Previous experiments in ventricular myocytes from the streptozotocin-induced diabetic rats have reported reduced caffeine-evoked [Ca.sup.2+] transients [82-91], SERCA2
activity, and [Ca.sup.2+] uptake [83, 88, 92-94] and decreased SR [Ca.sup.2+] channel (ryanodine receptor) activity [87, 95] suggesting decreased SR [Ca.sup.2+] content, [Ca.sup.2+] uptake, and [Ca.sup.2+] release mechanisms in ventricular myocytes from the streptozotocin-induced diabetic rat.
The virus carrying SERCA2
is delivered through the coronary arteries into the heart during a cardiac catheterization procedure.
The relaxation is facilitated by 1 ) the SR [Ca.sup.2+] ATPase (SERCA2
), which pumps [Ca.sup.2+] back into the SR and is primarily responsible for the myocardial relaxation (2, 5) 2) the [Na.sup.+]/[Ca.sup.2+] exchanger (NCX), which uses the energy of the [Na.sup.+] and [Ca.sup.2+] gradients across the plasma membrane to exchange 3 extracellular [Na.sup.+] ions for 1 intracellular [Ca.sup.2+] ion (28%) and 3) the plasma membrane [Ca.sup.2+] ATPase (PMCA), which presses out [Ca.sup.2+] from the cell using the energy liberated by ATP hydrolysis (5).
TNF-[alpha] can also decrease the expression of SERCA2
, which consequently prolongs the [Ca.sup.2+] transient duration and action potentials .
In the first weeks of life, genes that encode the isoform 1 of the glucose transporter, sodium/calcium exchanger, beta isoform of the myosin heavy chain and the p1 isoform of the TH receptor have a decreased expression, in contrast to those genes that encode the isoform 4 of the glucose transporter, SERCA2
, alpha myosin heavy chain and alpha isoform of thyroid receptor (17,23-25).
CAUSES: Mutations in the ATP2A2 gene cause functional disruptions in all domains of SERCA2
(the calcium pump), including reduction of ATP affinity, loss of calcium affinity, effects on phosphorylation of ATP and Pi, blocking of dephosphorylation, and uncoupling of calcium transport from ATP hydrolysis.
ATP2A2, located on 12q23-24.1, encodes the sarcoplasmic/endoplasmic reticulum Ca2+-ATP isoform 2 protein (SERCA2
), which is a calcium pump.4 This pump maintains a low cytoplasmic Ca2+ level by actively transporting calcium ions from the cytosol into the lumen of the endoplasmic reticulum.
Finsen et al., "Moderate heart dysfunction in mice with inducible cardiomyocyte-specific excision of the Serca2
gene," Journal of Molecular and Cellular Cardiology, vol.
Antibodies used were the following: for NOX2 (anti-[gp91.sup.phox] 1: 1000, catalog number: 611415, Lot: 15660), [p67.sup.phox] (1:1000, catalog number: 610913, Lot: 000079141) and eNOS (1:2000, catalog number: 610297, Lot: 35170) from BD Biosciences (San Jose, CA); for NOX4, from Thermo Scientific (1 : 1000, catalog number: PA146014), serine 16 phosphorylated phospholamban (1:1000, catalog number: A010-12, Lot: 0214-01) and total phospholamban (1:1000, catalog number: A101-14, Lot: 642016) were obtained from Badrilla (Leeds, UK); SERCA2
(1 : 2000, catalog number: SC 8094, Lot: C1115); GAPDH (1: 1000, catalog number: SC-365062, Lot: A2715); and secondary antibodies from Santa Cruz (Santa Cruz, CA).
Differential modulation of SERCA2
isoforms by calreticulin.
ATP2A2encoding the SERCA2
pump has been identified as the defective gene in Darier's disease.
Membranes were blocked in 5% nonfat dairy milk in TTBS (10 mM Tris, 100 mM NaCl, and 0.1% Tween-20, pH 7.5) for 1 hour and incubated overnight at 4[degrees]C with primary antibodies (Cell Signaling: Hsp70 1 : 4000, glycogen synthase 1:1000; Abcam: glycogen phosphorylase 1:2000, SERCA2
1 : 1000; Santa Cruz: glucose-6-phosphotase 1 : 200) diluted in TTBS with 2% nonfat dairy milk.