AKAP1 alleviates VSMC phenotypic modulation and neointima formation by inhibiting Drp1-dependent mitochondrial fission.

The roles and mechanisms of A-kinase anchoring protein 1 (AKAP1) in vascular smooth muscle cell (VSMC) phenotypic modulation and neointima formation are currently unknown. AKAP1 is a mitochondrial PKA-anchored protein and maintains mitochondrial homeostasis. This study aimed to investigate how AKAP1/PKA signaling plays a protective role in inhibiting VSMC phenotypic transformation and neointima formation by regulating mitochondrial fission. The results showed that both PDGF-BB treatment and balloon injury reduced the transcription, expression, and mitochondrial anchoring of AKAP1. In vitro, the overexpression of AKAP1 significantly inhibited PDGF-BB mediated VSMC proliferation and migration, whereas AKAP1 knockdown further aggravated VSMC phenotypic transformation. Additionally, in the balloon injury model in vivo, AKAP1 overexpression reduced neointima formation, the muscle fiber area ratio, and rat VSMC proliferation and migration. Furthermore, PDGF-BB and balloon injury inhibited Drp1 phosphorylation at Ser637 and promoted Drp1 activity and mitochondrial midzone fission; AKAP1 overexpression reversed these effects. AKAP1 overexpression also inhibited the distribution of mitochondria at the plasma membrane and the reduction of PKARIIß expression induced by PDGF-BB, as evidenced by an increase in mitochondria-plasma membrane distance as well as PKARIIß protein levels. Moreover, the PKA agonist promoted Drp1 phosphorylation (Ser637) and inhibited PDGF-BB-mediated mitochondrial fission, cell proliferation, and migration. The PKA antagonist reversed the increase in Drp1 phosphorylation (Ser637) and the decline in mitochondrial midzone fission and VSMC phenotypic transformation caused by AKAP1 overexpression. The results of this study reveal that AKAP1 protects VSMCs against phenotypic modulation by improving Drp1 phosphorylation at Ser637 through PKA and inhibiting mitochondrial fission, thereby preventing neointima formation.

The Impact of the Fluid-Solid Coupling Behavior of Macro and Microstructures in the Spiral Cochlea on Hearing.

The cilia of the outer hair cells (OHCs) are the key microstructures involved in cochlear acoustic function, and their interactions with lymph in the cochlea involve complex, highly nonlinear, coupled motion and energy conversions, including macroscopic fluid-solid coupling. Recent optical measurements have shown that the frequency selectivity of the cochlea at high sound levels is entirely mechanical and is determined by the interactions of the hair bundles with the surrounding fluid. In this paper, an analytical mathematical model of the spiral cochlea containing macro- and micromeasurements was developed to investigate how the phonosensitive function of OHCs' motions is influenced by the macrostructural and microstructural fluid-solid coupling in the spiral cochlea. The results showed that the macrostructural and microstructural fluid-solid coupling exerted the radial forces of OHCs through the flow field, deflecting the cilia and generating frequency-selective properties of the microstructures. This finding showed that microstructural frequency selectivity arises from the radial motions of stereocilia hair bundles and enhances the hearing of sound signals at specific frequencies. It also implied that the macrostructural and microstructural fluid-solid couplings influence the OHCs' radial forces and that this is a key factor in the excitation of ion channels that enables their activity in helping the brain to detect sound.

Vibration modes of three-dimensional spiral cochlea covering the organ of Corti.

So far, explaining the mechanism on active phonosensitive amplification in the cochlea is a major and difficult medical question. Among them, one of the key problems is that the motion pattern of the organ of Corti (OC) is still unknown. To this end, a multi-scale cochlear model including a three-dimensional spiral OC was established based on CT data and light source imaging experimental data, which complete combined the macroscopic and microscopic structure. On the basis of verifying the reliability of the model, acoustic-solid coupling calculation and modal analysis were performed on the model, and the vibration modes of basilar membrane (BM) and structures of the OC at different characteristic frequencies were discussed. The results show that tectorial membrane (TM) exhibits completely different vibration modes from BM at low frequencies, while the two movements gradually synchronize as the frequency increases. The amplitude position of OC's motion moves laterally with increasing frequency from Deiters' cells to Hensen's cells and then back to Deiters' cells. The OC exhibits longitudinal vibrations following BM when BM's displacement is large, while it manifests more as lateral movement of Deiters' cells when BM's displacement is small. This model can well simulate the motion process of BM and OC in the lymphatic fluid, which provides theoretical support and a numerical simulation computational platform to explore the interaction between macroscopic and microscopic tissue structures of the overall cochlea.

Pathogenic mechanism analysis of cochlear key structural lesion and phonosensitive hearing loss.

Due to ethical issues and the very fine and complex structure of the cochlea, it is difficult to directly perform experimental measurement on the human cochlea. Therefore, the finite element method has become an effective and replaceable new research means. Accurate numerical analysis on human ear using finite element method can provide better understanding of sound transmission and can be used to assess the influence of diseases on hearing and to treat hearing loss. In this research, a three-dimensional (3D) finite element model (FEM) of the human ear of cochlea was presented to investigate the destruction of basilar membrane (BM), round window (RW) sclerosis and perilymph fistula, the key structures of the cochlea, and analyze the effects of these abnormal pathological states in the cochlea on cochlear hearing, resulting in the changes in cochlear sense structure biomechanical behavior and quantitative prediction of the degree and harm of the disorder to the decline of human hearing. Therefore, this paper can deepen reader's understanding of the cochlear biomechanical mechanism and provide a theoretical foundation for clinical otology.

Neuronal aerobic glycolysis exacerbates synapse loss in aging mice.

Brain consumes nearly 20% supply of energy from glucose metabolism by oxidative phosphorylation and aerobic glycolysis. Less active state of glycolytic enzymes results in a limited capacity of glycolysis in the neurons of adult brain. Here we identified that Warburg effect is enhanced in hippocampal neurons during aging. As hippocampal neurons age, lactate levels progressively increase. Notably, we observed upregulated protein levels of PFKFB3 in the hippocampus of 20-month-old mice compared to young mice, and this higher PFKFB3 expression correlated with declining memory performance in aging mice. Remarkably, in aging mice, knocking down Pfkfb3 in hippocampal neurons rescued cognitive decline and synapse loss. Conversely, Pfkfb3 overexpression in hippocampal neurons led to cognitive impairment and synapse elimination, associated with heightened glycolysis. In vitro experiments with cultured primary neurons confirmed that Pfkfb3 overexpression increased glycolysis and that glycolytic inhibition could prevent apoptotic competency in neurons. These findings underscore that glycolysis in hippocampal neurons could potentially be targeted as a therapeutic avenue to mitigate cognitive decline and preserve synaptic integrity during aging.

Study on damage of the macrostructure of the cochlea under the impact load.

Due to the tiny and delicate structure of the cochlea, the auditory system is the most sensitive to explosion impact damage. After being damaged by the explosion impact wave, it usually causes long-term deafness, tinnitus, and other symptoms. To better understand the influence of impact load on the cochlea and basilar membrane (BM), a three-dimensional (3D) fluid-solid coupling finite element model was developed. This model accurately reflects the actual spatial spiral shape of the human cochlea, as well as the lymph environment and biological materials. Based on verifying the reliability of the model, the curve of impact load-amplitude response was obtained, and damage of impact load on the cochlea and the key macrostructure-BM was analyzed. The results indicate that impact wave at middle frequency has widest influence on the cochlea. Furthermore, impact loading causes tears in the BM and destroys the cochlear frequency selectivity.

RhoGDI3 at the trans-Golgi network participates in NLRP3 inflammasome activation, VSMC phenotypic modulation, and neointima formation.

BACKGROUND AND AIMS: The pathological roles and mechanisms of Rho-specific guanine nucleotide dissociation inhibitor 3 (RhoGDI3) in vascular smooth muscle cell (VSMC) phenotypic modulation and neointima formation are currently unknown. This study aimed to investigate how RhoGDI3 regulates the Nod-like receptor protein 3 (NLRP3) inflammasome in platelet-derived growth factor-BB (PDGF-BB)-induced neointima formation. METHODS: For in vitro assays, human aortic VSMCs (HA-VSMCs) were transfected with pcDNA3.1-GDI3 and RhoGDI3 siRNA to overexpress and knockdown RhoGDI3, respectively. HA-VSMCs were also treated with an NLRP3 inhibitor (CY-09) or agonist (NSS). Protein transcription and expression, cell proliferation and migration, Golgi morphology, and protein binding and colocalization were measured. For the in vivo assays, balloon injury (BI) rats were injected with recombinant adenovirus carrying RhoGDI3 shRNA. Carotid arterial morphology, protein expression and colocalization, and activation of the NLRP3 inflammasome were measured. RESULTS: PDGF-BB treatment induced transcription and expression of RhoGDI3 through PDGF receptor αß (PDGFRαß) rather than PDGFRαα or PDGFRßß in HA-VSMCs. RhoGDI3 suppression blocked PDGF-BB-induced VSMC phenotypic transformation. In contrast, RhoGDI3 overexpression further promoted PDGF-BB-induced VSMC dedifferentiation. The in vivo results also confirmed that RhoGDI3 expressed in VSMCs participated in neointima formation and muscle fiber and collagen deposition caused by balloon injury. In addition, PDGF-BB increased binding of RhoGDI3 to NLRP3 and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) at the trans-Golgi membrane, which depended on the normal Golgi network. However, recruitment of NLRP3 and ASC to the trans-Golgi network after PDGF-BB treatment was independent of RhoGDI3. Moreover, RhoGDI3 knockdown significantly inhibited ASC expression and NLRP3 inflammasome assembly and activation and reduced NLRP3 protein stability in PDGF-BB-treated HA-VSMCs. Inhibiting NLRP3 effectively prevented PDGF-BB-induced VSMC phenotypic modulation, and an NLRP3 agonist reversed the decline in VSMC phenotypic transformation caused by RhoGDI3 knockdown. Furthermore, RhoGDI3 suppression reduced the protein levels and assembly of NLRP3 and ASC, and the activation of the NLRP3 inflammasome in VSMCs in a rat balloon injury model. CONCLUSIONS: The results of this study reveal a novel mechanism through which RhoGDI3 regulates VSMC phenotypic modulation and neointima formation by activating the NLRP3 inflammasome.

Effects of basilar-membrane lesions on dynamic responses of the middle ear.

BACKGROUND: Numerical simulations can reflect the changes in physiological properties caused by various factors in the cochlea. AIMS/OBJECTIVE: To analyze the influence of lesions of the basilar membrane (BM) on the dynamic response of the middle ear. METHOD: Based on healthy human ear CT scan images, use PATRAN software to build a three-dimensional finite element model of the human ear, then apply NASTRAN software to conduct analysis of solid-fluid coupled frequency response. The influence of lesions in the BM on the dynamic response of the middle ear is simulated through the method of numerical simulation. RESULT: Through comparing experimental data and the frequency-response curve of displacement of BM and stapes, the validity of the model in this paper was verified. CONCLUSION: Regarding sclerosis in BM, the most obvious decline of displacement and velocity exists in the range of 800-10,000Hz and 800-2000Hz frequency, respectively. The higher degree of sclerosis, the more obvious decline becomes. The maximal decline of hearing can reach from 6.2 dB to 9.1 dB. Regarding added mass in BM, the most obvious decline of displacement exists in the range of 600-1000Hz frequency, and the maximal decline of hearing can reach 4.0 dB. There is no obvious decline in velocity.

Behavioral characteristics in sensing mechanism of the Corti.

Some experiments can't be realized because the cochlea's Corti is the most delicate and complex sensory organ. In this paper, some typical and special behavioral characteristics in the process of sensation were found in medical clinic. Based on the interdisciplinary principles of medicine, physics and biology, a real numerical simulation model of Corti is established. On the basis of verifying the correctness of the model, the mechanism corresponding to these typical and special behavior characteristics in the process of sensation is explored through simulation calculation and analysis. This study provides theoretical and applied basis for people to better understand the sound sensing mechanism, and provides a numerical simulation platform for further analyzing Corti's sensing mechanism and good clinical application.

Protective Role of Cytochrome C Oxidase 5A (COX5A) against Mitochondrial Disorder and Oxidative Stress in VSMC Phenotypic Modulation and Neointima Formation.

BACKGROUND: The pathological role of cytochrome c oxidase 5A (COX5A) in vascular neointima formation remains unknown. AIM: This study aims to investigate the role of COX5A on platelet-derived growth factor BB (PDGFBB)- mediated smooth muscle phenotypic modulation and neointima formation and clarify the molecular mechanisms behind this effect. METHODS: For in vitro assays, human aortic vascular smooth muscle cells (HA-VSMCs) were transfected with pcDNA3.1-COX5A and COX5A siRNA to overexpress and knockdown COX5A, respectively. Mitochondrial complex IV activity, oxygen consumption rate (OCR), H2O2 and ATP production, reactive oxygen species (ROS) generation, cell proliferation, and migration were measured. For in vivo assays, rats after balloon injury (BI) were injected with recombinant lentivirus carrying the COX5A gene. Mitochondrial COX5A expression, carotid arterial morphology, mitochondrial ultrastructure, and ROS were measured. RESULTS: The results showed that PDGF-BB reduced the level and altered the distribution of COX5A in mitochondria, as well as reduced complex IV activity, ATP synthesis, and OCR while increasing H2O2 synthesis, ROS production, and cell proliferation and migration. These effects were reversed by overexpression of COX5A and aggravated by COX5A knockdown. In addition, COX5A overexpression attenuated BI-induced neointima formation, muscle fiber area ratio, VSMC migration to the intima, mitochondrial ultrastructural damage, and vascular ROS generation. CONCLUSION: The present study demonstrated that COX5A protects VSMCs against phenotypic modulation by improving mitochondrial respiratory function and attenuating mitochondrial damage, as well as reducing oxidative stress, thereby preventing neointima formation.

Development of an Assessment Model for the Effect of the Replacement of Minimal Artificial Ossicles on Hearing in the Inner Ear.

Due to ethical issues and the nature of the ear, it is difficult to directly perform experimental measurements on living body elements of the human ear. Therefore, a numerical model has been developed to effectively assess the effect of the replacement of artificial ossicles on hearing in the inner ear. A healthy volunteer's right ear was scanned to obtain CT data, which were digitalized through the use of a self-compiling program and coalescent Patran-Nastran software to establish a 3D numerical model of the whole ear, and a frequency response of a healthy human ear was analyzed. The vibration characteristics of the basilar membrane (BM) after total ossicular replacement prosthesis (TORP) implantation were then analyzed. The results show that although the sound conduction function of the middle ear was restored after replacement of the TORP, the sensory sound function of the inner ear was affected. In the low frequency and medium frequency range, hearing loss was 5.2~10.7%. Meanwhile, in the middle-high frequency range, the replacement of a middle ear TORP in response to high sound pressure produced a high acoustic stimulation effect in the inner ear, making the inner ear structures susceptible to fatigue and more prone to fatigue damage compared to the structures in healthy individuals. This developed model is able to assess the effects of surgical operation on the entire hearing system.

Study of fatigue damage to the cochlea.

In order to explore the hearing loss resulting from exposure to continuous or intermittent loud noise. A three-dimensional liquid-solid coupling finite element model of spiral cochlea was established. The reliability of the model was verified, and the stress and amplitude of the basilar membrane of the pivotal structure in cochlea were analyzed. The results show that under the action of the same high-pressure sound, the preferential fatigue area of the cochlear high-frequency area mainly causes fatigue in the cochlear. The safer area is a sound pressure level below 70 dB, while one above 90 dB accelerates damage to the ear.

Three-dimensional finite element analysis on cochlear implantation electrode insertion.

Studying the insertion process of cochlear implant (CI) electrode array (EA) is important to ensure successful, sufficient, and safe implantation. A three-dimensional finite element (FE) model was developed to simulate the insertion process. The cochlear structures were reconstructed from an average statistical shape model (SSM) of human cochlea. The electrode is simplified as a long and tapered beam of homogeneous elastic materials, contacting and interacting with the stiff cochlear structures. A quasi-static insertion simulation was conducted, the insertion force and the contact pressure between the electrode and the cochlear wall, were calculated to evaluate the smoothness of insertion and the risk of potential cochlear trauma. Based on this model, different EA designs were analyzed, including the Young's modulus, the straight or bended shape, the normal or a more tapped section size. The influence of the insertion angle was also discussed. Our simulations indicate that reducing the EA Young's modulus, tapering and pre-bending are effective ways to ensure safe and successful EA implantation. This model is beneficial for optimizing EA designs and is potentially useful for designing patient-specific CI surgery.

Angiotensin II Inhibits Adipogenic Differentiation and Promotes Mature Adipocyte Browning through the Corepressor CtBP1.

The mechanisms of angiotensin II (Ang II) on regulating adipogenic differentiation and function remain unknown. In this study, we focus on revealing the role of C-terminal-binding protein 1 (CtBP1) on Ang II-mediated adipogenic differentiation and mature adipocyte browning. Amounts of 3T3-L1 and CtBP1-KO 3T3-L1 were treated with Ang II for 24 h and then induced adipogenic differentiation, or cells were first induced differentiation and then treated with Ang II. The expressions of CtBP1 and adipogenic markers were checked by Western blot. Transcription of CtBP1 was assayed by Real-time RT-PCR. Lipid droplet formation and size were detected by Oil Red O. Mitochondrial content and reactive oxygenspecies (ROS) were detected by Mito-tracker and MitoSOX. Mitochondrial respiratory function was detected with the corresponding kits. Mitochondrial membrane potential (MMP) (∆Ψm) was assayed by JC-1. The results show that Ang II promoted CtBP1 transcription and expression via AT1 receptor during 3T3-L1 adipogenic differentiation. Ang II significantly inhibited lipid droplet formation and adipogenic markers expression in 3T3-L1 differentiation, which was blocked by CtBP1 knockout. In mature 3T3-L1, Ang II treatment increased uncoupling protein-1 (UCP-1) expression and the number of lipid droplets, and also reduced lipid droplet size and single cell lipid accumulation, which was reversed by CtBP1 knockout. In addition, Ang II treatment enhanced mitochondrial numbers, ATP production, oxygen consumption rate (OCR) and ROS generation, and reduced MMP (∆Ψm) via CtBP1 in mature 3T3-L1 adipocytes. In conclusion, this study demonstrates that CtBP1 plays a key role in the inhibitory effect of Ang II on adipogenesis. Moreover, Ang II regulates the function of mature adipocyte via CtBP1, including promoting adipocyte browning, mitochondrial respiration and ROS generation.

The Effect of Endolymphatic Hydrops and Mannitol Dehydration Treatment on Guinea Pigs.

Background: Endolymphatic hydrops (EH) is considered as the pathological correlate of Menière's disease (MD) and cause of hearing loss. The mechanism of EH, remaining unrevealed, poses challenges for formalized clinical trials. Objective: This study aims to investigate the development of hearing loss, as well as the effect of dehydration treatment on EH animal models. Methods: In this study, different severity EH animal models were created. The laser Doppler vibrometer (LDV) and auditory brainstem responses (ABR) were used to study the effects of EH and the dehydration effects of mannitol. The LDV was used to measure the vibration of the round window membrane (RWM) reflecting the changes in inner ear impedance. ABR was used to evaluate the hearing changes. Furthermore, tissue section and scanning electron microscopy (SEM) observations were used to analyze the anatomical change to the cochlea and outer hair cells. Results: The RWM vibrations decreased with the severity of EH, indicating an increase in the cochlear impedance. The dehydration therapy lowered the impedance to restore acoustic transduction in EH 10- and 20-day animal models. Simultaneously, the ABR thresholds increased in EH models and were restored after dehydration. Moreover, a difference in the hearing was found between ABR and LDV results in severe EH animal models, and the dehydration therapy was less effective, indicating a sensorineural hearing loss (SNHL). Conclusion: Endolymphatic hydrops causes hearing loss by increasing the cochlear impedance in all tested groups, and mannitol dehydration is an effective therapy to restore hearing. However, SNHL occurs for the EH 30-day animal models, limiting the effectiveness of dehydration. Our results suggest the use of dehydrating agents in the early stage of EH.

Temperature Dependence of Interfacial Bonding and Configuration Transition in Graphene/Hexagonal Boron Nitride Containing Grain Boundaries and Functional Groups.

The quasi-three-dimensional effect induced by functional groups (FGo) and the in-plane stress and structural deformation induced by grain boundaries (GBs) may produce more novel physical effects. These physical effects are particularly significant in high-temperature environments and are different from the behavior in bulk materials, so its physical mechanism is worth exploring. Considering the external field (strain and temperature field), the internal field (FGo and GBs) and the effect of distance between FGs and GBs on the bonding energy, configuration transition, and stress distribution of graphene/h-BN with FGo and GBs (GrO-BN-GBs) in the interface region were studied by molecular dynamics (MD). The results show that the regions linked by hydroxyl + epoxy groups gradually change from honeycomb to diamond-like structures as a result of a hybridization transition from sp2 to sp3. The built-in distortion stress field generated by the coupling effect of temperature and tension loading induces the local geometric buckling of two-dimensional materials, according the von Mises stresses and deflection theory. In addition, the internal (FGo and GBs) and external field (strain and temperature field) have a negative chain reaction on the mechanical properties of GrO-BN-GBs, and the negative chain reaction increases gradually with the increase in the distance between FGo and GBs. These physical effects are particularly obvious in high-temperature environments, and the behavior of physical effects in two-dimensional materials is different from that in bulk materials, so its physical mechanism is worth exploring.

Effects of lesions of the organ of corti on hearing.

BACKGROUND: Lesions causing changes in the microstructure of the organ of Corti may lead to hearing impairment. AIMS/OBJECTIVES: The aim of this study was to investigate the effect of various structural lesions on the organ of Corti and the auditory function. METHODS: A finite element method of the cochlea and the organ of Corti were established based on computed tomography scanning and anatomical data. We evaluated the accuracy of the model by comparing the simulation results to reported experimental data. We simulated and analyzed the impact of the lesions on the sound-sensing function of the cochlea by adjusting the biomaterial parameters of each component of the cochlea. RESULTS: In the explored frequency range, the stereocilia and outer hair cells and basilar membrane sclerosis resulted in 23.4%, 47.2%, and 57.8% reduction of basilar membrane displacement, respectively. Lesions of the basilar membrane and stereocilia and outer hair cells in the Corti caused a hearing response curve shift to higher frequencies and a decrease of the amplitude of the basilar membrane. CONCLUSIONS AND SIGNIFICANCE: Lesions of the internal structure of the Corti cause diminished movement of basement membrane and decreased sensorial function, which ultimately lead to hearing loss.

Comparative Proteomic Analysis of tPVAT during Ang II Infusion.

Perivascular adipose tissue (PVAT) homeostasis plays an important role in maintaining vascular function, and PVAT dysfunction may induce several pathophysiological situations. In this study, we investigated the effect and mechanism of the local angiotensin II (Ang II) on PVAT. High-throughput comparative proteomic analysis, based on TMT labeling combined with LC-MS/MS, were performed on an in vivo Ang II infusion mice model to obtain a comprehensive view of the protein ensembles associated with thoracic PVAT (tPVAT) dysfunction induced by Ang II. In total, 5037 proteins were confidently identified, of which 4984 proteins were quantified. Compared with the saline group, 145 proteins were upregulated and 146 proteins were downregulated during Ang II-induced tPVAT pathogenesis. Bioinformatics analyses revealed that the most enriched GO terms were annotated as gene silencing, monosaccharide binding, and extracellular matrix. In addition, some novel proteins, potentially associated with Ang II infusion, were identified, such as acyl-CoA carboxylase α, very long-chain acyl-CoA synthetase (ACSVL), uncoupling protein 1 (UCP1), perilipin, RAS protein-specific guanine nucleotide-releasing factor 2 (RasGRF2), and hypoxia inducible factor 1α (HIF-1α). Ang II could directly participate in the regulation of lipid metabolism, transportation, and adipocyte differentiation by affecting UCP1 and perilipin. Importantly, the key KEGG pathways were involved in fatty acid biosynthesis, FABP3-PPARα/γ, RasGRF2-ERK-HIF-1α, RasGRF2-PKC-HIF-1α, and STAT3-HIF-1α axis. The present study provided the most comprehensive proteome profile of mice tPVAT and some novel insights into Ang II-mediated tPVAT dysfunction and will be helpful for understanding the possible relationship between local RAS activation and PVAT dysfunction.

RhoGDI1-Cdc42 Signaling Is Required for PDGF-BB-Induced Phenotypic Transformation of Vascular Smooth Muscle Cells and Neointima Formation.

RhoGTPase is involved in PDGF-BB-mediated VSMC phenotypic modulation. RhoGDIs are key factors in regulating RhoGTPase activation. In the present study, we investigated the regulatory effect of RhoGDI1 on the activation of RhoGTPase in VSMC transformation and neointima formation. Western blot and co-immunoprecipitation assays showed that the PDGF receptor inhibition by crenolanib promoted RhoGDI1 polyubiquitination and degradation. Inhibition of RhoGDI1 degradation via MG132 reversed the decrease in VSMC phenotypic transformation. In addition, RhoGDI1 knockdown significantly inhibited VSMC phenotypic transformation and neointima formation in vitro and in vivo. These results suggest that PDGF-BB promotes RhoGDI1 stability via the PDGF receptor and induces the VSMC synthetic phenotype. The co-immunoprecipitation assay showed that PDGF-BB enhanced the interaction of RhoGDI1 with Cdc42 and promoted the activation of Cdc42; these enhancements were blocked by crenolanib and RhoGDI1 knockdown. Moreover, RhoGDI1 knockdown and crenolanib pretreatment prevented the localization of Cdc42 to the plasma membrane (PM) to activate and improve the accumulation of Cdc42 on endoplasmic reticulum (ER). Furthermore, Cdc42 inhibition or suppression significantly reduced VSMC phenotypic transformation and neointima formation in vitro and in vivo. This study revealed the novel mechanism by which RhoGDI1 stability promotes the RhoGDI1-Cdc42 interaction and Cdc42 activation, thereby affecting VSMC phenotypic transformation and neointima formation.

Time-domain analysis of a three-dimensional numerical model of the human spiral cochlea at medium intensity.

For the processing and detection of speech and music, the human cochlea has an exquisite sensitivity and selectivity of frequency and a dynamic range. How the cochlea performs these remarkable functions has fascinated auditory scientists for decades. Because it is not possible to measure sound-induced vibrations within the cochlea in a living human being, mathematical modeling has played an important role in cochlear mechanics. For this study, a three-dimensional human cochlear model with a fluid‒structure coupling was constructed. Time-domain analysis was performed to calculate the displacement, velocity, and stress of the basilar membrane (BM) and osseous spiral lamina (OSL) at different times in response to a pure tone stimulus. The model reproduced the traveling-wave motion of the BM. The model also showed that the cochlea's spiral shape can induce asymmetrical mechanical behavior of the BM and cause cochlear fluid to move in a radial direction; this may contribute to human sound perception. The cochlea's spiral shape not only enhances a low-frequency vibration of the BM but also changes the maximization of the positions of vibration. Therefore, the spiral's characteristics play a key role in the cochlea's frequency selectivity for low-frequency sounds. And this suggests that the OSL can react to sound as quickly as the BM. Furthermore, the basal region of the BM tends to have more stress than its other regions, and this may explain the clinical observation that human sensorineural hearing loss often occurs at high frequencies.