
シナプス内の主要な足場タンパク質PSD95は、2つのサブユニットからなるスーパーコンプレックスを形成し、個々のサブユニットが徐々に置き換わることで、長期的にその構造が維持されている。この過程は脳領域によって異なり、長期記憶の保持に重要な大脳皮質で最も遅い。


coremsg

The concept that dimeric protein complexes in synapses can sequentially replace their subunits has been a cornerstone of Francis Crick’s 1984 hypothesis, explaining how long-term memories could be maintained in the face of short protein lifetimes. However, it is unknown whether the subunits of protein complexes that mediate memory are sequentially replaced in the brain and if this process is linked to protein lifetime. We address these issues by focusing on supercomplexes assembled by the abundant postsynaptic scaffolding protein PSD95, which plays a crucial role in memory. We used single-molecule detection, super-resolution microscopy and MINFLUX to probe the molecular composition of PSD95 supercomplexes in mice carrying genetically encoded HaloTags, eGFP and mEos2. We found a major population of PSD95-containing supercomplexes comprised of two copies of PSD95, with a dominant 12.7 nm separation. Time-stamping of PSD95 subunits in vivo revealed that each PSD95 subunit was sequentially replaced over days and weeks. Comparison of brain regions showed subunit replacement was slowest in the cortex, where PSD95 protein lifetime is longest. Our findings reveal that protein supercomplexes within the postsynaptic density can be maintained by gradual replacement of individual subunits providing a mechanism for stable maintenance of their organization. Moreover, we extend Crick’s model by suggesting that synapses with slow subunit replacement of protein supercomplexes and long protein lifetimes are specialized for long-term memory storage and that these synapses are highly enriched in superficial layers of the cortex where long-term memories are stored.

### Competing Interest Statement

The authors have declared no competing interest.

*   SR
    :   super-resolution
    PALM
    :   photoactivation localization microscopy
    MINFLUX
    :   MINimal photon FLUXes
    TIRF
    :   total internal reflection fluorescence
    GFP
    :   green fluorescent protein
    LPL
    :   long protein lifetime
    SPL
    :   short protein lifetime

Sequential replacement of PSD95 subunits in postsynaptic supercomplexes is slowest in the cortex

シナプス内タンパク質の組織化と回転による分子スーパーコンプレックスの維持

title_rewrite


PDGFRα シグナル伝達は Srsf3 の転写結合を調節し、PI3K シグナル伝達と小胞体輸送を制御する。


Signaling through the platelet-derived growth factor receptor alpha (PDGFRα) plays a critical role in craniofacial development, as mutations in PDGFRA are associated with cleft lip/palate in humans and Pdgfra mutant mouse models display varying degrees of facial clefting. Phosphatidylinositol 3-kinase (PI3K)/Akt is the primary effector of PDGFRα signaling during skeletal development in the mouse. We previously demonstrated that Akt phosphorylates the RNA-binding protein serine/arginine-rich splicing factor 3 (Srsf3) downstream of PI3K-mediated PDGFRα signaling in mouse embryonic palatal mesenchyme (MEPM) cells, leading to its nuclear translocation. We further showed that ablation of Srsf3 in the murine neural crest lineage results in severe midline facial clefting, due to defects in proliferation and survival of cranial neural crest cells, and widespread alternative RNA splicing (AS) changes. Here, we sought to determine the molecular mechanisms by which Srsf3 activity is regulated downstream of PDGFRα signaling to control AS of transcripts necessary for craniofacial development. We demonstrated via enhanced UV-crosslinking and immunoprecipitation (eCLIP) of MEPM cells that PDGF-AA stimulation leads to preferential binding of Srsf3 to exons and loss of binding to canonical Srsf3 CA-rich motifs. Through the analysis of complementary RNA-seq data, we showed that Srsf3 activity results in the preferential inclusion of exons with increased GC content and lower intron to exon length ratio. Moreover, we found that the subset of transcripts that are bound by Srsf3 and undergo AS upon PDGFRα signaling commonly encode regulators of PI3K signaling and early endosomal trafficking. Functional validation studies further confirmed that Srsf3 activity downstream of PDGFRα signaling leads to retention of the receptor in early endosomes and increases in downstream PI3K-mediated Akt signaling. Taken together, our findings reveal that growth factor-mediated phosphorylation of an RNA-binding protein underlies gene expression regulation necessary for mammalian craniofacial development.

### Competing Interest Statement

The authors have declared no competing interest.

PDGFRα signaling regulates Srsf3 transcript binding to affect PI3K signaling and endosomal trafficking

pdgfrα-シグナル伝達は-srsf3-転写結合を調節し-pi3k-シグナル伝達と小胞体輸送に影響を与える


PDGFRα シグナル伝達は Srsf3 転写結合を調節し、PI3K シグナル伝達と小胞体輸送に影響を与える



嗅上皮の単一細胞トランスクリプトーム解析により、新規の感覚神経細胞集団の発見、受容体発現の複雑性、受容体選択に関わる転写制御機構の解明を行った。


We have generated single cell transcriptomic atlases of vomeronasal organs (VNO) from juvenile and adult mice. Combined with spatial molecular imaging, we uncover a distinct, previously unidentified class of cells that express the vomeronasal receptors and a population of canonical olfactory sensory neurons in the VNO. High resolution trajectory and cluster analyses reveal the lineage relationship, spatial distribution of cell types, and a putative cascade of molecular events that specify the V1r, V2r, and OR lineages from a common stem cell population. The expression of vomeronasal and olfactory receptors follow power law distributions, but there is high variability in average expression levels between individual receptor and cell types. Substantial co-expression is found between receptors across clades, from different classes, and between olfactory and vomeronasal receptors, with nearly half from pairs located on the same chromosome. Interestingly, the expression of V2r, but not V1r, genes is associated with various transcription factors, suggesting distinct mechanisms of receptor choice associated with the two cell types. We identify association between transcription factors, surface axon guidance molecules, and individual VRs, thereby uncovering a molecular code that guides the specification of the vomeronasal circuitry. Our study provides a wealth of data on the development and organization of the accessory olfactory system at both cellular and molecular levels to enable a deeper understanding of vomeronasal system function.

### Competing Interest Statement

The authors have declared no competing interest.

Molecular, Cellular, and Developmental Organization of the Mouse Vomeronasal Organ at Single Cell Resolution

単一細胞解像度における-マウス嗅上皮の分子-細胞-発生学的組織化


単一細胞解像度における マウス嗅上皮の分子、細胞、発生学的組織化



IGHMBP2の欠失は細胞の翻訳を抑制し、統合ストレス応答を慢性的に活性化させる。


IGHMBP2 is a non-essential, superfamily 1 DNA/RNA helicase that is mutated in patients with rare neuromuscular diseases SMARD1 and CMT2S. IGHMBP2 is implicated in translational and transcriptional regulation via biochemical association with ribosomal proteins, pre-rRNA processing factors, and tRNA-related species. To uncover the cellular consequences of perturbing IGHMBP2, we generated full and partial IGHMBP2 deletion K562 cell lines. Using polysome profiling and a nascent protein synthesis assay, we found that IGHMBP2 deletion modestly reduces global translation. We performed Ribo-seq and RNA-seq and identified diverse gene expression changes due to IGHMBP2 deletion, including ATF4 upregulation. With recent studies showing the ISR can contribute to tRNA metabolism-linked neuropathies, we asked whether perturbing IGHMBP2 promotes ISR activation. We generated ATF4 reporter cell lines and found IGHMBP2 knockout cells demonstrate basal, chronic ISR activation. Our work expands upon the impact of IGHMBP2 in translation and elucidates molecular mechanisms that may link mutant IGHMBP2 to severe clinical phenotypes.

### Competing Interest Statement

The authors have declared no competing interest.

IGHMBP2 deletion suppresses translation and activates the integrated stress response

ighmbp2の欠失は翻訳を抑制し-統合ストレス応答を活性化する


IGHMBP2の欠失は翻訳を抑制し、統合ストレス応答を活性化する



スプライソソームの組み立てにおいて、外エクソン定義経路から内イントロン定義経路への切り替えのメカニズムが明らかになった。


Cryo-electron microscopy structures of cross-exon pre-B and B-like complexes contribute new insights into the molecular mechanisms that mediate the switch from a cross-exon to a cross-intron organized spliceosome.

Structural insights into the cross-exon to cross-intron spliceosome switch - Nature

人間型スプライソソームの組み立てにおける外エクソン-内イントロン切り替えの構造的洞察


PI3Kによるリン酸化を介してHSCBがTACC3を分解し、FOG1の核内移行を促進することで、赤血球造血とメガカリオポイエシスを制御する。


Erythropoiesis and megakaryopoiesis are stringently regulated by signaling pathways. However, the precise molecular mechanisms through which signaling pathways regulate key transcription factors controlling erythropoiesis and megakaryopoiesis remain partially understood. Herein, we identified heat shock cognate B (HSCB), which is well known for its iron-sulfur cluster delivery function, as an indispensable protein for friend of GATA 1 (FOG1) nuclear translocation during erythropoiesis of K562 human erythroleukemia cells and cord-blood-derived human CD34+CD90+ hematopoietic stem cells (HSCs), as well as during megakaryopoiesis of the CD34+CD90+ HSCs. Mechanistically, HSCB could be phosphorylated by phosphoinositol-3-kinase (PI3K) to bind with and mediate the proteasomal degradation of transforming acidic coiled-coil containing protein 3 (TACC3), which otherwise detained FOG1 in the cytoplasm, thereby facilitating FOG1 nuclear translocation. Given that PI3K is activated during both erythropoiesis and megakaryopoiesis, and that FOG1 is a key transcription factor for these processes, our findings elucidate an important, previously unrecognized iron-sulfur cluster delivery independent function of HSCB in erythropoiesis and megakaryopoiesis.

### Competing Interest Statement

The authors have declared no competing interest.

PI3K/HSCB axis facilitates FOG1 nuclear translocation to promote erythropoiesis and megakaryopoiesis

pi3k-hscb経路がfog1の核内移行を促進し-赤血球造血とメガカリオポイエシスを促進する


PI3K/HSCB経路がFOG1の核内移行を促進し、赤血球造血とメガカリオポイエシスを促進する



本研究は、分子表現の粒度を調整可能な新しい大規模な事前学習戦略「AdaMR」を提案する。AdaMRは、分子カノニカライゼーション事前学習タスクを通じて、SMILES表現の内在的な相関特徴を深く理解し、多様なタスクでの優れた性能を実現する。


分子表現の適応性を活用した統一的な事前学習戦略


等変量潜在拡散モデルを用いて、分子コンフォメーションの生成速度を大幅に向上させることができる。


分子コンフォメーションの生成を高速化する等変量潜在拡散モデルの段階的蒸留


非平衡分子テンプレート化ネットワークにおいて、個々の生成物の特異性と生成物分布のエントロピーは、経路の最大および最小自由エネルギー変化の関数によって上限および下限が決まる。最適なシステムは擬平衡状態であり、この非平衡分布を維持するための最小エントロピー生成率はない。


高効率な非平衡分子テンプレート化ネットワークにおける情報伝播は-わずかな消散を伴う擬平衡システムによって最適化される


高効率な非平衡分子テンプレート化ネットワークにおける情報伝播は、わずかな消散を伴う擬平衡システムによって最適化される
