The functions and mechanisms of prefoldin complex and prefoldin-subunits

Quantitative proteome dynamics across embryogenesis in a model chordate

The evolution of gene expression programs underlying the development of vertebrates remains poorly characterized. Here, we present a comprehensive proteome atlas of the model chordate Ciona, covering eight developmental stages and ∼7,000 translated genes, accompanied by a multi-omics analysis of co-evolution with the vertebrate Xenopus. Quantitative proteome comparisons argue against the widely held hourglass model, based solely on transcriptomic profiles, whereby peak conservation is observed during mid-developmental stages. Our analysis reveals maximal divergence at these stages, particularly gastrulation and neurulation. Together, our work provides a valuable resource for evaluating conservation and divergence of multi-omics profiles underlying the diversification of vertebrates.

Comparative proteomic analysis of renal tissue of normotensive and hypertensive rats

Comparative proteomic analysis of kidney tissue from normotensive (WKY) and spontaneously hypertensive (SHR) rats revealed quantitative and qualitative changes in renal proteins. The number of renal proteins specific for WKY rats (blood pressure 110-120 mm Hg) was 13-16. There were 20-24 renal proteins specific for SHR (blood pressure 180 mm Hg and more). The total number of identified renal proteins common for both rat strains included 972-975 proteins. A pairwise comparison of all possible (SHR-WKY) variants identified 8 proteins specific only for normotensive (WKY) animals, and 7 proteins specific only for hypertensive ones (SHR). Taking into consideration their biological roles, the lack of some enzyme proteins in hypertensive rats (for example, biliverdin reductase A) reduces the production of molecules exhibiting antihypertensive properties, while the appearance of others (e.g. betaine-homocysteine S-methyltransferase 2, septin 2, etc.) can be interpreted as a compensatory reaction. Renal proteins with altered relative content (with more than 2.5-fold change) accounted for no more than 5% of all identified proteins. Among the proteins with an increased relative content in hypertensive animals, the largest group consisted of proteins involved in the processes of energy generation and carbohydrate metabolism, as well as antioxidant and protective proteins. In the context of the development of hypertension, the identified relative changes can apparently be considered compensatory. Among the proteins with the most pronounced decrease in the relative content in hypertensive rats, the dramatic reduction in acyl-CoA medium-chain synthetase-3 (ACSM3) appears to make an important contribution to the development of renal pathology in these animals.

Model of the external force field for the protein folding process-the role of prefoldin

Introduction: The protein folding process is very sensitive to environmental conditions. Many possibilities in the form of numerous pathways for this process can-if an incorrect one is chosen-lead to the creation of forms described as misfolded. The aqueous environment is the natural one for the protein folding process. Nonetheless, other factors such as the cell membrane and the presence of specific molecules (chaperones) affect this process, ensuring the correct expected structural form to guarantee biological activity. All these factors can be considered components of the external force field for this process. Methods: The fuzzy oil drop-modified (FOD-M) model makes possible the quantitative evaluation of the modification of the external field, treating the aqueous environment as a reference. The FOD-M model (tested on membrane proteins) includes the component modifying the water environment, allowing the assessment of the external force field generated by prefoldin. Results: In this work, prefoldin was treated as the provider of a specific external force field for actin and tubulin. The discussed model can be applied to any folding process simulation, taking into account the changed external conditions. Hence, it can help simulate the in silico protein folding process under defined external conditions determined by the respective external force field. In this work, the structures of prefoldin and protein folded with the participation of prefoldin were analyzed. Discussion: Thus, the role of prefoldin can be treated as a provider of an external field comparable to other environmental factors affecting the protein folding process.

Prefoldin Subunits and Its Associate Partners: Conservations and Specificities in Plants

Prefoldins (PFDs) are ubiquitous co-chaperone proteins that originated in archaea during evolution and are present in all eukaryotes, including yeast, mammals, and plants. Typically, prefoldin subunits form hexameric PFD complex (PFDc) that, together with class II chaperonins, mediate the folding of nascent proteins, such as actin and tubulin. In addition to functioning as a co-chaperone in cytoplasm, prefoldin subunits are also localized in the nucleus, which is essential for transcription and post-transcription regulation. However, the specific and critical roles of prefoldins in plants have not been well summarized. In this review, we present an overview of plant prefoldin and its related proteins, summarize the structure of prefoldin/prefoldin-like complex (PFD/PFDLc), and analyze the versatile landscape by prefoldin subunits, from cytoplasm to nucleus regulation. We also focus the specific role of prefoldin-mediated phytohormone response and global plant development. Finally, we overview the emerging prefoldin-like (PFDL) subunits in plants and the novel roles in related processes, and discuss the next direction in further studies.

Microproteins-Discovery, structure, and function

Advances in proteogenomic technologies have revealed hundreds to thousands of translated small open reading frames (sORFs) that encode microproteins in genomes across evolutionary space. While many microproteins have now been shown to play critical roles in biology and human disease, a majority of recently identified microproteins have little or no experimental evidence regarding their functionality. Computational tools have some limitations for analysis of short, poorly conserved microprotein sequences, so additional approaches are needed to determine the role of each member of this recently discovered polypeptide class. A currently underexplored avenue in the study of microproteins is structure prediction and determination, which delivers a depth of functional information. In this review, we provide a brief overview of microprotein discovery methods, then examine examples of microprotein structures (and, conversely, intrinsic disorder) that have been experimentally determined using crystallography, cryo-electron microscopy, and NMR, which provide insight into their molecular functions and mechanisms. Additionally, we discuss examples of predicted microprotein structures that have provided insight or context regarding their function. Analysis of microprotein structure at the angstrom level, and confirmation of predicted structures, therefore, has potential to identify translated microproteins that are of biological importance and to provide molecular mechanism for their in vivo roles.

Dual RNA-seq to catalogue host and parasite gene expression changes associated with virulence of T. annulata-transformed bovine leukocytes: towards identification of attenuation biomarkers

The apicomplexan parasite Theileria annulata is transmitted by Hyalomma ticks and causes an acute lymphoproliferative disease that is invariably lethal in exotic cattle breeds. The unique ability of the schizont stage of T. annulata to transform infected leukocytes to a cancer-like phenotype and the simplicity of culturing and passaging T. annulata-transformed cells in vitro have been explored for live vaccine development by attenuating the transformed cells using lengthy serial propagation in vitro. The empirical in vivo evaluation of attenuation required for each batch of long-term cultured cells is a major constraint since it is resource intensive and raises ethical issues regarding animal welfare. As yet, the molecular mechanisms underlying attenuation are not well understood. Characteristic changes in gene expression brought about by attenuation are likely to aid in the identification of novel biomarkers for attenuation. We set out to undertake a comparative transcriptome analysis of attenuated (passage 296) and virulent (passage 26) bovine leukocytes infected with a Tunisian strain of T. annulata termed Beja. RNA-seq was used to analyse gene expression profiles and the relative expression levels of selected genes were verified by real-time quantitative PCR (RT-qPCR) analysis. Among the 3538 T. annulata genes analysed, 214 were significantly differentially expressed, of which 149 genes were up-regulated and 65 down-regulated. Functional annotation of differentially expressed T. annulata genes revealed four broad categories of metabolic pathways: carbon metabolism, oxidative phosphorylation, protein processing in the endoplasmic reticulum and biosynthesis of secondary metabolites. It is interesting to note that of the top 40 genes that showed altered expression, 13 were predicted to contain a signal peptide and/or at least one transmembrane domain, suggesting possible involvement in host-parasite interaction. Of the 16,514 bovine transcripts, 284 and 277 showed up-regulated and down-regulated expression, respectively. These were assigned to functional categories relevant to cell surface, tissue morphogenesis and regulation of cell adhesion, regulation of leucocyte, lymphocyte and cell activation. The genetic alterations acquired during attenuation that we have catalogued herein, as well as the accompanying in silico functional characterization, do not only improve understanding of the attenuation process, but can also be exploited by studies aimed at identifying attenuation biomarkers across different cell lines focusing on some host and parasite genes that have been highlighted in this study, such as bovine genes (CD69, ZNF618, LPAR3, and APOL3) and parasite genes such as TA03875.

Prefoldin 2 contributes to mitochondrial morphology and function

BACKGROUND

Prefoldin is an evolutionarily conserved co-chaperone of the tailless complex polypeptide 1 ring complex (TRiC)/chaperonin containing tailless complex 1 (CCT). The prefoldin complex consists of six subunits that are known to transfer newly produced cytoskeletal proteins to TRiC/CCT for folding polypeptides. Prefoldin function was recently linked to the maintenance of protein homeostasis, suggesting a more general function of the co-chaperone during cellular stress conditions. Prefoldin acts in an adenosine triphosphate (ATP)-independent manner, making it a suitable candidate to operate during stress conditions, such as mitochondrial dysfunction. Mitochondrial function depends on the production of mitochondrial proteins in the cytosol. Mechanisms that sustain cytosolic protein homeostasis are vital for the quality control of proteins destined for the organelle and such mechanisms among others include chaperones.

RESULTS

We analyzed consequences of the loss of prefoldin subunits on the cell proliferation and survival of Saccharomyces cerevisiae upon exposure to various cellular stress conditions. We found that prefoldin subunits support cell growth under heat stress. Moreover, prefoldin facilitates the growth of cells under respiratory growth conditions. We showed that mitochondrial morphology and abundance of some respiratory chain complexes was supported by the prefoldin 2 (Pfd2/Gim4) subunit. We also found that Pfd2 interacts with Tom70, a receptor of mitochondrial precursor proteins that are targeted into mitochondria.

CONCLUSIONS

Our findings link the cytosolic prefoldin complex to mitochondrial function. Loss of the prefoldin complex subunit Pfd2 results in adaptive cellular responses on the proteome level under physiological conditions suggesting a continuous need of Pfd2 for maintenance of cellular homeostasis. Within this framework, Pfd2 might support mitochondrial function directly as part of the cytosolic quality control system of mitochondrial proteins or indirectly as a component of the protein homeostasis network.

Discovery of Potential Protein Markers Associated with Quality Characteristics of Antarctic Krill (Euphausia superba) Surimi Gel

Antarctic krill are a consumption resource with great exploitation potential. However, the poor gel properties of Antarctic krill meat seriously limit its high-value application. In the present study, the quality characteristics and proteome changes of the κ-/ι-carrageenan-Antarctic krill surimi gel were systematically analyzed and compared. In addition, the transcriptome sequencing of Antarctic krill was carried out, which filled the gap in the Antarctic krill database. Higher molecular forces (disulfide bond and hydrophobic interaction) and the degree of network cross-linking significantly promoted the formation of κ/ι-carrageenan-Antarctic krill surimi compared to that of Antarctic krill surimi. This is the first study to investigate and map potential protein markers for quality characteristics of Antarctic krill surimi based on mass spectrometry-based label-free quantitative proteomics. The results could provide a theoretical reference for the quality control of Antarctic krill during application.

Systemic Blood Proteome Patterns Reflect Disease Phenotypes in Neovascular Age-Related Macular Degeneration

There is early evidence of extraocular systemic signals effecting function and morphology in neovascular age-related macular degeneration (nAMD). The prospective, cross-sectional BIOMAC study is an explorative investigation of peripheral blood proteome profiles and matched clinical features to uncover systemic determinacy in nAMD under anti-vascular endothelial growth factor intravitreal therapy (anti-VEGF IVT). It includes 46 nAMD patients stratified by the level of disease control under ongoing anti-VEGF treatment. Proteomic profiles in peripheral blood samples of every patient were detected with LC-MS/MS mass spectrometry. The patients underwent extensive clinical examination with a focus on macular function and morphology. In silico analysis includes unbiased dimensionality reduction and clustering, a subsequent annotation of clinical features, and non-linear models for recognition of underlying patterns. The model assessment was performed using leave-one-out cross validation. The findings provide an exploratory demonstration of the link between systemic proteomic signals and macular disease pattern using and validating non-linear classification models. Three main results were obtained: (1) Proteome-based clustering identifies two distinct patient subclusters with the smaller one (n = 10) exhibiting a strong signature for oxidative stress response. Matching the relevant meta-features on the individual patient's level identifies pulmonary dysfunction as an underlying health condition in these patients. (2) We identify biomarkers for nAMD disease features with Aldolase C as a putative factor associated with superior disease control under ongoing anti-VEGF treatment. (3) Apart from this, isolated protein markers are only weakly correlated with nAMD disease expression. In contrast, applying a non-linear classification model identifies complex molecular patterns hidden in a high number of proteomic dimensions determining macular disease expression. In conclusion, so far unconsidered systemic signals in the peripheral blood proteome contribute to the clinically observed phenotype of nAMD, which should be examined in future translational research on AMD.

Maintaining essential microtubule bundles in meter-long axons: a role for local tubulin biogenesis?

Axons are the narrow, up-to-meter long cellular processes of neurons that form the biological cables wiring our nervous system. Most axons must survive for an organism's lifetime, i.e. up to a century in humans. Axonal maintenance depends on loose bundles of microtubules that run without interruption all along axons. The continued turn-over and the extension of microtubule bundles during developmental, regenerative or plastic growth requires the availability of α/β-tubulin heterodimers up to a meter away from the cell body. The underlying regulation in axons is poorly understood and hardly features in past and contemporary research. Here we discuss potential mechanisms, particularly focussing on the possibility of local tubulin biogenesis in axons. Current knowledge might suggest that local translation of tubulin takes place in axons, but far less is known about the post-translational machinery of tubulin biogenesis involving three chaperone complexes: prefoldin, CCT and TBC. We discuss functional understanding of these chaperones from a range of model organisms including yeast, plants, flies and mice, and explain what is known from human diseases. Microtubules across species depend on these chaperones, and they are clearly required in the nervous system. However, most chaperones display a high degree of functional pleiotropy, partly through independent functions of individual subunits outside their complexes, thus posing a challenge to experimental studies. Notably, we found hardly any studies that investigate their presence and function particularly in axons, thus highlighting an important gap in our understanding of axon biology and pathology.

Functional Characterization of a Phf8 Processed Pseudogene in the Mouse Genome

Most pseudogenes are generated when an RNA transcript is reverse-transcribed and integrated into the genome at a new location. Pseudogenes are often considered as an imperfect and silent copy of a functional gene because of the accumulation of numerous mutations in their sequence. Here we report the presence of Pfh8-ps, a Phf8 retrotransposed pseudogene in the mouse genome, which has no disruptions in its coding sequence. We show that this pseudogene is mainly transcribed in testis and can produce a PHF8-PS protein in vivo. As the PHF8-PS protein has a well-conserved JmjC domain, we characterized its enzymatic activity and show that PHF8-PS does not have the intrinsic capability to demethylate H3K9me2 in vitro compared to the parental PHF8 protein. Surprisingly, PHF8-PS does not localize in the nucleus like PHF8, but rather is mostly located at the cytoplasm. Finally, our proteomic analysis of PHF8-PS-associated proteins revealed that PHF8-PS interacts not only with mitochondrial proteins, but also with prefoldin subunits (PFDN proteins) that deliver unfolded proteins to the cytosolic chaperonin complex implicated in the folding of cytosolic proteins. Together, our findings highlighted PHF8-PS as a new pseudogene-derived protein with distinct molecular functions from PHF8.

The unconventional prefoldin RPB5 interactor mediates the gravitropic response by modulating cytoskeleton organization and auxin transport in Arabidopsis

Gravity-induced root curvature involves the asymmetric distribution of the phytohormone auxin. This response depends on the concerted activities of the auxin transporters such as PIN-FORMED (PIN) proteins for auxin efflux and AUXIN RESISTANT 1 (AUX1) for auxin influx. However, how the auxin gradient is established remains elusive. Here we identified a new mutant with a short root, strong auxin distribution in the lateral root cap and an impaired gravitropic response. The causal gene encoded an Arabidopsis homolog of the human unconventional prefoldin RPB5 interactor (URI). AtURI interacted with prefoldin 2 (PFD2) and PFD6, two β-type PFD members that modulate actin and tubulin patterning in roots. The auxin reporter DR5_rev :GFP showed that asymmetric auxin redistribution after gravistimulation is disordered in aturi-1 root tips. Treatment with the endomembrane protein trafficking inhibitor brefeldin A indicated that recycling of the auxin transporter PIN2 is disrupted in aturi-1 roots as well as in pfd mutants. We propose that AtURI cooperates with PFDs to recycle PIN2 and modulate auxin distribution.

A distinct P-body-like granule is induced in response to the disruption of microtubule integrity in Saccharomyces cerevisiae

The Processing-body (P-body) is a conserved membraneless organelle that has been implicated in the storage and/or decay of mRNAs. Although P-bodies have been shown to be induced by a variety of conditions, the mechanisms controlling their assembly and their precise physiological roles in eukaryotic cells are still being worked out. In this study, we find that a distinct subtype of P-body is induced in response to conditions that disrupt microtubule integrity in the budding yeast, Saccharomyces cerevisiae. For example, treatment with the microtubule-destabilizing agent, benomyl, led to the induction of these novel ribonucleoprotein (RNP) granules. A link to microtubules had been noted previously and the observations here extend our understanding by demonstrating that the induced foci differ from traditional P-bodies in a number of significant ways. These include differences in overall granule morphology, protein composition and the manner in which their induction is regulated. Of particular note, several key P-body constituents are absent from these Benomyl-Induced Granules (BIGs), including the Pat1 protein that is normally required for efficient P-body assembly. However, these novel RNP structures still contain many known P-body proteins and exhibit similar hallmarks of a liquid-like compartment. In all, the data suggest that the disruption of microtubule integrity leads to the formation of a novel type of P-body granule that may have distinct biological activities in the cell. Future work will aim to identify the biological activities of these BIGs and to determine, in turn, whether these P-body-like granules have any role in the regulation of microtubule dynamics.

Cross-species transcriptomic signatures identify mechanisms related to species sensitivity and common responses to nanomaterials

Physico-chemical characteristics of engineered nanomaterials are known to be important in determining the impact on organisms but effects are equally dependent upon the characteristics of the organism exposed. Species sensitivity may vary by orders of magnitude, which could be due to differences in the type or magnitude of the biochemical response, exposure or uptake of nanomaterials. Synthesizing conclusions across studies and species is difficult as multiple species are not often included in a study, and differences in batches of nanomaterials, the exposure duration and media across experiments confound comparisons. Here three model species, Danio rerio, Daphnia magna and Chironomus riparius, that differ in sensitivity to lithium cobalt oxide nanosheets are found to differ in immune-response, iron-sulfur protein and central nervous system pathways, among others. Nanomaterial uptake and dissolution does not fully explain cross-species differences. This comparison provides insight into how biomolecular responses across species relate to the varying sensitivity to nanomaterials.

Secreted Amyloid Precursor Protein Alpha, a Neuroprotective Protein in the Brain Has Widespread Effects on the Transcriptome and Proteome of Human Inducible Pluripotent Stem Cell-Derived Glutamatergic Neurons Related to Memory Mechanisms

Secreted amyloid precursor protein alpha (sAPPα) processed from a parent human brain protein, APP, can modulate learning and memory. It has potential for development as a therapy preventing, delaying, or even reversing Alzheimer’s disease. In this study a comprehensive analysis to understand how it affects the transcriptome and proteome of the human neuron was undertaken. Human inducible pluripotent stem cell (iPSC)-derived glutamatergic neurons in culture were exposed to 1 nM sAPPα over a time course and changes in the transcriptome and proteome were identified with RNA sequencing and Sequential Window Acquisition of All THeoretical Fragment Ion Spectra-Mass Spectrometry (SWATH-MS), respectively. A large subset (∼30%) of differentially expressed transcripts and proteins were functionally involved with the molecular biology of learning and memory, consistent with reported links of sAPPα to memory enhancement, as well as neurogenic, neurotrophic, and neuroprotective phenotypes in previous studies. Differentially regulated proteins included those encoded in previously identified Alzheimer’s risk genes, APP processing related proteins, proteins involved in synaptogenesis, neurotransmitters, receptors, synaptic vesicle proteins, cytoskeletal proteins, proteins involved in protein and organelle trafficking, and proteins important for cell signalling, transcriptional splicing, and functions of the proteasome and lysosome. We have identified a complex set of genes affected by sAPPα, which may aid further investigation into the mechanism of how this neuroprotective protein affects memory formation and how it might be used as an Alzheimer’s disease therapy.

Prefoldin Function in Cellular Protein Homeostasis and Human Diseases

Cellular functions are largely performed by proteins. Defects in the production, folding, or removal of proteins from the cell lead to perturbations in cellular functions that can result in pathological conditions for the organism. In cells, molecular chaperones are part of a network of surveillance mechanisms that maintains a functional proteome. Chaperones are involved in the folding of newly synthesized polypeptides and assist in refolding misfolded proteins and guiding proteins for degradation. The present review focuses on the molecular co-chaperone prefoldin. Its canonical function in eukaryotes involves the transfer of newly synthesized polypeptides of cytoskeletal proteins to the tailless complex polypeptide 1 ring complex (TRiC/CCT) chaperonin which assists folding of the polypeptide chain in an energy-dependent manner. The canonical function of prefoldin is well established, but recent research suggests its broader function in the maintenance of protein homeostasis under physiological and pathological conditions. Interestingly, non-canonical functions were identified for the prefoldin complex and also for its individual subunits. We discuss the latest findings on the prefoldin complex and its subunits in the regulation of transcription and proteasome-dependent protein degradation and its role in neurological diseases, cancer, viral infections and rare anomalies.

Acute social isolation and regrouping cause short- and long-term molecular changes in the rat medial amygdala

Social isolation poses a severe mental and physiological burden on humans. Most animal models that investigate this effect are based on prolonged isolation, which does not mimic the milder conditions experienced by people in the real world. We show that in adult male rats, acute social isolation causes social memory loss. This memory loss is accompanied by significant changes in the expression of specific mRNAs and proteins in the medial amygdala, a brain structure that is crucial for social memory. These changes particularly involve the neurotrophic signaling and axon guidance pathways that are associated with neuronal network remodeling. Upon regrouping, memory returns, and most molecular changes are reversed within hours. However, the expression of some genes, especially those associated with neurodegenerative diseases remain modified for at least a day longer. These results suggest that acute social isolation and rapid resocialization, as experienced by millions during the COVID-19 pandemic, are sufficient to induce significant changes to neuronal networks, some of which may be pathological.

CoRe: a robustly benchmarked R package for identifying core-fitness genes in genome-wide pooled CRISPR-Cas9 screens

BACKGROUND

CRISPR-Cas9 genome-wide screens are being increasingly performed, allowing systematic explorations of cancer dependencies at unprecedented accuracy and scale. One of the major computational challenges when analysing data derived from such screens is to identify genes that are essential for cell survival invariantly across tissues, conditions, and genomic-contexts (core-fitness genes), and to distinguish them from context-specific essential genes. This is of paramount importance to assess the safety profile of candidate therapeutic targets and for elucidating mechanisms involved in tissue-specific genetic diseases.

RESULTS

We have developed CoRe: an R package implementing existing and novel methods for the identification of core-fitness genes (at two different level of stringency) from joint analyses of multiple CRISPR-Cas9 screens. We demonstrate, through a fully reproducible benchmarking pipeline, that CoRe outperforms state-of-the-art tools, yielding more reliable and biologically relevant sets of core-fitness genes.

CONCLUSIONS

CoRe offers a flexible pipeline, compatible with many pre-processing methods for the analysis of CRISPR data, which can be tailored onto different use-cases. The CoRe package can be used for the identification of high-confidence novel core-fitness genes, as well as a means to filter out potentially cytotoxic hits while analysing cancer dependency datasets for identifying and prioritising novel selective therapeutic targets.

A genetic approach reveals different modes of action of prefoldins

The prefoldin complex (PFDc) was identified in humans as a co-chaperone of the cytosolic chaperonin T-COMPLEX PROTEIN RING COMPLEX (TRiC)/CHAPERONIN CONTAINING TCP-1 (CCT). PFDc is conserved in eukaryotes and is composed of subunits PFD1-6, and PFDc-TRiC/CCT folds actin and tubulins. PFDs also participate in a wide range of cellular processes, both in the cytoplasm and in the nucleus, and their malfunction causes developmental alterations and disease in animals and altered growth and environmental responses in yeast and plants. Genetic analyses in yeast indicate that not all of their functions require the canonical complex. The lack of systematic genetic analyses in plants and animals, however, makes it difficult to discern whether PFDs participate in a process as the canonical complex or in alternative configurations, which is necessary to understand their mode of action. To tackle this question, and on the premise that the canonical complex cannot be formed if one subunit is missing, we generated an Arabidopsis (Arabidopsis thaliana) mutant deficient in the six PFDs and compared various growth and environmental responses with those of the individual mutants. In this way, we demonstrate that the PFDc is required for seed germination, to delay flowering, or to respond to high salt stress or low temperature, whereas at least two PFDs redundantly attenuate the response to osmotic stress. A coexpression analysis of differentially expressed genes in the sextuple mutant identified several transcription factors, including ABA INSENSITIVE 5 (ABI5) and PHYTOCHROME-INTERACTING FACTOR 4, acting downstream of PFDs. Furthermore, the transcriptomic analysis allowed assigning additional roles for PFDs, for instance, in response to higher temperature.

Pharmacological inhibition of HDAC1/3-interacting proteins induced morphological changes, and hindered the cell proliferation and migration of hepatocellular carcinoma cells

Liver diseases are particularly severe health problems, but the options available for preventing and treating them remain limited. Accumulating evidence has shown that there is altered expression of individual histone deacetylase (HDAC) family members in hepatocellular carcinoma cells. In a previous study, we have identified a set of proteins which interact with histone deacetylase 1 and 3 (HDAC1/3) in hepatocellular carcinoma cell lines HepG2 by proteomic approach. This study was designed to investigate the therapeutic potential and expression of HDAC1/3-interacting genes in a human hepatocellular carcinoma cell line (HepG2). Pharmacological and transcriptional inhibition of HDAC1/3 resulted in the suppression of cancer cell proliferation, change of cell morphology, and downregulation of HDAC1/3 genes in HepG2 cells. The pharmacological inhibition also resulted in inhibition of liver cancer cell migration by wound scratch assay. Taken together, the results from this study show that the upregulation of HDAC1/3 in hepatocellular carcinoma resulted in the overexpression of CNOT1, PFDN2/6, and HMG20B, and that these genes could serve as novel molecular targets in liver cancer.

Mapping Microproteins and ncRNA-Encoded Polypeptides in Different Mouse Tissues

Small open reading frame encoded peptides (SEPs), also called microproteins, play a vital role in biological processes. Plenty of their open reading frames are located within the non-coding RNA (ncRNA) range. Recent research has demonstrated that ncRNA-encoded polypeptides have essential functions and exist ubiquitously in various tissues. To better understand the role of microproteins, especially ncRNA-encoded proteins, expressed in different tissues, we profiled the proteomic characterization of five mouse tissues by mass spectrometry, including bottom-up, top-down, and de novo sequencing strategies. Bottom-up and top-down with database-dependent searches identified 811 microproteins in the OpenProt database. De novo sequencing identified 290 microproteins, including 12 ncRNA-encoded microproteins that were not found in current databases. In this study, we discovered 1,074 microproteins in total, including 270 ncRNA-encoded microproteins. From the annotation of these microproteins, we found that the brain contains the largest number of neuropeptides, while the spleen contains the most immunoassociated microproteins. This suggests that microproteins in different tissues have tissue-specific functions. These unannotated ncRNA-coded microproteins have predicted domains, such as the macrophage migration inhibitory factor domain and the Prefoldin domain. These results expand the mouse proteome and provide insight into the molecular biology of mouse tissues.