Distinct involvement of cAMP-response element-dependent transcriptions in functional and morphological maturation during retinoid-mediated human myeloid differentiation

Dietary dibutyryl cAMP supplementation regulates the fat deposition in adipose tissues of finishing pigs via cAMP/PKA pathway

This study investigated potential mechanism of dibutyryl-cAMP (db-cAMP) on porcine fat deposition. (1) Exp.1, 72 finishing pigs were allotted to 3 treatments (0, 10 or 20 mg/kg dbcAMP) with 6 replicates. dbcAMP increased the hormone sensitive lipase (HSL) activity and expression of β-adrenergic receptor (β-AR) and growth hormone receptor (GHR), but decreased expression of peroxisome proliferator-activated receptor gamma 2 (PPAR-γ2) and adipocyte fatty acid binding protein (A-FABP) in back fat. dbcAMP upregulated expression of β-AR, GHR, PPAR-γ2 and A-FABP, but decreased insulin receptor (INSR) expression in abdominal fat. Dietary dbcAMP increased HSL activity and expression of G protein-coupled receptor (GPCR), cAMP-response element-binding protein (CREB) and insulin-like growth factor-1 (IGF-1), but decreased fatty acid synthase (FAS) and lipoprotein lipase (LPL) activities, and expression of INSR, cAMP-response element-binding protein (C/EBP-α) and A-FABP in perirenal fat. (2) Exp. 2, dbcAMP suppressed the proliferation and differentiation of porcine preadipocytes in a time- and dose-dependent manner, which might be associated with increased activities of cAMP and protein kinase A (PKA), and expression of GPCR, β-AR, GHR and CREB via inhibiting C/EBP-α and PPAR-γ2 expression. Collectively, dbcAMP treatment may reduce fat deposition by regulating gene expression related to adipocyte differentiation and fat metabolism partially via cAMP-PKA pathway.

Exploring the genomic resources and analysing the genetic diversity and population structure of Chinese indigenous rabbit breeds by RAD-seq

Background

Chinese indigenous rabbits have distinct characteristics, such as roughage resistance, stress resistance and environmental adaptability, which are of great significance to the sustainable development of the rabbit industry in China. Therefore, it is necessary to study the genetic diversity and population structure of this species and develop genomic resources.

Results

In this study, we used restriction site-associated DNA sequencing (RAD-seq) to obtain 1,006,496 SNP markers from six Chinese indigenous rabbit breeds and two imported rabbit breeds. Jiuyishan and Fujian Yellow rabbits showed the highest nucleotide diversity (π) and decay of linkage disequilibrium (LD), as well as higher observed heterozygosity (Ho) and expected heterozygosity (He), indicating higher genetic diversity than other rabbits. The inbreeding coefficient (F_IS) of New Zealand rabbits and Belgian rabbits was higher than that of other rabbits. The neighbour-joining (NJ) tree, principal component analysis (PCA), and population structure analysis of autosomes and Y chromosomes showed that Belgian, New Zealand, Wanzai, Sichuan White, and Minxinan Black rabbits clustered separately, and Fujian Yellow, Yunnan Colourful, and Jiuyishan rabbits clustered together. Wanzai rabbits were clearly separated from other populations (K = 3), which was consistent with the population differentiation index (F_ST) analysis. The selection signature analysis was performed in two populations with contrasting coat colours. With Sichuan White and New Zealand rabbits as the reference populations and Minxinan Black and Wanzai rabbits as the target populations, 408, 454, 418, and 518 genes with a selection signature, respectively, were obtained. Gene Ontology (GO) classification and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were performed on the genes with a selection signature. The results showed that the genes with a selection signature were enriched in the melanogenesis pathway in all four sets of selection signature analyses.

Conclusions

Our study provides the first insights into the genetics and genomics of Chinese indigenous rabbit breeds and serves as a valuable resource for the further effective utilization of the species.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07833-6.

All-trans retinoic acid (ATRA)-induced TFEB expression is required for myeloid differentiation in acute promyelocytic leukemia (APL)

OBJECTIVE

In acute promyelocytic leukemia (APL), normal retinoid signaling is disrupted by an abnormal PML-RARα fusion oncoprotein, leading to a block in cell differentiation. Therapeutic concentrations of all-trans-retinoic acid (ATRA) can restore retinoid-induced transcription and promote degradation of the PML-RARα protein. Autophagy is a catabolic pathway that utilizes lysosomal machinery to degrade intracellular material and facilitate cellular re-modeling. Recent studies have identified autophagy as an integral component of ATRA-induced myeloid differentiation.

METHODS

As the molecular communication between retinoid signaling and the autophagy pathway is not defined, we performed RNA sequencing of NB4 APL cells treated with ATRA and examined autophagy-related transcripts.

RESULTS

ATRA altered the expression of >80 known autophagy-related transcripts, including the key transcriptional regulator of autophagy and lysosomal biogenesis, TFEB (11.5-fold increase). Induction of TFEB and its transcriptional target, sequestosome 1 (SQSTM1, p62), is reduced in ATRA-resistant NB4R cells compared to NB4 cells. TFEB knockdown in NB4 cells alters the expression of transcriptional targets of TFEB and reduces CD11b transcript levels in response to ATRA.

CONCLUSIONS

We show for the first time that TFEB plays an important role in ATRA-induced autophagy during myeloid differentiation and that autophagy induction potentiates leukemic cell differentiation (Note: this study includes data obtained from NCT00195156, https://clinicaltrials.gov/show/NCT00195156).

Protein kinase A inhibition of macrophage maturation is accompanied by an increase in DNA methylation of the colony-stimulating factor 1 receptor gene

Macrophage colony-stimulating factor 1 (CSF-1) plays a critical role in the differentiation of mononuclear phagocytes from bone marrow precursors, and maturing monocytes and macrophages exhibit increased expression of the CSF-1 receptor, CSF1R. The expression of CSF1R is tightly regulated by transcription factors and epigenetic mechanisms. We previously showed that prostaglandin E2 and subsequent activation of protein kinase A (PKA) inhibited CSF1R expression and macrophage maturation. Here, we examine the DNA methylation changes that occur at the Csf1r locus during macrophage maturation in the presence or absence of activated PKA. Murine bone marrow cells were matured to macrophages by incubating cells with CSF-1-containing conditioned medium for up to 6 days in the presence or absence of the PKA agonist 6-bnz-cAMP. DNA methylation of Csf1r promoter and enhancer regions was assayed by bisulphite pyrosequencing. DNA methylation of Csf1r decreased during normal macrophage maturation in concert with an increase in Csf1r mRNA expression. Treatment with the PKA agonist inhibited Csf1r mRNA and protein expression, and increased DNA methylation at the Csf1r promoter. This was associated with decreased binding of the transcription factor PU.1 to the Csf1r promoter. Treatment with the PKA agonist inhibited the responsiveness of macrophages to CSF-1. Levels of endogenous PKA activity decreased during normal macrophage maturation, suggesting that attenuation of this signalling pathway contributes to the increase in CSF1R expression during macrophage maturation. Together, these results demonstrate that macrophage maturation is accompanied by Csf1r hypomethylation, and illustrates for the first time the ability of PKA to increase Csf1r DNA methylation.

Induction of chemoresistance by all-trans retinoic acid via a noncanonical signaling in multiple myeloma cells

Despite the successful application of all-trans retinoic acid (ATRA) in multiple myeloma treatment, ATRA-induced chemoresistance in the myeloma patients is very common in clinic. In this study, we evaluated the effect of ATRA on the expression of apurinic endonuclease/redox factor-1 (Ape/Ref-1) in the U266 and RPMI-8226 myeloma cells to explore the chemoresistance mechanism involved. ATRA treatment induced upregulation of Ape/Ref-1 via a noncanonical signaling pathway, leading to enhanced pro-survival activity counteracting melphalan (an alkylating agent). ATRA rapidly activated p38-MSK (mitogen- and stress activated protein kinase) cascade to phosphorylate cAMP response element-binding protein (CREB). Phosphorylated CREB was recruited to the Ape/Ref-1 promoter to evoke the gene expression. The stimulation of ATRA on Ape/Ref-1 expression was attenuated by either p38-MSK inhibitors or overexpression of dominant-negative MSK1 mutants. Moreover, ATRA-mediated Ape/Ref-1 upregulation was correlated with histone modification and activation of CBP/p300, an important cofactors for CREB transcriptional activity. C646, a competitive CBP/p300 inhibitor, abolished the upregulation of Ape/Ref-1 induced by ATRA. Intriguingly, CBP rather than p300 played a dominant role in the expression of Ape/Ref-1. Hence, our study suggests the existence of a noncanonical mechanism involving p38-MSK-CREB cascade and CBP induction to mediate ATRA-induced Ape/Ref-1 expression and acquired chemoresistance in myeloma cells.

Social stress up-regulates inflammatory gene expression in the leukocyte transcriptome via β-adrenergic induction of myelopoiesis

Across a variety of adverse life circumstances, such as social isolation and low socioeconomic status, mammalian immune cells have been found to show a conserved transcriptional response to adversity (CTRA) involving increased expression of proinflammatory genes. The present study examines whether such effects might stem in part from the selective up-regulation of a subpopulation of immature proinflammatory monocytes (Ly-6c(high) in mice, CD16(-) in humans) within the circulating leukocyte pool. Transcriptome representation analyses showed relative expansion of the immature proinflammatory monocyte transcriptome in peripheral blood mononuclear cells from people subject to chronic social stress (low socioeconomic status) and mice subject to repeated social defeat. Cellular dissection of the mouse peripheral blood mononuclear cell transcriptome confirmed these results, and promoter-based bioinformatic analyses indicated increased activity of transcription factors involved in early myeloid lineage differentiation and proinflammatory effector function (PU.1, NF-κB, EGR1, MZF1, NRF2). Analysis of bone marrow hematopoiesis confirmed increased myelopoietic output of Ly-6c(high) monocytes and Ly-6c(intermediate) granulocytes in mice subject to repeated social defeat, and these effects were blocked by pharmacologic antagonists of β-adrenoreceptors and the myelopoietic growth factor GM-CSF. These results suggest that sympathetic nervous system-induced up-regulation of myelopoiesis mediates the proinflammatory component of the leukocyte CTRA dynamic and may contribute to the increased risk of inflammation-related disease associated with adverse social conditions.

Induction of long interspersed nucleotide element-1 (L1) retrotransposition by 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct

Long interspersed nucleotide element-1 (L1) is a retroelement comprising about 17% of the human genome, of which 80-100 copies are competent as mobile elements (retrotransposition: L1-RTP). Although the genetic structures modified during L1-RTP have been clarified, little is known about the cellular signaling cascades involved. Herein we found that 6-formylindolo[3,2-b]carbazole (FICZ), a tryptophan photoproduct postulated as a candidate physiological ligand of the aryl hydrocarbon receptor (AhR), induces L1-RTP. Notably, RNA-interference experiments combined with back-transfection of siRNA-resistant cDNAs revealed that the induction of L1-RTP by FICZ is dependent on AhR nuclear translocator-1 (ARNT1), a binding partner of AhR, and the activation of cAMP-responsive element-binding protein. However, our extensive analyses suggested that AhR is not required for L1-RTP. FICZ stimulated the interaction of the L1-encoded open reading frame-1 (ORF1) and ARNT1, and recruited ORF1 to chromatin in a manner dependent on the activation of mitogen-activated protein kinase. Along with our additional observations that the cellular cascades for FICZ-induced L1-RTP were different from those of L1-RTP triggered by DNA damage, we propose that the presence of the cellular machinery of ARNT1 mediates L1-RTP. A possible role of ARNT1-mediated L1-RTP in the adaptation of living organisms to environmental changes is discussed.

Synergistic Effects of Dehydroepiandrosterone and Retinoic Acid on Granulocytic Differentiation of Human Promyelocytic NB4 Cells

We report a novel effect of dehydroepiandrosterone (DHEA) on human granulocyte differentiation: DHEA enhances the all-trans-retinoic acid (ATRA)-induced differentiation of promyelocytic NB4 cells. DHEA (100 microM) significantly augmented the respiratory burst activity of NB4 cells treated with 1 nM ATRA, whereas DHEA alone did not induce respiratory burst activity. The protein and message expressions of p67phox, the gene for the dose-limiting component of phagocyte NADPH oxidase, were significantly enhanced by the coexistence of DHEA and ATRA. The protein expression of p47phox, another component of phagocyte NADPH oxidase, was also up-regulated by DHEA and ATRA. Moreover, the ATRA-induced increment of CCAAT/enhancer-binding protein beta (C/EBPbeta) and the reciprocal reduction in C/EBPUalpha expression were also potentiated by DHEA. In contrast, the expression of PU.1, a transcription factor reportedly involved in the basal expression of p67phox in monocytic cells, was only slightly up-regulated by DHEA and ATRA. Interestingly, DHEA sulfate (DHEAS), the sulfate ester of DHEA that exists in peripheral blood at a concentration approximately 3 orders of magnitude larger than that of DHEA, did not stimulate the ATRA-induced differentiation of NB4 cells. Thus, DHEA, but not DHEAS, plays important roles in synergy with ATRA during granulocyte differentiation of human promyelocytic NB4 cells.

PE-1/METS, an antiproliferative Ets repressor factor, is induced by CREB-1/CREM-1 during macrophage differentiation

The molecular mechanisms involved in regulating the balance between cellular proliferation and differentiation remain poorly understood. Members of the Ets-domain family of transcription factors are candidates for proteins that might differentially regulate cell cycle control and cell type-specific genes during the differentiation of myeloid progenitor cells. The Ets repressor PE-1/METS has been suggested to contribute to growth arrest during terminal macrophage differentiation by repressing Ets target genes involved in Ras-dependent proliferation. An important feature of this regulatory model is that PE-1/METS is itself induced by the program of macrophage differentiation elicited by M-CSF. Here, we present evidence that the PE-1/METS gene is a transcriptional target of the cyclic AMP response element-binding protein-1 (CREB-1). CREB-1 expression is dramatically up-regulated during macrophage differentiation and phosphorylation of CREB-1 and the related factor CREM-1 are stimulated by M-CSF in a SAPK2/p38-dependent manner. Chromatin immunoprecipitation experiments demonstrate that CREB-1/CREM-1 are recruited to the PE-1/METS promoter as well as to the promoters of other genes that are up-regulated during terminal macrophage differentiation. Overexpression of CREB-1 stimulates the activities of the PE-1/METS, and macrosialin promoters, while expression of a dominant negative form of CREB-1 during macrophage differentiation inhibits expression of the PE-1/METS and macrosialin genes. Inhibition of CREB function also results in reduced expression of CD54 and impaired cell adhesion. Taken together, these findings reveal new roles of CREB-1/CREM-1 as regulators of macrophage differentiation.

Lipid Droplet Formation in Human Myeloid NB4 Cells Stimulated by All Trans Retinoic Acid and Granulocyte Colony-Stimulating Factor: Possible Involvement of Peroxisome Proliferator-Activated Receptor .GAMMA

All trans retinoic acid (ATRA), a differentiation inducer for human myeloid NB4 cells, induced accumulation of lipid droplet as determined by positivity of Nile Red and Oil Red O in this cell line. Granulocyte colony-stimulating factor (G-CSF), although not having detectable effect by itself, exerted the additive effects on lipid droplet formation in NB4 cells when combined with ATRA. mRNA analysis for peroxisome proliferator-activated receptors (PPARs) revealed the initial transient downregulation followed by upregulation of the transcript for PPARgamma2, a master molecule for adipogenesis, and upregulation of PPARalpha. BADGE, a synthetic antagonist for PPARgamma, potently inhibited lipid droplet formation in NB4 cells stimulated by ATRA and/or G-CSF, but not the functional differentiation of the cells by ATRA and/or G-CSF. These results suggest that ATRA and G-CSF induce lipid droplet formation via certain PPARgamma-mediated specific mechanisms in human myeloid NB4 cells during functional differentiation.