New Study Provides Insight into the Assembly and Recruitment of the Human mRNA Export Machinery

Gene expression in eukaryotes is a complex, multi-steps processing which starts with transcription. Pre-mRNA undergoes processing including capping, polyadenylation and splicing before it is allowed to be exported to cytoplasm for translation. The highly conserved TREX complex plays key roles in mRNA export by bridging the interaction between mRNA and the export receptor Tap/p15. However, how human TREX is recruited to mRNA is still unknown. Now researchers from Chinese Academy of Sciences reported the critical roles of human TREX components Aly and THO in assembly and recruitment of TREX.

The TREX complex mainly contains proteins UAP56, Aly, Tex1 and the sub-complex THO. The human TREX is recruited to spliced mRNA in a splicing and 5’-cap dependent manner. In yeast, TREX components are recruited to mRNA in a stepwise manner. Prof. CHENG Hong and her colleagues from Shanghai Institute of Biochemistry and Cell Biology, CAS systematically studied the roles of each TREX components in TREX assembly and recruitment. They found that the three main TREX components THO, Aly and UAP56 form a highly integrated complex and associate with the spliced mRNA and function in mRNA export in an interdependent manner. Both Aly and THO function in mediating the interaction between TREX and the cap binding complex. Thus, in humans, TREX is likely to be recruited to the mRNA as a pre-formed particle with different components linking TREX to different processing machinery. In this way, only when the mRNA is fully mature, TREX can be efficiently recruited and mRNA can be effectively exported.

This study entitled “Aly and THO are required for assembly of the human TREX complex and association of TREX components with the spliced mRNA” has been published online on Nucleic Acids Research on Dec 7^th.

CONTACT:
CHENG Hong
Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai, China
Phone: 86-21-54921162;
E-mail: hcheng@sibcb.ac.cn

Models for TREX recruitment. Aly and THO are required for assembly of the human TREX complex and association of TREX components with the spliced mRNA. [Image provided by Prof. CHENG Hong]