Principles and correction of 5’-splice site selection

Abstract

In Eukarya, immature mRNA transcripts (pre-mRNA) often contain coding sequences, or exons, interleaved by non-coding sequences, or introns. Introns are removed upon splicing , and further regulation of the retained exons leads to alternatively spliced mRNA. The splicing reaction requires the stepwise assembly of the spliceosome, a macromolecular machine composed of small nuclear ribonucleoproteins (snRNPs). This review focuses on the early stage of spliceosome assembly, when U1 snRNP defines each intron 5’-splice site (5ʹss) in the pre-mRNA. We first introduce the splicing reaction and the impact of alternative splicing on gene expression regulation. Thereafter, we extensively discuss splicing descriptors that influence the 5ʹss selection by U1 snRNP, such as sequence determinants, and interactions mediated by U1-specific proteins or U1 small nuclear RNA (U1 snRNA). We also include examples of diseases that affect the 5ʹss selection by U1 snRNP, and discuss recent therapeutic advances that manipulate U1 snRNP 5ʹss selectivity with antisense oligonucleotides and small-molecule splicing switches.

Comparative Proteomic Analysis Provides New Insights into the Molecular Basis of Thermal-Induced Parthenogenesis in Silkworm (Bombyx mori)

“…Comparative transcriptomic analysis between obligately asexual and cyclically asexual rotifers also revealed that the expression of genes encoding ribosomal proteins is higher in OP lines than in CP lines [ 26 ]. Furthermore, five gene expression-related proteins, including small nuclear ribonucleoprotein G [ 42 ], U6 snRNA-associated Sm-like protein isoform X1 [ 43 ], small nuclear ribonucleoprotein Sm S2 [ 44 ], eukaryotic translation initiation factor 3 subunit G [ 45 ], and deoxyhypusine hydroxylase/monooxygenase [ 46 ], were increased in abundance in PL. We suggested that the increase in translation process might facilitate parthenogenetic development when subjected to thermal stimuli.…”

The diversity of splicing modifiers acting on A-1bulged 5’-splice sites reveals rules to guide rational design

“…Diseases are often caused by mutations at the invariant G+1 nucleotide and at positions -1, +2, and +5. In this study, we examined the chemical diversity of splicing modifiers targeting A-1 bulged 5'-splice sites for specific splicing correction, a promising class of RNA therapeutics (2). While the SMN2 splicing modifier SMN-C5 served as the prototype for this family and helped to clarify the mechanism of action and the concept of "5'-splice site bulge repair" (22), several small molecule splicing modifiers with different chemical scaffolds have similar biological activities (20,24,33).…”

“…A major limiting step in the splicing reaction is the definition of the 5'-splice site by the U1 small nuclear ribonucleoprotein (U1 snRNP), the first particle of the major spliceosome (2,3). The ribonucleoprotein uses the 5'-end of the U1 snRNA to base pair with the 5'-splice site and initiates the splicing reaction (4).…”

Small molecules modulating RNA splicing: a review of targets and future perspectives

“…In eukaryotic organisms, RNA splicing constitutes a critical maturation process. 1,2 This mechanism achieves the excision of non-coding intronic sequences and the subsequent ligation of coding exonic sequences within the precursor mRNA (pre-mRNA), yielding a mature, spliced mRNA (Fig. 1A).…”

“…[13][14][15][16] The therapeutic modulation of RNA splicing emerged as a promising avenue for the treatment of several diseases previously refractory to medical intervention. 2,17 Historically, antisense oligonucleotides (ASOs) have been used to target cis-regulatory sequences in the pre-mRNA (Fig. 1D).…”