Cell reports最新文献

Pseudomonas syringae deploys a type III secretion system (T3SS) to deliver effector proteins to facilitate infection of plant cells; however, little is known about the direct interactions between T3SS components and plants. Here, we show that the specialized lytic transglycosylase (SLT) domain of P. syringae pv. tomato (Pst) DC3000 T3SS component HrpH is necessary for effector translocation. HrpH and its SLT domain induce host cell death and suppress pattern-triggered immunity (PTI). Transgenic hrpH-Arabidopsis plants exhibit decreased PTI responses and enhanced susceptibility to Pst DC3000ΔhrcQ-U. HrpH suppresses salicylic acid (SA) signaling and interacts with the E3 ubiquitin ligase ATL2 via its SLT domain, independent of its catalytic glutamate. ATL2 silencing indicates that ATL2 is required for basal resistance to bacterial infection, HrpH-triggered cell death, and suppressing MAPK and SA signaling. Our findings highlight that beyond serving as a lytic transglycosylase for effector delivery, HrpH targets an E3 ligase to modulate plant immunity.

Bacteria encode various DNA repair pathways to maintain genome integrity. However, the high degree of homology between DNA repair proteins or their domains hampers accurate identification. Here, we describe a stringent search strategy to identify DNA repair proteins and provide a systematic analysis of taxonomic distribution and co-occurrence of DNA repair proteins involved in RecA-dependent homologous recombination. Our results reveal the widespread presence of RecA, SSB, and RecOR proteins and phyla-specific distribution for the DNA repair complexes RecBCD, AddAB, and AdnAB. Furthermore, we report co-occurrences of DNA repair proteins with immune systems, including specific CRISPR-Cas subtypes, prokaryotic Argonautes (pAgos), dGTPases, GAPS2, and Wadjet. Our results imply that while certain DNA repair proteins and immune systems might function in conjunction, no immune system strictly relies on a specific DNA repair protein. As such, these findings offer an updated perspective on the distribution of DNA repair systems and their connection to immune systems in bacteria.

Development and maintenance of posture is essential behavior for overground mammalian locomotion. Dopamine and noradrenaline strongly influence locomotion, and their dysregulation initiates the development of motor impairments linked to neurodegenerative disease. However, the precise cellular and circuit mechanisms are not well defined. Here, we investigated the role of catecholaminergic neuromodulation in a mouse model of spinal muscular atrophy (SMA). SMA is characterized by severe motor dysfunction and postural deficits. We identify progressive loss of catecholaminergic synapses from spinal neurons that occur via non-cell autonomous mechanisms. Importantly, the selective restoration of survival motor neuron (SMN) in either catecholaminergic or serotonergic neurons is sufficient to correct impairments in locomotion. However, only combined SMN restoration in both catecholaminergic and serotonergic neurons or pharmacological treatment with l-dopa improve the severe postural deficits. These findings uncover the synaptic and cellular mechanisms responsible for the postural and motor symptoms in SMA and identify catecholaminergic neuromodulation as a potential therapeutic target.

The sub-ventricular zone (SVZ) is the most well-characterized neurogenic area in the mammalian brain. We previously showed that in 65% of patients with glioblastoma (GBM), the SVZ is a reservoir of cancer stem-like cells that contribute to treatment resistance and the emergence of recurrence. Here, we build a single-nucleus RNA-sequencing-based microenvironment landscape of the tumor mass and the SVZ of 15 patients and two histologically normal SVZ samples as controls. We identify a ZEB1-centered mesenchymal signature in the tumor cells of the SVZ. Moreover, the SVZ microenvironment is characterized by tumor-supportive microglia, which spatially coexist and establish crosstalks with tumor cells. Last, differential gene expression analyses, predictions of ligand-receptor and incoming/outgoing interactions, and functional assays reveal that the interleukin (IL)-1β/IL-1RAcP and Wnt-5a/Frizzled-3 pathways represent potential therapeutic targets in the SVZ. Our data provide insights into the biology of the SVZ in patients with GBM and identify potential targets of this microenvironment.

Tumor-draining lymph node dendritic cells (DCs) are poor stimulators of tumor antigen-specific CD4 T cells; however, the mechanism behind this defect is unclear. We now show that, in tumor-draining lymph node DCs, a large proportion of major histocompatibility complex class II (MHC-II) molecules retains the class II-associated invariant chain peptide (CLIP) fragment of the invariant chain bound to the MHC-II peptide binding groove due to reduced expression of the peptide editor H2-M and enhanced activity of the CLIP-generating proteinase cathepsin S. The net effect of this is that MHC-II molecules are unable to efficiently bind antigenic peptides. DCs in mice expressing a mutation in the invariant chain sequence that results in enhanced MHC-II-CLIP accumulation are poor stimulators of CD4 T cells and have diminished anti-tumor responses. Our data reveal a previously unknown mechanism of immune evasion in which enhanced expression of MHC-II-CLIP complexes on tumor-draining lymph node DCs limits MHC-II availability for tumor peptides.

Efficient prime editor (PE) delivery in vivo is critical for realizing its full potential in disease modeling and therapeutic correction. Although PE has been divided into two halves and delivered using dual adeno-associated viruses (AAVs), the editing efficiency at different gene loci varies among split sites. Furthermore, efficient split sites within Cas9 nickase (Cas9n) are limited. Here, we verified that 1115 (Asn) is an efficient split site when delivering PEs by dual AAVs. Additionally, we utilized a feature in which reverse transcriptase could be detached from the Cas9n and designed split sites in the first half of Cas9n. We found that split-PE-367 enabled high editing efficiency with Rma intein. To test the editing efficiency in vivo, split-ePE3-367 was packaged in AAV9 and achieved 17.5% precise editing in mice. Our findings establish an alternative split-PE architecture that enables robust editing efficiency, facilitating potential utility in disease modeling and correction.

Inosine monophosphate dehydrogenase 2 (IMPDH2) is highly expressed in human cancers; however, its physiological relevance under growth signaling remains to be investigated. Here, we show that IMPDH2 serine 122 is phosphorylated by CDK1, and this modification attenuates the catalytic activity of IMPDH2 for IMP oxidation and simultaneously represses its allosteric modulation by purine nucleotides. Fibroblast growth factor receptor (FGFR) signaling activation triggers IMPDH2-Ser122 dephosphorylation mediated by protein phosphatase 2A (PP2A), which is dependent on FGFR3-mediated PPP2R1A-Tyr261 phosphorylation leading to PPP2CA-PPP2R1A-IMPDH2 interactions. In turn, Ser122 dephosphorylation positively modulates IMPDH2 activity and contributes to guanine nucleotide synthesis and purine homeostasis, thereby facilitating S-phase completion and cell proliferation. Accordingly, IMPDH2 dephosphorylation is implicated in FGFR activation-enhanced tumorigenesis, and the low level of IMPDH2-Ser122 phosphorylation predicts the poor prognosis of patients with colorectal cancer. These findings illustrate a regulatory mechanism of purine nucleotide production under FGFR signaling, in which the oncogenic effect of reinforced IMPDH2 activity is underscored.

In male animals, spermatogonia in testes differentiate into sperm, one of the most diverse cell types across species. Despite the evolutionary retention of key genes essential for spermatogenesis, the extent of their conservation remains unclear. To explore the genetic basis of spermatogenesis under strong selective pressure, we compare single-cell RNA sequencing (scRNA-seq) datasets from the testes of humans, mice, and fruit flies. Our analysis identifies conserved genes involved in key molecular programs, such as post-transcriptional regulation, meiosis, and energy metabolism. We perform gene knockout experiments of 20 candidate genes, three of which, when mutated in fruit flies, result in reduced male fertility, emphasizing the conservation of sperm centriole and steroid lipid processes across mammals and Drosophila. Additionally, deep-learning analysis uncovers potential transcriptional mechanisms driving gene-expression evolution. These findings establish a core genetic foundation for spermatogenesis, offering insights into sperm-phenotype evolution and the underlying mechanisms of male infertility.

Complexes that control mRNA stability and translation promote timely cell-state transitions during differentiation by ensuring appropriate expression patterns of key developmental regulators. The Drosophila RNA-binding protein brain tumor (Brat) promotes the degradation of target transcripts during the maternal-to-zygotic transition in syncytial embryos and uncommitted intermediate neural progenitors (immature INPs). We identify ubiquitin-specific protease 5 (Usp5) as a candidate Brat interactor essential for the degradation of Brat target mRNAs. Usp5 promotes the formation of the Brat-deadenylase pre-complex in mitotic neural stem cells (neuroblasts) by facilitating Brat interactions with the scaffolding components of deadenylase complexes. The adaptor protein Miranda binds the RNA-binding domain of Brat, limiting its ability to bind target mRNAs in mitotic neuroblasts. Cortical displacement of Miranda activates Brat-deadenylase complex activity in immature INPs. We propose that the assembly of an enzymatically inactive and RNA-binding-deficient pre-complex poises mRNA degradation machineries for rapid activation, driving timely developmental transitions.

Aberrant N⁶-methyladenosine (m⁶A) modification on mRNA results in dysregulated mRNA translation and cancer progression; however, the role of m⁶A modification on rRNA remains unclear in cancers. Here, we show that ZCCHC4 and its mediated m⁶A modification on 28S rRNA are upregulated in various cancers and correlated with poor survival. Functionally, ZCCHC4 promotes intrahepatic cholangiocarcinoma (ICC) progression via its catalytic activity. Mechanistically, tether of the N⁶-adenineMIase domain of ZCCHC4 to the m⁶A site on 28S rRNA facilitates the binding of the zf-GRF-containing domain to eIF3G in the translation initiation complex and the binding of zf-DHHC-containing domain to the 3' UTR of mRNA, therefore facilitating mRNA circularization and translation. Further analysis reveals that HPD mediates ZCCHC4's functions on tyrosine catabolism and ICC progression, and targeting HPD inhibits ICC progression in vivo. Overall, our findings uncover insights underlying mRNA translation control and provide a molecular basis for targeting the ZCCHC4-HPD axis in ICC.