Eukaryotic mRNA 3' processing: a common means to different ends.
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Animals↗
Biomedical subjects
Gregory M Gilmartin
Publications and source records attributed to Gregory M Gilmartin.
Analysis of a noncanonical poly(A) site reveals a tripartite mechanism for vertebrate poly(A) site recognition.
At least half of all human pre-mRNAs are subject to alternative 3' processing that may modulate both the coding capacity of the message and the array of post-transcriptional regulatory elements embedded within the 3' UTR. Vertebrate poly(A) site selection appears to rely primarily on the binding of CPSF to an A(A/U)UAAA hexamer upstream of the cleavage site and CstF to a downstream GU-rich element. At least one-quarter of all human poly(A) sites, however, lack the A(A/U)UAAA motif. We report that sequence-specific RNA binding of the human 3' processing factor CFI(m) can function as a primary determinant of poly(A) site recognition in the absence of the A(A/U)UAAA motif. CFI(m) is sufficient to direct sequence-specific, A(A/U)UAAA-independent poly(A) addition in vitro through the recruitment of the CPSF subunit hFip1 and poly(A) polymerase to the RNA substrate. ChIP analysis indicates that CFI(m) is recruited to the transcription unit, along with CPSF and CstF, during the initial stages of transcription, supporting a direct role for CFI(m) in poly(A) site recognition. The recognition of three distinct sequence elements by CFI(m), CPSF, and CstF suggests that vertebrate poly(A) site definition is mechanistically more similar to that of yeast and plants than anticipated.
3' Untranslated Regions↗
A mechanism for the regulation of pre-mRNA 3' processing by human cleavage factor Im.
Human cleavage factor I(m) (CFI(m)) is a heterodimeric RNA binding protein complex that functions at an early step in the assembly of the pre-mRNA 3' processing complex. In this report we show that CFI(m) can stimulate both cleavage and poly(A) addition, and can act to suppress poly(A) site cleavage in a sequence-dependent manner. Elevated levels of CFI(m) suppressed cleavage at the primary poly(A) site of the pre-mRNA encoding the 68 kDa subunit of CFI(m). CFI(m)-mediated suppression of poly(A) site cleavage was dependent upon the presence of three copies of an RNA element initially identified by CFI(m)-SELEX. These data provide evidence for a mechanism for the regulation of poly(A) site selection by a basal pre-mRNA 3' processing factor.
3' Untranslated Regions↗