James Q Yin’s research while affiliated with Chinese Academy of Sciences and other places

Recent studies have identified important roles for microRNAs (miRNAs) in many cardiac pathophysiological processes, including the regulation of cardiomyocyte hypertrophy. However, the role of miR-350 in the cardiac setting is still unclear. The objective of this study is to determine whether miR-350 alone can induce pathological cardiac hypertrophy by repressing the SAPK pathway in cardiomyocytes. Here we report that miR-350 plays a key role in determining pathological cardiomyocyte hypertrophy and apoptosis. Comprehensive microarray profiling of miRs and qPCR showed that this unique miRNA was significantly up-regulated in rat hearts in response to late-stage transverse aortic constriction. Western blotting and luciferase assays confirmed that the target mRNAs of miR-350 are mitogen activated protein kinase (MAPK) 11/14 and MAPK8/9 gene transcripts. Gain-of-unction and loss-of-function approaches were used to investigate the functional roles of miR-350. The forced over-expression of miR-350 was sufficient to induce hypertrophy of cardiomyocytes through the posttranslational suppression of p38 and JNK protein synthesis. Moreover, miR-350 led to an increase in unphosphorylated NFATc3 and its nuclear translocation, resulting in the over-expression of pathological hypertrophy markers. As predicted, these effects could effectively be imitated by siR-JNK/p38 through the degeneration of p38 and JNK mRNAs. Conversely, antagomir-350 could lower the levels of miR-350, reverse the expression of target proteins and reduce cell size and apoptosis relative to the administration of mutant antagomir-350. Our data provide the first evidence that miR-350 is a critical regulator of pathological cardiac hypertrophy and apoptosis in rats.

It is unclear whether siRNA-based agents can be a safe and effective therapy for diseases. In this study, we demonstrate that microphthalmia-associated transcription factor-siRNA (MITF-siR)-silenced MITF gene expression effectively induced a significant reduction in tyrosinase (TYR), tyrosinase-related protein 1, and melanocortin 1 receptor (MC1R) levels. The siRNAs caused obvious inhibition of melanin synthesis and melanoma cell apoptosis. Using a novel type of transdermal peptide, we developed the formulation of an MITF-siR cream. Results demonstrated that hyperpigmented facial lesions of siRNA-treated subjects were significantly lighter after 12 weeks of therapy than before treatment (P < 0.001); overall improvement was first noted after 4 weeks of siRNA treatment. At the end of treatment, clinical and colorimetric evaluations demonstrated a 90.4% lightening of the siRNA-treated lesions toward normal skin color. The relative melanin contents in the lesions and adjacent normal skin were decreased by 26% and 7.4%, respectively, after treatment with the MITF-siR formulation. Topical application of siRNA formulation significantly lightens brown facial hypermelanosis and lightens normal skin in Asian individuals. This treatment represents a safe and effective therapy for melasma, suggesting that siRNA-based agents could be developed for treating other diseases such as melanoma.

Human bone marrow mesenchymal stem cells (MSCs) are important cell population located in bone marrow that are thought to have multiple functions in cell transplantation and gene therapy. Although in vitro experiments have demonstrated that hMSCs are resistant to apoptosis induction by DNA damage agents such as chemotherapeutic substances used in bone marrow transplantation, the molecular mechanism underlying remains unclear. p73 is highly similar to p53 and plays crucial roles in regulating DNA damage-induced apoptosis pathways. In this study, we investigated the role of p73 alpha in response to chemotherapeutic substances in cultured human bone marrow MSCs. Cellular chemosensitivity and DNA damage-induced apoptotic cell death were examined in the hMSCs with exogenously over-expressed p73 alpha. Our results showed that the expression of retrovirus-driven human p73 alpha could be successfully induced in hMSCs, the over-expression of ectopic p73 alpha resulted in a significant increase of cellular sensitivity to cisplatin. The increase of cellular apoptosis was attributed to enhanced chemosensitivity in p73 alpha infected cells. Moreover, immunoblot analysis indicated that the co-activation of pro-apoptotic factors Bax and p21 were observed in the p73 alpha infected cells after cisplatin treatment. In conclusion, our findings suggested that p73 alpha is an important determinant of cellular chemosensitivity in human bone marrow MSCs.

Alignment of Alu elements longer than 200 nt.

Alignment of Alu elements shorter than 200 nt.

Sixty predicted miRNAs downstream of Alu elements.

The known miRNAs and predicted miRNAs identified by Solexa sequencing site downstream of MIRs.

Known miRNAs detected in K562 cells.

The relationships between predicted miRNA and its mature sequences identified by Solexa sequencing.

Despite many studies on the biogenesis, molecular structure and biological functions of microRNAs, little is known about the transcriptional regulatory mechanisms controlling the spatiotemporal expression pattern of human miRNA gene loci. Several lines of experimental results have indicated that both polymerase II (Pol-II) and polymerase III (Pol-III) may be involved in transcribing miRNAs. Here, we assessed the genomic evidence for Alu-directed transcriptional regulation of some novel miRNA genes in humans. Our data demonstrate that the expression of these Alu-related miRNAs may be modulated by Pol-III. We present a comprehensive exploration of the Alu-directed transcriptional regulation of some new miRNAs. Using a new computational approach, a variety of Alu-related sequences from multiple sources were pooled and filtered to obtain a subset containing Alu elements and characterized miRNA genes for which there is clear evidence of full-length transcription (embedded in EST). We systematically demonstrated that 73 miRNAs including five known ones may be transcribed by Pol-III through Alu or MIR. Among the new miRNAs, 33 were determined by high-throughput Solexa sequencing. Real-time TaqMan PCR and Northern blotting verified that three newly identified miRNAs could be induced to co-express with their upstream Alu transcripts by heat shock or cycloheximide. Through genomic analysis, Solexa sequencing and experimental validation, we have identified candidate sequences for Alu-related miRNAs, and have found that the transcription of these miRNAs could be governed by Pol-III. Thus, this study may elucidate the mechanisms by which the expression of a class of small RNAs may be regulated by their upstream repeat elements.