THOC5/FMIP, an mRNA export TREX complex protein, is essential for hematopoietic primitive cell survival in vivo

Abstract

BackgroundThe transcription/export complex is evolutionarily conserved from yeast to man and is required for coupled transcription elongation and nuclear export of mRNAs. FMIP(Fms interacting protein) is a member of the THO (suppressors of the transcriptional defects of hpr1delta by overexpression) complex which is a subcomplex of the transcription/export complex. THO complex (THOC) components are not essential for bulk poly (A)+ RNA export in higher eukaryotes, but for the nuclear export of subset of mRNAs, however, their exact role is still unclear.ResultsTo study the role of THOC5/Fms interacting protein in vivo, we generated THOC5/Fms interacting protein knockout mice. Since these mice are embryonic lethal, we then generated interferon inducible conditional THOC5/Fms interacting protein knockout mice. After three poly injections all of the mice died within 14 days. No pathological alterations, however, were observed in liver, kidney or heart. Thus we considered the hematopoietic system and found that seven days after poly injection, the number of blood cells in peripheral blood decreased drastically. Investigation of bone marrow cells showed that these became apoptotic within seven days after poly injection. Committed myeloid progenitor cells and cells with long term reconstituting potential were lost from bone marrow within four days after poly injection. Furthermore, infusion of normal bone marrow cells rescued mice from death induced by loss of THOC5/Fms interacting protein.ConclusionTHOC5/Fms interacting protein is an essential element in the maintenance of hematopoiesis. Furthermore, mechanistically depletion of THOC5/Fms interacting protein causes the down-regulation of its direct interacting partner, THOC1 which may contribute to altered THO complex function and cell death.

An ataxia-telangiectasia-mutated (ATM) kinase mediated response to DNA damage down-regulates the mRNA-binding potential of THOC5

“…We then examined the mRNA export function of THOC5 after etoposide treatment. We had previously generated a MEF cell line from THOC5 flox/ flox mice (Mancini et al 2010). Infection of THOC5/FMIP flox/flox MEF with Adenovirus carrying cre-recombinase and GFP genes (Ad-GFP-Cre) resulted in depletion of THOC5/ FMIP expression in these cells within 4 d after infection (Mancini et al 2010;Guria et al 2011).…”

“…We had previously generated a MEF cell line from THOC5 flox/ flox mice (Mancini et al 2010). Infection of THOC5/FMIP flox/flox MEF with Adenovirus carrying cre-recombinase and GFP genes (Ad-GFP-Cre) resulted in depletion of THOC5/ FMIP expression in these cells within 4 d after infection (Mancini et al 2010;Guria et al 2011). Using this system, we previously identified 10 THOC5-dependent genes, such as Grb10 interacting GYF protein 2 (Gigyf2 or Tnrc15), protein kinase C binding protein 1 (Prkcbp1), twisted gastrulation homolog 1 (Twsg1), enhancer of yellow 2 homolog (Eny2), solute carrier family 11 (proton-coupled divalent metal ion transporters), member 2 (Slc11a2), DHHC domain containing 2 (Zdhhc2) zinc finger, inhibitor of DNA binding 2 (ID2), or gap junction membrane channel protein a 1 (Gja1) (Guria et al 2011).…”

“…We have previously shown that depletion of THOC5 by siRNA or ectopic expression causes abnormal hematopoiesis and abnormal muscle differentiation in mouse myeloid progenitor or mesenchymal progenitor cell lines, indicating that the THO complex is essential for the differentiation process in mouse (Tamura et al 1999;Mancini et al 2007;Carney et al 2009). Furthermore, we generated interferoninducible THOC5 knockout mice to demonstrate that THOC5 is essential for maintaining primitive cells, such as embryonic or hematopoietic stem cells, but not terminally differentiated cells (Mancini et al 2010), similar to ATM kinase (Ito et al 2004). THOC5 is phosphorylated by several tyrosine kinases (Tamura et al 1999;Pierce et al 2008), protein kinase C (Mancini et al 2004), and ATM kinase (Matsuoka et al 2007), suggesting that extracellular stimulation regulates the function of THOC5.…”

p53 and PI3K/AKT Signalings Are Up-Regulated in Flies with Defects in the THO Complex

“…Several lines of recent evidence have suggested that metazoan THO has cell type-specific roles during development (Griaud et al, 2012;Kopytova et al, 2010;Mancini et al, 2010;Moon et al, 2011;Wang et al, 2009). In mice homozygous for a hyphomorphic Thoc1 allele, spermatogenesis was severely compromised due to defects in the expression of genes required for normal cell differentiation in the testis, while most other tissues appeared to be unaffected (Wang et al, 2009).…”

“…In mice homozygous for a hyphomorphic Thoc1 allele, spermatogenesis was severely compromised due to defects in the expression of genes required for normal cell differentiation in the testis, while most other tissues appeared to be unaffected (Wang et al, 2009). Using conditional knock-out mice, Mancini et al (2010) showed that THOC5 was an essential element in the maintenance of hematopoiesis, whereas it was less important in differentiated cell types such as hepatocytes and heart muscles. In addition, it has been shown that THOC1 was differentially expressed in human cancers; it was up-regulated in ovarian and lung tumors, while down-regulated in testis and skin tumors (Dominguez-Sanchez et al, 2011).…”