The Prp19C/NTC subunit Syf2 and the Prp19C/NTC-associated protein Cwc15 function in TREX occupancy and transcription elongation.

The Prp19 complex (Prp19C), also named NineTeen Complex (NTC), is conserved from yeast to human and functions in many different processes such as genome stability, splicing, and transcription elongation. In the latter, Prp19C ensures TREX occupancy at transcribed genes. TREX, in turn, couples transcription to nuclear mRNA export by recruiting the mRNA exporter to transcribed genes and consequently to nascent mRNAs. Here, we assess the function of the nonessential Prp19C subunit Syf2 and the nonessential Prp19C-associated protein Cwc15 in the interaction of Prp19C and TREX with the transcription machinery, Prp19C and TREX occupancy, and transcription elongation. Whereas both proteins are important for Prp19C-TREX interaction, Syf2 is needed for full Prp19C occupancy, and Cwc15 is important for the interaction of Prp19C with RNA polymerase II and TREX occupancy. These partially overlapping functions are corroborated by a genetic interaction between Δcwc15 and Δsyf2 Finally, Cwc15 also interacts genetically with the transcription elongation factor Dst1 and functions in transcription elongation. In summary, we uncover novel roles of the Prp19C component Syf2 and the Prp19C-associated protein Cwc15 in Prp19C's function in transcription elongation.

MicroRNA-621 inhibits the growth of gastric cancer cells by targeting SYF2.

Increasing evidence indicates that aberrantly expressed microRNAs play a role in tumorigenesis and progression of gastric cancer. Recently, a novel cancer-related microRNA, miR-621, was found to be involved in cancer pathogenesis. However, the precise molecular mechanisms underlying the oncogenic activity of miR-621 remain unclear and require further investigation. In the current study, we demonstrate that miR-621 expression is downregulated in gastric cancer tissues and cell lines, and its reduction is associated with malignant clinical features including tumor size, lymph node metastasis, tumor-node-metastasis stage and poor prognosis. Functional studies involving gain- and loss-of-function experiments revealed that miR-621 represses cell viability, colony formation, cell cycle progression and proliferation in vitro, and miR-621 overexpression inhibited tumor growth in a gastric cancer xenograft model. SYF2 was identified as a direct target gene of miR-621 in gastric cancer. MiR-621 directly interacts with the SYF2 3'-UTR and post-transcriptionally repressed SYF2 expression in gastric cancer cells. SYF2 was significantly overexpressed in gastric cancer tissues and negatively correlated with miR-621 expression. Moreover, inhibition of SYF2 expression reversed the effects of miR-621 loss in gastric cancer cells. SYF2 overexpression was similar to that induced by miR-621 loss in gastric cancer. Taken together, these studies suggest that miR-621 may be a viable therapeutic target in gastric cancer.

Overexpression of SYF2 correlates with enhanced cell growth and poor prognosis in human hepatocellular carcinoma.

SYF2, also known as p29/NTC31/CBPIN, encodes a nuclear protein that interacts with Cyclin D-type binding-protein 1. SYF2 has been reported to be involved in pre-mRNA splicing and cell cycle regulation. In the present study, we observed that SYF2 was obviously upregulated in HCC tumor tissues and cell lines, and its level was positively correlated with the tumor grade and Ki-67 expression, as well as poor prognosis of HCC. In vitro, using serum starvation-refeeding experiment, our results suggested that SYF2 was upregulated in proliferating HCC cells, and was positive correlated with the expression of PCNA and Cyclin D1. In addition, depletion of SYF2 decreased PCNA and Cyclin D1 levels. Accordingly, interference of SYF2 resulted in cells cycle arrest at G1/S phase in Huh7 HCC cells. Furthermore, we found that SYF2 might interact with Cyclin D1 and could confer doxorubicin resistance in HCC cells. These findings revealed that SYF2 might play a regulatory role in the proliferation of HCC cells. In summary, SYF2 may be a novel prognostic marker and serve as a potential therapeutic target in HCC.

Upregulation of SYF2 is associated with neuronal apoptosis caused by reactive astrogliosis to neuroinflammation.

SYF2, known as CCNDBP1-interactor or p29, is likely involved in pre-mRNA splicing and cell cycle progression. The present study was designed to elucidate dynamic changes in SYF2 expression and distribution in the cerebral cortex in a lipopolysaccharide (LPS)-induced neuroinflammation rat model. It was found that SYF2 expression was induced strongly in active astrocytes after LPS injection. In vitro studies showed that the upregulation of SYF2 might be involved in the activation of C6 cells after LPS challenge and the neuronal apoptosis after conditioned media challenge. In addition, with silencing of SYF2 in C6 and PC12 cells by siRNA, the results indicated that SYF2 was required for astrocyte activation and neuronal apoptosis induced by LPS. Our findings on the cellular signaling pathway may provide a new therapeutic strategy against neuroinflammation in the CNS.

SYF2 suppression mitigates neurodegeneration in models of diverse forms of ALS.

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease caused by many diverse genetic etiologies. Although therapeutics that specifically target causal mutations may rescue individual types of ALS, such approaches cannot treat most patients since they have unknown genetic etiology. Thus, there is a critical need for therapeutic strategies that rescue multiple forms of ALS. Here, we combine phenotypic chemical screening on a diverse cohort of ALS patient-derived neurons with bioinformatic analysis of large chemical and genetic perturbational datasets to identify broadly effective genetic targets for ALS. We show that suppressing the gene-encoding, spliceosome-associated factor SYF2 alleviates TDP-43 aggregation and mislocalization, improves TDP-43 activity, and rescues C9ORF72 and causes sporadic ALS neuron survival. Moreover, Syf2 suppression ameliorates neurodegeneration, neuromuscular junction loss, and motor dysfunction in TDP-43 mice. Thus, suppression of spliceosome-associated factors such as SYF2 may be a broadly effective therapeutic approach for ALS.

Genome-wide comparison and in silico analysis of splicing factor SYF2/NTC31/p29 in eukaryotes: Special focus on vertebrates.

The gene SYF2-an RNA splicing factor-can interact with Cyclin D-type binding protein 1 (GICP) in many biological processes, including splicing regulation, cell cycle regulation, and DNA damage repair. In our previous study we performed genome-wide identification and functional analysis of SYF2 in plant species. The phylogenetic relationships and expression profiles of SYF2 have not been systematically studied in animals, however. To this end, the gene structure, genes, and protein conserved motifs of 102 SYF2 homologous genes from 91 different animal species were systematically analyzed, along with conserved splicing sites in 45 representative vertebrate species. A differential comparative analysis of expression patterns in humans and mice was made. Molecular bioinformatics analysis of SYF2 showed the gene was conserved and functional in different animal species. In addition, expression pattern analysis found that SYF2 was highly expressed in hematopoietic stem cells, T cells, and lymphoid progenitor cells; in ovary, lung, and spleen; and in other cells and organs. This suggests that changes in SYF2 expression may be associated with disease development in these cells, tissues, or organs. In conclusion, our study analyzes the SYF2 disease resistance genes of different animal species through bioinformatics, reveals the relationship between the SYF2 genotype and the occurrence of certain diseases, and provides a theoretical basis for follow-up study of the relationship between the SYF2 gene and animal diseases.

Hsa-circ_0000064 accelerates the malignant progression of gastric cancer via sponging microRNA-621.

Gastric cancer (GC) is one of the most common digestive system tumors in the world. Many circular RNAs (circRNAs) are involved in the progression of GC. The purpose of this study was to delve into the expression characteristics and biological functions of circ_0000064 in GC, and further study its mechanisms. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect circ_0000064 expression in 61 GC tissues and cell lines. Circ_0000064 knockdown was successfully modeled with siRNA. The effects of circ_0000064 on the biological functions of GC cells were analyzed by CCK-8, BrdU, and Transwell assays. Bioinformatics and dual-luciferase reporter gene assay were adopted to explore the relations between circ_0000064 and microRNA-621 (miR-621). Western blot was used to examine the regulatory function of circ_0000064 and miR-621 on SYF2 pre-mRNA splicing factor 2. Cric_0000064 expression was elevated in GC tissues and cell lines. Knocking down cric_0000064 could inhibit the viability, migration, and invasion of GC cells. Dual-luciferase reporter gene assay showed that miR-621 could bind circ_0000064 and SYF2 3'UTR; in addition, miR-621 overexpression or SYF2 knockdown could partially weaken the cancer-promoting effect of circ_0000064 on GC cells. Circ_0000064 expression was negatively correlated with miR-621 expression in GC tissues while positively with SYF2 expression. Circ_0000064 can participate in the GC progression via modulating miR-621/SYF2 axis. This implies that circ_0000064 may be a new diagnosed biomarker or a new therapeutic target of GC.

Influence of miR-376c-3p/SYF2 Axis on the Progression of Gastric Cancer.

MicroRNA-376c-3p was previous reported to have a crucial role in the progression of human cancer. This study was aimed to investigate the influence of microRNA-376c-3p on the proliferation and migration of human gastric cancer cells and the associated mechanism. We explored the expression of microRNA-376c-3p in gastric cancer cells using reverse transcription-quantitative polymerase chain reaction. Also, we analyzed the association and biological significance of microRNA-376c-3p and SYF2 pre-mRNA-splicing factor in gastric cancer. MicroRNA-376c-3p expression was found downregulated in gastric cancer cell lines compared to the normal cell line. MicroRNA-376c-3p directly targeted SYF2 and reduced SYF2 expression. Overexpression of microRNA-376c-3p inhibits gastric cancer cell proliferation and migration. Besides that, overexpression of SYF2 abrogates the inhibitory influences on gastric cancer cell behaviors caused by microRNA-376c-3p mimic. These results showed that microRNA-376c-3p inhibits the proliferation and migration of gastric cancer cells via targeting SYF2.

Overexpression of SYF2 promotes cell proliferation and correlates with poor prognosis in human breast cancer.

SYF2, a known cell cycle regulator, is reported to be involved in cell cycle arrest by interacting with cyclin-D-type binding protein 1. In the present study, we investigated the role of SYF2 in human breast cancer (BC) progression. SYF2 was highly upregulated in BC tissues and cell lines, as per Western blot and immunohistochemistry analysis. The SYF2 expression level had a significant correlation with the tumor grade and Ki-67 expression. In vitro starvation-refeeding experiment and SYF2-siRNA transfection assay demonstrated that SYF2 could promote proliferation of BC cells, while SYF2 knockdown resulted in cells cycle arrest at G1/S phase, reducing the cell growth rate of BC cells. These results indicated that SYF2 promotes human BC progression by accelerating the BC cells' proliferation. SYF2 could be a novel therapeutic target in human BC therapies.

Involvement of p29/SYF2/fSAP29/NTC31 in the progression of NSCLC via modulating cell proliferation.

p29, also known as SYF2/fSAP29/NTC31, is a protein associated with chromatin and involved in DNA damage response, cell cycle arrest and pre-mRNA splicing. In p29-depleted cells, DNA replication was reduced and cell population in G1 phase increased. In this study, we investigated the potential role of p29 in the regulation of non-small cell lung cancer (NSCLC) progression. Western blot and immunohistochemistry staining showed that p29 was up-regulated in clinical NSCLC tissues compared with adjacent non-cancerous tissues, and the expression of p29 had a positive correlation with clinical stage and histological differentiation, as well as expression of Ki-67, a proliferating marker. Kaplan-Meier analysis indicated that patients with high level of p29 expression had poor overall survival. In addition, small interfering RNA of p29 was performed, and the effects on NSCLC growth were examined. Interference of p29 blocked S phase entry, inhibited proliferation of A549 cells and up-regulated level of p21 expression. Taken together, these results suggested that p29 might contribute to the progression of NSCLC by enhancing cell proliferation, implicating that targeting p29 might provide beneficial effects on the clinical therapy of NSCLC.