Objective: To investigate the regulatory effects of bio-intensity electric field on directional migration and microtubule acetylation in human epidermal cell line HaCaT, aiming to provide molecular theoretical basis for the clinical treatment of wound repair. Methods: The experimental research methods were used. HaCaT cells were collected and divided into simulated electric field group (n=54) placed in the electric field device without electricity for 3 h and electric field treatment group (n=52) treated with 200 mV/mm electric field for 3 h (the same treatment methods below). The cell movement direction was observed in the living cell workstation and the movement velocity, trajectory velocity, and direction of cosθ of cell movement within 3 h of treatment were calculated. HaCaT cells were divided into simulated electric field group and electric field treatment 1 h group, electric field treatment 2 h group, and electric field treatment 3 h group which were treated with 200 mV/mm electric field for corresponding time. HaCaT cells were divided into simulated electric field group and 100 mV/mm electric field group, 200 mV/mm electric field group, and 300 mV/mm electric field group treated with electric field of corresponding intensities for 3 h. The protein expression of acetylated α-tubulin was detected by Western blotting (n=3). HaCaT cells were divided into simulated electric field group and electric field treatment group, and the protein expression of acetylated α-tubulin was detected and located by immunofluorescence method (n=3). Data were statistically analyzed with Kruskal-Wallis H test,Mann-Whitney U test, Bonferroni correction, one-way analysis of variance, least significant difference test, and independent sample t test. Results: Within 3 h of treatment, compared with that in simulated electric field group, the cells in electric field treatment group had obvious tendency to move directionally, the movement velocity and trajectory velocity were increased significantly (with Z values of -8.53 and -2.05, respectively, P<0.05 or P<0.01), and the directionality was significantly enhanced (Z=-8.65, P<0.01). Compared with (0.80±0.14) in simulated electric field group, the protein expressions of acetylated α-tubulin in electric field treatment 1 h group (1.50±0.08) and electric field treatment 2 h group (1.89±0.06) were not changed obviously (P>0.05), while the protein expression of acetylated α-tubulin of cells in electric field treatment 3 h group (3.37±0.36) was increased significantly (Z=-3.06, P<0.05). After treatment for 3 h, the protein expressions of acetylated α-tubulin of cells in 100 mV/mm electric field group, 200 mV/mm electric field group, and 300 mV/mm electric field group were 1.63±0.05, 2.24±0.08, and 2.00±0.13, respectively, which were significantly more than 0.95±0.27 in simulated electric field group (P<0.01). Compared with that in 100 mV/mm electric field group, the protein expressions of acetylated α-tubulin in 200 mV/mm electric field group and 300 mV/mm electric field group were increased significantly (P<0.01); the protein expression of acetylated α-tubulin of cells in 300 mV/mm electric field group was significantly lower than that in 200 mV/mm electric field group (P<0.05). After treatment for 3 h, compared with that in simulated electric field group, the acetylated α-tubulin of cells had enhanced directional distribution and higher protein expression (t=5.78, P<0.01). Conclusions: Bio-intensity electric field can induce the directional migration of HaCaT cells and obviously up-regulate the level of α-ubulin acetylation after treatment at 200 mV/mm bio-intensity electric field for 3 h.
Humans ; Acetylation ; Tubulin/metabolism* ; Microtubules/metabolism* ; Electricity ; Epidermal Cells/metabolism*

Cell division and expansion require the ordered arrangement of microtubules, which are subject to spatial and temporal modifications by developmental and environmental factors. Understanding how signals translate to changes in cortical microtubule organization is of fundamental importance. A defining feature of the cortical microtubule array is its association with the plasma membrane; modules of the plasma membrane are thought to play important roles in the mediation of microtubule organization. In this review, we highlight advances in research on the regulation of cortical microtubule organization by membrane-associated and membrane-tethered proteins and lipids in response to phytohormones and stress. The transmembrane kinase receptor Rho-like guanosine triphosphatase, phospholipase D, phosphatidic acid, and phosphoinositides are discussed with a focus on their roles in microtubule organization.
Cell Membrane ; metabolism ; Environment ; Microtubules ; metabolism ; Plant Cells ; metabolism ; Plant Development ; Signal Transduction

Plant cells response to water deficit through a variety of physiological processes. In this work, we studied the function of microtubule cytoskeleton during dehydration/rehydration cycle in moss (Atrichum undulatum) protonemal cells as a model system. The morphological and cytological change of protonemal cells during dehydration and rehydration cycle were first investigated. Under normal conditions, protonemal cells showed bright green colour and appeared wet and fresh. Numerous chloroplasts distributed regularly throughout the cytoplasm in each cell. After dehydration treatment, protonemal cells lost most of their chlorophylls and turned to look yellow and dry. In addition, dehydration caused plasmolysis in these cells. Upon rehydration, the cells could recover completely from the dehydrated state. These results indicated that moss had a remarkable intrinsic ability to survive from the extreme drought stress. Microtubule, an important component of cytoskeleton, is considered to play crucial roles in the responses to some environmental stresses such as cold and light. To see if it is also involved in the drought tolerance, dynamic organization of microtubules in protonemal cells of Atrichum undulatum subjected to drought and rehydration were examined by indirect immunofluorescence combined with confocal lasersharp scanning microscopy. The cortical microtubules were arranged into a fine structure with a predominant orientation parallel to the long axis of the cells in the control cells. After dehydration, the microtubule organization was remarkablly altered and the fine microtubule structure disappeared whereas some thicker cables formed. When the cells were grown under rehydration conditions, the fine microtubule arrays reappeared. These results provided a piece of evidence that microtubules play a role in the cellular responses to drought stress in moss. Furthermore, we analyzed the effects of the microtubule-disrupting agent colchicine on the morphology recovery of the protonemal cells during rehydration process. The cells were incubated with colchicine, followed by drought stress treatment and rehydration in the presence of colchicine to prevent recovery of microtubule organization. Results from immunofluorescence showed that microtubule arrays were broken down into smaller fragments. Compared to the cells treated with drought stress alone, the cells treated with drought stress in the presence of colchicine could not recover after rehydration treatment. The morphology resembled those of the drought treated cells, with obvious plasmolysis phenomena and loss of chlorophyll content. These results support the notion that microtubules were involved in the deccication tolerance mechanism in Atrichum undulatum.
Bryophyta ; metabolism ; physiology ; Droughts ; Gene Expression Regulation, Plant ; physiology ; Microscopy ; Microtubules ; metabolism

OBJECTIVETo study the influence of serum from scalded rats on the cytoskeleton of colonic smooth muscle cells (CSMC) of rats cultured in vitro, and to probe the possible mechanism of gastrointestinal motility disorder after burn.

METHODSCSMC isolated from healthy adult Wistar rat were cultured and divided into scald serum group (SS) and normal serum group (NS) according to the random number talbi. Two normal Wistar rats were used, one of which was inflicted with deep partial-thickness scald. Serum was obtained from blood collected from these two rats respectively and diluted to 20% in concentration. Serum from scald and normal rats were respectively added to the culture of CSMC in SS and NS groups. The expression of actin and the relative content of β-tubulin in CSMC was respectively determined with flow cytometry and Western blot at post treatment hour (PTH) 1, 3, 6, and 12 (with 10 samples in each group at each time point). Data were processed with t test.

RESULTSFluorescence intensity of actin in SS group at PTH 1, 3, 6, and 12 was respectively 59 ± 4, 26 ± 6, 39 ± 6, and 42 ± 6, all significantly lower than those in NS group (95 ± 10, 91 ± 10, 102 ± 9, and 97 ± 9, with t value respectively 10.528, 18.069, 18.748, 16.647, P < 0.05 or P < 0.01). In SS group, the fluorescence intensity decreased to the nadir at PTH 3, and then increased persistently at PTH 6 and 12. (2) Relative content of β-tubulin in SS group at PTH 1, 3, 6, and 12 was respectively 14.44 ± 0.26, 8.61 ± 0.19, 11.76 ± 0.31, and 12.13 ± 0.29, all significantly less than those in NS group (22.37 ± 1.15, 21.87 ± 1.79, 23.24 ± 1.55, and 21.99 ± 2.02, with t value respectively 21.176, 23.365, 23.000, 15.273, P values all below 0.01). In SS group, the relative content of β-tubulin decreased to the nadir at PTH 3 and increased slowly at PTH 6 and 12.

CONCLUSIONSThe reduction of CMSC content which has the tendency of increasing later, can be attributed to the influence of scald serum in initial stage. This may be related to the tolerance and adaptation to scald serum and self-repair of CMSC.

Animals ; Burns ; metabolism ; Cells, Cultured ; Colon ; cytology ; Cytoskeleton ; metabolism ; Male ; Microtubules ; metabolism ; Myocytes, Smooth Muscle ; metabolism ; Rats ; Rats, Wistar ; Serum

Hypoxia-inducible factor 1 (HIF1) is a master transcription factor that induces the transcription of genes involved in the metabolism and behavior of stem cells. HIF1-mediated adaptation to hypoxia is required to maintain the pluripotency and survival of stem cells under hypoxic conditions. HIF1 activity is well known to be tightly controlled by the alpha subunit of HIF1 (HIF1α). Understanding the regulatory mechanisms that control HIF1 activity in stem cells will provide novel insights into stem cell biology under hypoxia. Recent research has unraveled the mechanistic details of HIF1α regulating processes, suggesting new strategies for regulating stem cells. This review summarizes recent experimental studies on the role of several regulatory factors (including calcium, 2-oxoglutarate-dependent dioxygenase, microtubule network, importin, and coactivators) in regulating HIF1α activity in stem cells.
Anoxia ; Biology ; Calcium ; Hypoxia-Inducible Factor 1 ; Karyopherins ; Metabolism ; Microtubules ; Stem Cells ; Transcription Factors

OBJECTIVETo explore the response of rat bone marrow mesenchymal stem cells (MSCs and calvarial osteoblasts to mechanical strain and the consequent changes of cytoskeleton F-actin.

METHODSBone marrow MSCs and calvarial osteoblasts were isolated from SD rats and cultured in vitro. Mechanical stretch was performed on passage 3 cells at 2 000 microepsilon for 0, 2, 6 and 12 hours using four-point bending system. The response of cells and the distribution of F-actin were observed using fluorescent staining under laser scanning confocal microscope and the morphological parameters were quantified using image analysis software Laserpix.

RESULTSUnder mechanical stretch, the fluorescent staining decreased obviously at both MSCs and osteoblasts, and F-actin filaments were rearranged and became tenuous, thinner, and abnormally distributed. The outline of nucleus became unclear and apoptotic changes were observed at some of both cells. Cellular size decreased more significantly in MSCs than in osteoblasts. Quantity analysis showed that total area of cells, total fluorescent density and green fluorescent density (F-actin) were all significantly decreased in MSCs (P < 0.05 or P < 0.01), and total fluorescent density, green fluorescent density and red fluorescent density (nuclei) did also in osteoblasts (P < 0.05 or P < 0.01).

CONCLUSIONMechanical stretch caused extensive response on both MSCs and osteoblasts which led to the rearrangement of F-actin filament and apoptosis in some of these cells. MSCs were more sensitive to mechanical strain than osteoblasts.

Actin Cytoskeleton ; metabolism ; Actins ; metabolism ; Animals ; Bone Marrow Cells ; Cells, Cultured ; Cytoskeleton ; Mesenchymal Stromal Cells ; Microtubules ; Osteoblasts ; Rats ; Stress, Mechanical

OBJECTIVETo investigate the degree of injury to microtubule of myocardium at early post-hypoxia stage.

METHODSCardiomyocytes from Wistar rats were isolated and cultured, and they were then divided into normal control and hypoxia groups. The distribution and morphological changes in microtubules were observed with laser confocal microscopy and scanning electron microscope at 10, 20, 30 post-hypoxia minutes (PHM) and 1 post-hypoxia hour (PHH). Then the fluorescence intensity of alpha-microtubule was detected with RT-PCR, the morphology of microtubule was observed, and the expression of dissociative alpha-microtubule was determined by Western blot.

RESULTSCompared with normal control group, the bead-like structure of the microtubule in hypoxia group disappeared at 10 PHM, but no obvious change was observed in the distribution and number of microtubules. Despite the disappearance of bead-like structure of the microtubule, the microtubule derangement and loss of microtubule at the edge of cell were observed at 20 PHM. The fragmentation, derangement of texture, and loss of regularity in cardiomyocytes were observed at 30 PHM and 1 PHH. The fluorescence intensity of alpha-microtubule in hypoxia group was evidently decreased than that in normal group in a time-dependent manner. The expression of dissociative alpha-microtubule in hypoxia group at 10 PHM (46,644 +/- 145) was obviously higher than that in normal group (13,357 +/- 98, P < 0.01), and its increase was maintained with elapse of time.

CONCLUSIONMicrotubule injury to cardiomyocytes occurs at early stage of post-hypoxia, with destruction of its structure and distribution.

Animals ; Cell Hypoxia ; Cells, Cultured ; Microtubule-Associated Proteins ; biosynthesis ; Microtubules ; metabolism ; pathology ; Myocytes, Cardiac ; metabolism ; pathology ; Rats ; Rats, Wistar

OBJECTIVETo investigate the influence of microtubule depolymerization of myocardial cells on distribution and activity of mitochondria, and energy metabolism of cells in adult rats.

METHODSMyocardial cells of SD adult rats and SD suckling rats were isolated and cultured. They were divided into adult and suckling rats control groups (AC and SC, normally cultured without any stimulating factor), adult and suckling rats microtubule depolymerization agent groups (AMDA and SMDA, cultured with 8 micromol/L colchicine containing nutrient solution for 30 minutes) according to the random number table. (1) The expression of polymerized beta tubulin in myocardial cells of adult and suckling rats was detected with Western blot. (2) Myocardial cells of rats in AC and AMDA groups were collected. The expression of cytochrome c was detected with Western blot. Distribution of voltage-dependent anion channels (VDAC) and polymerized beta tubulin in myocardial cells were observed with immunofluorescent staining. Mitochondrial inner membrane potential was determined with immunocytochemical method. Activity of myocardial cells was detected with MTT method. Contents of ATP, adenosine diphosphate (ADP), and adenosine monophosphate (AMP) and energy charge of cells were determined with high performance liquid chromatography.

RESULTS(1) The expression of polymerized beta tubulin:in AMDA group it was 0.52 + or - 0.07, which was obviously lower than that (1.25 + or - 0.12) in AC group (F = 31.002, P = 0.000); in SMDA group it was 0.76 + or - 0.12, which was significantly lower than that (1.11 + or - 0.24) in SC group (F = 31.002, P = 0.000), but was obviously higher than that in AMDA group (F = 31.002, P = 0.009). (2) The expression of cytochrome c in AC group was 0.26 + or - 0.03, which was obviously lower than that (1.55 + or - 0.13) in AMDA group (t = -24.056, P = 0.000). (3) Immunofluorescent staining result: in AC group, microtubules of myocardial cells were in linear tubiform, distributed in parallel with myocardial fiber; VDAC staining result showed that mitochondria were in granular form, distributed in the same direction as microtubules. In AMDA group, the normal distribution regularity of microtubules was destroyed, with weakened immune fluorescence intensity, microtubules structure indistinct, continuity lost, rough in appearance, and the distribution of mitochondria became disrupted. (4) Mitochondrial inner membrane potential in AC group fluorescent intensity was 1288 + or - 84, which was obviously higher than that (331 + or - 27) in AMDA group (t = 26.508, P = 0.000). (5) Cellular activity: in AC group absorbance value was 1.75 + or - 0.11, which was obviously lower than that (0.81 + or - 0.07) in AMDA group (t = 17.348, P = 0.000). (6) Energy metabolism: compared with those in AC group, content of ATP decreased, contents of ADP and AMP increased, and ATP/ADP value and energy charge decreased in AMDA group.

CONCLUSIONSMicrotubules and mitochondria distribute in the same direction in normal myocardial cells in adult rats. After microtubule depolymerization, mitochondria are arranged in disorder fashion; cytochrome c leaks from mitochondria; mitochondrial membrane potential, energy supply, and cellular activity decrease in the myocardial cells.

Animals ; Cells, Cultured ; Energy Metabolism ; Male ; Membrane Potential, Mitochondrial ; Microtubules ; metabolism ; Mitochondria, Heart ; metabolism ; Myocytes, Cardiac ; metabolism ; Rats ; Rats, Sprague-Dawley ; Tubulin ; metabolism

Rat brain kinesin is a conventional kinesin that uses the energy from ATP hydrolysis to walk along the microtubule progressively. Studying how the chemical energy in ATP is utilized for mechanical movement is important to understand this moving function. The monomeric motor domain, rK354, was crystallized. An ATP analog, AMPPNP, was soaked in the active site. Comparing the complex structure of rK354 x AMPPNP and that of rK354ADP, a hypothesis is proposed that Glu237 in the Switch II region sensors the presence of gamma-phosphate and transfers the signal to the microtubule binding region.
Adenosine Triphosphate ; metabolism ; Adenylyl Imidodiphosphate ; metabolism ; Animals ; Brain ; metabolism ; Catalytic Domain ; Crystallography ; Hydrolysis ; Kinesin ; metabolism ; Microtubules ; metabolism ; Phosphates ; Protein Binding ; Rats

OBJECTIVETo explore the effects of microtubule depolymerization (MD) on the spontaneous beating rate, action potential (AP), and oxygen consumption of cardiac myocytes in rats and its mechanism.

METHODSOne-hundred and eighty neonatal SD rats divided into 12 batches were used in the experiment, and 15 rats in each batch were sacrificed for the isolation and culture of cardiac myocytes after the heart tissues were harvested. The cardiac myocytes were respectively inoculated in one 12-well plate filled with 6 round cover slips, one 12-well plate filled with 6 square cover slips, two cell culture flasks, and two cell culture dishes. After routine culture for three days, the cardiac myocytes from all the containers were divided into normal control group (NC, routinely cultured with 3 mL DMEM/F12 solution rewarmed at 37 °C for 3 h) and group MD (routinely cultured with 3 mL DMEM/F12 solution rewarmed at 37 ° and containing 8 µmol/L colchicine for 3 h) according to the random number table, with 3 holes, 1 flask, or 1 dish in each group. The morphological changes in microtubules were observed with confocal laser scanning microscope after immunofluorescent staining. The content of polymerized or dissociative α-tubulin was determined by Western blotting. Spontaneous beating rate of the cells was observed and calculated under inverted microscope. Dissolved oxygen concentration of DMEM/F12 solution containing cardiac myocytes was determined by oxygen microelectrode system before and after the addition of colchicine. Additionally, dissolved oxygen concentration of DMEM/F12 solution and colchicine + DMEM/F12 solution was determined. The whole-cell patch-clamp technique was used to record AP, delayed rectifier K+ current (I(K)), and L-type Ca2+ current (I(Ca-L)) in cardiac myocytes; current density-voltage (I-V) curves were drawn based on the traces. Data were processed with independent or paired samples t-test.

RESULTS(1) In group NC, microtubules of cardiac myocytes were around the nucleus in radial distribution with intact and clear linear tubiform structure. The microtubules in group MD were observed in dispersive distribution with damaged structure and rough linear tubiform structure. (2) In group MD, the content of dissociative α-tubulin of cells (0.61 ± 0.03) was obviously higher than that in group NC (0.46 ± 0.03, t = -6.99, P < 0.05), while the content of polymerized α-tubulin (0.57 ± 0.04) was significantly lower than that in group NC (0.88 ± 0.04, t = 9.09, P < 0.05). (3) Spontaneous beating rate of cells was (59 ± 8) times per min in group MD, which was distinctly higher than that in group NC [(41 ± 7) times per min, t = 5.62, P < 0.01]. (4) Dissolved oxygen concentration of DMEM/F12 solution containing cardiac myocytes was (138.4 ± 2.5) µmol/L, and it was reduced to (121.7 ± 3.6) µmol/L after the addition of colchicine ( t = 26.31, P < 0.05). There was no obvious difference in dissolved oxygen concentration between DMEM/F12 solution and colchicine + DMEM/F12 solution (t = 0.72, P > 0.05). (5) Compared with that of group NC, AP morphology of cells in group MD changed significantly, with unobvious repolarization plateau phase and shorter action potential duration (APD). The APD20, APD50, and APD90 were respectively (36.2 ± 3.8), (73.7 ± 5.7), and (115.1 ± 8.0) ms in group MD, which were significantly shorter than those of group NC [(40.2 ± 2.3), (121.4 ± 7.0), and (169.4 ± 5.6) ms, with t values respectively 2.61, 15.88, and 16.75, P values below 0.05]. (6) Compared with that of group NC, the I-V curve of I(K) of cells in group MD moved up with higher current density under each test voltage (0 to 40 mV) after activation ( with t values from 2. 70 to 3. 76, P values below 0.05) . (7) There was not much alteration in current density of I(Ca-L) under each test voltage (-30 to 50 mV) between 2 groups (with t values from -1.57 to 1.66, P values above 0.05), and their I-V curves were nearly overlapped.

CONCLUSIONSAfter MD, the I(K) is enhanced without obvious change in I(Ca-L), making AP repolarization faster and APD shortened. Then the rapid spontaneous beating rate increases oxygen consumption of cardiac myocytes of rats.

Action Potentials ; Animals ; Cells, Cultured ; Energy Metabolism ; Microtubules ; metabolism ; Mitochondria, Heart ; metabolism ; Myocytes, Cardiac ; metabolism ; Rats ; Rats, Sprague-Dawley ; Tubulin ; metabolism