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Reprogramming oncogenic signaling pathways to generate anti-tumor effects is a promising strategy for targeted cancer intervention, without significant off-target effects. Although reprogramming multi-oncoprotein interactions in a single signaling pathway axis has been shown to achieve sustained efficacy, there are several challenges that limit its clinical application. Herein, we transformed the mouse double minute 2 homolog (MDM2)-heat shock cognate protein 70 (HSC70) axis, a tumor-promoting pathway, into an activator of anti-tumor immunity using the Path-editor, an artificial selenoprotein. Once it enters the cell, Path-editor decomposes into PMI and PPI peptides: PMI inhibits MDM2-mediated p53 degradation and promotes HSC70 expression, while PPI binds to HSC70, enabling its ability to selectively degrade the programmed cell death ligand 1 (PD-L1). As a proof of concept, we tested its performance in microsatellite-stable (MSS) colorectal cancer, which typically displays limited responsiveness to immunotherapy. The results indicated that Path-editor effectively attenuated PD-L1 expression and reversed immune evasion in both CT26 allografts and humanized patient-derived tumor xenograft (PDX) models, thereby inhibiting tumor progression with high biosafety. Therefore, this paper introduces Path-editor as a paradigm for reprogramming oncogenic multi-protein pathways, utilizing selenium-assisted approach to achieve the rapid design of tumor-specific pathway editors. This strategy is expected to reverse immune escape in MSS colorectal cancer and treat difficult malignancies. [Display omitted] •Reprogram MDM2-HSC70 axis triggers antitumor immunity via selenoprotein Path-editor.•Dual-peptide Path-editor degrades PD-L1 and boosts p53 for overcoming immune evasion.•Selenium-driven pathway editing inhibits tumor growth with high biosafety in vivo.

Emerging evidence indicates that a subset of RNA molecules annotated as noncoding contain short open reading frames that code for small functional proteins called microproteins, which have largely been overlooked due to their small size. To search for cardiac-expressed microproteins, we used a comparative genomics approach and identified mitolamban (Mtlbn) as a highly conserved 47-amino acid transmembrane protein that is abundantly expressed in the heart. Mtlbn localizes specifically to the inner mitochondrial membrane where it interacts with subunits of complex III of the electron transport chain and with mitochondrial respiratory supercomplexes. Genetic deletion of Mtlbn in mice altered complex III assembly dynamics and reduced complex III activity. Unbiased metabolomic analysis of heart tissue from Mtlbn knockout mice further revealed an altered metabolite profile consistent with deficiencies in complex III activity. Cardiac-specific Mtlbn overexpression in transgenic (TG) mice induced cardiomyopathy with histological, biochemical, and ultrastructural pathologic features that contributed to premature death. Metabolomic analysis and biochemical studies indicated that hearts from Mtlbn TG mice exhibited increased oxidative stress and mitochondrial dysfunction. These findings reveal Mtlbn as a cardiac-expressed inner mitochondrial membrane microprotein that contributes to mitochondrial electron transport chain activity through direct association with complex III and the regulation of its assembly and function.

The roles of concealed microproteins encoded by long noncoding RNAs (lncRNAs) are gradually being exposed, but their functions in tumorigenesis are still largely unclear. Here, we identify and characterize a conserved 99-amino acid microprotein named KRASIM that is encoded by the putative lncRNA NCBP2-AS2. KRASIM is differentially expressed in normal hepatocytes and hepatocellular carcinoma (HCC) cells and can suppress HCC cell growth and proliferation. Mechanistically, KRASIM interacts and colocalizes with the KRAS protein in the cytoplasm of human HuH-7 hepatoma cells. More importantly, the overexpression of KRASIM decreases the KRAS protein level, leading to the inhibition of ERK signaling activity in HCC cells. These results demonstrate a novel microprotein repressor of the KRAS pathway for the first time and provide new insights into the regulatory mechanisms of oncogenic signaling and HCC therapy.

Buried seedlings undergo dramatic developmental transitions when they emerge from soil into sunlight. As central transcription factors suppressing light responses, PHYTOCHROME-INTERACTING FACTORs (PIFs) and ETHYLENE-INSENSITIVE 3 (EIN3) actively function in darkness and must be promptly repressed upon light to initiate deetiolation. Microproteins are evolutionarily conserved small single-domain proteins that act as posttranslational regulators in eukaryotes. Although hundreds to thousands of microproteins are predicted to exist in plants, their target molecules, biological roles, and mechanisms of action remain largely unknown. Here, we show that two microproteins, miP1a and miP1b (miP1a/b), are robustly stimulated in the dark-to-light transition. miP1a/b are primarily expressed in cotyledons and hypocotyl, exhibiting tissuespecific patterns similar to those of PIFs and EIN3. We demonstrate that PIFs and EIN3 assemble functional oligomers by self-interaction, while miP1a/b directly interact with and disrupt the oligomerization of PIFs and EIN3 by forming nonfunctional protein complexes. As a result, the DNA binding capacity and transcriptional activity of PIFs and EIN3 are predominantly suppressed. These biochemical findings are further supported by genetic evidence. miP1a/b positively regulate photomorphogenic development, and constitutively expressing miP1a/b rescues the delayed apical hook unfolding and cotyledon development of plants overexpressing PIFs and EIN3. Our study reveals that microproteins provide a temporal and negative control of the master transcription factors’ oligomerization to achieve timely developmental transitions upon environmental changes.

Background In the budding yeast Saccharomyces cerevisiae , the widespread adoption of ribosome profiling technology has allowed the discovery of evidence of transcription and translation for thousands of small proteins or microproteins whose importance was once disregarded. Both conserved and evolutionarily short-lived microproteins have demonstrated relevant involvement in biological functions. However, sequences exist in a broad spectrum of conservation. Here, we tested whether these small proteins in yeast detected by ribosome profiling technology have different properties across their levels of conservation, and how do these properties compare with the canonical small protein-coding sequences. Results Here, we applied a phylostratigraphic approach to peptides encoded by small open reading frames. We compared 20,023 ribo-seq-detected small peptides against annotated small proteins belonging to reference annotations on the basis of their respective conservation patterns. We identified 1134 unannotated microproteins that, despite their difficulty in being detected by methods other than ribosome profiling, display hallmarks of functionality such as conservation across many taxonomical levels and signals of purifying selection not dissimilar to those of canonical proteins of comparable length. Sequences that initially did not show evidence of belonging to any gene family were found to possess signals of homology traceable mostly at genus level when compared against noncoding regions and using TBLASTN, but also, to a lesser extent, to species belonging to the phyla Basidiomycota and Microsporidia. In addition, we show an analysis of the mutations behind the origin of small open reading frames exclusive to S. cerevisiae and identified changes in the initiation codon as the most common group of mutations when compared to Saccharomyces paradoxus , the closest species to S. cerevisiae. Conclusions Our work, by presenting robust analysis of the extended landscape of small proteins in yeast, suggests that small conserved sequences, either canonical or not, possess a shared evolutionary trajectory, as demonstrated by their properties. These results shed some light into the evolutionary processes behind the extended landscape of small proteins in yeast.

The APOE4 allele is recognized as a significant genetic risk factor to Alzheimer's disease (AD) and influences longevity. Nonetheless, some APOE4 carriers exhibit resistance to AD even in advanced age. Humanin, a mitochondrial‐derived peptide comprising 24 amino acids, has variants linked to cognitive resilience and longevity. Our research uncovered a unique humanin variant, P3S, specifically enriched in centenarians with the APOE4 allele. Through in silico analyses and subsequent experimental validation, we demonstrated a strong affinity between humanin P3S and APOE4. Utilizing an APOE4‐centric mouse model of amyloidosis (APP/PS1/APOE4), we observed that humanin P3S significantly attenuated brain amyloid‐beta accumulation compared to the wild‐type humanin. Transcriptomic assessments of mice treated with humanin P3S highlighted its potential mechanism involving the enhancement of amyloid beta phagocytosis. Additionally, in vitro studies corroborated humanin P3S's efficacy in promoting amyloid‐beta clearance. Notably, in the temporal cortex of APOE4 carriers, humanin expression is correlated with genes associated with phagocytosis. Our findings suggest a role of the rare humanin variant P3S, especially prevalent among individuals of Ashkenazi descent, in mitigating amyloid beta pathology and facilitating phagocytosis in APOE4‐linked amyloidosis, underscoring its significance in longevity and cognitive health among APOE4 carriers. A rare variant of the mitochondrial‐DNA‐encoded microprotein humanin interacts with APOE4 genotype in a small centenarian population. This humanin variant induces an amino acid change at its third residue from proline to serine (P3S). Humanin P3S binds to APOE4 and, upon administration to APP/PS1/APOE4 TR model mice, reduces amyloidosis.

Background Extremely high temperatures due to global warming are increasingly threatening crop production, and plants have evolved highly sophisticated mechanisms to respond to harsh environmental stresses and survive. At the translational level, how bread wheat responds to high temperatures remains largely unknown. Results We use ribosome profiling and high-throughput sequencing to investigate the translatome of wheat grains in response to high temperatures. Our study reveals that heat stress profoundly reshapes the translatomic landscapes, significantly affecting the translation of the mRNAs involved in the translation process, grain development, and heat stress response. A subset of the upstream open reading frames (uORFs) and RNA-binding proteins specifically link to their potential target with associated translatomic changes under high temperature. Divergent translation of duplicated genes is affected by the imbalanced expression of uORFs. Interestingly, the high temperature stimulates expression of small ORFs in long non-coding RNAs (lORFs). Microproteins encoded by key heat-responsive lORFs localize to cellular regions including the nucleus, endoplasmic reticulum, and P-body, and interact with heat shock proteins. Furthermore, the microprotein and RNA-binding protein contribute to the heat tolerance variation among wheat accessions. Conclusions This study provides new insights into the translational regulatory mechanism in wheat heat tolerance, accelerating genetic improvements in crops for optimal climate resilience.

A short open reading frame (sORFs) constitutes ≤ 300 bases, encoding a microprotein or sORF-encoded protein (SEP) which comprises ≤ 100 amino acids. Traditionally dismissed by genome annotation pipelines as meaningless noise, sORFs were found to possess coding potential with ribosome profiling (RIBO-Seq), which unveiled sORF-based transcripts at various genome locations. Nonetheless, the existence of corresponding microproteins that are stable and functional was little substantiated by experimental evidence initially. With recent advancements in multi-omics, the identification, validation, and functional characterisation of sORFs and microproteins have become feasible. In this review, we discuss the history and development of an emerging research field of sORFs and microproteins. In particular, we focus on an array of bioinformatics and OMICS approaches used for predicting, sequencing, validating, and characterizing these recently discovered entities. These strategies include RIBO-Seq which detects sORF transcripts via ribosome footprints, and mass spectrometry (MS)-based proteomics for sequencing the resultant microproteins. Subsequently, our discussion extends to the functional characterisation of microproteins by incorporating CRISPR/Cas9 screen and protein–protein interaction (PPI) studies. Our review discusses not only detection methodologies, but we also highlight on the challenges and potential solutions in identifying and validating sORFs and their microproteins. The novelty of this review lies within its validation for the functional role of microproteins, which could contribute towards the future landscape of microproteomics.

Background Small open reading frame (smORF) is open reading frame with a length of less than 100 codons. Microproteins, translated from smORFs, have been found to participate in a variety of biological processes such as muscle formation and contraction, cell proliferation, and immune activation. Although previous studies have collected and annotated a large abundance of smORFs, functions of the vast majority of smORFs are still unknown. It is thus increasingly important to develop computational methods to annotate the functions of these smORFs. Results In this study, we collected 617,462 unique smORFs from three studies. The expression of smORF RNAs was estimated by reannotated microarray probes. Using a speed-optimized correlation algorism, the functions of smORFs were predicted by their correlated genes with known functional annotations. After applying our method to 5 known microproteins from literatures, our method successfully predicted their functions. Further validation from the UniProt database showed that at least one function of 202 out of 270 microproteins was predicted. Conclusions We developed a method, smORFunction, to provide function predictions of smORFs/microproteins in at most 265 models generated from 173 datasets, including 48 tissues/cells, 82 diseases (and normal). The tool can be available at https://www.cuilab.cn/smorfunction .

Rice tocopherols, vitamin E compounds with antioxidant activity, play essential roles in human health. Even though the key genes involved in vitamin E biosynthetic pathways have been identified in plants, the genetic architecture of vitamin E content in rice grain remains unclear. A genome-wide association study (GWAS) on 179 genotypically diverse rice accessions with 34,323 SNP markers was conducted to detect QTLs that define total and α- tocopherol contents in rice grains. Total and α-tocopherol contents had a strong positive correlation and varied greatly across the accessions, ranging from 0.230-31.76 and 0.011-30.83 (μg/g), respectively. A total of 13 QTLs were identified, which were spread across five of the rice chromosomes. Among the 13 QTLs, 11 were considered major with phenotypic variation explained (PVE) greater than 10%. Twelve transcription factor (TF) genes, one microprotein (miP), and a transposon were found to be associated with the QTLs with putative roles in controlling tocopherol contents. Moreover, intracellular transport proteins, ABC transporters, nonaspanins, and SNARE, were identified as associated genes on chromosomes 1 and 8. In the vicinity of seven QTLs, protein kinases were identified as key signaling factors. Haplotype analysis revealed the QTLs qAlph1.1, qTot1.1, qAlph2.1, qAlph6.1, qTot6.1 , and qTot8.3 to have significant haplogroups. Quantitative RT-PCR validated the expression direction and magnitude of WRKY39 ( Os02g0265200 ), PIP5Ks ( Os08g0450800 ), and MADS59 ( Os06g0347700 ) in defining the major tocopherol contents. This study provides insights for ongoing biofortification efforts to breed and/or engineer vitamin E and antioxidant levels in rice and other cereals.