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Query: UMLS:C0001511 (Adhesion)
 5,955 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. A mesodermal stem cell line C3H10T1/2 was induced to differentiate to muscle by adding 0.3 microM-5-aza-2'-deoxy-cytidine to the medium for 24 h. The changes in membrane currents during differentiation were studied by whole-cell recording and changes in the expression of fibronectin, Neural Cell Adhesion Molecule (NCAM), myosin and desmin were studied immunohistochemically. 2. The stem cells showed the morphology of fibroblastic cells. Most of the stem cells showed ATP-induced slow K+ current. T-type Ca2+ current and inward rectifier K+ current were observed in 19% of the stem cells. The stem cells expressed fibronectin, but not NCAM, myosin or desmin. 3. About 2 weeks after the addition of 5-aza-2'-deoxy-cytidine, large multinucleated skeletal muscle-like cells appeared. Most of the induced muscles showed L-type Ca2+ current, responses to acetylcholine, outward K+ current, inward rectifier K+ current and contraction upon depolarizing stimulation. They expressed NCAM, myosin and desmin, but not fibronectin, and showed no ATP response. 4. In some batches (2/14), the induced muscles showed spontaneous twitches, and possessed tetrodotoxin (TTX)-sensitive Na+ current in addition to the currents described above. Furthermore clear striation was observed in some of the twitching muscles under Nomarski optics. 5. To ascertain the properties of cells at the initial step of muscle differentiation, whose differentiation is determined but not yet evident morphologically or electrophysiologically, subcloning was performed from the heterogeneous cells 10 days after induction. Three myogenic clones were obtained, which proliferated at low cell densities but differentiated to muscle with a high incidence at high cell densities, as well as ten non-myogenic clones. 6. Most myogenic clones still showed ATP-induced K+ current and fibronectin. In addition, most of them showed T-type Ca2+ current and inward rectifier K+ current. They had already expressed NCAM. No other properties observed in muscles had yet been expressed. Most cells of the non-myogenic clones showed ATP-induced K+ current and fibronectin. T-type Ca2+ current was also expressed, but not inward rectifier K+ current or NCAM. 7. The properties of the observed ionic currents were studied. The TTX-sensitive Na+ current could be completely blocked by 0.1 microM-TTX. It could be evoked by depolarizing steps to a level above -40 mV, while steady-state inactivation was detectable around -75 mV and reached half by -52 mV. T-type Ca2+ current could be evoked by a depolarizing pulse to a level above -45 mV, with a maximum amplitude around -15 mV.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Electrophysiological and immunohistochemical analysis of muscle differentiation in a mouse mesodermal stem cell line. 166 64

1. Electrophysiological and immunohistochemical properties during the early stages of muscle differentiation were studied in two myoblastic cell lines, mouse C2C12 and rat L6, and compared to those in myogenic clonal cells derived from the mouse mesodermal stem cell line C3H10T1/2, studied in the preceding paper. 2. Mouse C2C12 cells were induced to differentiate to muscle by changing from 10% fetal calf serum to 2% horse serum in the medium. Most of the C2C12 cells before serum reduction showed ATP-induced slow K+ current. Twelve per cent showed inward rectifier K+ current. They expressed fibronectin and Neural Cell Adhesion Molecule (NCAM). Small spindle-shaped cells at an early stage of muscle differentiation began to appear 24 h after serum reduction. In contrast to cells before serum reduction, only 13% of these spindle-shaped cells showed an ATP response. Most showed tetrodotoxin (TTX)-resistant Na+ current and outward K+ current. Thirty-eight per cent had inward rectifier K+ current. They expressed NCAM but not fibronectin. The T-type Ca2+ current was not observed up to the latest stage of differentiation investigated. 3. Rat L6 cells in maintaining culture medium showed only infrequent ATP responses, but already showed TTX-resistant Na+ current. No clear T-type Ca2+, inward rectifier K+ or outward K+ currents were observed. About one-third of the cells did not express fibronectin. From these results, L6 cells appear to be at a stage near to but slightly earlier than that of C2C12 cells after serum reduction. 4. The properties of the early stages of muscle differentiation in C3H10T1/2 cells, such as the disappearance of ATP-induced K+ current and fibronectin, and the appearance of NCAM, were also seen in C2C12 and L6. However, T-type Ca2+ and inward K+ currents, which were found in the initial stages of C3H10T1/2 muscle differentiation, were not clearly observed in C2C12 and L6. Instead, C2C12 and L6 showed a TTX-resistant Na+ current which was never observed in C3H10T1/2 cells. 5. The properties of the TTX-resistant Na+ current were investigated. In L6 cells, it was reduced to 60% by 1 microM-TTX. It could be evoked by depolarizations to a level above -50 mV with a maximum amplitude at around -15 mV. Steady-state inactivation was detectable with pre-pulses to -100 mV for 100 ms and reached half at pre-pulses of -78 mV. These parameters of inactivation are clearly different from those of the TTX-sensitive Na+ current observed in C3H10T1/2-derived mature muscle cells in the preceding paper.
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PMID:Comparison of initial stages of muscle differentiation in rat and mouse myoblastic and mouse mesodermal stem cell lines. 179 50