A Systematic Review of Circulatory microRNAs in Major Depressive Disorder: Potential Biomarkers for Disease Prognosis.

Major depressive disorder (MDD) is a neuropsychiatric disorder, which remains challenging to diagnose and manage due to its complex endophenotype. In this aspect, circulatory microRNAs (cimiRNAs) offer great potential as biomarkers and may provide new insights for MDD diagnosis. Therefore, we systemically reviewed the literature to explore various cimiRNAs contributing to MDD diagnosis and underlying molecular pathways. A comprehensive literature survey was conducted, employing four databases from 2012 to January 2021. Out of 1004 records, 157 reports were accessed for eligibility criteria, and 32 reports meeting our inclusion criteria were considered for in-silico analysis. This study identified 99 dysregulated cimiRNAs in MDD patients, out of which 20 cimiRNAs found in multiple reports were selected for in-silico analysis. KEGG pathway analysis indicated activation of ALS, MAPK, p53, and P13K-Akt signaling pathways, while gene ontology analysis demonstrated that most protein targets were associated with transcription. In addition, chromosomal location analysis showed clustering of dysregulated cimiRNAs at proximity 3p22-p21, 9q22.32, and 17q11.2, proposing their coregulation with specific transcription factors primarily involved in MDD physiology. Further analysis of transcription factor sites revealed the existence of HIF-1, REST, and TAL1 in most cimiRNAs. These transcription factors are proposed to target genes linked with MDD, hypothesizing that first-wave cimiRNA dysregulation may trigger the second wave of transcription-wide changes, altering the protein expressions of MDD-affected cells. Overall, this systematic review presented a list of dysregulated cimiRNAs in MDD, notably miR-24-3p, let 7a-5p, miR-26a-5p, miR135a, miR-425-3p, miR-132, miR-124 and miR-16-5p as the most prominent cimiRNAs. However, various constraints did not permit us to make firm conclusions on the clinical significance of these cimiRNAs, suggesting the need for more research on single blood compartment to identify the biomarker potential of consistently dysregulated cimiRNAs in MDD, as well as the therapeutic implications of these in-silico insights.

Hypergravity-induced enrichment of ß1 integrin on the cell membranes of osteoblast-like cells via caveolae-dependent endocytosis.

In bone cells, integrins on the cellular surface are the primary sensors of their mechanical environment. Although gravitational changes are known to affect the adhesion and functions of bone cells, whether integrins respond to hypergravity in osteoblasts remains unclear. In this work, we demonstrate that exposure to a hypergravitational environment (20 × g via centrifugation) resulted in the concentration of ß1, but not ß3, integrin on the cell membrane of osteoblast-like (MC3T3-E1) cells. Notably, the total expression of both integrins was unaffected by the hypergravitational environment. In addition, caveolin-dependent endocytosis was discovered to be involved in the regulation of the enrichment of ß1 integrin on the cell surface after stimulation by hypergravity. These findings could aid in the improvement of our understanding of the mechanisms underlying the effects of different gravitational forces on the human body.

Preparation and characterization of liquefied eggplant branch bio-based controlled-release fertilizer.

Bio-based coating materials have received increased attention because of their low-cost, environmentally friendly, and sustainable properties. In this paper, a novel coating material was developed to coat ureas using bio-based coating material derived from liquefied eggplant branches to form controlled-release ureas (CRUs). Also, the optimum proportion of liquefier was studied. Furthermore, dimethyl siloxane was used to modify liquified eggplant branches to make them hydrophobic, resulting in hydrophobic controlled-release ureas (SCRUs). This hydrophobic-enabled coating is environmentally friendly and highly efficient. The products were characterized by specific scanning electron microscopy, energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry, and the water contact angles of CRUs and SCRUs were determined. The nutrient-release characteristics of the SCRUs in water were determined at 25 °C and compared with those of CRUs. The results showed that the modification with dimethyl siloxane reduced the N release rate and increased the longevity of the fertilizer coated with hydrophobic bio-based coating material. In addition, organosilicon atoms on the SCRU surface also block the micro-holes on the coating and thus reduce the entry of water onto the coating. The results suggest that the new coating technology can create a hydrophobic surface on bio-based coating material and thus improve their controlled-release characteristics.

Rapid alterations of cell cycle control proteins in human T lymphocytes in microgravity.

In our study we aimed to identify rapidly reacting gravity-responsive mechanisms in mammalian cells in order to understand if and how altered gravity is translated into a cellular response. In a combination of experiments using "functional weightlessness" provided by 2D-clinostats and real microgravity provided by several parabolic flight campaigns and compared to in-flight-1g-controls, we identified rapid gravity-responsive reactions inside the cell cycle regulatory machinery of human T lymphocytes. In response to 2D clinorotation, we detected an enhanced expression of p21 Waf1/Cip1 protein within minutes, less cdc25C protein expression and enhanced Ser147-phosphorylation of cyclinB1 after CD3/CD28 stimulation. Additionally, during 2D clinorotation, Tyr-15-phosphorylation occurred later and was shorter than in the 1 g controls. In CD3/CD28-stimulated primary human T cells, mRNA expression of the cell cycle arrest protein p21 increased 4.1-fold after 20s real microgravity in primary CD4+ T cells and 2.9-fold in Jurkat T cells, compared to 1 g in-flight controls after CD3/CD28 stimulation. The histone acetyltransferase (HAT) inhibitor curcumin was able to abrogate microgravity-induced p21 mRNA expression, whereas expression was enhanced by a histone deacetylase (HDAC) inhibitor. Therefore, we suppose that cell cycle progression in human T lymphocytes requires Earth gravity and that the disturbed expression of cell cycle regulatory proteins could contribute to the breakdown of the human immune system in space.

[Mircocarriers' motion in rotating wall vessels].

Rotating wall vessels (RWVS), an ingenious apparatus for three-dimensional suspension culture, is widely used to build a simulated microgravity-effect on cell. Independent researchers have proposed hypotheses to illustrate why RWVS can simulate certain aspects of microgravity. Many of the hypotheses stated that the culture condition in RWVS is determined by the cellular mechanical environment which is a result of low fluid shear and microcarrier's motion. The microcarrier's motions consist of primary and secondary motions. In the light of the analysis of forces loaded by the microcarriers, some conclusions are drawn from the data on microcarriers' primary and secondary motions about which many simulations and observations have already been conducted.

Effects of microgravity and hypergravity on platelet functions.

Many serious thrombotic and haemorrhagic diseases or fatalities have been documented in human being exposed to microgravity or hypergravity environments, such as crewmen in space, roller coaster riders, and aircrew subjected to high-G training. Some possible related organs have been examined to explore the mechanisms underlying these gravity change-related diseases. However, the role of platelets which are the primary players in both thrombosis and haemostasis is unknown. Here we show that platelet aggregation induced by ristocetin or collagen and platelet adhesion to von Willebrand factor (VWF) were significantly decreased after platelets were exposed to simulated microgravity. Conversely, these platelet functions were increased after platelets were exposed to hypergravity. The tail bleeding time in vivo was significantly shortened in mice exposed to high-G force, whereas, was prolonged in hindlimb unloaded mice. Furthermore, three of 23 mice died after 15 minutes of -8 Gx stress. Platelet thrombi disseminated in the heart ventricle and blood vessels in the brain, lung, and heart from the dead mice. Finally, glycoprotein (GP) Ibalpha surface expression and its association with the cytoskeleton were significantly decreased in platelets exposed to simulated microgravity, and obviously increased in hypergravity-exposed platelets. These data indicate that the platelet functions are inhibited in microgravity environments, and activated under high-G conditions, suggesting a novel mechanism for gravity change-related haemorrhagic and thrombotic diseases. This mechanism has important implications for preventing and treating gravity change-related diseases, and also suggests that special attentions should be paid to human actions under different gravity conditions.

[Preparation and preliminary application of rabbit polyclonal antibodies against intracellular peptides of human platelet glycoprotein GPIbalpha].

OBJECTIVE: To prepare rabbit polyclonal antibodies against intracellular peptides of human platelet glycoprotein GPIbalpha. METHODS: Two peptides corresponding to human platelet GPIbalpha C-terminus were synthesized and purified by high-performance liquid chromatography (HPLC). The peptides were cross-linked with keyhole limpet hemocyanin (KLH). Two New Zealand white rabbits were immunized with conjugated peptides for 3 times. The polyclonal antibodies were purified by Ammonium Sulfate Precipitation and identified by dot blotting and ELISA. GPIbalpha intracellular peptides phosphorylation was tested with these polyclonal antibodies by ELISA. RESULTS: The titers of the two polyclonal antibodies against the GPIbalpha C-terminus peptides were 1:32 000 and 1:64 000 respectively and both of these antibodies reacted with purified GPIbalpha. CONCLUSIONS: Two rabbit polyclonal antibodies against C-terminal peptides of human platelet GPIbalpha have been prepared successfully, providing a way for the preparation of these kinds of antibody. Both phosphorylation and dephosphorylation states exist in the intracellular peptide of human platelets.

[Determination of the detachment force of platelet membrane protein GPIb/IX and von Willebrand factor].

CHO cells expressing human GPIb/IX and rabbit red blood cells coated with human von Willebrand factor (VWF) were adapted to our study on the binding probability and the detachment force of GPIb/IX and VWF. With the micropipette system, the two cells were impinged under a constant force for controlled time. When the cells were pulled apart, the deformation of RBC was recorded, and the binding score and detachment force of the proteins were determined. After the two cells were impinged into 0.5 microm for 30 s, the binding probability of the two cells carrying GPIb/IX and VWF was 15.0%. Via analyzing the deformation of red blood cells, we found out the distribution of rupture forces of cells with GPIb/IX and VWF. Therefore, we infer that the continuous distribution of the detachment force is due to the stochastic effect. The most probable value of the detachment force was 10 pN.

Effects of von Willebrand factor concentration and platelet collision on shear-induced platelet activation.

The binding of plasma von Willebrand factor (vWF) to platelet glycoprotein (GP) Ibalpha in a high shear stress field, and subsequent integrin-GPIIb/IIIa-vWF conjunction induces platelet aggregation (SIPA). However, the specific biomechanical mechanism of the vWF-GPIb interaction still remains to be elucidated. A parallel-plate rectangular flow chamber was built to simulate a stenopeic artery flow pattern. Using the flow chamber, we examined shear-induced platelet activation (SIPAct) at different vWF concentrations (5-25 microg/ml) and several simulated stenotic high shear rates. P-selectin expression on the platelets and annexin V binding to the platelets were used as two markers of platelet activation. At different localized shear rates (3,000 s(-1)-9,500 s(-1)), the percentage of annexin V and P-selectin positive cells increased from 8.3 +/- 0.4% to 22.3 +/- 1.8% ( p 0.05) and from 17.4 +/- 0.5% to 33.5 +/- 2.5% (p 0.05), respectively. As the vWF concentration increased from 5 microg/ml to 25 microg/ml, the annexin V binding rate increased from 7.2 +/- 0.6% to 53.4 +/- 3.8% (p 0.05), and P-selectin expression increased from 16.5 +/- 1.2% to 65.9 +/- 5.2% (p 0.05). A test in a uniform shear field using cone-plate viscometer rheometry showed that the platelet activation rate was proportional to the platelet concentration. This result suggests that platelet collision is one of the impact factors of SIPAct.

[(Possible) molecular mechanism of cells in gravisensing].

Although it is clear that changes of gravity can alter dramatically the functions and structures of cells, little is known about how living cells sense these signals and convert them into a biochemical response. Recent studies estimated that the changes of gravity might influence the single cell directly and indirectly. So far, the molecular mechanism of gravisensing remains unknown, however, according to a great deal of researches focusing on this point, several pathways could be considered: (1) Pre-stress perception pathway; (2) Cytoskeleton-perception pathway; (3) Stress-sensitive ion channel pathway; (4) Indirect effects of gravitational change.

[Advances in the research of cell electrofusion under microgravity].

Bioseperation, cell cultivation and cell electrofusion are three main biological processes in space laboratories. Microgravity is free from the influences of convection and sedimentation. Therefore, it is an ideal realm for cell electrofusion and hence it can be used in the research of monoclonal antibody, cross breeding and microgravity biology. This paper reviews the research of cell electrofusion under microgravity, including the changes of cytoskeleton and the mechanism of cell electrofusion.

[Ex vivo studies of ACL and MCL injury of rats under mechanical stretch].

This study sought to detect the pathological changes of anterior cruciate ligament (ACL) and medial collateral ligament (MCL) under injury stretch. Bone-ACL-Bone (B-ACL-B) and B-MCL-B complexes were isolated from 20 male Wister rats, and were immersed in phosphate buffered saline. The complexes were stretched with 10% or 20% strain for 10 min or 30 min. After being stretched, the specimens were fixed in 10% buffered formalin, then mounted in paraffin. Sections were stained with Alcian blue-PAS and HE. The following results were found: In the control group, the matrix in ACL contained much more GAGs, as compared with that in MCL. When stretched with 10%, most of the fibroblasts in ACL were elongated like spindles in shape, and some pyknotic nuclei were found increased with stretching time. With 20% strain, ACL showed disruption in parts of collagen fibrils and lysis. But MCL was often torn at its tibia end. The injury can be detected in pathological slices under microscope, even this injury can not be found with naked eye. This injury first starts with the disturbance of the nucleus in the ligament, but following further stretching, it will extend to the rupture of collagen fibrils, and the serious injury of the fibroblasts is especially bad to the repair of the ligament.

Tellimagrandin I enhances gap junctional communication and attenuates the tumor phenotype of human cervical carcinoma HeLa cells in vitro.

Tellimagrandin I and chebulinic acid, two hydrolysable tannins, have been shown to exert anti-tumor properties. Dysfunctional gap junctional communication (GJIC) has been recognized as being involved in carcinogenesis. The human cervical carcinoma HeLa cells have been reported to be deficient in functional GJIC. In present study, we investigated whether tellimagrandin I and chebulinic acid might restore functional GJIC in HeLa cells. Both compounds could inhibit the growth of HeLa cells. Either Lucifer yellow transfer assay or calcein transfer assay demonstrated that tellimagrandin I improved GJIC in HeLa cells while chebulinic acid showed no effect on GJIC. The GJIC enhancement by tellimagrandin I occurred along with an increase of Cx43 gene expression at mRNA and protein levels. Exposure to tellimagrandin I also led to inhibition of proliferation and anchorage-independent growth of HeLa cells. In addition, tellimagrandin I decreased the percentage of cells in the G0/G1 and G2/M phases coinciding with an increase in the percentage of cells in the S phase. The accumulation of cells in S phase was coupled with a decreased expression of cyclin A that was critical to the progression of S phase. These results suggested that restoring GJIC might be one explanation for tellimagrandin I antitumor effects, whereas chebulinic acid exerted antitumor action through other pathways.

Effect of Kaiyu Qingwei Jianji on the morphometry and residual strain distribution of small intestine in experimental diabetic rats.

AIM: To investigate the effect of a Chinese medicine, Kaiyu Qingwei Jianji (KYQWJJ) used for diabetic treatment, on the morphometry and residual strain distribution of the small intestine in streptozotocin (STZ) -induced diabetic rats. Correlation analysis was also performed between the opening angle and residual strain with the blood glucose level. METHODS: Forty-two male Wistar rats weighing 220-240 g were included in this study. Thirty-two STZ-induced diabetic rats were subdivided into four groups (n = 8 in each group), i.e. diabetic control group (DM); high dose of KYQWJJ (T1, 36 g/kg per day); low dose of KYQWJJ (T2, 17 g/kg per day) and Gliclazide (T3, 50 mg/kg per day). Another ten rats were used as non-diabetic control (CON). The medicines were poured directly into stomach lumen by gastric lavage twice daily. The rats of CON and DM groups were only poured the physiological saline. Blood glucose and plasma insulin levels were measured. Experimental period was 35 d. At the end of experiment, three 5-cm long segments were harvested from the duodenum, jejunum and ileum. Three rings of 1-2 mm in length for no-load and zero-stress state tests were cut from the middle of different segments. The morphometric data, such as the circumferential length, the wall thickness and the opening angle were measured from the digitized images of intestinal segments in the no-load state and zero-stress state. The residual strain was computed from the morphometry data. Furthermore, the linear regression analysis was performed between blood glucose level with morphometric and biomechanical data in the different intestinal segments. RESULTS: The blood glucose level of DM group was consistent 4-fold to 5-fold higher than those in CON group during the experiment (16.89+/-1.11 vs 3.44+/-0.15 mmol/L, P < 0.001). The blood glucose level in the T1 (16.89+/-1.11 vs 11.08+/-2.67 mmol/L, P < 0.01) and T3 groups (16.89+/-1.11 vs 13.54+/-1.73 mmol/L, P < 0.05), but not in T2 group (P > 0.05) was significantly lower than those in DM group. The plasma insulin levels of DM, T1, T2 and T3 groups were significantly lower than those in CON group (10.98+/-1.02, 12.52+/-1.42,13.54+/-1.56,10.96+/-0.96 vs 17.84+/-2.34 pmol/L respectively, P < 0.05), but no significantly difference among the groups with exception of CON group. The wet weight/cm and total wall thickness of duodenum, jejunum and ileum in DM group were significantly higher than those in CON group (wet weight (g/cm): duodenum 0.209+/-0.012 vs 0.166+/-0.010, jejunum 0.149+/-0.008 vs 0.121+/-0.004, ileum 0.134+/-0.013 vs 0.112+/-0.007; Wall thickness (mm): duodenum 0.849+/-0.027 vs 0.710+/-0.026, jejunum 0.7259+/-0.034 vs 0.627+/-0.025, ileum 0.532+/-0.023 vs 0.470+/-0.010, all P < 0.05), T1 and T3 treatment could partly restore change of wall thickness, but T2 could not. The opening angle and absolute value of inner and outer residual stain were significantly smaller in duodenal segment (188+/-11 degrees, -0.31+/-0.02 and 0.35+/-0.03 vs 259+/-15 degrees, -0.40+/-0.02 and 0.43+/-0.05) and larger in jejunal (215+/-20 degrees, -0.30+/-0.03 and 0.36+/-0.06 vs 172+/-19 degrees, -0.25+/-0.02 and 0.27+/-0.02) and ileal segments (183+/-20 degrees, -0.28+/-0.01 and 0.34+/-0.05 vs 153+/-14 degrees, -0.23+/-0.03 and 0.29+/-0.04) in DM group than in CON group (P < 0.01). T1 and T3 treatment could partly restore this biomechanical alteration, but strong effect was found in T1 treatment (duodenum 243+/-14 degrees, -0.36+/-0.02 and 0.42+/-0.06, jejunum 180+/-15 degrees, -0.26+/-0.03 and 0.30+/-0.06 and ileum 163+/-17 degrees, -0.23+/-0.03 and 0.30+/-0.05, compared with DM, P < 0.05). The linear association was found between the glucose level with most morphometric and biomechanical data. CONCLUSION: KYQWJJ (high dose) treatment could partly restore the changes of blood glucose level and the remodeling of morphometry and residual strain of small intestine in diabetic rats. The linear regression analysis demonstrated that the effect of KYQWJJ on intestinal opening angle and residual strain is partially through its effect on the blood glucose level.

Effects of Hypergravity on Osteopontin Expression in Osteoblasts.

Mechanical stimuli play crucial roles in bone remodeling and resorption. Osteopontin (OPN), a marker for osteoblasts, is important in cell communication and matrix mineralization, and is known to function during mechanotransduction. Hypergravity is a convenient approach to forge mechanical stimuli on cells. It has positive effects on certain markers of osteoblast maturation, making it a possible strategy for bone tissue engineering. We investigated the effects of hypergravity on OPN expression and cell signaling in osteoblasts. Hypergravity treatment at 20 g for 24 hours upregulated OPN expression in MC3T3-E1 cells at the protein as well as mRNA level. Hypergravity promoted OPN expression by facilitating focal adhesion assembly, strengthening actin bundles, and increasing Runx2 expression. In the hypergravity-triggered OPN expression pathway, focal adhesion assembly-associated FAK phosphorylation was upstream of actin bundle assembly.

Morphological properties and residual strain along the small intestine in rats.

AIM: Residual stress and strain are important for gastrointestinal function and relate to the geometric configuration, the loading conditions and the zero-stress state of the gastrointestinal tract. The purpose of this project is to provide morphometric data and residual strains for the rat small intestine ( n =11). METHODS: To approach the no-load state, the intestine was surgically excised, transferred to an organ bath and cut transversely into short ring-shaped segments. Each ring was cut radially for obtaining the zero-stress state. The residual stress can be characterised by an opening angle. The strain difference between the zero-stress state and the no-load state is called residual strain. RESULTS: Large morphometric variations were found along the small intestine. The wall thickness was highest in the proximal duodenum and decreased in distal direction along the axis of the small intestine (P<0.001). The circumferential length of the inner and outer surfaces decreased rapidly along the length of duodenum by 30-50% (P<0.001). The wall area and lumen area showed a similar pattern (P<0.001). In zero-stress state the rings always opened up after making the cut. The experiments resulted in larger inner circumferential length and smaller outer circumferential length when compared to the no-load state. The wall thickness and wall area did not differ between the no-load and zero-stress state. The opening angle and tangent rotation angle increased along the length of the duodenum and had its highest value 30% down the intestine. Further down the intestine it decreased again (P<0.001). The serosal residual strain was tensile with the highest value close to the ligament of Treitz (P<0.001). The mucosal residual strain was compressive in all segments of the small intestine with average values between -0.25 and -0.4 and with the lowest values close to the ligament of Treitz (P<0.001). CONCLUSION: Axial variation in morphometric properties and residual strains were found in the small intestine. Existence of large residual strains indicates that the zero-stress state must be considered in future biomechanical studies in the gastrointestinal tract.

The morphometry and biomechanical properties of the rat small intestine after systemic treatment with epidermal growth factor.

Morphometric and passive biomechanical properties were studied in isolated segments of the duodenum, jejunum and ileum in 22 EGF-treated rats and 12 control rats. The rats were allocated to groups with EGF treatment for 2, 4, 7, and 14 days (n = 6 for each EGF treatment group except n = 4 for the 14 days group) or saline treatment (n = 3 for each group). The intestinal segments were pressurized with Krebs solution from 0 to 8 cmH2O for duodenum and 0 to 6 cmH2O for jejunum and ileum using a ramp distension protocol. The diameter and length were recorded at different pressure levels. Circumferential and longitudinal stresses (force per area) and strains (deformation) were computed from the length, diameter, pressure and the zero-stress state data. EGF treatment was associated with pronounced morphometric changes, e.g., the wall thickness, wall area, and the circumferential lengths significantly increased during EGF treatment in all intestinal segments (P < 0.05). Histological analysis showed that the thickness and area of the layers increased after EGF treatment. With respect to the biomechanical data, the opening angle increased in all segments during EGF treatment with the highest value in the 14 days EGF treatment group (P < 0.05). The same result was found for residual strain and the residual strain gradient through the intestinal wall. Linear regression analysis demonstrated that the opening angle mainly depended on the mucosa thickness and area. Furthermore, the circumferential stiffness increased in the duodenum and decreased in the jejunum and ileum during EGF treatment. A plateau was reached after 7 days where after it started to normalize (P < 0.01). In the longitudinal direction, all intestinal segments became stiffer after EGF treatment for 7 days. After 14 days the curve started to normalize in duodenum and jejunum but not in the ileum.

Comparative studies of LFA-1/ICAM-1 interaction by micropipette and flow chamber techniques.

Interaction of lymphocyte function-associated antigen-1 (LFA-1) with intercellular adhesive molecule-1 (ICAM-1) is important in a number of cellular events, including inflammation, adhesion, transendothelial migration. The aim of this work was to study comparatively the adhesive interaction between LFA-1 and ICAM-1 by a micropipette technique and a flow chamber method, and also to explore the effects of tumor necrosis factor (TNF-alpha), phytohemagglutinin (PHA), and tetramethylpyrazine (TMP) on this interaction. The adhesion probability (Pa) between a lymphocyte cell line SKW-3 expressing LFA-1 and a red blood cell (RBC) coated with soluble ICAM-1 was approached by the micropipette technique, while the flow chamber allowed to observe the firm adhesion of SKW-3 on human umbilical vein endothelial cells (HUVECs). Experimental results show that PHA stimulation of lymphocytes resulted in significant increases in the adhesion probability (Pa) and in number of firmly adhered lymphocytes to HUVECs, but TMP treatment could significantly inhibit such increases.

Effects of stress fiber contractility on uniaxial stretch guiding mitosis orientation and stress fiber alignment.

It has been documented that mitosis orientation (MO) is guided by stress fibers (SFs), which are perpendicular to exogenous cyclic uniaxial stretch. However, the effect of mechanical forces on MO and the mechanism of stretch-induced SFs reorientation are not well elucidated to date. In the present study, we used murine 3T3 fibroblasts as a model, to investigate the effects of uniaxial stretch on SFO and MO utilizing custom-made stretch device. We found that cyclic uniaxial stretch induced both SFs and mitosis directions orienting perpendicularly to the stretch direction. The F-actin and myosin II blockages, which resulted in disoriented SFs and mitosis directions under uniaxial stretch, suggested a high correlation between SFO and MO. Y27632 (10 µM), ML7 (50 µM, or 75 µM), and blebbistatin (50 µM, or 75 µM) treatments resulted in SFO parallel to the principle stretch direction. Upon stimulating and inhibiting the phosphorylation of myosin light chain (p-MLC), we observed a monotonic proportion of SFO to the level of p-MLC. These results suggested that the level of cell contraction is crucial to the response of SFs, either perpendicular or parallel, to the external stretch. Showing the possible role of cell contractility in tuning SFO under external stretch, our experimental data are valuable to understand the predominant factor controlling SFO response to exogenous uniaxial stretch, and thus helpful for improving mechanical models.

Epimorphin regulates bile duct formation via effects on mitosis orientation in rat liver epithelial stem-like cells.

Understanding how hepatic precursor cells can generate differentiated bile ducts is crucial for studies on epithelial morphogenesis and for development of cell therapies for hepatobiliary diseases. Epimorphin (EPM) is a key morphogen for duct morphogenesis in various epithelial organs. The role of EPM in bile duct formation (DF) from hepatic precursor cells, however, is not known. To address this issue, we used WB-F344 rat epithelial stem-like cells as model for bile duct formation. A micropattern and a uniaxial static stretch device was used to investigate the effects of EPM and stress fiber bundles on the mitosis orientation (MO) of WB cells. Immunohistochemistry of liver tissue sections demonstrated high EPM expression around bile ducts in vivo. In vitro, recombinant EPM selectively induced DF through upregulation of CK19 expression and suppression of HNF3alpha and HNF6, with no effects on other hepatocytic genes investigated. Our data provide evidence that EPM guides MO of WB-F344 cells via effects on stress fiber bundles and focal adhesion assembly, as supported by blockade EPM, beta1 integrin, and F-actin assembly. These blockers can also inhibit EPM-induced DF. These results demonstrate a new biophysical action of EPM in bile duct formation, during which determination of MO plays a crucial role.