Sirpα on tumor-associated myeloid cells restrains antitumor immunity in colorectal cancer independent of its interaction with CD47.

Immunosuppressive myeloid cells hinder immunotherapeutic efficacy in tumors, but the precise mechanisms remain undefined. Here, by performing single-cell RNA sequencing in colorectal cancer tissues, we found tumor-associated macrophages and granulocytic myeloid-derived suppressor cells increased most compared to their counterparts in normal tissue and displayed the highest immune-inhibitory signatures among all immunocytes. These cells exhibited significantly increased expression of immunoreceptor tyrosine-based inhibitory motif-bearing receptors, including SIRPA. Notably, Sirpa-/- mice were more resistant to tumor progression than wild-type mice. Moreover, Sirpα deficiency reprogramed the tumor microenvironment through expansion of TAM_Ccl8hi and gMDSC_H2-Q10hi subsets showing strong antitumor activity. Sirpa-/- macrophages presented strong phagocytosis and antigen presentation to enhance T cell activation and proliferation. Furthermore, Sirpa-/- macrophages facilitated T cell recruitment via Syk/Btk-dependent Ccl8 secretion. Therefore, Sirpα deficiency enhances innate and adaptive immune activation independent of expression of CD47 and Sirpα blockade could be a promising strategy to improve cancer immunotherapy efficacy.

SIRT3-dependent delactylation of cyclin E2 prevents hepatocellular carcinoma growth.

Lysine lactylation (Kla) is a recently discovered histone mark derived from metabolic lactate. The NAD+ -dependent deacetylase SIRT3, which can also catalyze removal of the lactyl moiety from lysine, is expressed at low levels in hepatocellular carcinoma (HCC) and has been suggested to be an HCC tumor suppressor. Here we report that SIRT3 can delactylate non-histone proteins and suppress HCC development. Using SILAC-based quantitative proteomics, we identify cyclin E2 (CCNE2) as one of the lactylated substrates of SIRT3 in HCC cells. Furthermore, our crystallographic study elucidates the mechanism of CCNE2 K348la delactylation by SIRT3. Our results further suggest that lactylated CCNE2 promotes HCC cell growth, while SIRT3 activation by Honokiol induces HCC cell apoptosis and prevents HCC outgrowth in vivo by regulating Kla levels of CCNE2. Together, our results establish a physiological function of SIRT3 as a delactylase that is important for suppressing HCC, and our structural data could be useful for the future design of activators.

GARP-mediated active TGF-ß1 induces bone marrow NK cell dysfunction in AML patients with early relapse post-allo-HSCT.

Relapse is a leading cause of death after allogeneic hematopoietic stem cell transplantation (allo-HSCT) for acute myeloid leukemia (AML). However, the underlying mechanisms remain poorly understood. Natural killer (NK) cells play a crucial role in tumor surveillance and cancer immunotherapy, and NK cell dysfunction has been observed in various tumors. Here, we performed ex vivo experiments to systematically characterize the mechanisms underlying the dysfunction of bone marrow-derived NK (BMNK) cells isolated from AML patients experiencing early relapse after allo-HSCT. We demonstrated that higher levels of active transforming growth factor ß1 (TGF-ß1) were associated with impaired effector function of BMNK cells in these AML patients. TGF-ß1 activation was induced by the overexpression of glycoprotein A repetitions predominant on the surface of CD4+ T cells. Active TGF-ß1 significantly suppressed mTORC1 activity, mitochondrial oxidative phosphorylation, the proliferation, and cytotoxicity of BMNK cells. Furthermore, pretreatment with the clinical stage TGF-ß1 pathway inhibitor, galunisertib, significantly restored mTORC1 activity, mitochondrial homeostasis, and cytotoxicity. Importantly, the blockade of the TGF-ß1 signaling improved the antitumor activity of NK cells in a leukemia xenograft mouse model. Thus, our findings reveal a mechanism explaining BMNK cell dysfunction and suggest that targeted inhibition of TGF-ß1 signaling may represent a potential therapeutic intervention to improve outcomes in AML patients undergoing allo-HSCT or NK cell-based immunotherapy.

Long-term forest restoration influences succession patterns of soil bacterial communities.

Microorganisms have a major influence on soil biogeochemical processes and vegetation establishment. However, their long-term succession patterns and short-term turnover are not well-understood in artificial forest ecosystems. The aim of the present study was to investigate the effects of stand ages and seasons on soil bacterial community in a chronosequence of Chinese Pinus massoniana plantations, in 3, 19, and 58-year-old plots. Soil physicochemical properties were measured in three stand ages between two seasons (dry-rainy). The soil bacterial community composition was determined by 16S rRNA Illumina HiSeq sequencing. The results showed that soil bacterial community diversity and structure significantly differed among three stand ages, but was not different between two seasons. The diversity of soil bacterial community increased with an increase in stand age. Proteobacteria, Acidobacteria, and Actinobacteria were the dominant phyla in the three stands. The soil bacterial community structure in all the stands was influenced by soil pH, available phosphorus content, and litter phosphorus content. With the accumulation of available phosphorus, the relative abundance of Acidobacteria decreased, while that of Proteobacteria increased. These shifts suggested that dominant microbial communities transitioned from oligotrophic to copiotrophic with increasing stand age. Extending rotation periods could increase soil bacterial diversity, and in turn help improving soil quality of P. massoniana plantations.

High-throughput sequencing-based assembly of chloroplast genomes of five pine tree species.

Pinus plants are the largest existing group of gymnosperms and one of the most highly differentiated taxa. Due to its huge ecological, economic, and scientific value, the genetic diversity and the relationship between the intraspecific evolution of Pinus plants have gained wide attention. In this study, the chloroplast genomes of several common pine trees in southwest and south China, including P. massoniana (masson pine), P. yunnanensis (yunnan pine), P. latteri (south asia pine), P. crassicorticea (la ya pine), and P. elliottii (slash pine), and entire cpDNA sequences were obtained. Characteristics including the structure, repeated sequence, and codon bias of the cpDNA for these five pine tree species were analyzed.

Histone variant H3.3-mediated chromatin remodeling is essential for paternal genome activation in mouse preimplantation embryos.

Derepression of chromatin-mediated transcriptional repression of paternal and maternal genomes is considered the first major step that initiates zygotic gene expression after fertilization. The histone variant H3.3 is present in both male and female gametes and is thought to be important for remodeling the paternal and maternal genomes for activation during both fertilization and embryogenesis. However, the underlying mechanisms remain poorly understood. Using our H3.3B-HA-tagged mouse model, engineered to report H3.3 expression in live animals and to distinguish different sources of H3.3 protein in embryos, we show here that sperm-derived H3.3 (sH3.3) protein is removed from the sperm genome shortly after fertilization and extruded from the zygotes via the second polar bodies (PBII) during embryogenesis. We also found that the maternal H3.3 (mH3.3) protein is incorporated into the paternal genome as early as 2 h postfertilization and is detectable in the paternal genome until the morula stage. Knockdown of maternal H3.3 resulted in compromised embryonic development both of fertilized embryos and of androgenetic haploid embryos. Furthermore, we report that mH3.3 depletion in oocytes impairs both activation of the Oct4 pluripotency marker gene and global de novo transcription from the paternal genome important for early embryonic development. Our results suggest that H3.3-mediated paternal chromatin remodeling is essential for the development of preimplantation embryos and the activation of the paternal genome during embryogenesis.