Reduced Cell Size Research Articles

Metamorphosis of a unicellular green alga in the presence of acetate and a spatially structured three-dimensional environment.

Photosynthetic protists, named microalgae, are key players in global primary production. The green microalga Chlamydomonas reinhardtii is a well-studied model organism. In nature, it dwells in acetate-rich paddy rice soil, which is not mimicked by standard liquid laboratory conditions. Here, we maintained the algae in a liquid environment with spatially structured 3-D components (S3-D) and acetate recreating natural conditions. We perform transcriptome sequencing, immunoblotting, fluorescence and electron microscopy, and Raman microspectroscopy to characterize the algae in S3-D vs homogeneous conditions. The algae undergo a metamorphosis-like process when transitioned from homogeneous aquatic to a lifestyle simulating acetate-rich rice soil. These conditions result in reduced cell size and cilia length, an enlarged eyespot and many cells with double-layered cell walls. RNA-Seq reveals alterations in c. 2400 transcripts. Four key photoreceptors including CRY-DASH1 and phototropin governing plastid metabolism along with its eyespot are altered in their protein expression. Consequently, photosynthetic pigments, lipids and starch levels vary as do starch distribution patterns. Fitness against antagonistic bacteria is enhanced concurrently with the downregulation of an involved Ca2+ channel transcript. This study highlights the profound impact of S3-D initiating processes inaccessible under homogeneous laboratory conditions. Thus, overexpression lines for certain photoreceptors and starch are naturally created.

Investigating the Acoustic Behavior of Polyurethane Foam Reinforced with Clay Nanoparticles

Introduction: Disturbing noise can cause physical and mental illnesses among workers; for this reason, it is necessary to restrain it, especially in workplaces. Using sound-absorbing materials with suitable acoustic properties has been a growing trend in mitigating noise. This study aimed to improve the acoustic properties of polyurethane foam (PUF) as a sound absorber. Material and Methods: In the present study, PUF was synthesized with different percentages of clay nanoparticles (0 -1.2 wt.%), and then the Sound Absorption Coefficient (SAC) of the synthesized PUF was measured by the acoustic impedance tube in the frequency range of 63 to 6400 Hz according to the ISIRI 9803 standard. The morphology of the foam was also investigated by Scanning Electron Microscope (SEM) Results: The results showed that the addition of clay nanoparticles to PUF improved the sound absorption behavior of the samples, and the best sound absorption behavior was for PUF with 1.2% weight of nanoparticles at low frequencies (500-2600 Hz). This increase in the absorption coefficient can be due to the increase in the number and smaller size of the pores with the increase in the amount of nanoparticles in PUF. Conclusion: This study illustrates that the incorporation of clay nanoparticles into PUF at varying percentages results in an enhanced absorption coefficient. The presence of clay nanoparticles leads to a reduction in cell size and an increase in the number of pores, consequently enhancing surface friction. The absorption coefficient was observed to increase with the growing concentration of clay nanoparticles in PUF.

Quantifying the fractal complexity of nutrient transport channels in Escherichia coli biofilms under varying cell shape and growth environment.

Recent mesoscopic characterization of nutrient-transporting channels in Escherichia coli has allowed the identification and measurement of individual channels in whole mature colony biofilms. However, their complexity under different physiological and environmental conditions remains unknown. Analysis of confocal micrographs of colony biofilms formed by cell shape mutants of E. coli shows that channels have high fractal complexity, regardless of cell phenotype or growth medium. In particular, colony biofilms formed by the mutant strain ΔompR, which has a wide-cell phenotype, have a higher fractal dimension when grown on rich medium than when grown on minimal medium, with channel complexity affected by glucose and agar concentrations in the medium. Osmotic stress leads to a dramatic reduction in the ΔompR cell size but has a limited effect on channel morphology. This work shows that fractal image analysis is a powerful tool to quantify the effect of phenotypic mutations and growth environment on the morphological complexity of internal E. coli biofilm structures. If applied to a wider range of mutant strains, this approach could help elucidate the genetic determinants of channel formation in E. coli colony biofilms.

Dapagliflozin mitigates cellular stress and inflammation through PI3K/AKT pathway modulation in cardiomyocytes, aortic endothelial cells, and stem cell-derived β cells

Dapagliflozin (DAPA), a sodium-glucose cotransporter 2 (SGLT2) inhibitor, is well-recognized for its therapeutic benefits in type 2 diabetes (T2D) and cardiovascular diseases. In this comprehensive in vitro study, we investigated DAPA’s effects on cardiomyocytes, aortic endothelial cells (AECs), and stem cell-derived beta cells (SC-β), focusing on its impact on hypertrophy, inflammation, and cellular stress. Our results demonstrate that DAPA effectively attenuates isoproterenol (ISO)-induced hypertrophy in cardiomyocytes, reducing cell size and improving cellular structure. Mechanistically, DAPA mitigates reactive oxygen species (ROS) production and inflammation by activating the AKT pathway, which influences downstream markers of fibrosis, hypertrophy, and inflammation. Additionally, DAPA’s modulation of SGLT2, the Na+/H + exchanger 1 (NHE1), and glucose transporter (GLUT 1) type 1 highlights its critical role in maintaining cellular ion balance and glucose metabolism, providing insights into its cardioprotective mechanisms. In aortic endothelial cells (AECs), DAPA exhibited notable anti-inflammatory properties by restoring AKT and phosphoinositide 3-kinase (PI3K) expression, enhancing mitogen-activated protein kinase (MAPK) activation, and downregulating inflammatory cytokines at both the gene and protein levels. Furthermore, DAPA alleviated tumor necrosis factor (TNFα)-induced inflammation and stress responses while enhancing endothelial nitric oxide synthase (eNOS) expression, suggesting its potential to preserve vascular function and improve endothelial health. Investigating SC-β cells, we found that DAPA enhances insulin functionality without altering cell identity, indicating potential benefits for diabetes management. DAPA also upregulated MAFA, PI3K, and NRF2 expression, positively influencing β-cell function and stress response. Additionally, it attenuated NLRP3 activation in inflammation and reduced NHE1 and glucose-regulated protein GRP78 expression, offering novel insights into its anti-inflammatory and stress-modulating effects. Overall, our findings elucidate the multifaceted therapeutic potential of DAPA across various cellular models, emphasizing its role in mitigating hypertrophy, inflammation, and cellular stress through the activation of the AKT pathway and other signaling cascades. These mechanisms may not only contribute to enhanced cardiac and endothelial function but also underscore DAPA’s potential to address metabolic dysregulation in T2D.Graphical abstract

DYRK1A interacts with the tuberous sclerosis complex and promotes mTORC1 activity

DYRK1A, a ubiquitously expressed kinase, is linked to the dominant intellectual developmental disorder, microcephaly, and Down syndrome in humans. It regulates numerous cellular processes such as cell cycle, vesicle trafficking, and microtubule assembly. DYRK1A is a critical regulator of organ growth; however, how it regulates organ growth is not fully understood. Here, we show that the knockdown of DYRK1A in mammalian cells results in reduced cell size, which depends on mTORC1. Using proteomic approaches, we found that DYRK1A interacts with the tuberous sclerosis complex (TSC) proteins, namely TSC1 and TSC2, which negatively regulate mTORC1 activation. Furthermore, we show that DYRK1A phosphorylates TSC2 at T1462, a modification known to inhibit TSC activity and promote mTORC1 activity. We also found that the reduced cell growth upon knockdown of DYRK1A can be rescued by overexpression of RHEB, an activator of mTORC1. Our findings suggest that DYRK1A inhibits TSC complex activity through inhibitory phosphorylation on TSC2, thereby promoting mTORC1 activity. Furthermore, using the Drosophila neuromuscular junction as a model, we show that the mnb, the fly homologs of DYRK1A, is rescued by RHEB overexpression, suggesting a conserved role of DYRK1A in TORC1 regulation.

DYRK1A interacts with the tuberous sclerosis complex and promotes mTORC1 activity.

DYRK1A, a ubiquitously expressed kinase, is linked to the dominant intellectual developmental disorder, microcephaly, and Down syndrome in humans. It regulates numerous cellular processes such as cell cycle, vesicle trafficking, and microtubule assembly. DYRK1A is a critical regulator of organ growth; however, how it regulates organ growth is not fully understood. Here, we show that the knockdown of DYRK1A in mammalian cells results in reduced cell size, which depends on mTORC1. Using proteomic approaches, we found that DYRK1A interacts with the tuberous sclerosis complex (TSC) proteins, namely TSC1 and TSC2, which negatively regulate mTORC1 activation. Furthermore, we show that DYRK1A phosphorylates TSC2 at T1462, a modification known to inhibit TSC activity and promote mTORC1 activity. We also found that the reduced cell growth upon knockdown of DYRK1A can be rescued by overexpression of RHEB, an activator of mTORC1. Our findings suggest that DYRK1A inhibits TSC complex activity through inhibitory phosphorylation on TSC2, thereby promoting mTORC1 activity. Furthermore, using the Drosophila neuromuscular junction as a model, we show that the mnb, the fly homologs of DYRK1A, is rescued by RHEB overexpression, suggesting a conserved role of DYRK1A in TORC1 regulation.

A gamma rays-induced novel fertile subsessile leaf mutant in cowpea [Vigna unguiculata (L.) Walp

Protein-rich legumes contribute to nutritional security by complementing cereals-based diets rich in carbohydrates. In cowpea, an arid legume with a narrow genetic base, we attempted to induce ideotype mutations using gamma rays for augmenting productivity and discovered a novel fertile, subsessile leaf mutant ‘PLM211’. Despite the mutant and the parent exhibiting similar individual leaf area and node number, the rudimentary petioles, shortened rachis, little to no branching, and consequently fewer leaves greatly influenced the canopy structure of the mutant. Histological sections of the mutant’s 0.55- 1.01 cm short petioles showed reduced cell size and number as opposed to the parent’s 12.64-14.55 cm long petioles. The potential for uncovering the underlying genes associated with petiole length, leaf morphogenesis, and branching highlights the significance of the mutant as a genetic treasure, opening up avenues for manipulating plant architecture, especially in legumes.

Blastocystis species growth inhibition in vitro by plant extracts

BackgroundThe protist Blastocystis species (sp.) inhabits the gastrointestinal tracts of humans and animals. In recent decades, alternative natural products derived from plants have demonstrated potential as effective treatments for Blastocystis infection. The anti-Blastocystis activity of three herbal ethanolic extracts— Odontites linkii subsp. cyprius, Ptilostemon chamaepeuce subsp. cyprius and Quercus alnifolia—were investigated in this study. MethodsThree distinct isolates of Blastocystis sp. maintained in vitro were molecularly subtyped. Cytotoxicity analysis was performed on individual Blastocystis sp. isolates using 250, 500, 1000, and 2000 μg/mL herbal ethanolic extracts for 24 and 48 hours. Quantitative, morphological, and size alterations of Blastocystis cells assessed the cytotoxicity of herbal anti-Blastocystis effect. ResultsFollowing subtyping analysis, one strain of Blastocystis had ST3 and ST1 mixed subtypes, and two strains had ST1 subtypes. Starting after 24 h of incubation, P. cham. subsp. cyprius (1000 μg/mL) exhibited the most pronounced and consistent anti-Blastocystis cytotoxicity against all three strains, comparable to metronidazole. The Ptilostemon chamaepeuce subsp. cyprius anti-Blastocystis cytotoxicity was evident in parasite quantitative distress, morphological alterations, and significant reductions in cell size. Odontites linkii subsp. cyprius cytotoxicity varied among the three Blastocystis strains. The three Blastocystis strains were resistant to Quercus alnifolia. ConclusionP. cham. subsp. cyprius was a potent and promising new herbal extract against Blastocystis sp. in vitro assays.

Activation of Yes-Associated Protein Is Indispensable for Transformation of Kidney Fibroblasts into Myofibroblasts during Repeated Administration of Cisplatin.

Cisplatin is a potent chemotherapy medication that is used to treat various types of cancer. However, it can cause nephrotoxic side effects, which lead to acute kidney injury (AKI) and subsequent chronic kidney disease (CKD). Although a clinically relevant in vitro model of CKD induced by repeated administration of low-dose cisplatin (RAC) has been established, its underlying mechanisms remain poorly understood. Here, we compared single administration of high-dose cisplatin (SAC) to repeated administration of low-dose cisplatin (RAC) in myofibroblast transformation and cellular morphology in a normal rat kidney fibroblast NRK-49F cell line. RAC instead of SAC transformed the fibroblasts into myofibroblasts as determined by α-smooth muscle actin, enlarged cell size as represented by F-actin staining, and increased cell flattening as expressed by the semidiameter ratio of attached cells to floated cells. Those phenomena, as well as cellular senescence, were significantly detected from the time right before the second administration of cisplatin. Interestingly, inhibition of the interaction between Yes-associated protein (YAP) and the transcriptional enhanced associated domain (TEAD) using Verteporfin remarkedly reduced cell size, cellular senescence, and myofibroblast transformation during RAC. These findings collectively suggest that YAP activation is indispensable for cellular hypertrophy, senescence, and myofibroblast transformation during RAC in kidney fibroblasts.

Differential allelopathic effects of mangrove plants Kandelia obovata and Aegiceras corniculatum on harmful algal species: Potential applications in algal bloom control

This study examined effects of mangrove plants Kandelia obovata and Aegiceras corniculatum on harmful algal species. While A. corniculatum leaf extract had no inhibitory effect, K. obovata leaf extract significantly inhibited the growth of two harmful algal species Alexandrium tamarense and Karenia mikimotoi. The inhibitory effect was concentration-dependent, with over 90 % inhibition at the highest concentration. Morphological changes and cell size reduction were observed in both microalgae. Excessive production of reactive oxygen species and damage to algal photosynthetic system were found. The allelopathic effect of K. obovata on K. mikimotoi with low-concentration repeated exposure was more effective than high-concentration single exposure. The EC50 of K. obovata (0.33 g L−1) was lower than reported values on other coastal plants. Higher inhibitory effects of K. obovata were found on naked algal species than the armoured ones. These findings suggest potential applications of K. obovata leaf extract in controlling harmful algal blooms.

Impact of Krill Meal on Enhancing Skin Mucosal Health and Reducing Sea Lice in Atlantic Salmon

The salmon industry’s challenges with skin health and sea lice emphasize the necessity for fish-sensitive measures like functional nutrition to boost skin health and fish welfare. The present study investigated the efficacy of krill meal (KM) for skin mucosal health and sea lice in Atlantic salmon (170 g). Following an 8-week feeding period, in duplicate tanks, on test diets (8% KM, 12% KM, and the control group), fish underwent a 2-week sea lice challenge, reaching 350 g. The 8% KM diet group had thicker skin epithelium (72.3 µ) compared to the 12% KM (51.3 µ) and the control groups (43.8 µ) after 8 weeks. Additionally, skin mucosal health parameters—cell size (208 µ2), cell density (25.2%), and defense activity (1.19)—were significantly enhanced with 8% KM compared to the 12% KM (cell size: 162.3 µ2, cell density: 17%, defense activity: 1.04) and the control group (cell size: 173.5 µ2, cell density: 16.4%, defense activity: 0.93). Furthermore, fish fed with 8% KM significantly showed the lowest sea lice, along with reduced cell size while maintaining a high abundance of skin mucous cells, suggesting efficient turnover of the skin mucosal layer to remove sea lice effectively. This study highlights the potential of KM as part of a functional nutrition strategy to enhance skin mucosal health and mitigate sea lice challenges.

Abstract Mo088: RBFOX2 haploinsufficiency impairs cardiomyocyte adhesion and contractility through faulty RNA metabolism

Background: Hypoplastic left heart syndrome (HLHS) is a severe form of congenital heart disease that is uniformly lethal if left untreated. Protein damaging mutations in one allele of RBFOX2, a highly conserved RNA binding protein, are enriched in HLHS patients, suggesting they are causal. However, it remains unclear how RBFOX2 haploinsufficiency contributes to disease pathogenesis as heterozygous animal models appear healthy. Methods: We generated and characterized RBFOX2 heterozygous and null human induced pluripotent stem cells (hiPSCs) and assessed their phenotypes in differentiated cardiomyocytes (iPSC-CMs) in 2D culture. To learn if altered function might be revealed in a more native microenvironment, we also generated 3D engineered heart tissues (EHTs) from RBFOX2 heterozygous hiPSC-CMs. To delineate the underlying molecular mechanisms, we performed bulk RNA-seq to reveal differential gene expression (DGE) and alternative splicing events (ASEs) between the different genetic cohorts and eCLIP-seq to detect RNAs directly bound by RBFOX2 in the CM lineage. Results: We observed dose-dependent reductions in cell adhesion, size, maturation, respiration, calcium handling, and action potential duration with no significant effect on proliferation in 2D culture. Although myofibril alignment and contractility were completely abolished in null hiPSC-CMs, these features were surprisingly preserved in heterozygous cells. However, in EHTs, we found that RBFOX2 is haploinsufficient for tissue maturation and contractility, suggesting that myocardial-intrinsic defects contribute to RBFOX2 -mediated HLHS. Integration of DGE, ASEs and eCLIP-seq datasets uncovered significant enrichment of DGE and/or ASEs of RBFOX2-bound and unbound transcripts involved in cell adhesion between the extracellular matrix (ECM) and the actin cytoskeleton/sarcomere network. Included in the direct targets with altered expression and alternative splicing was the ECM ligand FIBRONECTIN 1 ( FN1 ), which when downregulated was previously associated with HLHS. Conclusions: Our data suggest that RBFOX2 sits atop an expression and splicing hierarchy that promotes optimal CM cell growth, adhesion, and contractility that protects the heart from HLHS pathogenesis.

Cell size regulates human endoderm specification through actomyosin-dependent AMOT-YAP signaling

Cell size is a crucial physical property that significantly impacts cellular physiology and function. However, the influence of cell size on stem cell specification remains largely unknown. Here, we investigated the dynamic changes in cell size during the differentiation of human pluripotent stem cells into definitive endoderm (DE). Interestingly, cell size exhibited a gradual decrease as DE differentiation progressed with higher stiffness. Furthermore, the application of hypertonic pressure or chemical to accelerate the reduction in cell size significantly and specifically enhanced DE differentiation. By functionally intervening in mechanosensitive elements, we have identified actomyosin activity as a crucial mediator of both DE differentiation and cell size reduction. Mechanistically, the reduction in cell size induces actomyosin-dependent angiomotin (AMOT) nuclear translocation, which suppresses Yes-associated protein (YAP) activity and thus facilitates DE differentiation. Together, our study has established a novel connection between cell size diminution and DE differentiation, which is mediated by AMOT nuclear translocation. Additionally, our findings suggest that the application of osmotic pressure can effectively promote human endodermal lineage differentiation.

Direct and indirect cumulative effects of temperature, nutrients, and light on phytoplankton growth.

Temperature and resource availability are pivotal factors influencing phytoplankton community structures. Numerous prior studies demonstrated their significant influence on phytoplankton stoichiometry, cell size, and growth rates. The growth rate, serving as a reflection of an organism's success within its environment, is linked to stoichiometry and cell size. Consequently, alterations in abiotic conditions affecting cell size or stoichiometry also exert indirect effects on growth. However, such results have their limitations, as most studies used a limited number of factors and factor levels which gives us limited insights into how phytoplankton respond to environmental conditions, directly and indirectly. Here, we tested for the generality of patterns found in other studies, using a combined multiple-factor gradient design and two single species with different size characteristics. We used a structural equation model (SEM) that allowed us to investigate the direct cumulative effects of temperature and resource availability (i.e., light, N and P) on phytoplankton growth, as well as their indirect effects on growth through changes in cell size and cell stoichiometry. Our results mostly support the results reported in previous research thus some effects can be identified as dominant effects. We identified rising temperature as the dominant driver for cell size reduction and increase in growth, and nutrient availability (i.e., N and P) as dominant factor for changes in cellular stoichiometry. However, indirect effects of temperature and resources (i.e., light and nutrients) on species' growth rates through cell size and cell stoichiometry differed across the two species suggesting different strategies to acclimate to its environment.

Layer-by-layer coated cellulose reduces the fire risk of polyurethane foam biocomposites

Cellulose implementation as filler in polyurethane foams (PUF) often leads to an increased the fire risk associated to the prepared biocomposite. To address this problem, this paper presents a novel approach where the cellulose filler is coated by a nanostructured layer-by-layer (LbL) assembly with flame retardant characteristics before its addition to the biocomposite. During PUF production, the presence of cellulose led to a reduced cell size distribution with improved thermal insulation properties. By forced combustion tests, the use of neat cellulose produced a detrimental effect by increasing the PUF heat release rates (up to +21 %). Conversely, the coated cellulose simultaneously decreased the peak of heat release rate (-22 %) and the total smoke release (-32 %) if compared with the reference PUF. The proposed approach represents a viable strategy for the production of PUF biocomposites where sustainability and fire protection are optimized.

Mechanical and Insulation Performance of Rigid Polyurethane Foam Reinforced with Lignin-Containing Nanocellulose Fibrils.

Isocyanates are critical components that affect the crosslinking density and structure of polyurethane (PU) foams. However, due to the cost and hazardous nature of the precursor for isocyanate synthesis, there is growing interest in reducing their usage in polyurethane foam production-especially in rigid PU foams (RPUF) where isocyanate is used in excess of the stoichiometric ratio. In this study, lignin-containing nanocellulose fibrils (LCNF) were explored as mechanical reinforcements for RPUF with the goal of maintaining the mechanical performance of the foam while using less isocyanate. Different amounts of LCNF (0-0.2 wt.%) were added to the RPUF made using isocyanate indices of 1.1, 1.05, 1.0, and 0.95. Results showed that LCNF served as a nucleating agent, significantly reducing cell size and thermal conductivity. LCNF addition increased the crosslinking density of RPUF, leading to enhanced compressive properties at an optimal loading of 0.1 wt.% compared to unreinforced foams at the same isocyanate index. Furthermore, at the optimal loading, LCNF-reinforced foams made at lower isocyanate indices showed comparable stiffness and strength to unreinforced foams made at higher isocyanate indices. These results highlight the reinforcing potential of LCNF in rigid polyurethane foams to improve insulation and mechanical performance with lower isocyanate usage.

Fabrication and Characterization of PLA/PBAT Blends, Blend-Based Nanocomposites, and Their Supercritical Carbon Dioxide-Induced Foams.

In this study, a twin-screw extruder was used to fabricate poly(lactic acid) (PLA)/poly(butylene adipate-co-terephthalate) (PBAT) blends and blend-based nanocomposites with carbon nanotube (CNT) or nanocarbon black (CB) as nanofillers. The fabricated samples were subsequently treated with supercritical carbon dioxide (scCO2) to fabricate the corresponding foams. Bi-phasic morphology and selective distribution of CNTs or CBs in the PBAT phase were observed in the blends/composites through scanning electron microscopy. After the scCO2 treatment, the selective foaming of the PBAT phase in the prepared blends/composites was confirmed. The cellular structure of PBAT phase in scCO2-treated blends is similar to the size/shape of PBAT domains in untreated blends or treated neat PBAT foam. The addition of CNTs or CBs in the blends led to a slight reduction in cell size of the foamed PBAT phase, demonstrating CNT/CB-induced cell nucleation. Differential scanning calorimetry (DSC) results showed that CNTs and CBs played as nucleating agents and increased the initial crystallization temperature up to 14 °C compared with neat PBAT for PBAT in different composites during cooling. The scCO2 treatment induced the bimodal stability of PBAT crystals in different samples, which melted mainly in two temperature regions in DSC studies. Thermogravimetric analyses revealed that compared with parent blends, the addition of CNTs or CBs increased the temperature at 80 wt.% loss (degradation of PBAT portion) up to 6 °C. The electrical resistivity decreased by more than six orders of magnitude for certain CNT- or CB-added composites compared with the parent blends. The hardness of the blends slightly increased after forming the corresponding composites and then declined after the scCO2 treatment.

Enhancing the foamability of poly(L-lactide-co-ε-caprolactone) through formation of stereocomplex crystal by introducing of poly(D-lactic acid)

The bio-elastomer poly (L-lactide-co-ε-caprolactone) (PLCL) with linear random molecular chain structure exhibits low viscosity and melt strength, resulting in poor foamability, cell merging, or collapse during the foaming process. Consequently, PLCL foams have large cell sizes and low cell densities, limiting their use as biodegradable elastomeric foams. To enhance the foamability of PLCL, poly (D-lactic acid) (PDLA) was incorporated into the PLCL matrix. Stereocomplex crystals (Sc-crystals) formed between the L-LA segments of PLCL and the molecular segments of PDLA. The effects of varying PDLA content on the basic properties and foaming behavior of the blends were investigated. Results indicate that optimal Sc-crystal formation occurs in the PLCL/PDLA-10 blend. The presence of Sc-crystals enhances melt strength and facilitates cell nucleation, reducing cell size from 351.2 to 11.8 μm and increasing cell density from 1.4 × 104 to 1.7 × 108 cells/cm³. Consequently, the mechanical properties of the foam are significantly improved. The Sc-crystal formation between PLCL and PDLA provides an effective method to enhance the processability of linear chain copolymers containing L-lactide.

RhoB plays a central role in hyperosmolarity-induced cell shrinkage in renal cells.

The small Rho GTP-binding proteins are important cell morphology, function, and apoptosis regulators. Unlike other Rho proteins, RhoB can be subjected to either geranylgeranylation (RhoB-GG) or farnesylation (RhoB-F), making that the only target of the farnesyltransferase inhibitor (FTI). Fluorescence resonance energy transfer experiments revealed that RhoB is activated by hyperosmolarity. By contrast, hyposmolarity did not affect RhoB activity. Interestingly, treatment with farnesyltransferase inhibitor-277 (FTI-277) decreased the cell size. To evaluate whether RhoB plays a role in volume reduction, renal collecting duct MCD4 cells and Human Kidney, HK-2 were transiently transfected with RhoB-wildtype-Enhance Green Fluorescence Protein (RhoB-wt-EGFP) and RhoB-CLLL-EGFP which cannot undergo farnesylation. A calcein-based fluorescent assay revealed that hyperosmolarity caused a significant reduction of cell volume in mock and RhoB-wt-EGFP-expressing cells. By contrast, cells treated with FTI-277 or expressing the RhoB-CLLL-EGFP mutant did not properly respond to hyperosmolarity with respect to mock and RhoB-wt-EGFP expressing cells. These findings were further confirmed by 3D-LSCM showing that RhoB-CLLL-EGFP cells displayed a significant reduction in cell size compared to cells expressing RhoB-wt-EGFP. Moreover, flow cytometry analysis revealed that RhoB-CLLL-EGFP expressing cells as well as FTI-277-treated cells showed a significant increase in cell apoptosis. Together, these data suggested that: (i) RhoB is sensitive to hyperosmolarity and not to hyposmolarity; (ii) inhibition of RhoB farnesylation associates with an increase in cell apoptosis, likely suggesting that RhoB might be a paramount player controlling apoptosis by interfering with responses to cell volume change.

Cytosolic N-terminal formyl-methionine deformylation derives cancer stem cell features and tumor progression

Eukaryotic cells can synthesize formyl-methionine (fMet)-containing proteins not only in mitochondria but also in the cytosol to some extent. Our previous study revealed substantial upregulation of N-terminal (Nt)-fMet-containing proteins in the cytosol of SW480 colorectal cancer cells. However, the functional and pathophysiological implications remain unclear. Here, we demonstrated that removal of the Nt-formyl moiety of Nt-fMet-containing proteins (via expressing Escherichia coli PDF peptide deformylase) resulted in a dramatic increase in the proliferation of SW480 colorectal cancer cells. This proliferation coincided with the acquisition of cancer stem cell features, including reduced cell size, enhanced self-renewal capacity, and elevated levels of the cancer stem cell surface marker CD24 and pluripotent transcription factor SOX2. Furthermore, deformylation of Nt-fMet-containing proteins promoted the tumorigenicity of SW480 colorectal cancer cells in an in vivo xenograft mouse model. Taken together, these findings suggest that cytosolic deformylation has a tumor-enhancing effect, highlighting its therapeutic potential for cancer treatment.