Gene structure and chromosome mapping of mouse transcription elongation factor S-II (Tcea1)

Quantitative Proteomic Analysis Reveals Key Proteins Involved in Testicular Development of Yaks

Male reproductive health is largely determined already in the early development of the testis. Although much work has been carried out to study the mechanisms of testicular development and spermatogenesis, there was previously no information on the differences in the protein composition of yak testicles during early development. In this study, the protein profiles in the testicles of 6- (M6), 18- (M18), and 30-month-old (M30) yaks were comparatively analyzed using TMT proteomics. A total of 5521 proteins were identified, with 13, 1295, and 1397 differentially expressed proteins (DEPs) in 30- vs. 18-, 18- vs. 6-, and 30- vs. 6-month-old testes, respectively. Gene Ontology (GO) annotation and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis showed that DEPs were mainly involved in signaling pathways related to testicular development and spermatogenesis, including the MAPK, PI3K-Akt, Wnt, mTOR, TGF-β, and AMPK signaling pathways. Furthermore, we also identified eight potential proteins (TEX101, PDCL2, SYCP2, SYCP3, COL1A1, COL1A2, ADAM10, and ATF1) that may be related to the testicular development and spermatogenesis of yaks. This study may provide new insights into the molecular mechanisms of the testicular development and spermatogenesis of yaks.

Transcription stress at telomeres leads to cytosolic DNA release and paracrine senescence

Transcription stress has been linked to DNA damage -driven aging, yet the underlying mechanism remains unclear. Here, we demonstrate that Tcea1-/- cells, which harbor a TFIIS defect in transcription elongation, exhibit RNAPII stalling at oxidative DNA damage sites, impaired transcription, accumulation of R-loops, telomere uncapping, chromatin bridges, and genome instability, ultimately resulting in cellular senescence. We found that R-loops at telomeres causally contribute to the release of telomeric DNA fragments in the cytoplasm of Tcea1-/- cells and primary cells derived from naturally aged animals triggering a viral-like immune response. TFIIS-defective cells release extracellular vesicles laden with telomeric DNA fragments that target neighboring cells, which consequently undergo cellular senescence. Thus, transcription stress elicits paracrine signals leading to cellular senescence, promoting aging.

Genomic binding of Pol III transcription machinery and relationship with TFIIS transcription factor distribution in mouse embryonic stem cells

RNA polymerase (Pol) III synthesizes the tRNAs, the 5S ribosomal RNA and a small number of untranslated RNAs. In vitro, it also transcribes short interspersed nuclear elements (SINEs). We investigated the distribution of Pol III and its associated transcription factors on the genome of mouse embryonic stem cells using a highly specific tandem ChIP-Seq method. Only a subset of the annotated class III genes was bound and thus transcribed. A few hundred SINEs were associated with the Pol III transcription machinery. We observed that Pol III and its transcription factors were present at 30 unannotated sites on the mouse genome, only one of which was conserved in human. An RNA was associated with >80% of these regions. More than 2200 regions bound by TFIIIC transcription factor were devoid of Pol III. These sites were associated with cohesins and often located close to CTCF-binding sites, suggesting that TFIIIC might cooperate with these factors to organize the chromatin. We also investigated the genome-wide distribution of the ubiquitous TFIIS variant, TCEA1. We found that, as in Saccharomyces cerevisiae, TFIIS is associated with class III genes and also with SINEs suggesting that TFIIS is a Pol III transcription factor in mammals.

Defective FESTA/EAF2-mediated transcriptional activation in S-II-deficient embryonic stem cells

S-II is a transcription stimulation factor that enhances RNA synthesis by RNA polymerase II in vitro. To elucidate the function of S-II in transcriptional activation in mammalian cells, we generated an S-II-deficient murine embryonic stem (ES) cell line, DKO20, through targeted gene disruption. The DKO20 cells were viable, grew normally, and had a stable karyotype. The ability to evoke transcriptional activation of hsp70 and c-fos genes was not significantly altered in DKO20. In contrast, transcriptional activation mediated by FESTA/EAF2, a transcription factor that interacts with S-II, was decreased in DKO20 cells. The reduced transactivation potential of FESTA/EAF2 was rescued by introducing the wild-type S-II gene in DKO20. The amino-terminal region of S-II, a binding surface for FESTA/EAF2, was essential for the recovery. These results suggest that S-II is selectively required for positive transcriptional regulation of a subset of genes in murine ES cells.

Transcription elongation factor S-II is required for definitive hematopoiesis

Transcription elongation factor S-II/TFIIS promotes readthrough of transcriptional blocks by stimulating nascent RNA cleavage activity of RNA polymerase II in vitro. The biologic significance of S-II function in higher eukaryotes, however, remains unclear. To determine its role in mammalian development, we generated S-II-deficient mice through targeted gene disruption. Homozygous null mutants died at midgestation with marked pallor, suggesting severe anemia. S-II(-/-) embryos had a decreased number of definitive erythrocytes in the peripheral blood and disturbed erythroblast differentiation in fetal liver. There was a dramatic increase in apoptotic cells in S-II(-/-) fetal liver, which was consistent with a reduction in Bcl-x(L) gene expression. The presence of phenotypically defined hematopoietic stem cells and in vitro colony-forming hematopoietic progenitors in S-II(-/-) fetal liver indicates that S-II is dispensable for the generation and differentiation of hematopoietic stem cells. S-II-deficient fetal liver cells, however, exhibited a loss of long-term repopulating potential when transplanted into lethally irradiated adult mice, indicating that S-II deficiency causes an intrinsic defect in the self-renewal of hematopoietic stem cells. Thus, S-II has critical and nonredundant roles in definitive hematopoiesis.