Biology subjects

Li, C.-Y.

Publications and source records attributed to Li, C.-Y..

22 records · Page 2Linked to original sources

bioRxiv2019

JMJD6 Cleaves MePCE to Release P-TEFb

More than 30% of genes in higher eukaryotes are regulated by promoter-proximal pausing of RNA polymerase II (Pol II). Phosphorylation of Pol II-CTD by positive transcription elongation factor (P-TEFb) is a necessary precursor event that enables productive transcription elongation. The exact mechanism on how the sequestered P-TEFb is released from the 7SK snRNP complex and recruited to Pol II-CTD remains unknown. In this report, we reveal methylphosphate capping enzyme (MePCE), a core component of the 7SK snRNP complex, as the cognate substrate for Jumonji domain-containing 6 (JMJD6)s novel proteolytic function. Our evidences consist of a crystal structure of JMJD6 bound to methyl-arginine, enzymatic assays of JMJD6 cleaving MePCE in vivo and in vitro, binding assays, and downstream effects of Jmjd6 knockout and overexpression on Pol II-CTD phosphorylation. We propose that JMJD6 assists bromodomain containing 4 (BRD4) to recruit P-TEFb to Pol II-CTD by disrupting the 7SK snRNP complex.

biochemistry↗

bioRxiv2018

Multiplexed pooled library screening with Cpf1

RNA interference and CRISPR/Cas9-based pooled library screens have revolutionized the field of functional genomics. However, currently available pooled library screens face a trade-off between library effectiveness and library complexity. We developed a multiplexed, high-throughput screening strategy based on an optimized AsCpf1 nuclease that minimizes library size without sacrificing gene targeting efficiency. Our AsCpf1-based multiplexed library performed similarly well compared to currently available CRISPR/Cas9 libraries, but with a single polycistronic crRNA clone targeting each gene. With this strategy, we constructed the smallest whole-genome knock-out library available, \"Mini-human\" for the human genome, which is one-fourth the size of the smallest CRISPR library currently available.

systems biology↗

bioRxiv2018

AICAR induces apoptosis and inhibits migration of prostate cancer cells through an AMPK/mTOR-dependent pathway

AICAR (5-aminoimidazole-4-carbox-amide-1-{beta}-D-ribofuranoside), an AMP-activated protein kinase (AMPK) agonist, has demonstrated antitumor activities for several types of cancers. However, the activity of AICAR on the cell growth and metastasis of prostate cancer has not been extensively studied. Herein we examine the effects of AICAR on the cell growth and metastasis of prostate cancer cells, 22RV1 cells. Cell growth was performed by MTT assay and soft agar assay. Cell apoptosis was examined by Annexin V/PI staining and PARP cleavage Western blot. Cell migration was evaluated by wound-healing assay. The expression of EMT-related protein and the activity of the AMPK/ mTOR-dependent pathway were analyzed by Western blot. In addition, we also tested the effect of AICAR on the chemosensitivity to docetaxel using MTT assay. Our results indicated that AICAR inhibits cell growth, induces apoptosis, attenuates TGF-{beta}-induced cell migration and EMT-related protein expression, and enhances the chemosensitivity to docetaxel through regulating the AMPK/mTOR-dependent pathway. Collectively, these findings support AICAR as a potential therapeutic agent for the treatment of prostate cancer.

cancer biology↗

bioRxiv2017

Outperforming nature: synthetic enzyme built from DNA flips lipids of biological membranes at record rates

Mimicking enzyme function and increasing performance of naturally evolved proteins is one of the most challenging and intriguing aims of nanoscience. Here, we employ DNA nanotechnology to design a synthetic enzyme that substantially outperforms its biological archetypes. Consisting of only eight strands, our DNA nanostructure spontaneously inserts into biological membranes by forming a toroidal pore that connects the membranes inner and outer leaflets. The membrane insertion catalyzes spontaneous transport of lipid molecules between the bilayer leaflets, rapidly equilibrating the lipid composition. Through a combination of microscopic simulations and single-molecule experiments we find the lipid transport rate catalyzed by the DNA nanostructure to exceed 107 molecules per second, which is three orders of magnitude higher than the rate of lipid transport catalyzed by biological enzymes. Furthermore, we show that our DNA-based enzyme can control the composition of human cell membranes, which opens new avenues for applications of membrane-interacting DNA systems in medicine.

biophysics↗