Knockdown of nucleosome assembly protein 1-like 1 promotes dimethyl sulfoxide-induced differentiation of P19CL6 cells into cardiomyocytes

Bone marrow mesenchymal stem cell-derived exosomes shuttle microRNAs to endometrial stromal fibroblasts that promote tissue proliferation /regeneration/ and inhibit differentiation

BACKGROUND

Human bone marrow-derived stem cells (hBMDSCs) are well characterized mediators of tissue repair and regeneration. An increasing body of evidence indicates that these cells exert their therapeutic effects largely through their paracrine actions rather than clonal expansion and differentiation. Here we studied the role of microRNAs (miRNAs) present in extracellular vesicles (EVs) from hBMDSCs in tissue regeneration and cell differentiation targeting endometrial stromal fibroblasts (eSF).

METHODS

Extracellular vesicles (EVs) are isolated from hBMDSCs, characterized by transmission electron microscopy (TEM) and nanoparticle tracking analysis (NTA) techniques. Extracted total RNA from EVs was subjected to RNA seq analysis. Transfection and decidualization studies were carried out in endometrial stromal fibroblasts (eSF). Gene expression was analyzed by qRTPCR. Unpaired t-test with Welch's correction was used for data analysis between two groups.

RESULTS

We identified several microRNAs (miRNAs) that were highly expressed, including miR-21-5p, miR-100-5p, miR-143-3p and let7. MiR-21 is associated with several signaling pathways involved in tissue regeneration, quiescence, cellular senescence, and fibrosis. Both miR-100-5p and miR-143-3p promoted cell proliferation. MiR-100-5p specifically promoted regenerative processes by upregulating TGF-ß3, VEGFA, MMP7, and HGF. MiR-100-5p blocked differentiation or decidualization as evidenced by morphologic changes and downregulation of decidualization mediators including HOXA10, IGFBP1, PRL, PR-B, and PR.

CONCLUSION

EVs delivered to tissues by hBMDSCs contain specific miRNAs that prevent terminal differentiation and drive repair and regeneration. Delivery of microRNAs is a novel treatment paradigm with the potential to replace BMDSCs in cell-free regenerative therapies.

Nucleosome assembly protein 1 like 1 (NAP1L1) promotes cardiac fibrosis by inhibiting YAP1 ubiquitination and degradation

Myocardial fibrosis post myocardial infarction (MI) is characterized by abnormal extracellular matrix (ECM) deposition and cardiac dysfunction could finally develop into serious heart disease, like heart failure. Lots of regulating factors involved in this pathological process have been reported while the specific mediators and underlying mechanisms remain to need to be further investigated. As part of the NAP1 family, Nucleosome assembly protein 1 like 1 (NAP1L1) is expressed in a wide variety of tissues. Here, we report that NAP1L1 is a significant regulator of cardiac fibrosis and is upregulated in ischemic cardiomyopathy patient hearts. Enhanced expression of NAP1L1 can promote cardiac fibroblasts (CFs) proliferation, migration, and differentiation into myofibroblasts. In contrast, loss of NAP1L1 decreased fibrosis-related mRNA and protein levels, inhibited the trans-differentiation, and blunted migration and proliferation of CFs after Transforming Growth Factorβ1（TGF-β1）stimulation. In vivo, NAP1L1 knockout mice enhanced cardiac function and reduced fibrosis area in response to MI stimuli. Mechanically, NAP1L1 binding to Yes-associated protein 1 (YAP1) protein influences its stability, and silencing NAP1L1 can inhibit YAP1 expression by promoting its ubiquitination and degradation in CFs. Collectively, NAP1L1 could potentially be a new therapeutic target for various cardiac disorders, including myocardial fibrosis.

NAP1L5 Promotes Nucleolar Hypertrophy and Is Required for Translation Activation During Cardiomyocyte Hypertrophy

Pathological growth of cardiomyocytes during hypertrophy is characterized by excess protein synthesis; however, the regulatory mechanism remains largely unknown. Using a neonatal rat ventricular myocytes (NRVMs) model, here we find that the expression of nucleosome assembly protein 1 like 5 (Nap1l5) is upregulated in phenylephrine (PE)-induced hypertrophy. Knockdown of Nap1l5 expression by siRNA significantly blocks cell size enlargement and pathological gene induction after PE treatment. In contrast, Adenovirus-mediated Nap1l5 overexpression significantly aggravates the pro-hypertrophic effects of PE on NRVMs. RNA-seq analysis reveals that Nap1l5 knockdown reverses the pro-hypertrophic transcriptome reprogramming after PE treatment. Whereas, immune response is dominantly enriched in the upregulated genes, oxidative phosphorylation, cardiac muscle contraction and ribosome-related pathways are remarkably enriched in the down-regulated genes. Although Nap1l5-mediated gene regulation is correlated with PRC2 and PRC1, Nap1l5 does not directly alter the levels of global histone methylations at K4, K9, K27 or K36. However, puromycin incorporation assay shows that Nap1l5 is both necessary and sufficient to promote protein synthesis in cardiomyocyte hypertrophy. This is attributable to a direct regulation of nucleolus hypertrophy and subsequent ribosome assembly. Our findings demonstrate a previously unrecognized role of Nap1l5 in translation control during cardiac hypertrophy.

TBX6 compound inheritance leads to congenital vertebral malformations in humans and mice

Congenital vertebral malformations (CVMs) are associated with human TBX6 compound inheritance that combines a rare null allele and a common hypomorphic allele at the TBX6 locus. Our previous in vitro evidence suggested that this compound inheritance resulted in a TBX6 gene dosage of less than haploinsufficiency (i.e. <50%) as a potential mechanism of TBX6-associated CVMs. To further investigate this pathogenetic model, we ascertained and collected 108 Chinese CVM cases and found that 10 (9.3%) of them carried TBX6 null mutations in combination with common hypomorphic variants at the second TBX6 allele. For in vivo functional verification and genetic analysis of TBX6 compound inheritance, we generated both null and hypomorphic mutations in mouse Tbx6 using the CRISPR-Cas9 method. These Tbx6 mutants are not identical to the patient variants at the DNA sequence level, but instead functionally mimic disease-associated TBX6 variants. Intriguingly, as anticipated by the compound inheritance model, a high penetrance of CVM phenotype was only observed in the mice with combined null and hypomorphic alleles of Tbx6. These findings are consistent with our experimental observations in humans and supported the dosage effect of TBX6 in CVM etiology. In conclusion, our findings in the newly collected human CVM subjects and Tbx6 mouse models consistently support the contention that TBX6 compound inheritance causes CVMs, potentially via a gene dosage-dependent mechanism. Furthermore, mouse Tbx6 mutants mimicking human CVM-associated variants will be useful models for further mechanistic investigations of CVM pathogenesis in the cases associated with TBX6.

Mechanical stresses induce paracrine β-2 microglobulin from cardiomyocytes to activate cardiac fibroblasts through epidermal growth factor receptor

By employing a proteomic analysis on supernatant of mechanically stretched cardiomyocytes, we found that stretch induced a significantly high level of β-2 microglobulin (β2M), a non-glycosylated protein, which is related to inflammatory diseases but rarely known in cardiovascular diseases. The present data showed that serum β2M level was increased in patients with hypertension and further increased in patients with chronic heart failure (HF) as compared with control group, and the high level of serum β2M level correlated to cardiac dysfunction in these patients. In pressure overload mice model by transverse aortic constriction (TAC), β2M levels in serum and heart tissue increased progressively in a time-dependent manner. Exogenous β2M showed pro-fibrotic effects in cultured cardiac fibroblasts but few effects in cardiomyocytes. Adeno-associated virus 9 (AAV9)-mediated knockdown of β2M significantly reduced cardiac β2M level and inhibited myocardial fibrosis and cardiac dysfunction but not cardiac hypertrophy at 4 weeks after TAC. In vitro, mechanical stretch induced the rapid secretion of β2M mainly from cardiomyocytes by activation of extracellular-regulated protein kinase (ERK). Conditional medium (CM) from mechanically stretched cardiomyocytes activated cultured cardiac fibroblasts, and the effect was partly abolished by CM from β2M-knockdown cardiomyocytes. In vivo, knockdown of β2M inhibited the increase in phosphorylation of epidermal growth factor receptor (EGFR) induced by TAC. In cultured cardiac fibroblasts, inhibition of EGFR significantly attenuated the β2M-induced the activation of EGFR and pro-fibrotic responses. The present study suggests that β2M is a paracrine pro-fibrotic mediator and associated with cardiac dysfunction in response to pressure overload.

[The influence of doxorubicin incorporated in phospholipid drug delivery nanosystem on HEPG2 cells proteome]

A phospholipid drug delivery nanosystem with particle size up to 30 nm elaborated at the Institute of Biomedical Chemistry has been used earlier for incorporation of doxorubicin (Doxolip). This system demonstrated higher antitumor effect in vivo as compared with free doxorubicin. In this study the effect of this nanosystem containing doxorubicin on HepG2 cell proteome has been investigated. Cells were incubated in a medium containing phospholipid nanoparticles (0.5 mg/ml doxorubicin, 10 mg/mL phosphatidylcholine). After incubation for 48 h their survival represented 10% as compared with untreated cells. Cell proteins were analyzed by quantitative two-dimensional gel electrophoresis followed by identification of differentially expressed proteins with MALDI-TOF mass spectrometry. The phospholipid transport nanosystem itself insignificantly influenced the cell proteome thus confirming previous data on its safety. Doxorubicin, as both free substance and Doxolip (i.e. included into phospholipid nanoparticles) induced changes in expression of 28 proteins. Among these proteins only four of them demonstrated different in response to the effect of the free drug substance and Doxolip. Doxolip exhibited a more pronounced effect on expression of certain proteins; the latter indirectly implies increased penetration of the drug substance (included into nanoparticles) into the tumor cells. Increased antitumor activity of doxorubicin included into phospholipid nanoparticles may be associated with more active increase of specific protein expression.

Knockdown of nucleosome assembly protein 1-like 1 induces mesoderm formation and cardiomyogenesis via notch signaling in murine-induced pluripotent stem cells

Low efficiency of cardiomyocyte differentiation from induced pluripotent stem cells (iPSCs) hinders the clinical application of iPSC technology for cardiac repair strategy. Recently, we screened out nucleosome assembly protein 1-like 1 (Nap1l1), which was downregulated during the differentiation of P19CL6 cells into cardiomyocytes. Here, we attempted to study the role of Nap1l1 in cardiomyogenesis of iPSC. Nap1l1 was downregulated during the differentiation of iPSC. Knockdown of Nap1l1 dramatically enhanced the differentiation of iPSC into functional cardiomyocytes while overexpression of Nap1l1 sharply lowered the differentiation. Moreover, although Nap1l1-knockdown had little effect on endoderm differentiation, the Nap1l1 modulation significantly accelerated mesoderm development. Re-expressing Nap1l1 in Nap1l1-knockdown-iPSC rescued the effects of Nap1l1. Inducibly overexpressing Nap1l1 at early stage of differentiation greatly inhibited mesoderm induction and cardiogenesis of iPSC. However, mesoderm stem cells (Flk-1-positive cells) originated from Nap1l1-knockdown- or -overexpression-iPSC showed no difference in further cardiomyocyte differentiation compared with that of control-iPSC. Further study revealed that Nap1l1-overexpression increased γ-secretase activity and the expression of Notch intracellular domain (NICD) and downstream genes during the differentiation of iPSC. γ-Secretase inhibitor DAPT (N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycinet-butyl ester) greatly suppressed the production of NICD and abolished the inhibitory effects of Nap1l1-overexpression on mesoderm induction and cardiogenesis. These findings demonstrate that downregulation of Nap1l1 significantly enhances mesodermal induction and subsequent cardiogenesis of murine iPSC via inhibition of γ-secretase-regulated Notch signaling, which would facilitate the application of iPSC in heart diseases.

TBX6 null variants and a common hypomorphic allele in congenital scoliosis

BACKGROUND

Congenital scoliosis is a common type of vertebral malformation. Genetic susceptibility has been implicated in congenital scoliosis.

METHODS

We evaluated 161 Han Chinese persons with sporadic congenital scoliosis, 166 Han Chinese controls, and 2 pedigrees, family members of which had a 16p11.2 deletion, using comparative genomic hybridization, quantitative polymerase-chain-reaction analysis, and DNA sequencing. We carried out tests of replication using an additional series of 76 Han Chinese persons with congenital scoliosis and a multicenter series of 42 persons with 16p11.2 deletions.

RESULTS

We identified a total of 17 heterozygous TBX6 null mutations in the 161 persons with sporadic congenital scoliosis (11%); we did not observe any null mutations in TBX6 in 166 controls (P<3.8×10(-6)). These null alleles include copy-number variants (12 instances of a 16p11.2 deletion affecting TBX6) and single-nucleotide variants (1 nonsense and 4 frame-shift mutations). However, the discordant intrafamilial phenotypes of 16p11.2 deletion carriers suggest that heterozygous TBX6 null mutation is insufficient to cause congenital scoliosis. We went on to identify a common TBX6 haplotype as the second risk allele in all 17 carriers of TBX6 null mutations (P<1.1×10(-6)). Replication studies involving additional persons with congenital scoliosis who carried a deletion affecting TBX6 confirmed this compound inheritance model. In vitro functional assays suggested that the risk haplotype is a hypomorphic allele. Hemivertebrae are characteristic of TBX6-associated congenital scoliosis.

CONCLUSIONS

Compound inheritance of a rare null mutation and a hypomorphic allele of TBX6 accounted for up to 11% of congenital scoliosis cases in the series that we analyzed. (Funded by the National Basic Research Program of China and others.).

Comparative proteomics study on liver mitochondria of primary biliary cirrhosis mouse model

Background

Primary biliary cirrhosis (PBC) is a liver specific chronic disease with unclear pathogenesis, especially for the early stage molecular events. The mitochondrion is a multi-functional organelle associated with various diseases including PBC. The purpose of this study was to discover the alterations in the mitochondria proteome using an early stage PBC mouse model for revealing the possible pathogenesis mechanisms in the early stages of PBC.

Methods

Mouse model of early stage of PBC was constructed by consecutive administration of poly I:C. Mitochondria of mouse models and controls were purified and comparative proteomics was performed by iTRAQ technology. Then, differentially expressed proteins were validated by western blotting.

Results

In total 354 proteins that satisfied the criteria for comparative proteomics study were identified. Of them, nine proteins were downregulated and 20 were up-regulated in liver mitochondria of PBC mouse model. Most differentially expressed proteins are associated with oxidation-reduction and lipid metabolism, and some are involved in the biosynthesis of steroid hormone and primary bile acid. Interestingly, four proteins (HCDH, CPT I, DECR, ECHDC2) involved in the fatty acid beta-oxidation were all upregulated.

Conclusions

iTRAQ is a powerful tool for comparative proteomics study of PBC mouse model and differentially expressed proteins in mitochondria proteome of PBC mouse model provide insights for the pathogenesis mechanism at early stage of PBC.