C9orf72 Dipeptide Repeats Impair the Assembly, Dynamics, and Function of Membrane-Less Organelles.

Expansion of a hexanucleotide repeat GGGGCC (G4C2) in C9ORF72 is the most common cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD). Transcripts carrying (G4C2) expansions undergo unconventional, non-ATG-dependent translation, generating toxic dipeptide repeat (DPR) proteins thought to contribute to disease. Here, we identify the interactome of all DPRs and find that arginine-containing DPRs, polyGly-Arg (GR) and polyPro-Arg (PR), interact with RNA-binding proteins and proteins with low complexity sequence domains (LCDs) that often mediate the assembly of membrane-less organelles. Indeed, most GR/PR interactors are components of membrane-less organelles such as nucleoli, the nuclear pore complex and stress granules. Genetic analysis in Drosophila demonstrated the functional relevance of these interactions to DPR toxicity. Furthermore, we show that GR and PR altered phase separation of LCD-containing proteins, insinuating into their liquid assemblies and changing their material properties, resulting in perturbed dynamics and/or functions of multiple membrane-less organelles.

mFOLFIRINOX versus mFOLFOX 6 as adjuvant treatment for high-risk stage III colon cancer - the FROST trial: study protocol for a multicenter, randomized controlled, phase II trial.

BACKGROUND: High-risk stage III colon cancer has a considerably poorer prognosis than stage II and low-risk stage III colon cancers. Nevertheless, most guidelines recommend similar adjuvant treatment approaches for all these stages despite the dearth of research focusing on high-risk stage III colon cancer and the potential for improved prognosis with intensive adjuvant treatment. Given the the proven efficacy of triplet chemotherapy in metastatic colorectal cancer treatment, the goal of this study is to evaluate the oncologic efficacy and safety of mFOLFIRINOX in comparison to those of the current standard of care, mFOLFOX 6, as an adjuvant treatment for patients diagnosed with high-risk stage III colon cancer after radical resection. METHODS: This multicenter, randomized (1:1), open-label, phase II trial will assess and compare the effectiveness and toxicity of mFOLFIRINOX and mFOLFOX 6 in patients with high-risk stage III colon cancer after radical resection. The goal of the trial is to enroll 312 eligible patients, from 11 institutes, aged between 20 and 70 years, with an Eastern Cooperative Oncology Group (ECOG) performance status of 0-2, or between 70 and 75 with an ECOG performance status of 0. Patients will be randomized into two arms - Arm A, the experimental arm, and Arm B, the reference arm - and will receive 12 cycles of mFOLFIRINOX and mFOLFOX 6 every 2 weeks, respectively. The primary endpoint of this study is the 3-year disease-free survival, and secondary endpoints include the 3-year overall survival and treatment toxicity. DISCUSSION: The Frost trial would help determine the oncologic efficacy and safety of adjuvant triplet chemotherapy for high-risk stage III colon cancers and ultimately improve prognoses. TRIAL REGISTRATION: ClinicalTrials.gov NCT05179889, registered on 17 December 2021.

Cultivation of human skin cells under physiological oxygen concentration modulates expression of skin significant genes and response to hydroxy acids.

Physiological oxygen concentration (physioxia) ranges from 1 to 8% in human tissues while many researchers cultivate mammalian cells under an atmospheric concentration of 21% (hyperoxia). Oxygen is one of the significant gases which functions in human cells including energy production in mitochondria, metabolism in peroxidase, and transcription of various genes in company with HIF (Hypoxia-inducible factors) in the nucleus. Thus, mammalian cell culture should be deliberated on the oxygen concentration to mimic in vivo physiology. Here, we studied if the cultivation of human skin cells under physiological conditions could affect skin significant genes in barrier functions and dermal matrix formation. We further examined that some representative active ingredients in dermatology such as glycolic acid, gluconolactone, and salicylic acid work in different ways depending on the oxygen concentration. Taken together, we present the importance of oxygen concentration in skin cell culture for proper screening of novel ingredients as well as the mechanistic study of skin cell regulation.

Impact of chlorogenic acid on modulation of significant genes in dermal fibroblasts and epidermal keratinocytes.

Chlorogenic acid is one of the most abundant polyphenols found in human diet. It is well-documented that chlorogenic acid has a significant impact on human cells, especially in the regulation of inflammation and metabolic processes. However, its role in regulating skin functions, especially with respect to the dermal collagen network or epidermal skin barrier, has not yet been elucidated. Here, we report that chlorogenic acid treatment can induce production of procollagen type I in human dermal fibroblast, Hs68 cell lines. Moreover, this treatment can stimulate upregulation of skin barrier genes, including the ones encoding filaggrin (FLG), involucrin (IVL), and envoplakin (EVPL), in epidermal keratinocytes. Chlorogenic acid also triggered a multifaceted response in the cytokine profile of keratinocytes. Therefore, we suggest that chlorogenic acid can be used to restore the impaired dermal matrix network as well as the epidermal skin barrier.

GGGGCC repeat expansion in C9orf72 compromises nucleocytoplasmic transport.

The GGGGCC (G4C2) repeat expansion in a noncoding region of C9orf72 is the most common cause of sporadic and familial forms of amyotrophic lateral sclerosis and frontotemporal dementia. The basis for pathogenesis is unknown. To elucidate the consequences of G4C2 repeat expansion in a tractable genetic system, we generated transgenic fly lines expressing 8, 28 or 58 G4C2-repeat-containing transcripts that do not have a translation start site (AUG) but contain an open-reading frame for green fluorescent protein to detect repeat-associated non-AUG (RAN) translation. We show that these transgenic animals display dosage-dependent, repeat-length-dependent degeneration in neuronal tissues and RAN translation of dipeptide repeat (DPR) proteins, as observed in patients with C9orf72-related disease. This model was used in a large-scale, unbiased genetic screen, ultimately leading to the identification of 18 genetic modifiers that encode components of the nuclear pore complex (NPC), as well as the machinery that coordinates the export of nuclear RNA and the import of nuclear proteins. Consistent with these results, we found morphological abnormalities in the architecture of the nuclear envelope in cells expressing expanded G4C2 repeats in vitro and in vivo. Moreover, we identified a substantial defect in RNA export resulting in retention of RNA in the nuclei of Drosophila cells expressing expanded G4C2 repeats and also in mammalian cells, including aged induced pluripotent stem-cell-derived neurons from patients with C9orf72-related disease. These studies show that a primary consequence of G4C2 repeat expansion is the compromise of nucleocytoplasmic transport through the nuclear pore, revealing a novel mechanism of neurodegeneration.

RNA-Binding Proteins and the Complex Pathophysiology of ALS.

Genetic analyses of patients with amyotrophic lateral sclerosis (ALS) have identified disease-causing mutations and accelerated the unveiling of complex molecular pathogenic mechanisms, which may be important for understanding the disease and developing therapeutic strategies. Many disease-related genes encode RNA-binding proteins, and most of the disease-causing RNA or proteins encoded by these genes form aggregates and disrupt cellular function related to RNA metabolism. Disease-related RNA or proteins interact or sequester other RNA-binding proteins. Eventually, many disease-causing mutations lead to the dysregulation of nucleocytoplasmic shuttling, the dysfunction of stress granules, and the altered dynamic function of the nucleolus as well as other membrane-less organelles. As RNA-binding proteins are usually components of several RNA-binding protein complexes that have other roles, the dysregulation of RNA-binding proteins tends to cause diverse forms of cellular dysfunction. Therefore, understanding the role of RNA-binding proteins will help elucidate the complex pathophysiology of ALS. Here, we summarize the current knowledge regarding the function of disease-associated RNA-binding proteins and their role in the dysfunction of membrane-less organelles.

Regulation of Gene Expression by Telomere Position Effect.

Many diseases that involve malignant tumors in the elderly affect the quality of human life; therefore, the relationship between aging and pathogenesis in geriatric diseases must be under-stood to develop appropriate treatments for these diseases. Recent reports have shown that epigenetic regulation caused by changes in the local chromatin structure plays an essential role in aging. This review provides an overview of the roles of telomere shortening on genomic structural changes during an age-dependent shift in gene expression. Telomere shortening is one of the most prominent events that is involved in cellular aging and it affects global gene expression through genome rearrangement. This review provides novel insights into the roles of telomere shortening in disease-affected cells during pathogenesis and suggests novel therapeutic approaches.

HNRNP A1 Promotes Lung Cancer Cell Proliferation by Modulating VRK1 Translation.

THeterogeneous nuclear ribonucleoprotein (HNRNP) A1 is the most abundant and ubiquitously expressed member of the HNRNP protein family. In recent years, it has become more evident that HNRNP A1 contributes to the development of neurodegenerative diseases. However, little is known about the underlying role of HNRNP A1 in cancer development. Here, we report that HNRNP A1 expression is significantly increased in lung cancer tissues and is negatively correlated with the overall survival of patients with lung cancer. Additionally, HNRNP A1 positively regulates vaccinia-related kinase 1 (VRK1) translation via binding directly to the 3' untranslated region (UTR) of VRK1 mRNA, thus increasing cyclin D1 (CCND1) expression by VRK1-mediated phosphorylation of the cAMP response element-binding protein (CREB). Furthermore, HNRNP A1 binding to the cis-acting region of the 3'UTR of VRK1 mRNA contributes to increased lung cancer cell proliferation. Thus, our study unveils a novel role of HNRNP A1 in lung carcinogenesis via post-transcriptional regulation of VRK1 expression and suggests its potential as a therapeutic target for patients with lung cancer.

The RNA-binding protein hnRNP Q represses translation of the clock gene Bmal1 in murine cells.

Most living creatures have a circadian rhythm that is generated by a precisely regulated transcriptional-translational feedback loop of clock genes. Brain and muscle ARNT-like 1 (BMAL1) is one of the core clock genes and transcription factors that represents a positive arm of this autoregulatory circadian clock system. Despite the indispensable role of BMAL1 in the circadian rhythm, the molecular mechanisms underlying translational control of BMAL1 are largely unknown. Here, using murine NIH-3T3 cells, gene constructs, and a variety of biochemical approaches, including RNAi- and luciferase reporter gene-based assays, along with immunoblotting, in vitro transcription, quantitative real-time PCR, and real-time bioluminescence experiments, we show that translation of Bmal1 is negatively regulated by an RNA-binding protein, heterogeneous nuclear ribonucleoprotein Q (hnRNP Q). Interestingly, we found that hnRNP Q rhythmically binds to a specific region of the Bmal1 mRNA 5' UTR and controls its time-dependent expression. Moreover, we demonstrate that knockdown of hnRNP Q modulates BMAL1 protein oscillation amplitude without affecting mRNA rhythmic patterns. Furthermore, hnRNP Q depletion increases the mRNA oscillation amplitudes of BMAL1-regulated target genes. Together, our results suggest that hnRNP Q plays a pivotal role in both Bmal1 translation and BMAL1-regulated gene expression.

PTBP1 Positively Regulates the Translation of Circadian Clock Gene, Period1.

Circadian oscillations of mRNAs and proteins are the main features of circadian clock genes. Among them, Period1 (Per1) is a key component in negative-feedback regulation, which shows a robust diurnal oscillation and the importance of circadian rhythm and translational regulation of circadian clock genes has been recognized. In the present study, we investigated the 5'-untranslated region (5'-UTR) of the mouse core clock gene, Per1, at the posttranscriptional level, particularly its translational regulation. The 5'-UTR of Per1 was found to promote its translation via an internal ribosomal entry site (IRES). We found that polypyrimidine tract-binding protein 1 (PTBP1) binds to the 5'-UTR of Per1 and positively regulates the IRES-mediated translation of Per1 without affecting the levels of Per1 mRNA. The reduction of PTBP1 level also decreased the endogenous levels of the PER1 protein but not of its mRNA. As for the oscillation of PER1 expression, the disruption of PTBP1 levels lowered the PER1 expression but not the phase of the oscillation. PTBP1 also changed the amplitudes of the mRNAs of other circadian clock genes, such as Cryptochrome 1 (Cry1) and Per3. Our results suggest that the PTBP1 is important for rhythmic translation of Per1 and it fine-tunes the overall circadian system.

Ultraviolet-C (UVC) ray acts as a synchronizing cue for circadian rhythm control in murine fibroblast.

Ultraviolet-C (UVC) electromagnetic radiation is the most damaging type of the UV radiation and causes many cellular and physiological responses. UVC has been using for sterilization and disinfection, and the risk of exposure to the UVC is increasing. Here, we determined the effect of the UVC on the cellular circadian clock system. UVC irradiation synchronized the biological clock system and induced time-dependent expression of clock genes including Clock, Cry1, and Per1. The rhythmic expression of clock genes is also followed by time-dependent mRNA degradation or non-canonical translation initiation of clock genes. Furthermore, we show a translocation of PERIOD1 (PER1) protein after UVC irradiation, which mediates the rhythmic feedback loop of clock genes. Our results suggest that UVC can synchronize the circadian clock system, and induces rhythmic expression of clock genes via time-dependent transcription, post-transcription, and post-translational modification.

Fubp1 supports the lactate-Akt-mTOR axis through the upregulation of Hk1 and Hk2.

Cells require energy for homeostatic activities, growth and division. By utilizing glucose as the main energy source, cells generate ATP and metabolic precursors through glycolysis and citric acid cycle. Although the oxidative phosphorylation can produce more ATP molecules from one molecule of glucose than glycolysis, rapidly growing cells primarily metabolize glucose via aerobic glycolysis. This aerobic glycolysis makes cells to uptake glucose at a higher rate and to efficiently convert glucose into the macromolecules required for new daughter cells. Recent evidence suggests that Fubp1 promotes cell proliferation and survival, and it is overexpressed in a variety of cancers. However, the role of Fubp1 in cellular metabolism remains unclear. In the present study, we demonstrated that Fubp1 upregulates the mRNA levels of two hexokinase genes, Hk1 and Hk2. We also found the positive correlation in mRNA expression between Fubp1 and both of hexokinase genes in several types of cancers. We suggest that Fubp1 contributes to cell survival through supporting lactate-Akt-mTOR axis.

Necessity of Genetic Evaluation of Metachronous Metastases of Colorectal Cancer: Quantitative Analysis of Genetic Discordance Between Metachronous Metastases and Radically Resected Primary Colorectal Cancers Using Next-Generation Sequencing.

BACKGROUND: Mutation analyses provide the basis of selecting an appropriate target agent for the treatment of metastatic colorectal cancer. However, metachronous metastases developed after the treatment of primary tumor could create significant opportunities for different genetic profiles relative to the primary tumors. OBJECTIVE: The purpose of this study was to assess the necessity of genetic evaluation of metachronous metastases; we performed a quantitative analysis of genetic discordance between metachronous metastases and radically resected primary colorectal cancers using next-generation sequencing. DESIGN: This was a retrospective study. SETTINGS: Patients from a single-institution tertiary care center were studied. PATIENTS: We enrolled 33 patients who underwent resection of metachronous metastases between January 2014 and December 2016, ≥6 months after radical resection of primary colorectal cancer and whose tissue was available for analysis. MAIN OUTCOME MEASURES: Tumor samples were analyzed by next-generation sequencing. The mutant allele frequency was analyzed to evaluate the proportion of mutations in the tumor tissue. RESULTS: The mutant allele frequency of KRAS in metachronous metastases was higher in 6 cases (mean difference =% 25.5% (range, 9.5%-58.0%)) and lower in 3 cases (mean difference = 9.3% (range, 8.0-10.0%) compared with each of their primary tumors. In 1 case, the KRAS mutant-type (mutant allele frequency = 22.6%) metachronous metastasis had developed from the KRAS wild-type primary tumor. LIMITATIONS: Tumor sample may not represent perfectly the whole tumor of the patient because of heterogeneity. CONCLUSIONS: Genetic discordance can exist between metachronous metastases and radically resected primary colorectal cancers. For appropriate target therapy, genetic evaluation of metachronous metastases needs to be considered when possible. See Video Abstract at http://links.lww.com/DCR/A932.

Feeding by common heterotrophic protists on the mixotrophic alga Gymnodinium smaydae (Dinophyceae), one of the fastest growing dinoflagellates.

Gymnodinium smaydae is one of the fastest growing dinoflagellates. However, its population dynamics are affected by both growth and mortality due to predation. Thus, feeding by common heterotrophic dinoflagellates Gyrodinium dominans, Gyrodinium moestrupii, Oblea rotunda, Oxyrrhis marina, and Polykrikos kofoidii, and the naked ciliate Pelagostrobilidium sp. on G. smaydae was investigated in the laboratory. Furthermore, growth and ingestion rates of O. marina, G. dominans, and Pelagostrobilidium sp. on G. smaydae in response to prey concentration were also determined. Oxyrrhis marina, G. dominans, G. moestrupii, and Pelagostrobilidium sp. were able to feed on G. smaydae, but P. kofoidii and O. rotunda did not feed on this dinoflagellate. The maximum growth rate of O. marina on G. smaydae was 0.411 per day. However, G. smaydae did not support the positive growth of Pelagostrobilidium sp. The maximum ingestion rates of O. marina and Pelagostrobilidium sp. on G. smaydae were 0.27 and 6.91 ng C · predator-1  · d-1 , respectively. At the given mean prey concentrations, the highest growth and ingestion rates of G. dominans on G. smaydae were 0.114 per day and 0.04 ng C · predator-1  · d-1 , respectively. The maximum growth and ingestion rates of O. marina on G. smaydae are lower than those on most of the other algal prey species. Therefore, O. marina may be an effective predator of G. smaydae, but G. smaydae may not be the preferred prey for supporting high growth of the predator in comparison to other species as inferred from a literature survey.

The Antitumor Natural Compound Falcarindiol Disrupts Neural Stem Cell Homeostasis by Suppressing Notch Pathway.

Neural stem cells (NSCs) are undifferentiated, multi-potent cells that can give rise to functional neurons and glial cells. The disruption in NSC homeostasis and/or the impaired neurogenesis lead to diverse neurological diseases, including depression, dementia, and neurodegenerative disorders. Falcarindiol (FAD) is a polyacetylene found in many plants, and FAD shows the cytotoxicity against breast cancers and colon cancers. However, there is no research on the consequence of FAD treatment in normal stem cells. Here, we suggest that FAD has anticancer roles against glioblastoma cells by inducing the differentiation of glioblastoma stem-like cells, as well as activating apoptosis pathway in glioblastoma cells. On the other hand, we also show that FAD has detrimental effects by disrupting the maintenance of normal NSCs and altering the balance between self-renewal and differentiation of NSCs.

Yihiella yeosuensis gen. et sp. nov. (suessiaceae, dinophyceae), a novel dinoflagellate isolated from the coastal waters of Korea.

A small (7-11 µm long) dinoflagellate with thin amphiesmal plates was isolated into culture from a water sample collected in coastal waters of Yeosu, southern Korea, and examined by LM, SEM, and TEM, and molecular analyses. The hemispheric episome was smaller than the hyposome. The nucleus was oval and situated from the central to the episomal region of the cell. A large yellowish-brown chloroplast was located at the end of the hyposome, and some small chloroplasts extended into the periphery of the episome. The dinoflagellate had a single elongated apical vesicle (EAV) and a type E eyespot, which are key characteristics of the family Suessiaceae. Unlike other genera in this family, it had two long furrow lines, one on the episome and the other on the hyposome, and encircling the dorsal, and lateral sides of the cell body. The pyrenoid lacked starch sheaths, but tubular invaginations into the pyrenoid matrix from the cytoplasm were observed. In the TEM, the dinoflagellate was observed to have cable-like structures (CLSs) near the eyespot but so far not observed in other dinoflagellates. The SSU rDNA sequences examined were 1.2%-5.1% different from those of other genera in the family Suessiaceae, whereas the LSU (D1-D3) rDNA sequences of this dinoflagellate were 15.1%-31.5% different. The dinoflagellate lacked a 51-bp fragment in domain D2 of the LSU rDNA, but it had an ~100-bp fragment in domain D2. This feature has been found previously only in the genera Leiocephalium and Polarella, two other genera of the Suessiaceae. The molecular phylogeny and sequence divergence based on SSU, and LSU rDNA indicate that the Korean dinoflagellate holds a taxonomically distinctive position and we consider it to be a new species in a new genus in the family Suessiaceae, named Yihiella yeosuensis gen. et sp. nov.

Effects of mushroom extract on textural properties and muscle protein degradation of bovine longissimus dorsi muscle.

We investigated the effects of Sarcodon aspratus, Agaricus bisporus, and Lentinula edodes aqueous extracts on the tenderization of bovine longissimus dorsi muscle. Meat quality and muscle protein degradation were examined as well. Beef chunks were marinated in distilled water (control), 5% S. aspratus (SA), 5% A. bisporus (AB), or 5% L. edodes (LE) extracts. SA was shown to have a higher enzymatic activity (p < 0.001) and water-holding capacity than LE (p < 0.01). SA and AB extracts exhibited lower shear force values compared with the control (p < 0.05). SA, AB, and LE showed superior muscle proteolytic effects compared with the control. SA demonstrated the ability to degrade myosin heavy chains and actin, which was not observed after AB and LE extract treatments. This suggests that SA extract may affect tenderization. Taken together, our results show that aqueous extract of S. aspratus affects the tenderness of the bovine longissimus dorsi muscle.

Most Low-Abundance "Background" Symbiodinium spp. Are Transitory and Have Minimal Functional Significance for Symbiotic Corals.

Speculation surrounds the importance of ecologically cryptic Symbiodinium spp. (dinoflagellates) that occur at low abundances in reef-building corals and in the surrounding environment. Evidence acquired from extensive sampling, long-term monitoring, and experimental manipulation can allow us to deduce the ecology and functional significance of these populations and whether they might contribute to the response of coral-dinoflagellate mutualisms to climate change. Quantitative PCR was used here to diagnose the prevalence, seasonal variation, and abundances of Symbiodinium spp. within and between colonies of the coral, Alveopora japonica. Consistent with broader geographic sampling, only one species comprised 99.9 %, or greater, the population of symbionts in every sample. However, other Symbiodinium including the non-mutualistic species, Symbiodinium voratum, were often detected, but at estimated cell densities thousands-fold less than the dominant symbiont. The temporal variation in prevalence and abundances of these "background" Symbiodinium could not be definitively related to any particular environmental factor including seasonality and water chemistry. The prevalence (proportion detected among host samples), but not abundance, of S. voratum may weakly correspond to increases in environmental inorganic silica (SiO2) and possibly nitrogen (NO3). When multiple background Symbiodinium occurred within an individual polyp, the average cell densities were positively correlated, suggesting non-specific processes of cell sorting and retention by the animal. While these findings substantiate the existence of a broader, yet uncharacterized, diversity of Symbiodinium, we conclude that only those species which can occur in high abundance and are temporally stable are ultimately important to coral-dinoflagellate mutualisms. Many transient Symbiodinium spp., which occur only at trace abundances in the coral's microbiome, belong to different functional guilds and likely have little, if any, importance to a coral's physiology. The successful integration between host and symbiont into a stable functional unit should therefore be considered when defining host-symbiont specificity.

AUF1 contributes to Cryptochrome1 mRNA degradation and rhythmic translation.

In the present study, we investigated the 3' untranslated region (UTR) of the mouse core clock gene cryptochrome 1 (Cry1) at the post-transcriptional level, particularly its translational regulation. Interestingly, the 3'UTR of Cry1 mRNA decreased its mRNA levels but increased protein amounts. The 3'UTR is widely known to function as a cis-acting element of mRNA degradation. The 3'UTR also provides a binding site for microRNA and mainly suppresses translation of target mRNAs. We found that AU-rich element RNA binding protein 1 (AUF1) directly binds to the Cry1 3'UTR and regulates translation of Cry1 mRNA. AUF1 interacted with eukaryotic translation initiation factor 3 subunit B and also directly associated with ribosomal protein S3 or ribosomal protein S14, resulting in translation of Cry1 mRNA in a 3'UTR-dependent manner. Expression of cytoplasmic AUF1 and binding of AUF1 to the Cry1 3'UTR were parallel to the circadian CRY1 protein profile. Our results suggest that the 3'UTR of Cry1 is important for its rhythmic translation, and AUF1 bound to the 3'UTR facilitates interaction with the 5' end of mRNA by interacting with translation initiation factors and recruiting the 40S ribosomal subunit to initiate translation of Cry1 mRNA.

Rhythmic control of mRNA stability modulates circadian amplitude of mouse Period3 mRNA.

The daily oscillations observed in most living organisms are endogenously generated with a period of 24 h, and the underlying structure of periodic oscillation is an autoregulatory transcription-translation feedback loop. The mechanisms of untranslated region (UTR)-mediated post-transcriptional regulation (e.g., mRNA degradation and internal ribosomal entry site (IRES)-mediated translation) have been suggested to fine-tune the expression of clock genes. Mouse Period3 (mPer3) is one of the paralogs of Period gene and its function is important in peripheral clocks and sleep physiology. mPer3 mRNA displays a circadian oscillation as well as a circadian phase-dependent stability, while the stability regulators still remain unknown. In this study, we identify three proteins - heterogeneous nuclear ribonucleoprotein (hnRNP) K, polypyrimidine tract-binding protein (PTB), and hnRNP D - that bind to mPer3 mRNA 3'-UTR. We show that hnRNP K is a stabilizer that increases the amplitude of circadian mPer3 mRNA oscillation and hnRNP D is a destabilizer that decreases it, while PTB exhibits no effect on mPer3 mRNA expression. Our experiments describe their cytoplasmic roles for the mRNA stability regulation and the circadian amplitude formation. Moreover, our mathematical model suggests a mechanism through which post-transcriptional mRNA stability modulation provides not only the flexibility of oscillation amplitude, but also the robustness of the period and the phase for circadian mPer3 expression. Mouse Period3 (mPer3) is one of well-known clock genes. We identified three 3'-UTR-binding proteins that modulate the mRNA stability, and they influenced to the amplitude of circadian mPer3 mRNA oscillation. Our mathematical model not only showed the relationship between mRNA stability and its oscillation profile but provided the molecular mechanism for the robustness of the period and the phase in circadian oscillation. hnK, heterogeneous nuclear ribonucleoprotein (hnRNP) K; hnD, hnRNP D; PTB, polypyrimidine tract-binding protein.