Genes to Cells最新文献

This study used AlphaFold2 to investigate allosteric structural changes during c-Abl transactivation. Two structural forms of c-Abl (positions of SH2 and SH3 domains relative to kinase domain) and four active site types (types 0–3) were identified. Key interactions were predicted between the c-Crk SH3 domain (CrkSH3N) and four c-Abl PxxPxK/R motifs, particularly the 612–617 motif, where residue 617R plays a critical role. A residue-level analysis using our developed PAE_json2excel tool supported these findings. The predicted CrkSH3N position relative to c-Abl kinase domain varied. The c-Abl's active site displayed structural flexibility, categorized into four types on the basis of the presence or absence of residues 286E and 381D within the hydrogen-bond distance (3.2 Å) to the side-chain nitrogen of 271K: type 0 (neither 286E nor 381D), type 1 (286E present), type 2 (381D present), and type 3 (both 286E and 381D present). The Abl(SH3W110K) may coincide with the presence of type 1 in the c-Abl mutant alone and may display types 0–3 when complexed. Multiple interactions between CrkSH3N and c-Abl PxxPxK/R motifs may coincide with the presence of type 2. These findings provide new insights into the dynamic flexibility of the c-Abl active site during c-Abl transactivation.

Epigenetic regulation has fundamental roles in the maintenance and differentiation of neural stem cells as well as fate determination of neural lineage. Although neural differentiation is irreversible under physiological conditions, neural dedifferentiation into NSCs was observed under a damaged condition and in an aged brain. However, molecular mechanisms triggering neural fate regulation still remain to be elucidated. In this study, we show that a neural turnover in the adult brain is induced by the lack of JMJD3 using NSC-visualized neural JMJD3 deleted mice. In the JMJD3 deleted brain, a marked expansion of the Nestin-GFP positive population in the hippocampus was observed. Moreover, neurosphere assays revealed not only that JMJD3 deleted neurospheres showed a significantly higher self-renewal potential but also that Nestin-negative neural progenitors converted into a Nestin-positive state in the absence of JMJD3. Intriguingly, a combination of upregulation of Plagl2 and inhibition of Dylk1a as well as increased expressions of HMGAs were detected in the neurospheres lacking JMJD3, suggesting that the lack of JMJD3 could enhance rejuvenation of chromatin state. These results suggest that JMJD3 could be involved in the fate regulation of NSC/NPCs and could provide novel and important insights to promote neural repair and regeneration.

Neuroblastoma (NB) is a pediatric solid tumor originating from neural crest cells (NCCs), which are precursors of the sympathetic nervous system. MYCN amplification is a key factor contributing to the poor prognosis of NB. Anaplastic lymphoma kinase (ALK) alterations, including mutations and amplification, activate oncogenic signaling pathways that, together with MYCN amplification, further enhance tumor malignancy. NCCs are mainly classified into cranial NCCs (cNCCs) and trunk NCCs (tNCCs). Recent studies have reported NB development from tNCCs. However, the potential for NB development from cNCCs remains unexplored. In this study, we sought to mimic the tumorigenic process of NB by overexpressing MYCN and ALK in cNCCs derived from human induced pluripotent stem cells. These modified cells, when subcutaneously transplanted into immunodeficient mice, induced NB-like tumors and could thus be used as an in vitro model to study this tumor. Through extensive gene expression profiling and whole-exome sequencing of MYCN/ALK-induced clones, we identified key features of NB, including loss of NF1 and gain of 17q chromosome, which are critical for the development of malignant tumor. This model provides a valuable platform for studying the biological mechanisms driving ALK and MYCN amplification in NB derived from cNCCs.

Various molecular mechanisms in mature adipose tissue regulate whole-body physiology. In contrast, our current understanding of the development of this tissue is limited. The adult fat body (AFB) of Drosophila melanogaster is an emerging model for investigating the regulatory mechanisms of adipose tissue morphogenesis in vivo. AFB precursor cells undergo long-range directional and collective migration, proliferation, and homotypic adhesion, leading to the formation of monolayered AFB during metamorphosis. Here, we show that a Drosophila ADAM10 transmembrane metalloprotease, Kuzbanian (Kuz), is required for AFB morphogenesis in the precursor cells at the onset of adhesion. Histological and ultrastructural analyses revealed that the kuz knocked-down AFB cells formed multilayered structures or clumps, indicating that Kuz is essential for forming a single-cell-thick tissue sheet. Furthermore, adults with the morphologically altered AFB were supersensitive to starvation stress. Finally, we tested the hypothesis that Notch (N), a well-characterized substrate for Kuz or ADAM10, participates in AFB development, and found that knocking down N reduced AFB area coverage and made the adults less adaptive to starvation, similar to kuz knockdown. Altogether, our study highlights the critical role of Kuz in both the architecture and function of adult adipose tissue.

In epithelia, the desmosome is a cell–cell adhesive junction that anchors keratin filaments, thereby providing tissue integrity and mechanical resistance. Compared with considerable study on the desmosome in stratified epithelia, the mechanism of desmosome assembly and its functional roles remain incompletely understood in single-layered (simple) epithelia. Here we show that not only E-cadherin (E-cad) but also cadherin-6 (Cdh6) participates in recruitment of plakoglobin (Pg) from E-cad-containing cytoplasmic vesicles to cell–cell junctional regions during Ca²⁺-induced desmosome formation in simple epithelial MDCK cells. Subsequently, Pg cooperates with its related proteins plakophilin-2 (PKP2) and plakophilin-3 (PKP3), being recruited independently of E-cad/Cdh6, in junctional localization of the desmosomal cadherins desmoglein-2 (Dsg2) and desmocollin-2 (Dsc2) and the keratin-anchoring protein desmoplakin (DP), leading to functional keratin filament network formation. We also demonstrate that DP contributes to establishment of apical-basal cell polarity during cystogenesis in 3D culture of MDCK cells; depletion of DP results in formation of aberrant cysts containing cells with inverted polarity. Furthermore, the morphology of the nucleus in MDCK cells appears to be regulated by proper desmosome assembly and subsequent keratin network formation, because depletion of DP as well as that of E-cad/Cdh6, Pg, or PKP2/3 results in an irregular nuclear shape.

Heme synthesis has been considered essential, yet cancer cells paradoxically maintain high proliferation despite suppressing the pathway, with low expression of δ-aminolevulinate dehydratase (ALAD), the second enzyme of the pathway, which correlates with a poor prognosis. We propose that this suppression is a novel survival strategy to avoid toxic intermediates. Supporting this, we observed that cancer cells vigorously grow after the complete knockout of the essential ALAD gene, demonstrating the pathway's non-essentiality in malignancy. This ALAD suppression offers a dual advantage: evading growth suppression and promoting malignant phenotypes (epithelial–mesenchymal transition). Crucially, the toxicity induced by reactivating the pathway is not dependent on conventional porphyrin (PpIX) or reactive oxygen species, but rather on an unknown intermediate metabolite upstream of PpIX. Activating the heme pathway, for example, by administration of its starting substrate 5-aminolevulinic acid, provides the impetus for a new therapeutic approach to break this defense.

Var2CSA, a member of the Plasmodium falciparum erythrocyte membrane protein (PfEMP) family, specifically binds to various human cancer cells through oncofetal chondroitin sulfate (ofCS) expressed on cell surfaces. This unique binding property has raised considerable expectations for the application of var2CSA in cancer-targeted diagnostics and therapies. Baculovirus vectors, known for their safety compared with other viral vectors, possess the ability to introduce genes into human cancer cells. We previously constructed a baculovirus expressing var2CSA containing DBL1X-DBL3X domains (var2CSA-type baculovirus) and demonstrated enhanced gene transduction efficiency in cancer cells. In the present study, we sought to further improve gene delivery by generating two truncated var2CSA constructs: rVAR2 (DBL1X-ID2a) and ID1-DBL2Xb. The rVAR2 was successfully expressed in purified budded virions, whereas the ID1-DBL2Xb showed no detectable expression in budded virions due to very low protein levels in insect Sf9 cells. Functional evaluation in HepG2 hepatocellular carcinoma cells revealed that rVAR2-type baculovirus exhibited significantly higher gene delivery efficiency than the var2CSA-type baculovirus. These findings suggest that rVAR2-expressing baculovirus represents a promising tool for cancer gene therapy, where enhanced gene delivery efficiency is highly desirable.