D). HuR promotes growth of intestinal mucosa | ...
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... investigate the in vivo function of HuR in intestinal epithelium, we generated intestinal epithelial-specific HuR deletion (IE-HuR −/− ) mice by crossing HuR fl/fl mice with mice carrying Villin-Cre (Supple- mental Figure S1A). As described previously ( Mosmann et al., 1983;Katasanou et al., 2009), HuR fl/fl mice were produced via standard gene-targeting procedures in embryonic stem cells and contained a Consistent with this finding, HuR mRNA and protein in the small intestinal and colonic mucosa were undetectable in IE-HuR −/− mice ( Figure 1B), whereas HuR expression levels in the intestinal mucosa of HuR fl/fl -Cre − and HuR fl/+ mice were normal. Immunohis- tochemical staining assays revealed that HuR levels almost completely disappeared in epithelial cells in the intestinal mucosa of IE-HuR −/− mouse, but its expression was un- affected in submucosal connective tissue ( Figure 1C). On the other hand, there were no changes in HuR expression levels in stomach mucosa, lung, liver, and pancreas in IE-HuR −/− mice compared with those ob- served in littermates (Supplemental Figure S1, B and C). These findings suggest that the IE-HuR −/− mouse is a suitable gene-tar- geting model of HuR deficiency in the intes- tinal epithelium. Generally, IE-HuR −/− mice looked normal; there were no significant differences in body weight (Figure 2A), gastrointestinal gross morphology ( Figure 2B), reproduction, and general appearances between IE-HuR −/− mice and littermate controls. Of interest, IE- HuR −/− mice exhibited significant mucosal atrophy in the small intestine, as indicated by a decrease in the lengths of villi and crypts ( Figure 2, C and D). The proliferating crypt cell population, marked by bromode- oxyuridine (BrdU; S phase), decreased re- markably in the small intestine of HuR −/− mice compared with those from littermates ( Figure 2E). Accordingly, the levels of cell proliferation marker proteins proliferating cell nuclear antigen (PCNA) and Ki67 were also decreased in the small intestinal mu- cosa of IE-HuR −/− mice ( Figure 2F). More- over, the loss of HuR in IECs inhibited the regenerative potential of crypt progenitors, since S-phase descendants in the villous re- gions decreased significantly in IE-HuR −/− mice compared with those observed in con- trol littermates after exposure to irradiation (Figure 3, A and B). Consistently, the villus/ crypt ratio in IE-HuR −/− mice also decreased when measured 10 h after irradiation ( Figure 3C). We also examined changes in colonic mucosal growth in IE-HuR −/− mice and found that epithelium-specific HuR de- letion did not alter mucosal growth in the colon. There were no significant decreases in the lengths of villi and crypts and BrdU- labeled cell proliferation in IE-HuR −/− mice compared with littermate controls (unpub- lished data). In addition, specific HuR deletion in IECs did not affect lineage dif- ferentiation in the intestine (Supplemental Figure S2, A and B), gut permeability (Sup- plemental Figure S2C), or crypt number per tissue area (Supplemental Figure S2D). HuR promotes growth of intestinal mucosa | ...
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... investigate the mediators of the HuR-elicited effects, we found that the HuR-deficient intestinal epithelium was associated with de- creased levels of Lrp6 mRNA and LDL-receptor-related protein 6 (LRP6; Figure 4, A-C). In contrast, HuR deletion increased expression of p65 and Smad7 in the intestinal mucosa, although it failed to alter the levels of Frizzled-7 (Fzd7) or E-cadherin ( Figure 4D). Because there are several potential hits of HuR motif in the Lrp6 mRNA, we further examined whether HuR directly interacted with the Lrp6 mRNA in cultured IEC-6 cells by performing ribonucleoprotein im- munoprecipitation (RIP) assays using anti-HuR antibody under con- ditions that preserved RNP integrity (Lal et al., 2004). The interaction of Lrp6 mRNA with HuR was examined by isolating RNA from the immunoprecipitated material and subjecting it to reverse transcrip- tion (RT), followed by either conventional PCR or real-time quantita- tive PCR (qPCR) analyses. As shown in Figure 5A, the Lrp6 PCR prod- ucts were highly enriched in HuR samples compared with control immunoglobulin G (IgG) samples. HuR was also found to bind the p65 mRNA, although it did not preferentially associate with Fzd7, E-cad, and Smad7 mRNAs (Supplemental Figure S3). To determine whether HuR binds to specific regions of the Lrp6 5′-UTR, CR, and Post irradiation ...
Citations
... Intestinal stem cells and amplified progenitor cells divide continuously in the crypts and drive renewal process, while the newly divided cells differentiate into various mature cell types when they migrate up along the crypt-villus axis. Apoptosis takes place in both the crypt area, where it maintains the balance in cell number between survival cells and newly divided cells, and the luminal surface of the intestine, where apoptosis causes a loss of differentiated cells [4,5]. The intestinal mucosa also displays a spectrum of responses after acute injury and can repair itself quickly to restore epithelial integrity. ...
... HuR is primarily distributed in the nucleus in unstimulated cells, but it can rapidly translocate to the cytoplasm when exposed to various pathophysiological stresses [14][15][16]. HuR participates in different physiological and pathological processes, including proliferation, apoptosis, migration, tissue injury/repair, inflammation, and angiogenesis [4,[17][18][19][20] and its dysfunction is linked to several gut mucosal disorders such as inflammatory bowel disease (IBD) and malignancies [21][22][23][24]. In this review, we highlight the important roles of HuR in the intestinal epithelial homeostasis and pathologies and further discuss in some detail the mechanisms by which HuR regulates the stability and translation of target mRNAs through interaction with ncRNAs. ...
... To examine the functional role of HuR in the intestinal epithelium in vivo, we used a Cre-LoxP system to generate a mouse bearing with intestinal epithelium tissue-specific HuR deletion (IE-HuR −/− ) [4]. Although there are no significant differences in gut gross morphology, body weight, and general activity between IE-HuR −/− mice and littermate mice, HuR-deficient mice exhibit disrupted growth of small intestinal mucosa. ...
The mammalian intestinal epithelium is a rapidly self-renewing tissue in the body and its homeostasis is tightly controlled by numerous factors at multiple levels. The RNA-binding protein HuR (human antigen R) is intimately involved in many aspects of gut mucosal pathobiology and plays an important role in maintaining integrity of the intestinal epithelium by regulating stability and translation of target mRNAs. Nonetheless, deregulation of HuR expression and altered binding affinity of HuR for target transcripts occur commonly in various gut mucosal disorders. In this review, we highlight the essential role of HuR in the intestinal epithelium homeostasis and discuss recent results that interactions between HuR and noncoding RNAs (ncRNAs), including circular RNAs, long ncRNAs, small vault RNAs, and microRNAs, influence gut mucosal regeneration and regulate barrier function in various pathophysiological conditions. These exciting discoveries advance our knowledge of HuR biological function in the gut mucosa and also create a fundamental basis for developing novel therapies to protect intestinal epithelial integrity in critically ill patients.
... In our previous studies, we found declines in the levels of tissue HuR -along with inhibition of the growth of the intestinal mucosa -in patients with various illnesses, including inflammatory bowel disease (IBD) (Xiao et al, 2019;Li et al, 2020). Specific ablation of HuR in the intestinal epithelium of mice (IE-HuR −/− ) causes atrophy of the mucosa in the small intestine and compromises the regeneration of the gut mucosa and adaptation after irradiation (Liu et al, 2014), septic stress (Zhang et al, 2020), and mesenteric ischemia and reperfusion (Liu et al, 2017). Recently, HuR was shown to regulate PC function in the intestinal epithelium by altering the membrane localization of Tolllike receptor 2 via posttranscriptional control of chaperone protein CNPY3 (Xiao et al, 2019;Chung et al, 2021). ...
... HuR deletion causes defects in the PC/ISC niche function in the mucosa of the small intestine To determine if HuR promotes intestinal epithelial renewal by augmenting ISC proliferation via PCs, we used IE-HuR −/− mice that were generated by crossing HuR fl/fl mice with villin-Cre-expressing mice as described (Liu et al, 2014). HuR levels in the mucosa of the small intestine and colon were undetectable in IE-HuR −/− mice, but there were no changes in HuR expression in other tissues and organs such as the gastric mucosa, lung, liver, kidney, and pancreas, as reported previously (Liu et al, 2014(Liu et al, , 2017. ...
... HuR deletion causes defects in the PC/ISC niche function in the mucosa of the small intestine To determine if HuR promotes intestinal epithelial renewal by augmenting ISC proliferation via PCs, we used IE-HuR −/− mice that were generated by crossing HuR fl/fl mice with villin-Cre-expressing mice as described (Liu et al, 2014). HuR levels in the mucosa of the small intestine and colon were undetectable in IE-HuR −/− mice, but there were no changes in HuR expression in other tissues and organs such as the gastric mucosa, lung, liver, kidney, and pancreas, as reported previously (Liu et al, 2014(Liu et al, , 2017. Immunohistochemistry analysis showed that HuR staining almost completely disappeared in epithelial cells in the small intestinal mucosa of IE-HuR −/− mice, although HuR expression levels were unaffected in submucosal connective tissue (Fig 1A). ...
Rapid self-renewal of the intestinal epithelium requires the activity of intestinal stem cells (ISCs) that are intermingled with Paneth cells (PCs) at the crypt base. PCs provide multiple secreted and surface-bound niche signals and play an important role in the regulation of ISC proliferation. Here, we show that control of PC function by RNA-binding protein HuR via mitochondria affects intestinal mucosal growth by altering ISC activity. Targeted deletion of HuR in mice disrupted PC gene expression profiles, reduced PC-derived niche factors, and impaired ISC function, leading to inhibited renewal of the intestinal epithelium. Human intestinal mucosa from patients with critical surgical disorders exhibited decreased levels of tissue HuR and PC/ISC niche dysfunction, along with disrupted mucosal growth. HuR deletion led to mitochondrial impairment by decreasing the levels of several mitochondrial-associated proteins including prohibitin 1 (PHB1) in the intestinal epithelium, whereas HuR enhanced PHB1 expression by preventing microRNA-195 binding to the Phb1 mRNA. These results indicate that HuR is essential for maintaining the integrity of the PC/ISC niche and highlight a novel role for a defective PC/ISC niche in the pathogenesis of intestinal mucosa atrophy.
... To explore the adhesion molecules that are deregulated after quercetin treatment, we investigated protein levels of β-catenin and CD44 for two reasons; firstly, both the adhesion proteins are deregulated in breast cancer, specifically TNBCs (41,42). Secondly, β-catenin, as well as CD44, are the downstream targets of HuR signaling in cancer (either directly or indirectly) (43). So, we next treated MDA-MB-231 cells with quercetin and analyzed the changes in protein expression of HuR, β-catenin, and CD44 by western blotting. ...
... After activation through phosphorylation [84], methylation [85], and acetylation [86], HuR can shuttle from the nucleus to the cytoplasm, maintain the stability of bound mRNA, and promote mRNA translation [87,88]. Given that HuR can interact with a variety of cytokines that promote tumor progression (such as survivin [89], COX-2 [90], VEGF [91], low-density lipoprotein receptor-related protein [92], etc.), mRNAs stably bind and promote its translation, which in turn leads to the abnormal distribution of tumor-promoting factors in the nucleocytoplasm of tumor cells. Therefore, inhibition of the nucleocytoplasmic shuttling of HuR may also become a potential tumor therapy. ...
Simple Summary
Bladder cancer (BC) is a common malignant tumor of the urinary system. Despite extensive advances in the treatment of BC, it remains one of the most recurring and life-threatening tumors. At present, there have been increasing reports of studies on the presence of aberrant regulation of RBPs in BC. However, the complex regulatory network of these RBPs in BC remains to be fully elaborated. RBPs have a very high potential in tumor prediction and personalized therapy. Moreover, only with a deep understanding of their regulatory mechanisms, expression characteristics, and potential binding sites, among other issues, will it become possible to apply RBPs to clinical applications. This article aims to summarize the research progress of RBPs in BC. It also attempts to encourage clinicians and researchers to devote attention this field of study and provides a reference for researchers who aspire to pursue a career in this area.
Abstract
RNA-binding proteins (RBPs) are key regulators of transcription and translation, with highly dynamic spatio-temporal regulation. They are usually involved in the regulation of RNA splicing, polyadenylation, and mRNA stability and mediate processes such as mRNA localization and translation, thereby affecting the RNA life cycle and causing the production of abnormal protein phenotypes that lead to tumorigenesis and development. Accumulating evidence supports that RBPs play critical roles in vital life processes, such as bladder cancer initiation, progression, metastasis, and drug resistance. Uncovering the regulatory mechanisms of RBPs in bladder cancer is aimed at addressing the occurrence and progression of bladder cancer and finding new therapies for cancer treatment. This article reviews the effects and mechanisms of several RBPs on bladder cancer and summarizes the different types of RBPs involved in the progression of bladder cancer and the potential molecular mechanisms by which they are regulated, with a view to providing information for basic and clinical researchers.
... The assessments of TNFα/CHX-induced apoptosis in intestinal organoids were confirmed by increased levels of cleaved caspase-3 protein in both groups as measured by Western blotting analysis, with augmented caspase-3 activation in uc.230-deficient organoids ( Figure 3F). Furthermore, silencing uc.230 also enhanced LPS-induced cell death in organoids, as evidenced by a significant increase in the number of caspase-3 + cells in uc.230-deficient organoids after exposure to LPS, compared with controls ( HuR, a master posttranscriptional regulator of intestinal epithelial homeostasis associated with many aspects of intestinal mucosal pathology (31,32), is commonly dysfunctional in IBD (6). To expand the potential clinical relevance of our current findings, we explored whether uc.230 protects the epithelium against apoptosis in HuR-deficient enteroids. ...
... To expand the potential clinical relevance of our current findings, we explored whether uc.230 protects the epithelium against apoptosis in HuR-deficient enteroids. To do so, intestinal organoids were derived from tissues with intestinal epithelial-selective HuR deletion (IE-HuR -/-) mice (31). Consistent with previous reports (6,33), compared with enteroids generated from control littermates or WT mice, HuR-deficient enteroids exhibited reduced growth and increased susceptibility to TNF-α/CHX-induced apoptosis. ...
... Studies in murine and human tissues. WT C57BL/6J mice (male and female, 6-to 9-week-old) were purchased from Jackson Labs, while IE-HuR -/and littermate (HuR fl/fl Cre -) mice were generated by crossing HuR fl/fl with villin-Cre mice as described in our previous studies (6,31). All animals were housed in a pathogen-free animal facility at the Baltimore VA Medical Center. ...
Intestinal epithelial integrity is commonly disrupted in patients with critical disorders, but the exact underlying mechanisms are unclear. Long noncoding RNAs transcribed from ultraconserved regions (T-UCRs) control different cell functions and are involved in pathologies. Here, we investigated the role of T-UCRs in intestinal epithelial homeostasis and identified T-UCR uc.230 as a major regulator of epithelial renewal, apoptosis, and barrier function. Compared with controls, intestinal mucosal tissues from patients with ulcerative colitis and from mice with colitis or fasted for 48 hours had increased levels of uc.230. Silencing uc.230 inhibited the growth of intestinal epithelial cells (IECs) and organoids and caused epithelial barrier dysfunction. Silencing uc.230 also increased IEC vulnerability to apoptosis, whereas increasing uc.230 levels protected IECs against cell death. In mice with colitis, reduced uc.230 levels enhanced mucosal inflammatory injury and delayed recovery. Mechanistic studies revealed that uc.230 increased CUG-binding protein 1 (CUGBP1) by acting as a natural decoy RNA for miR-503, which interacts with Cugbp1 mRNA and represses its translation. These findings indicate that uc.230 sustains intestinal mucosal homeostasis by promoting epithelial renewal and barrier function and that it protects IECs against apoptosis by serving as a natural sponge for miR-503, thereby preserving CUGBP1 expression.
... Targeting HuR can serve as a potent therapeutic target to treat several diseases, especially cancer [8]. In addition, deficiency of HuR triggers a reduction in the expression of LRP6 in the mucosal tissues [9]. Of interest, LRP6 has been considered as an important therapeutic target for multiple diseases, particularly for osteoporosis [10]. ...
... Published literature has reported that HuR functions as a post-transcriptional regulator of gene expression mainly due to its RNA-binding activity [29]. In addition, at the molecular level, HuR can bind to the LRP6 mRNA via its 3'UTR and increases LRP6 expression by stabilizing LRP6 mRNA and stimulating its translation; meanwhile, HuR deficiency can induce a decrease in the expression of LRP6 in the mucosal tissues [9]. Additionally, LRP6 has been shown to promote the osteogenic differentiation of osteoblasts [30]. ...
Background
Emerging evidence has correlated the human antigen R (HuR) with the low-density lipoprotein receptor-related protein 6 (LRP6) gene, an important therapeutic target for osteoporosis. Herein, we sought to probe the regulatory role of HuR in the LRP6 gene and their interaction in the progression of osteoporosis.
Methods
HuR and downstream potential target genes were predicted by bioinformatics analysis to identify their potential functions in bone metabolism following osteoporosis. The effect of HuR on the osteoblastic differentiation and viability and apoptosis of mouse embryo osteoblast precursor cells (MC3T3-E1) was evaluated after artificial modulation of HuR expression.
Results
Bone phenotypes were observed in ovariectomized mice in response to adenovirus-mediated HuR overexpression. Poor expression of HuR was identified in the bone tissues of ovariectomized mice. Silencing of HuR inhibited the osteoblastic differentiation of MC3T3-E1 cells, as evidenced by decreased expression of Runx2 and Osterix along with reduced ALP activity. Mechanistically, HuR stabilized LRP6 mRNA and promoted its translation by binding to the 3'UTR of LRP6 mRNA, leading to activation of the downstream Wnt pathway. By this mechanism, osteoblastic differentiation of MC3T3-E1 cells was induced. In ovariectomized mice, overexpression of HuR alleviated osteoporosis-related phenotypes.
Conclusion
Overall, these data together support the promoting role of HuR in the osteoblastic differentiation, highlighting a potential novel strategy for osteoporosis treatment.
... CircStag1 promotes the Wnt signaling pathway by altering the subcellular localization of the HuR protein in BMSCs HuR, a nucleocytoplasmic shuttle protein, can regulate the stability of its target mRNAs 28 . Recently, cytoplasmic HuR protein has been reported to activate the Wnt signaling pathway by stabilizing Lrp5/6 and β-catenin mRNAs, thereby increasing their protein expression [29][30][31][32] . However, the roles of HuR in bone metabolism remain unclear. ...
... Nuclear β-catenin can promote the expression of osteogenic markers by interacting with the CREB-binding protein and T-cell factor/ lymphocyte enhancer factor 1 complex 8 . Moreover, several studies have shown that cytoplasmic HuR can stabilize Lrp5/6 and β-catenin mRNAs, thereby increasing their protein expression and enhancing Wnt signaling activity 29,31,45,46 . Consistently, in the present study, we found that circStag1-induced cytoplasmic accumulation of HuR could activate the Wnt signaling pathway by stabilizing Lrp5/6 and β-catenin mRNAs, thereby promoting the osteogenesis of BMSCs. ...
Postmenopausal osteoporosis is a common bone metabolic disorder characterized by deterioration of the bone microarchitecture, leading to an increased risk of fractures. Recently, circular RNAs (circRNAs) have been demonstrated to play pivotal roles in regulating bone metabolism. However, the underlying functions of circRNAs in bone metabolism in postmenopausal osteoporosis remain obscure. Here, we report that circStag1 is a critical osteoporosis-related circRNA that shows significantly downregulated expression in osteoporotic bone marrow mesenchymal stem cells (BMSCs) and clinical bone tissue samples from patients with osteoporosis. Overexpression of circStag1 significantly promoted the osteogenic capability of BMSCs. Mechanistically, we found that circStag1 interacts with human antigen R (HuR), an RNA-binding protein, and promotes the translocation of HuR into the cytoplasm. A high cytoplasmic level of HuR led to the activation of the Wnt signaling pathway by stabilizing and enhancing low-density lipoprotein receptor-related protein 5/6 ( Lrp5/6) and β-catenin expression, thereby stimulating the osteogenic differentiation of BMSCs. Furthermore, overexpression of circStag1 in vivo by circStag1-loaded adeno-associated virus (circStag1-AAV) promoted new bone formation, thereby preventing bone loss in ovariectomized rats. Collectively, we show that circStag1 plays a pivotal role in promoting the regeneration of bone tissue via HuR/Wnt signaling, which may provide new strategies to prevent bone metabolic disorders such as postmenopausal osteoporosis.
... The small molecule inhibitor MS-444, as a blocker of HuR dimerization and nuclear/cytoplasmic shuttle, is increasingly used in research on tumor therapy [27,[46][47][48]. HuR is among the most well-known translation and turnover regulating RBPs, which is involved in many post-transcriptional gene regulation events, including mRNA stabilization, and translation [49][50][51][52].HuR is highly expressed in the cytoplasm of many cancer cells and plays a regulatory and promoting role in almost every feature of cancer [26,32]. Will MS-444 damage women's fertility when used in cancer treatment? ...
Background
With the improvement of the survival rate of cancer patients, fertility maintenance has become a major concern of cancer treatment for women of reproductive age. Thus, it is important to examine the impact on fertility of anticancer drugs that have been clinically used or are undergoing trials. The HuR small-molecule inhibitor MS-444 has been used in many cancer treatment studies, but its reproductive toxicity in females is unknown.
Results
Combining analysis of low-input RNA-seq for MS-444-treated 2-cell embryos and mapping binding sites of RNA binding protein, Agbl2 was predicted to be the target gene of MS-444. For further confirmation, RNAi experiment in wild-type zygotes showed that Agbl2 knockdown reduced the proportion of embryos successfully develop to the blastocyst stage: from 71% in controls to 23%. Furthermore, RNA-FISH and luciferase reporter analysis showed that MS-444 blocked the nucleocytoplasmic transport of Agbl2 mRNA and reduced its stability by inhibiting HuR dimerization. In addition, optimized stochastic optical reconstruction microscopy (STORM) imaging showed that MS-444 significantly reduced the HuR dimerization, and HuR mainly existed in the form of clusters in 2-cell stage embryos.
Conclusion
Those results showed that MS-444 blocked the nucleocytoplasmic transport of Agbl2 mRNA by inhibiting HuR dimerization, resulting in the developmental arrest of 2-cell stage embryos in mouse. This study provides clinical guidance for maintaining fertility during the treatment of cancer with MS-444 in women of reproductive age. And also, our research provides guidance for the application of STORM in the nanometer scale study of embryonic cells.
... Like other RBPs, HuR binds to many RNAs and changes their fates. The data from systemic and tissue-specific deletion of HuR gene indicate that HuR plays a critical role in embryonic development and the regulation of physiological function (23)(24)(25)(26). Therefore, it was natural to hypothesize that an abnormal level of HuR may be involved in the development or progression of cardiovascular disease. ...
... HuR fl/fl mice were provided by Jian-Ying Wang from the University of Maryland at Baltimore (Baltimore, Maryland, USA) (25) and crossed with Tie2-Cre mice (The Jackson Laboratory) to generate EC-specific HuR-KO mice (Tie2-HuR -/mice; Figure 3A). HuR WT/WT mice were used as WT control for Tie2-HuR -/mice. ...
Patients with diabetes with coronary microvascular disease (CMD) exhibit higher cardiac mortality than patients without CMD. However, the molecular mechanism by which diabetes promotes CMD is poorly understood. RNA-binding protein human antigen R (HuR) is a key regulator of mRNA stability and translation; therefore, we investigated the role of HuR in the development of CMD in mice with type 2 diabetes. Diabetic mice exhibited decreases in coronary flow velocity reserve (CFVR; a determinant of coronary microvascular function) and capillary density in the left ventricle. HuR levels in cardiac endothelial cells (CECs) were significantly lower in diabetic mice and patients with diabetes than the controls. Endothelial-specific HuR-KO mice also displayed significant reductions in CFVR and capillary density. By examining mRNA levels of 92 genes associated with endothelial function, we found that HuR, Cx40, and Nox4 levels were decreased in CECs from diabetic and HuR-KO mice compared with control mice. Cx40 expression and HuR binding to Cx40 mRNA were downregulated in CECs from diabetic mice. Cx40-KO mice exhibited decreased CFVR and capillary density, whereas endothelium-specific Cx40 overexpression increased capillary density and improved CFVR in diabetic mice. These data suggest that decreased HuR contributes to the development of CMD in diabetes through downregulation of gap junction protein Cx40 in CECs.
... Autophagy is required for maintaining normal structure and function of various cellular organelles such as ER and mitochondria in Paneth cells, while lysozyme secretion by Paneth cells is mediated via secretory autophagy to limit intestinal bacterial infection [26,31]. Mutation of the autophagy-related genes (Atgs) leads to dysfunctional mitochondria and ER and subsequent defects in Paneth cells, thus enhancing the release of inflammatory cytokines in dextran sulfate sodium-induced colitis in mice and other pathological conditions [31,32,37,40,43]. Mice with hypomorphic IBD-associated allele Atg16L1 exhibit reduced Paneth cells, which is associated with an inhibition of secretory granule formation, a decrease in lysozyme synthesis, and an increase in inflammatory cytokines by macrophages [32,33]. ...
... RBPs are a big family of proteins that contain functional and structural motifs including dsRNA binding domain and RNA recognition motif (RRM) and play a pivotal role in processing of newly transcribed mRNAs [16,43]. RBPs directly associate with specific subsets of mRNAs and regulate mRNA splicing, nuclear degradation/exportation, stability, and translation. ...
... Notable changes in the binding affinity of RBPs for their target transcripts, mutations and defects in their binding sites, and disruption of RBP expression and subcellular localization have been described in different diseases such as IBD and colonic cancers in humans [35,39,47]. Table 2 summarizes recent studies showing that RBPs function as key regulators of Paneth cell function in response to various stressful environments [27,32,43]. ...
Paneth cells are specialized intestinal epithelial cells that are located at the base of small intestinal crypts and play a vital role in preserving the gut epithelium homeostasis. Paneth cells act as a safeguard from bacterial translocation across the epithelium and constitute the niche for intestinal stem cells in the small intestine by providing multiple niche signals. Recently, Paneth cells have become the focal point of investigations defining the mechanisms underlying the epithelium-microbiome interactions and pathogenesis of chronic gut mucosal inflammation and bacterial infection. Function of Paneth cells is tightly regulated by numerous factors at different levels, while Paneth cell defects have been widely documented in various gut mucosal diseases in humans. The post-transcription events, specific change in mRNA stability and translation by RNA-binding proteins (RBPs) and noncoding RNAs (ncRNAs) are implicated in many aspects of gut mucosal physiology by modulating Paneth cell function. Deregulation of RBPs and ncRNAs and subsequent Paneth cell defects are identified as crucial elements of gut mucosal pathologies. Here, we overview the posttranscriptional regulation of Paneth cells by RBPs and ncRNAs, with a particular focus on the increasing evidence of RBP HuR and long ncRNA H19 in this process. We also discuss the involvement of Paneth cell dysfunction in altered susceptibility of the intestinal epithelium to chronic inflammation and bacterial infection following disrupted expression of HuR and H19.
