CAF1-knockout mice are more susceptive to lipopolysaccharide-induced acute lung injury

Poplar CCR4-associated factor PtCAF1I is necessary for poplar development and defense response

Poplar is one of the most widely used tree species in afforestation projects. CCR4 associated factor 1 (CAF1) is a major member of CCR4-NOT and plays an important role in eukaryotic mRNA deadenylation. However, its role in poplar remains unclear. In this study, the full-length cDNA of the PtCAF1I gene was cloned from the poplar by screening the highly expressed PtCAF1I gene in the identified PtCAF1 gene family by poplar sterilization. PtCAF1I was localized in the nucleus. Through sequence alignment, it was found that the PtCAF1I sequence contains three motifs and is highly similar to the CAF1 protein sequence of other species. In the quantitative expression analysis of tissues, the expression of PtCAF1I in different tissues of Populus trichocarpa, 'Nanlin895', and Shanxinyang was not much different. In addition, the analysis of the expression of the PtCAF1I gene under different stress treatments showed that PtCAF1I responded to abscisic acid (ABA), salicylic acid (SA), methyl jasmonate (MeJA), NaCl, PEG₆₀₀₀, hydrogen peroxide (H₂O₂) and cold stress to different degrees. To study the potential biological functions of PtCAF1I, 6 transgenic lines were obtained through transformation using an Agrobacterium tumefaciens infection system. The transcriptome sequencing results showed that DEGs were mainly concentrated in pathways of phenylpropanoid biosynthesis, biosynthesis of secondary metabolites, carbon metabolism, and carotenoid biosynthesis. Compared with WT poplar, the contents of cellulose, hemicellulose, lignin, total sugar, and flavonoids, and the cell wall thickness of PtCAF1I overexpression poplars were significantly higher. Under Septotinia populiperda treatment, transgenic poplars clearly exhibited certain disease resistance. Meanwhile, upregulation of the expression of JA and SA pathway-related genes also contributed to improving the disease tolerance of transgenic poplar. In conclusion, our results suggest that PtCAF1I plays an important role in the growth and development of poplars and their resistance to pathogens.

FACT maintains nucleosomes during transcription and stem cell viability in adult mice

Preservation of nucleosomes during replication has been extensively studied, while the maintenance of nucleosomes during transcription has gotten less attention. The histone chaperone FACT has a role in transcription elongation, although whether it disassembles or assembles nucleosomes during this process is unclear. To elucidate the function of FACT in mammals, we deleted the Ssrp1 subunit of FACT in adult mice. FACT loss is lethal, possibly due to the loss of the earliest progenitors in bone marrow and intestine, while more differentiated cells are not affected. Using cells isolated from several tissues, we show that FACT loss reduces the viability of stem cells but not of cells differentiated in vitro. FACT depletion increases chromatin accessibility in a transcription-dependent manner in adipose mesenchymal stem cells, indicating that nucleosomes are lost in these cells during transcription in the absence of FACT. We also observe activation of interferon (IFN) signaling and the accumulation of immunocytes in organs sensitive to FACT loss. Our data indicate that FACT maintains chromatin integrity during transcription in mammalian adult stem cells, suggesting that chromatin transcription in stem cells and differentiated cells is different.

Genome-Wide and Comprehensive Analysis of the Multiple Stress-Related CAF1 (CCR4-Associated Factor 1) Family and Its Expression in Poplar

Poplar is one of the most widely used tree in afforestation projects. However, it is susceptible to abiotic and biotic stress. CCR4-associated factor 1 (CAF1) is a major member of CCR4-NOT, and it is mainly involved in transcriptional regulation and mRNA degradation in eukaryotes. However, there are no studies on the molecular phylogeny and expression of the CAF1 gene in poplar. In this study, a total of 19 PtCAF1 genes were identified in the Populus trichocarpa genome. Phylogenetic analysis of the PtCAF1 gene family was performed with two closely related species (Arabidopsis thaliana and Oryza sativa) to investigate the evolution of the PtCAF1 gene. The tissue expression of the PtCAF1 gene showed that 19 PtCAF1 genes were present in different tissues of poplar. Additionally, the analysis of the expression of the PtCAF1 gene showed that the CAF1 family was up-regulated to various degrees under biotic and abiotic stresses and participated in the poplar stress response. The results of our study provide a deeper understanding of the structure and function of the PtCAF1 gene and may contribute to our understanding of the molecular basis of stress tolerance in poplar.