Developmental regulation of expression of the α₁ and α₂ subunits mRNAs of the voltage‐dependent calcium channel in a differentiating myogenic cell line

Abstract

The voltage-dependent calcium channel (VDCC) in skeletal muscle probably plays a key role in transducing membrane charge movement to the calcium release channel. We report here that the expression of VDCC al and 0q mRNAs is developmentally regulated in differentiating C2Ci2 myogenic cells. The a 1 mRNA is not detectable in the myoblast form of C2C12 cells while its expression is induced 20-fold in differentiated myotubes. In contrast, the cq mRNA is weakly expressed in myoblasts but is also induced upon myogenic differentiation.

Regulation of voltage-gated calcium channel activity by the Rem and Rad GTPases

“…Replication-deficient adenoviruses expressing GFP as a marker protein and Rem were constructed as described (10). C2C12(A) cells were infected with Ad-Ctr or Ad-Rem adenoviruses, placed in differentiation media (DM) for 6 days to induce robust Ca 2ϩ channel expression (11)(12)(13), and then loaded with 1 M fura 2 acetoxymethyl ester (fura 2-AM) with 1:1 dilution of Pluronic F127 (Molecular Probes) for 5 min at 37°C in a 5% CO 2 humidified incubator. Deesterification and removal of unincorporated fura 2-AM was accomplished by rinsing cells for 20-30 min in imaging bath solution containing 140 mM NaCl, 4 mM KCl, 1 mM MgCl 2 , 1 mM CaCl 2 , 1 mM NaHPO 4 , 5 mM dextrose, and 10 mM Hepes, pH 7.4.…”

Molecular Pharmacology of Voltage-Dependent Calcium Channels

“…A prominent transcript of a,s was detected only in a RNA preparation from skeletal muscle by Northern blot analysis (156). However, successful isolation of this cDNA class from the brain, pancreatic p-cell-derived hamster insulin-secreting tumor (HIT) cells and ovary implies that this class cannot be considered as an exclusive skeletal muscle gene (157); a,s is expressed in a developmentally regulated fashion, being induced upon myogenic differentiation (158,159). Interestingly, a,s cDNAs encoding a two-motif isoform have been isolated (160).…”

Endogenous cardiac Ca2+ channels do not overcome the E‐C coupling defect in immortalized dysgenic muscle cells: evidence for a missing link

“…The pattern of expression offl messages in immortalized normal and dysgenic muscle cells is somewhat different from that seen in normal skeletal muscle. The immortalized cells express commensurable amounts of all four fl messages while the fit gene product is prevalent in normal skeletal muscle [19], cardiac el; 5.2-kb EcoRI fragment of the rabbit cDNA [20], skeletal ez; 3.5-kb EcoRI fragment of the rabbit cDNA [19], skeletal fl; 1.6-kb EcoRI fragment of the rabbit cDNA [21], RflA; 1.6-kb PstI fragment of the cross-hybridizing rat fl-actin probe [23], GAPDH; 0.7-kb PstI/XbaI fragment of the glyceraldehyde-3-phosphate dehydrogenase cDNA [22]. and the expression of f12 and f13 genes is significantly lower.…”

“…Hybridization with this probe shows that during differentiation the expression of ~-actin is turned on, however, fl,),-actin expression is not completely eliminated. This phenomenon is typical for the immortalized muscle cells [23]. The expression of skeletal and cardiac al transcrips were assessed relative to the level of the glyceraldehyde-3-phosphate dehydrogenase housekeeping gene.…”