Efficient globin production during terminal erythropoiesis depends on the synergistic action of TENT5C poly(A) polymerase and LARP4/5

Abstract

Red blood cell development is a unique process where reduced transcriptome and proteome complexity facilitates vast hemoglobin production. Here, we describe the cooperative role of cytoplasmic poly(A) polymerase TENT5C and the poly(A) tail-protecting LARP4/5 RNA-binding proteins in ensuring proper hemoglobin production. TENT5C catalytic mutant knock-in mice display microcytic hypochromic anemia resembling constitutive knockout. TENT5C counteracts gradual globin mRNA deadenylation during erythropoiesis. In the late stages, TENT5C dysfunction leads to globin poly(A) tail shortening and a drastic reduction of mRNA levels in reticulocytes. Proteomic experiments revealed transient but specific association of TENT5C with LARP4/5. Indeed, LARP4/5 depletion leads to downregulation and poly(A) tail shortening of globin mRNAs. Furthermore, lack of TENT5C catalytic activity is accompanied by compensatory upregulation of LARP4/5. Finally, the importance of precise regulation of globin poly(A) tails by deadenylation and re-adenylation is highlighted by the destabilization of TENT5C by CCR4-NOT deadenylase complex-associated E3 ubiquitin ligase CNOT4. O_FIG O_LINKSMALLFIG WIDTH=198 HEIGHT=200 SRC="FIGDIR/small/623596v1_ufig1.gif" ALT="Figure 1"> View larger version (59K): org.highwire.dtl.DTLVardef@82c736org.highwire.dtl.DTLVardef@1e4ea16org.highwire.dtl.DTLVardef@1c482b7org.highwire.dtl.DTLVardef@61e54a_HPS_FORMAT_FIGEXP M_FIG C_FIG