Functional analysis of a novel nonsense variant c.91A>T of the TRAPPC2 gene in a Chinese family with X-linked recessive autosomal spondyloepiphyseal dysplasia tarda.

Spondyloepiphyseal dysplasia tarda (SEDT) is a condition involving late-onset, X-linked recessive skeletal dysplasia caused by mutations in the TRAPPC2 gene. In this paper, we identified a novel nonsense variant in a SEDT pedigree and analyzed the function of the variant in an attempt to explain the new pathogenesis of the TRAPPC2 protein in SEDT. Briefly, DNA and RNA samples from the peripheral blood of SEDT individuals were prepared. The causative variant in the Chinese SEDT family was identified by clinic whole-exome sequencing analysis. Then, we observed the mRNA expression of TRAPPC2 in patients and the mutant TRAPPC2 level in vitro and analyzed the protein stability and subcellular distribution by cell fluorescence and Western blotting. We also investigated the effect of TRAPPC2 knockdown on the expression and secretion of COL2A1 in SW1353 cells or primary human chondrocytes. Herein, we found a nonsense variant, c.91A>T, of the TRAPPC2 gene in the pedigree. TRAPPC2 mRNA expression levels were significantly decreased in the available peripheral blood cell samples of two affected patients. An in vitro study showed that the mutant plasmid exhibited significantly lower mRNA and protein of TRAPPC2, and the mutant protein changed its membrane distribution. TRAPPC2 knockdown resulted in decreased COL2A1 expression and collagen II secretions. Our data indicate that the novel nonsense variant, c.91A>T, of the TRAPPC2 gene is the cause of SEDT in this pedigree. The variant results in a lowered expression of TRAPPC2 and then affects the COL2A1 expression and collagen II secretions, which may explain the mechanism of loss of function of the variant.

Change and challenge: An online course in Medical Biochemistry and Molecular Biology.

The development of information technology and portable devices has sparked a revolution in the field of education, facilitating access to diverse educational resources and lifelong learning. In particular, the COVID-19 pandemic has accelerated the transition from face-to-face to distance teaching, which requires online education to be provided worldwide. Biochemistry and Molecular Biology are key basic medical courses in laboratory-based science that cover complicated theories and applications. The balance between traditional and online courses, and the effectiveness of online courses, are fundamental to the teaching quality of Biochemistry and Molecular Biology. In this study, we explored the concepts, designs, and practices of a new blended online course and identified potential challenges. We hope that our experiences will provide new ideas for online teaching and promote teaching reform and the development of Medical Biochemistry and Molecular Biology education.

X Chromosome Inactivation Pattern and Pregnancy Outcome of Female Carriers of Pathogenic Heterozygous X-Linked Deletions.

Prenatal risk assessment of carriers of heterozygous X-linked deletion is a big challenge due to the phenotypic modification induced by X chromosome inactivation (XCI). Herein, we described four Chinese pedigrees with maternal-inherited X-deletions above 1 Mb. The pathogenic evaluation revealed that all X-deletions are harmful to heterozygous carriers; however, the asymptomatic pregnant female carriers in these families tremendously complicate the prognostic assessment of the unborn heterozygous embryos. In this study, we detected the XCI pattern of 11 female carriers of heterozygous X-linked deletions and 4 non-carrier females in these families and performed the first prenatal XCI pattern analysis in a fetal female carrier of heterozygous PCDH19-deletion to make risk prediction. In an adult female who lost one copy of the terminal of X chromosome short arm (Xp), a region enriching a large number of XCI escapees, the expression level of representative XCI escape genes was also detected. Pregnancy outcomes of all families were followed up or retrospected. Our research provides clinical evidence that X-deletions above 1 Mb are indeed associated with extremely skewed XCI. The favorable skewed XCI in combination with potential compensatory upregulation of XCI escapees would protect some but not all female carriers with pathogenic X-deletion from severe clinical consequences, mainly depending on the specific genetic contents involved in the deletion region. For PCDH19-disorder, the XCI pattern is considered as the decisive factor of phenotype expression, of which prenatal XCI assay using uncultured amniocytes could be a practicable way for risk prediction of this disease. These results provide valuable information about the usage of XCI assay in the prenatal risk assessment of heterozygous X-linked deletions.

Functional Analysis of a Compound Heterozygous Mutation in the VPS13B Gene in a Chinese Pedigree with Cohen Syndrome.

Cohen syndrome (CS) is an autosomal recessive congenital disorder characterized by mutation in the vacuolar protein sorting 13 homolog B (VPS13B; formerly COH1) gene. In the current study, a Chinese family has two young sibling cases having a developmental delay, physical obesity, high myopia, and a special face, which suspected to be CS. The purpose of the study was to identify variants and further analyze their pathogenicity for CS. Next-generation sequencing (NGS) revealed a compound heterozygous mutation in VPS13B gene in the proband, which comprises a frameshift mutation in NM_017890.4: c.10076_10077delCA (p.T3359fs*29) and a putative splice site mutation in c.6940 + 1G > T. Both Minigene assay in vitro and splicing assay in vivo confirmed that the splicing mutation in c.6940 + 1G > T generates a frameshift transcript with whole exon 38 skipping. Eventually, quantitative real-time PCR demonstrated that either of the two mutations can lead to degradation of the VPS13B gene at the transcriptional level. Functional studies of variants identified in CS patients are essential for their subsequent genetic counseling and prenatal diagnoses and could also be the start point for new therapeutic approaches, currently based only on symptomatic treatment.

Monoacylglycerol lipase regulates cannabinoid receptor 2-dependent macrophage activation and cancer progression.

Metabolic reprogramming greatly contributes to the regulation of macrophage activation. However, the mechanism of lipid accumulation and the corresponding function in tumor-associated macrophages (TAMs) remain unclear. With primary investigation in colon cancer and confirmation in other cancer models, here we determine that deficiency of monoacylglycerol lipase (MGLL) results in lipid overload in TAMs. Functionally, macrophage MGLL inhibits CB2 cannabinoid receptor-dependent tumor progression in inoculated and genetic cancer models. Mechanistically, MGLL deficiency promotes CB2/TLR4-dependent macrophage activation, which further suppresses the function of tumor-associated CD8+ T cells. Treatment with CB2 antagonists delays tumor progression in inoculated and genetic cancer models. Finally, we verify that expression of macrophage MGLL is decreased in cancer tissues and positively correlated with the survival of cancer patients. Taken together, our findings identify MGLL as a switch for CB2/TLR4-dependent macrophage activation and provide potential targets for cancer therapy.

ER-α36 mediates cisplatin resistance in breast cancer cells through EGFR/HER-2/ERK signaling pathway.

BACKGROUND: ER-α36, a novel ER-α66 variant, has been demonstrated to promote tamoxifen resistance in breast cancer cells. However, the role and mechanisms of ER-α36 in cisplatin resistance of breast cancer cells remain unclear. This study investigates the expression and role of ER-α36 in cisplatin resistance of breast cancer cells and elucidates its underlying mechanisms. METHODS: The expression of ER-α36 and the proteins involved in nongenomic estrogen signaling was evaluated by western blot analysis. Cisplatin sensitivity was explored by CCK-8 assay, monolayer colony formation assay and apoptosis assays, respectively. ER-α36 siRNAs/shRNAs and overexpression vector were transfected into cells to down-regulate or up-regulate ER-α36 expression. Loss-and gain-of function assays were performed to investigate the role of ER-α36 in cisplatin sensitivity. The interaction between ER-α36 and EGFR/HER-2 were detected using CoIP. A mouse xenograft model of breast cancer was established to verify the role of ER-α36 in vivo. RESULTS: ER-α36 is expressed at higher levels in cisplatin-resistant breast cancer cells compared to cisplatin sensitive cells. Cisplatin induced up-regulation of ER-α36 in a dose-dependent manner in breast cancer cells. Overexpression of ER-α36 leaded to cell resistant to cisplatin and knockdown of ER-α36 in cisplatin-resistant breast cancer cells restored cisplatin sensitivity. The up-regulation of ER-α36 resulted in increased activation of nongenomic estrogen signaling, which was responsible for cisplatin resistance. Disruption of ER-α36-mediated nongenomic estrogen signaling with kinase inhibitors significantly inhibited cisplatin-induced expression of ER-α36 and increased cisplatin sensitivity. The in vivo experiment also confirmed that up-regulation of ER-α36 attenuated cisplatin sensitivity in a mouse xenograft model of breast cancer. CONCLUSIONS: The results for the first time demonstrated that ER-α36 mediates cisplatin resistance in breast cancer cells through nongenomic estrogen signaling, suggesting that ER-α36 may serve as a novel target for cisplatin resistance and a potential indicator of cisplatin sensitivity in breast cancer treatment.

NF-κB potentiates tumor growth by suppressing a novel target LPTS.

BACKGROUND: Chronic inflammation is causally linked to the carcinogenesis and progression of most solid tumors. LPTS is a well-identified tumor suppressor by inhibiting telomerase activity and cancer cell growth. However, whether and how LPTS is regulated by inflammation signaling is still incompletely elucidated. METHODS: Real-time PCR and western blotting were used to determine the expression of p65 and LPTS. Reporter gene assay, electrophoretic mobility shift assay and chromatin immunoprecipitation were performed to decipher the regulatory mechanism between p65 and LPTS. Cell counting kit-8 assays and xenograt models were used to detect p65-LPTS-regulated cancer cell growth in vitro and in vivo, respectively. RESULTS: Here we for the first time demonstrated that NF-κB could inhibit LPTS expression in the mRNA and protein levels in multiple cancer cells (e.g. cervical cancer and colon cancer cells). Mechanistically, NF-κB p65 could bind to two consensus response elements locating at -1143/-1136 and -888/-881 in the promoter region of human LPTS gene according to EMSA and ChIP assays. Mutation of those two binding sites rescued p65-suppressed LPTS promoter activity. Functionally, NF-κB regulated LPTS-dependent cell growth of cervical and colon cancers in vitro and in xenograft models. In translation studies, we verified that increased p65 expression was associated with decreased LPTS level in multiple solid cancers. CONCLUSIONS: Taken together, we revealed that NF-κB p65 potentiated tumor growth via suppressing a novel target LPTS. Modulation of NF-κB-LPTS axis represented a potential strategy for treatment of those inflammation-associated malignancies.

Piwi-Interacting RNAs (piRNAs) Are Dysregulated in Renal Cell Carcinoma and Associated with Tumor Metastasis and Cancer-Specific Survival.

Piwi-interacting RNAs (piRNAs) are a distinct group of small noncoding RNAs (sncRNAs) that silence transposable genetic elements to protect genome integrity. Because of their limited expression in gonads and sequence diversity, piRNAs remain the most mysterious class of small RNAs. Studies have shown piRNAs are present in somatic cells and dysregulated in gastric, breast and liver cancers. By deep sequencing 24 frozen benign kidney and clear cell renal cell carcinoma (ccRCC) specimens and using the publically available piRNA database, we found 26,991 piRNAs present in human kidney tissue. Among 920 piRNAs that had at least two copies in one specimen, 19 were differentially expressed in benign kidney and ccRCC tissues, and 46 were associated with metastasis. Among the metastasis-related piRNAs, we found three piRNAs (piR-32051, piR-39894 and piR-43607) to be derived from the same piRNA cluster at chromosome 17. We confirmed the three selected piRNAs not to be miRNAs or miRNA-like sncRNAs. We further validated the aberrant expression of the three piRNAs in a 68-case formalin-fixed and paraffin-embedded (FFPE) ccRCC tissue cohort and showed the up-regulation of the three piRNAs to be highly associated with ccRCC metastasis, late clinical stage and poor cancer-specific survival.

MicroRNA-363-mediated downregulation of S1PR1 suppresses the proliferation of hepatocellular carcinoma cells.

S1PR1 plays a crucial role in promoting proliferation of hepatocellular carcinoma (HCC). Over expression of S1PR1 is observed in HCC cell lines. The mechanisms underlying the aberrant expression of S1PR1 are not known well. MircroRNAs are important regulators of gene expression and disproportionate microRNAs can result in dysregulation of oncogenes in cancer cells. In this study, we found that miR-363, a potential tumor suppressor microRNA, downregulated the expression of S1PR1 and inhibited the proliferation of HCC cells. Bioinformatic analysis predicted a putative binding site of miR-363 within the 3'-UTR of S1PR1 mRNA. Luciferase reporter assay showed that miR-363 directly targeted the 3'-UTR of S1PR1 mRNA. Transfection of miR-363 mimics suppressed S1PR1 expression in HCC cells, followed by the repression of the activation of ERK and STAT3. Moreover, we found that the expression of downstream genes of ERK and STAT3, including PDGF-A, PDGF-B, MCL-1 and Bcl-xL, was suppressed after miR-363 transfection. Taken together, the present study demonstrated that miR-363 was a negative regulator of S1PR1 expression in HCC cells and inhibited cell proliferation, suggesting that the miR-363/S1PR1 pathway might be a novel target for the treatment of HCC.

MicroRNA-1 and microRNA-206 suppress LXRα-induced lipogenesis in hepatocytes.

Liver X receptor α (LXRα) plays a critical role in the transcriptional control of lipid metabolism. LXR activation induces the expression of lipogenic genes, which promote hepatic steatosis and steatohepatitis. However, the regulation of LXR is not fully understood. MicroRNAs (miRs) are regarded as important negative regulators of gene expression. In this study, we found that miR-1/miR-206 repressed LXRα-induced accumulation of lipid droplets in hepatocytes. In addition, bioinformatic analysis predicted a same putative target-site for miR-1/miR-206 located within the 3'-untranslated region (3'-UTR) of LXRα mRNA. The reporter assay revealed that miR-1/miR-206 directly targeted the 3'-UTR of LXRα mRNA. Furthermore, miR-1/miR-206 repressed LXRα expression at both mRNA and protein levels, accompanied with the inhibition of expression of LXRα target genes, such as sterol-regulatory element binding protein 1c, fatty acid synthase, carbohydrate responsive element-binding protein and acetyl-CoA carboxylase 1, which are important effectors of LXRα implicated in lipogenesis. Moreover, ectopic expression of LXRα without the 3'-UTR dramatically attenuated the miR-1/miR-206-induced decrease of lipogenic genes and lipid droplet accumulation. Taken together, we for the first time demonstrated that miR-1/miR-206 attenuated LXRα-induced lipogenesis by targeting the 3'-UTR of LXRα mRNA, suggesting that miR-1/miR-206-LXRα pathway may be a novel target for the treatment of lipogenesis-associated diseases.

Activation of farnesoid X receptor increases the expression of cytokine inducible SH2-containing protein in HepG2 cells.

Cytokine inducible SH2-containing protein (CISH), which negatively regulates cytokine signaling by inhibiting JAK2/STAT5 activity, is regarded as a therapeutic target for inflammatory diseases. Farnesoid X receptor (FXR), a ligand-activated transcription factor, has been proposed to play a protective function in the inflammatory responses. However, the role of FXR in modulation of CISH expression is unknown. In the present study, we for the first time identified that in human hepatoma cell line HepG2 the activation of FXR by the natural agonist chenodeoxycholic acid (CDCA) and the synthetic specific agonist GW4064 upregulated CISH at both transcriptional and translational levels, and inhibited interleukin (IL)6-induced STAT5 activation. Moreover, the in vivo experiment demonstrated that gavaging mice with CDCA increased CISH expression and reduced basal STAT5 phosphorylation in liver tissues. Reporter assay showed that FXR agonists enhanced the transcriptional activity of CISH promoter. These data suggest that FXR may serve as a novel molecular target for manipulating CISH expression in hepatocytes. FXR-mediated upregulation of CISH may play an important role in the homeostasis of cytokine signal networks and be beneficial to control cytokine-associated inflammatory diseases.

MiR-137 targets estrogen-related receptor alpha and impairs the proliferative and migratory capacity of breast cancer cells.

ERRα is an orphan nuclear receptor emerging as a novel biomarker of breast cancer. Over-expression of ERRα in breast tumor is considered as a prognostic factor of poor clinical outcome. The mechanisms underlying the dysexpression of this nuclear receptor, however, are poorly understood. MicroRNAs (miRNAs) regulate gene expression at the post-transcriptional level and play important roles in tumor initiation and progression. In the present study, we have identified that the expression of ERRα is regulated by miR-137, a potential tumor suppressor microRNA. The bioinformatics search revealed two putative and highly conserved target-sites for miR-137 located within the ERRα 3'UTR at nt 480-486 and nt 596-602 respectively. Luciferase-reporter assay demonstrated that the two predicted target sites were authentically functional. They mediated the repression of reporter gene expression induced by miR-137 in an additive manner. Moreover, ectopic expression of miR-137 down-regulated ERRα expression at both protein level and mRNA level, and the miR-137 induced ERRα-knockdown contributed to the impaired proliferative and migratory capacity of breast cancer cells. Furthermore, transfection with miR-137 mimics suppressed at least two downstream target genes of ERRα-CCNE1 and WNT11, which are important effectors of ERRα implicated in tumor proliferation and migration. Taken together, our results establish a role of miR-137 in negatively regulating ERRα expression and breast cancer cell proliferation and migration. They suggest that manipulating the expression level of ERRα by microRNAs has the potential to influence breast cancer progression.

FXR ligands protect against hepatocellular inflammation via SOCS3 induction.

Because of the anti-inflammatory actions of farnesoid X receptor (FXR) agonists, FXR has received much attention as a potential therapeutic target. However, the molecular mechanisms of actions have not yet been elucidated. In the present study, we reported that in the animal model of LPS-induced liver injury, administration of the FXR natural ligand CDCA could attenuate hepatocyte inflammatory damage, reduce transaminase activities, suppress inflammation mediators (IL-6, TNF-α and ICAM-1) expression and inhibit STAT3 phosphorylation. These protective effects of FXR were accompanied by an increased expression of suppressor of cytokine signaling 3 (SOCS3), which is a negative feedback regulator of cytokine-STAT3 signaling. We then demonstrated that the beneficial effects of FXR agonist in STAT3 activation were weakened by small interfering RNA-mediated SOCS3 knockdown in hepacytes. Moreover we observed both natural ligand CDCA and synthetic ligand GW4064 could upregulate SOCS 3 expression by enhancing the promoter activity in hepatocytes. These results suggest modulation of SOCS3 expression may represent a novel mechanism through which FXR activation could selectively affect cytokine bioactivity in inflammation response. FXR ligands may be potentially therapeutic in the treatment of liver inflammatory diseases via SOCS3 induction.