Interrogating bromodomain inhibitor resistance in KMT2A-rearranged leukemia through combinatorial CRISPR screens.

Bromo- and extra-terminal domain inhibitors (BETi) have exhibited therapeutic activities in many cancers. However, the mechanisms controlling BETi response and resistance are not well understood. We conducted genome-wide loss-of-function CRISPR screens using BETi-treated KMT2A-rearranged (KMT2A-r) cell lines. We revealed that Speckle-type POZ protein (SPOP) gene (Speckle Type BTB/POZ Protein) deficiency caused significant BETi resistance, which was further validated in cell lines and xenograft models. Proteomics analysis and a kinase-vulnerability CRISPR screen indicated that cells treated with BETi are sensitive to GSK3 perturbation. Pharmaceutical inhibition of GSK3 reversed the BETi-resistance phenotype. Based on this observation, a combination therapy regimen inhibiting both BET and GSK3 was developed to impede KMT2A-r leukemia progression in patient-derived xenografts in vivo. Our results revealed molecular mechanisms underlying BETi resistance and a promising combination treatment regimen of ABBV-744 and CHIR-98014 by utilizing unique ex vivo and in vivo KMT2A-r PDX models.

A Novel in Duck Myoblasts: The Transcription Factor Retinoid X Receptor Alpha (RXRA) Inhibits Lipid Accumulation by Promoting CD36 Expression.

Retinoid X receptor alpha (RXRA) is a well-characterized factor that regulates lipid metabolism; however, the regulatory mechanism in muscle cells of poultry is still unknown. The overexpression and the knockdown of RXRA in myoblasts (CS2 cells), RT-PCR, and western blotting were used to detect the expression levels of genes and proteins related to PPAR-signaling pathways. Intracellular triglycerides (TGs), cholesterol (CHOL), and nonesterified free fatty acids (NEFAs) were detected by the Elisa kit. Fat droplets were stained with Oil Red O. The double-fluorescein reporter gene and chromatin immunoprecipitation (CHIP) were used to verify the relationship between RXRA and candidate target genes. The RXRA gene was highly expressed in duck breast muscle, and its mRNA and its protein were reduced during the differentiation of CS2 cells. The CS2 cells, with the overexpression of RXRA, showed reduced content in TGs, CHOL, NEFAs, and lipid droplets and upregulated the mRNA expression of CD36, ACSL1, and PPARG genes and the protein expression of CD36 and PPARG. The knockdown of RXRA expression in CS2 cells enhanced the content of TGs, CHOL, NEFAs, and lipid droplets and downregulated the mRNA and protein expression of CD36, ACLS1, ELOVL6, and PPARG. The overexpression of the RXRA gene, the activity of the double-luciferase reporter gene of the wild-type CD36 promoter was higher than that of the mutant type. RXRA bound to -860/-852 nt, -688/-680 nt, and -165/-157 nt at the promoter region of CD36. Moreover, the overexpression of CD36 in CS2 cells could suppress the content of TGs, CHOL, NEFAs, and lipid droplets, while the knockdown expression of CD36 increased the content of TGs, CHOL, NEFAs, and lipid droplets. In this study, the transcription factor, RXRA, inhibited the accumulation of TGs, CHOL, NEFAs, and fat droplets in CS2 cells by promoting CD36 expression.

[Systematic review and Meta-analysis of Gusongbao preparation in treatment of primary osteoporosis].

This study aims to provide evidence for clinical practice by systematically reviewing the efficacy and safety of Gusongbao preparation in the treatment of primary osteoporosis(POP). The relevant papers were retrieved from four Chinese academic journal databases and four English academic journal databases(from inception to May 31, 2022). The randomized controlled trial(RCT) of Gusongbao preparation in the treatment of POP was included after screening according to the inclusion and exclusion criteria. The quality of articles was evaluated using risk assessment tools, and the extracted data were subjected to Meta-analysis in RevMan 5.3. A total of 657 articles were retrieved, in which 15 articles were included in this study, which involved 16 RCTs. A total of 3 292 patients(1 071 in the observation group and 2 221 in the control group) were included in this study. In the treatment of POP, Gusongbao preparation+conventional treatment was superior to conventional treatment alone in terms of increasing lumbar spine(L2-L4) bone mineral density(MD=0.03, 95%CI[0.02, 0.04], P<0.000 01) and femoral neck bone mineral density, reducing low back pain(MD=-1.69, 95%CI[-2.46,-0.92], P<0.000 1) and improving clinical efficacy(RR=1.36, 95%CI[1.21, 1.53], P<0.000 01). Gusongbao preparation was comparable to similar Chinese patent medicines in terms of improving clinical efficacy(RR=0.95, 95%CI[0.86, 1.04], P=0.23). Gusongbao preparation was inferior to similar Chinese patent medicines in reducing traditional Chinese medicine syndrome scores(MD=1.08, 95%CI[0.44, 1.71], P=0.000 9) and improving Chinese medicine syndrome efficacy(RR=0.89, 95%CI[0.83, 0.95], P=0.000 4). The incidence of adverse reactions of Gusongbao preparation alone or combined with conventio-nal treatment was comparable to that of similar Chinese patent medicines(RR=0.98, 95%CI[0.57, 1.69], P=0.94) or conventio-nal treatment(RR=0.73, 95%CI[0.38, 1.42], P=0.35), and the adverse reactions were mainly gastrointestinal discomforts. According to the available data, Gusongbao preparation combined with conventional treatment is more effective than conventional treatment alone in increasing lumbar spine(L2-L4) bone mineral density and femoral neck bone mineral density, reducing low back pain, and improving clinical efficacy. The adverse reactions of Gusongbao preparation were mainly gastrointestinal discomforts, which were mild.

Evaluation of longitudinal trajectory of functional tricuspid regurgitation on the risk of right ventricular dysfunction after mitral valve replacement.

OBJECTIVE: Functional tricuspid regurgitation (FTR) levels can vary over time and its longitudinal changing patterns may predict right ventricular dysfunction (RVD) risk. We aim to identify different trajectories of FTR in those who received mitral valve replacement (MVR) and investigate the association between longitudinal trajectory groups and RVD risk in a cohort study. METHODS AND RESULTS: A prospective cohort study, reported usual FTR levels at baseline in 2005-2015 and the participants of MVR have been followed up for 5-6 years, approximately every 1 year, and so far, the data have been collected across five subsequent phases. Five-year longitudinal trajectories of FTR were identified using group-based trajectory modeling (GBTM). We identified 3 distinct trajectories using a GBTM, labeled by initial value and changing pattern: stable group (258/378, 68.2%), increasing-slow group (67/378, 17.6%) and increasing-fast group (53/378, 14.2%). Treating the stable group as the reference, the age- and sex-adjusted odds ratio (OR) was 25.84 (95% confidence interval [CI]: 11.78-56.65) for the increasing-slow group and 139.94 (95% CI: 45.47-430.68) for the increasing-fast group by logistic regression model. After adjustment for every potential confounding factors, the OR is 14.21 (95% CI: 4.36-46.33) and 49.34 (95% CI: 8.88-273.87), respectively. CONCLUSIONS: The longitudinal trajectories of worsening FTR were mostly associated with increased risk of RVD outcomes, which is independent of other factors including FTR levels. These findings have implications for intervention and prevention of RVD among individuals who received MVR.

Establishment and Validation of a Predictive Model for Long-Term Severe Functional Tricuspid Regurgitation after Mitral Valve Replacement.

BACKGROUND: The objective was to develop and validate an individualized nomogram to predict severe functional tricuspid regurgitation (S-FTR) after mitral valve replacement (MVR) via retrospective analysis of rheumatic heart disease (RHD) patients' pre-clinical characteristics. METHODS: Between 2001-2015, 442 MVR patients of RHD were examined. Transthoracic echocardiography detected S-FTR, and logistic regression model analyzed its independent predictors. R software established a nomogram prediction model, and Bootstrap determined its theoretical probability, which subsequently was compared with the actual patient probability to calculate the area under the curve (AUC) and calibration plots. Decision curve analysis (DCA) identified its clinical utility. RESULTS: Ninety-six patients developed S-FTR during the follow-up period. Both uni- and multivariate analyses found significant correlations between S-FTR occurrence with gender, age, atrial fibrillation (AF), pulmonary arterial hypertension (PH), left atrial diameter (LAD), and tricuspid regurgitation area (TRA). The individualized nomogram model had the AUC of 0.99 in internal verification. Calibration test indicated high agreement of predicted and actual S-FTR onset. DCA also showed that utilization of those six aforementioned factors was clinically useful. CONCLUSION: The nomogram for the patient characteristics of age, gender, AF, PH, LAD, and TRA found that they were highly predictive for future S-FTR onset within 5 years. This predictive ability therefore allows clinicians to optimize postoperative patient care and avoid unnecessary tricuspid valve surgeries.

Circulating Exosomes Control CD4+ T Cell Immunometabolic Functions via the Transfer of miR-142 as a Novel Mediator in Myocarditis.

CD4+ T cells undergo immunometabolic activation to mount an immunogenic response during experimental autoimmune myocarditis (EAM). Exosomes are considered key messengers mediating multiple T cell functions in autoimmune responses. However, the role of circulating exosomes in EAM immunopathogenesis and CD4+ T cell dysfunction remains elusive. Our objective was to elucidate the mechanism of action for circulating exosomes in EAM pathogenesis. We found that serum exosomes harvested from EAM mice induced CD4+ T cell immunometabolic dysfunction. Treatment with the exosome inhibitor GW4869 protected mice from developing EAM, underlying that exosomes are indispensable for the pathogenesis of EAM. Furthermore, by transfer of EAM exosomes, we confirmed that circulating exosomes initiate the T cell pathological immune response, driving the EAM pathological process. Mechanistically, EAM-circulating exosomes selectively loaded abundant microRNA (miR)-142. We confirmed methyl-CpG binding domain protein 2 (MBD2) and suppressor of cytokine signaling 1 (SOCS1) as functional target genes of miR-142. The miR-142/MBD2/MYC and miR-142/SOCS1 communication axes are critical to exosome-mediated immunometabolic turbulence. Moreover, the in vivo injection of the miR-142 inhibitor alleviated cardiac injury in EAM mice. This effect was abrogated by pretreatment with EAM exosomes. Collectively, our results indicate a newly endogenous mechanism whereby circulating exosomes regulate CD4+ T cell immunometabolic dysfunction and EAM pathogenesis via cargo miR-142.

Melatonin attenuates doxorubicin-induced cardiotoxicity through preservation of YAP expression.

There are increasing concerns related to the cardiotoxicity of doxorubicin in the clinical setting. Recently, melatonin has been shown to exert a cardioprotective effect in various cardiovascular diseases, including cardiotoxic conditions. In this study, we examined the possible protective effects of melatonin on doxorubicin-induced cardiotoxicity and explored the underlying mechanisms related to this process. We found that in vitro doxorubicin treatment significantly decreased H9c2 cell viability and induced apoptosis as manifested by increased TUNEL-positive cells, down-regulation of anti-apoptotic protein Bcl-2, as well as up-regulation of pro-apoptotic protein Bax. This was associated with increased reactive oxygen species (ROS) levels and decreased mitochondrial membrane potentials (MMP). In vivo, five weeks of doxorubicin treatment significantly decreased cardiac function, as evaluated by echocardiography. TUNEL staining results confirmed the increased apoptosis caused by doxorubicin. On the other hand, combinational treatment of doxorubicin with melatonin decreased cardiomyocyte ROS and apoptosis levels, along with increasing MMP. Such doxorubicin-melatonin co-treatment alleviated in vivo doxorubicin-induced cardiac injury. Western Blots, along with in vitro immunofluorescence and in vivo immunohistochemical staining confirmed that doxorubicin treatment significantly down-regulated Yes-associated protein (YAP) expression, while YAP levels were maintained under co-treatment of doxorubicin and melatonin. YAP inhibition by siRNA abolished the protective effects of melatonin on doxorubicin-treated cardiomyocytes, with reversed ROS level and apoptosis. Our findings suggested that melatonin treatment attenuated doxorubicin-induced cardiotoxicity through preserving YAP levels, which in turn decreases oxidative stress and apoptosis.

Knock-out of MicroRNA 145 impairs cardiac fibroblast function and wound healing post-myocardial infarction.

Prevention of infarct scar thinning and dilatation and stimulation of scar contracture can prevent progressive heart failure. Since microRNA 145 (miR-145) plays an important role in cardiac fibroblast response to wound healing and cardiac repair after an myocardial infarction (MI), using a miR-145 knock-out (KO) mouse model, we evaluated contribution of down-regulation of miR-145 to cardiac fibroblast and myofibroblast function during adverse cardiac remodelling. Cardiac function decreased more and the infarct size was larger in miR-145 KO than that in WT mice after MI and this phenomenon was accompanied by a decrease in cardiac fibroblast-to-myofibroblast differentiation. Quantification of collagen I and α-SMA protein levels as well as wound contraction revealed that transdifferentiation of cardiac fibroblasts into myofibroblasts was lower in KO than WT mice. In vitro restoration of miR-145 induced more differentiation of fibroblasts to myofibroblasts and this effect involved the target genes Klf4 and myocardin. MiR-145 contributes to infarct scar contraction in the heart and the absence of miR-145 contributes to dysfunction of cardiac fibroblast, resulting in greater infarct thinning and dilatation. Augmentation of miR-145 could be an attractive target to prevent adverse cardiac remodelling after MI by enhancing the phenotypic switch of cardiac fibroblasts to myofibroblasts.

Evidence for the existence of CD34+ angiogenic stem cells in human first-trimester decidua and their therapeutic for ischaemic heart disease.

Stem cell transplantation is nearly available for clinical application in the treatment of ischaemic heart disease (IHD), where it may be joined traditional methods (intervention and surgery). The angiogenic ability of seed cells is essential for this applicability. The aim of this study was to reveal the presence of CD34+ angiogenic stem cells in human decidua at the first trimester and to use their strong angiogenic capacity in the treatment of IHD. In vitro, human decidual CD34+ (dCD34+ ) cells from the first trimester have strong proliferation and clonality abilities. After ruling out the possibility that they were vascular endothelial cells and mesenchymal stem cells (MSCs), dCD34+ cells were found to be able to form tube structures after differentiation. Their angiogenic capacity was obviously superior to that of bone marrow mesenchymal stem cells (BMSCs). At the same time, these cells had immunogenicity similar to that of BMSCs. Following induction of myocardial infarction (MI) in adult rats, infarct size decreased and cardiac function was significantly enhanced after dCD34+ cell transplantation. The survival rate of cells increased, and more neovasculature was found following dCD34+ cell transplantation. Therefore, this study confirms the existence of CD34+ stem cells with strong angiogenic ability in human decidua from the first trimester, which can provide a new option for cell-based therapies for ischaemic diseases, especially IHD.

Conditional deletion of HDAC4 from collagen type 2α1-expressing cells increases angiogenesis in vivo.

BACKGROUND: HDAC4 is a key regulator of chondrocyte hypertrophy and skeletal development, but it is not clear whether the increase in vascular invasion at growth plates is related to HDAC4 expression. To determine it, we investigated the relationship between HDAC4 and angiogenesis in both in vivo and in vitro models. METHODS: HDAC4 was deleted in Col2α1-Cre; HDAC4fl/fl mice. Growth of the Col2α1-Cre; HDAC4d/d mice was compared with HDAC4fl/fl mice at postnatal days 2, 4, 6, and 8. X-rays were taken to examine skeletal development. At postnatal days 14 and 21, mice were euthanized for specimen collection. Murine chondrocytes were isolated from the ventral parts of rib cages of 6-day-old mice (C57Bl/6) and transfected with a vector expressing HDAC4 as a fusion protein with green fluorescent protein (GFP). Relative expression levels of HDAC4, VEGF, and Hif1α were measured in these cells by Western blot, RT-qPCR, enzyme-linked immunosorbent, histology, and immunohistochemistry assays. RESULTS: The Col2α1-Cre; HDAC4d/d mice were markedly smaller compared with the control mice. At postnatal days 14 and 21, the Col2α1-Cre; HDAC4d/d mice exhibited a shortened growth plate, a larger secondary ossification center, and stronger staining of CD31 and CD34 compared to control mice. The isolated chondrocyte cells exhibited a high transfection efficiency of HDAC4 which resulted in the detection of a significant decrease in VEGF and Hif1α levels compared with the control chondrocytes. CONCLUSIONS: HDAC4 expression in chondrocytes contributes to angiogenesis in the growth plate, and its absence in vivo negatively affects growth plates.

Heterogeneity of Triple-Negative Breast Cancer: Differences in Clinicopathologic and Ultrasound Features Between Premenopausal and Postmenopausal Patients.

OBJECTIVES: The aim of this study was to determine whether any salient differences exist in triple-negative breast cancer (TNBC) between premenopausal and postmenopausal patients by comprehensively comparing the ultrasound (US) and clinicopathologic features of these patients. METHODS: A detailed evaluation of the US and clinicopathologic features of 60 tumors from 60 patients with a diagnosis of TNBC (36 premenopausal and 24 postmenopausal women) was conducted in this retrospective study. RESULTS: Triple-negative breast cancer in premenopausal patients was more likely to show a round or oval shape and microlobulated margins, more commonly exerted effects on surrounding tissue, and showed grade 3 blood flow according to the method of Adler et al (Ultrasound Med Biol 1990; 16:553-559) compared with tumors in postmenopausal women. Triple-negative breast cancer in postmenopausal patients showed some similar US features as those observed in estrogen receptor-positive tumors, including irregular shapes, angular or spiculated margins, and nonparallel growth to the skin (P < .05 for all). CONCLUSIONS: Although US cannot be used to unequivocally identify TNBC, it can distinguish some salient US features regarding TNBC between premenopausal and postmenopausal women. Such information can then provide some valuable predictive information on the diagnosis of TNBC for clinicians.

The early alteration of left ventricular strain and dys-synchrony index in breast cancer patients undergoing anthracycline therapy using layer-specific strain analysis.

PURPOSE: The primary aim of this study was to evaluate early changes in cardiac function after anthracycline therapy with layer-specific speckle-tracking echocardiography (STE) and mechanical dys-synchrony. METHODS: A total of 78 breast cancer patients (ranging 31~72 years) exposed to anthracycline treatment were recruited in this study. All patients received both conventional two-dimensional speckle-tracking echocardiographs at baseline, as well as after the completion of 2 and 4 cycles of the regimen. Layer-specific longitudinal strain (LS) and circumferential strain (CS) of the 3 myocardial layers (endocardium, mid-myocardium, and epicardium) were automatically measured. Peak systolic dispersion (PSD) was defined as the standard deviation of the time to peak strain of the 18 segments, divided by the RR interval. RESULTS: There were no significant differences in conventional echocardiographic parameters during treatment (all P > .05). Peak endocardium CS at basal level decreased significantly after 2 and 4 cycles compared with baseline (both P = .001), while PSD significantly increased in that same period versus baseline (both P = .000). Endocardium and mid-myocardium LS, peak mid-myocardium and epicardium CS at the basal level, peak CS of all three layers at the papillary level, and peak endocardium and mid-myocardium CS at the apical level all significantly decreased after 4 cycles, compared with baseline and 2 cycles (all P = .000). CONCLUSION: This study showed that myocardial deformation impairment occurred as early as 2 cycles after anthracycline chemotherapy. Endocardium CS at the basal level and left ventricular dys-synchrony index PSD were the initial cardiac abnormalities in anthracycline-treated breast cancer patients.

Young bone marrow Sca-1 cells protect aged retina from ischaemia-reperfusion injury through activation of FGF2.

Retinal ganglion cell apoptosis and optic nerve degeneration are prevalent in aged patients, which may be related to the decrease in bone marrow (BM) stem cell number/function because of the possible cross-talk between the two organs. This pathological process is accelerated by retinal ischaemia-reperfusion (I/R) injury. This study investigated whether young BM stem cells can regenerate and repair the aged retina after acute I/R injury. Young BM stem cell antigen 1 positive (Sca-1+ ) or Sca-1- cells were transplanted into lethally irradiated aged recipient mice to generate Sca-1+ and Sca-1- chimaeras, respectively. The animals were housed for 3 months to allow the young Sca-1 cells to repopulate in the BM of aged mice. Retinal I/R was then induced by elevation of intraocular pressure. Better preservation of visual function was found in Sca-1+ than Sca-1- chimaeras 7 days after injury. More Sca-1+ cells homed to the retina than Sca-1- cells and more cells differentiated into glial and microglial cells in the Sca-1+ chimaeras. After injury, Sca-1+ cells in the retina reduced host cellular apoptosis, which was associated with higher expression of fibroblast growth factor 2 (FGF2) in the Sca-1+ chimaeras. Young Sca-1+ cells repopulated the stem cells in the aged retina and diminished cellular apoptosis after acute I/R injury through FGF2 and Akt signalling pathways.

Sirtuin3 protects aged human mesenchymal stem cells against oxidative stress and enhances efficacy of cell therapy for ischaemic heart diseases.

Sirtuin3 (SIRT3) is associated with oxidative stress and lifespan. However, the possible mechanisms underlying its influence are unknown. We hypothesized that SIRT3 increases the antioxidant capacity of aged cells and improves the efficacy of human mesenchymal stem cell (hMSC) therapy for ischaemic heart diseases in aged patients. In vitro, the antioxidant capacity of old hMSCs (O-hMSCs) was increased after SIRT3 overexpression using a gene transfection technique, while the antioxidant capacity of young hMSCs (Y-hMSCs) was decreased by SIRT3 silencing. The levels of forkhead box O3a (FoxO3a) in the nucleus, and antioxidant enzymes Mn-superoxide dismutase (MnSOD) and catalase (CAT) increased in SIRT3-overexpressed O-hMSCs while they decreased in SIRT3-silenced Y-hMSCs after oxidative stress. Following myocardial infarction in adult rats in vivo, infarct size decreased and cardiac function was significantly enhanced after cell transplantation with SIRT3 overexpressed O-hMSCs. The number of apoptotic cells decreased and the survival rate of transplanted cells increased following SIRT3 overexpression in O-hMSCs. SIRT3 protects aged hMSCs against oxidative stress by positively regulating antioxidant enzymes (MnSOD and CAT) via increasing the expression of FoxO3a in the nucleus. The efficacy of aged hMSC transplantation therapy for ischaemic heart diseases can be improved by SIRT3 overexpression.

Mitigation of acute kidney injury by cell-cycle inhibitors that suppress both CDK4/6 and OCT2 functions.

Acute kidney injury (AKI) is a potentially fatal syndrome characterized by a rapid decline in kidney function caused by ischemic or toxic injury to renal tubular cells. The widely used chemotherapy drug cisplatin accumulates preferentially in the renal tubular cells and is a frequent cause of drug-induced AKI. During the development of AKI the quiescent tubular cells reenter the cell cycle. Strategies that block cell-cycle progression ameliorate kidney injury, possibly by averting cell division in the presence of extensive DNA damage. However, the early signaling events that lead to cell-cycle activation during AKI are not known. In the current study, using mouse models of cisplatin nephrotoxicity, we show that the G1/S-regulating cyclin-dependent kinase 4/6 (CDK4/6) pathway is activated in parallel with renal cell-cycle entry but before the development of AKI. Targeted inhibition of CDK4/6 pathway by small-molecule inhibitors palbociclib (PD-0332991) and ribociclib (LEE011) resulted in inhibition of cell-cycle progression, amelioration of kidney injury, and improved overall survival. Of additional significance, these compounds were found to be potent inhibitors of organic cation transporter 2 (OCT2), which contributes to the cellular accumulation of cisplatin and subsequent kidney injury. The unique cell-cycle and OCT2-targeting activities of palbociclib and LEE011, combined with their potential for clinical translation, support their further exploration as therapeutic candidates for prevention of AKI.

Compression regulates gene expression of chondrocytes through HDAC4 nuclear relocation via PP2A-dependent HDAC4 dephosphorylation.

Biomechanics plays a critical role in the modulation of chondrocyte function. The mechanisms by which mechanical loading is transduced into intracellular signals that regulate chondrocyte gene expression remain largely unknown. Histone deacetylase 4 (HDAC4) is specifically expressed in chondrocytes. Mice lacking HDAC4 display chondrocyte hypertrophy, ectopic and premature ossification, and die early during the perinatal period. HDAC4 has a remarkable ability to translocate between the cell's cytoplasm and nucleus. It has been established that subcellular relocation of HDAC4 plays a critical role in chondrocyte differentiation and proliferation. However, it remains unclear whether subcellular relocation of HDAC4 in chondrocytes can be induced by mechanical loading. In this study, we first report that compressive loading induces HDAC4 relocation from the cytoplasm to the nucleus of chondrocytes via stimulation of Ser/Thr-phosphoprotein phosphatases 2A (PP2A) activity, which results in dephosphorylation of HDAC4. Dephosphorylated HDAC4 relocates to the nucleus to achieve transcriptional repression of Runx2 and regulates chondrocyte gene expression in response to compression. Our results elucidate the mechanism by which mechanical compression regulates chondrocyte gene expression through HDAC4 relocation from the cell's cytoplasm to the nucleus via PP2A-dependent HDAC4 dephosphorylation.

Targeted myocardial delivery of GDF11 gene rejuvenates the aged mouse heart and enhances myocardial regeneration after ischemia-reperfusion injury.

Ischemic cardiac injury is the main contributor to heart failure, and the regenerative capacity of intrinsic stem cells plays an important role in tissue repair after injury. However, stem cells in aged individuals have reduced regenerative potential and aged tissues lack the capacity to renew. Growth differentiation factor 11 (GDF11), from the activin-transforming growth factor ß superfamily, has been shown to promote stem cell activity and rejuvenation. We carried out non-invasive targeted delivery of the GDF11 gene to the heart using ultrasound-targeted microbubble destruction (UTMD) and cationic microbubble (CMB) to investigate the ability of GDF11 to rejuvenate the aged heart and improve tissue regeneration after injury. Young (3 months) and old (21 months) mice were used to evaluate the expression of GDF11 mRNA in the myocardium at baseline and after ischemia/reperfusion (I/R) and myocardial infarction. GDF11 expression decreased with age and following myocardial injury. UTMD-mediated delivery of the GDF11 plasmid to the aged heart after I/R injury effectively and selectively increased GDF11 expression in the heart, and improved cardiac function and reduced infarct size. Over-expression of GDF11 decreased senescence markers, p16 and p53, as well as the number of p16+ cells in old mouse hearts. Furthermore, increased proliferation of cardiac stem cell antigen 1 (Sca-1+) cells and increased homing of endothelial progenitor cells and angiogenesis in old ischemic hearts occurred after GDF11 over-expression. Repetitive targeted delivery of the GDF11 gene via UTMD can rejuvenate the aged mouse heart and protect it from I/R injury.

An Inhibitory Role of Osthole in Rat MSCs Osteogenic Differentiation and Proliferation via Wnt/ß-Catenin and Erk1/2-MAPK Pathways.

BACKGROUND/AIMS: Bone marrow-derived mesenchymal stem cells (MSCs) are responsible for new bone formation during adulthood. Accumulating evidences showed that Osthole promotes the osteogenic differentiation in primary osteoblasts. The aim of this study was to investigate whether Osthole exhibits a potential to stimulate the osteogenic differentiation of MSCs and the underlying mechanism. METHODS: MSCs were treated with a gradient concentration of Osthole (6.25 µM, 12.5 µM, and 25 µM). Cell proliferation was assessed by western blotting with the proliferating cell nuclear antigen (PCNA) and Cyclin D1 antibodies, fluorescence activated cell sorting (FACS), and cell counting kit 8 (CCK8). MSCs were cultured in osteogenesis-induced medium for one or two weeks. The osteogenic differentiation of MSCs was estimated by Alkaline Phosphatase (ALP) staining, Alizarin red staining, Calcium influx, and quantitative PCR (qPCR). The underlying mechanism of Osthole-induced osteogenesis was further evaluated by western blotting with antibodies in Wnt/ß-catenin, PI3K/Akt, BMPs/smad1/5/8, and MAPK signaling pathways. RESULTS: Osthole inhibited proliferation of rat MSCs in a dose-dependent manner. Osthole suppressed osteogenic differentiation of rat MSCs by down-regulating the activities of Wnt/ß-catenin and Erk1/2-MAPK signaling. CONCLUSIONS: Osthole inhibits the proliferation and osteogenic differentiation of rat MSCs, which might be mediated through blocking the Wnt/ß-catenin and Erk1/2-MAPK signaling pathways.

Three-Dimensional Speckle-Tracking Echocardiographic Monitoring of Acute Rejection in Heart Transplant Recipients.

OBJECTIVES: This study assessed the use of 3-dimensional (3D) speckle-tracking echocardiography for noninvasive monitoring and diagnosis of acute rejection in heart transplant recipients. METHODS: Fifteen heart transplant recipients underwent 32 endomyocardial biopsies; echocardiography was performed within 3 hours before biopsy. Twenty-four biopsies (acute rejection-negative group) showed grade 0 or 1A rejection, and 8 biopsies (acute rejection-positive group) showed grade 1B or higher rejection (based on the International Society for Heart and Lung Transplantation criteria). Two-dimensional, M-mode, pulsed Doppler, and tissue Doppler echocardiography were performed to assess conventional heart structure and function, and 3D full-volume echocardiography was recorded and analyzed. RESULTS: Global peak longitudinal strain was significantly lower in the acute rejection-negative group compared to the positive group (mean ± SD, -7.38% ± 1.34% versus -10.88% ± 3.81%; P = .017). Differences in left ventricular global peak radial strain (28.79% ± 10.79% versus 24.32% ± 5.24%; P= .272), global peak circumferential strain (-12.16% ± 4.87% versus -12.61% ± 2.38%; P = .806), and ejection fraction (49.42% ± 12.17% versus 50.68% ± 7.26%; P = .824) between the negative and positive groups were not significant. Significant correlations were observed between the left ventricular ejection fraction and global peak longitudinal, global peak radial, and global peak circumferential (r = -0.72; P < .001; r = 0.60; P < 0.001; and r = -0.69; P < 0.001, respectively). Receiver operating characteristic curve analysis showed that a global peak longitudinal strain cutoff value of less than -9.55% could predict grade 1B or higher rejection with sensitivity of 87.50% and specificity of 54.17%. CONCLUSIONS: Three-dimensional speckle-tracking echocardiography-derived global peak longitudinal strain is a useful parameter for detecting acute rejection; thus, 3D speckle-tracking echocardiography can monitor dynamic and acute rejection (≥1B) in heart transplant recipients.

Oxaliplatin-induced neurotoxicity is dependent on the organic cation transporter OCT2.

Oxaliplatin is an integral component of colorectal cancer therapy, but its clinical use is associated with a dose-limiting peripheral neurotoxicity. We found that the organic cation transporter 2 (OCT2) is expressed on dorsal root ganglia cells within the nervous system where oxaliplatin is known to accumulate. Cellular uptake of oxaliplatin was increased by 16- to 35-fold in cells overexpressing mouse Oct2 or human OCT2, and this process was associated with increased DNA platination and oxaliplatin-induced cytotoxicity. Furthermore, genetic or pharmacologic knockout of Oct2 protected mice from hypersensitivity to cold or mechanical-induced allodynia, which are established tests to assess acute oxaliplatin-induced neurotoxicity. These findings provide a rationale for the development of targeted approaches to mitigate this debilitating toxicity.