• Molecules and Cells
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• v.26 no.3
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• pp.265-269
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• 2008

Calumenin, a multiple EF-hand $Ca^{2+}$ binding protein is located in the SR of mammalian heart, but the functional role of the protein in the heart is unknown. In the present study, an adenovirus gene transfer system was employed for neonatal rat heart to examine the effects of calumenin over-expression (Calu-OE) on $Ca^{2+}$ transients. Calu-OE (8 folds) did not alter the expression levels of DHPR, RyR2, NCX, SERCA2, CSQ and PLN. However, Calu-OE affected several parameters of $Ca^{2+}$ transients. Among them, prolongation of time to 50% baseline ($T_{50}$) was the most outstanding change in electrically-evoked $Ca^{2+}$ transients. The higher $T_{50}$ was due to an inhibition of SERCA2-mediated $Ca^{2+}$ uptake into SR, as tested by oxalate-supported $Ca^{2+}$ uptake. Furthermore, co-IP study showed a direct interaction between calumenin and SERCA2. Taken together, calumenin in the cardiac SR may play an important role in the regulation of $Ca^{2+}$ uptake during the EC coupling process.

• Proceedings of the Korean Society for Food Science of Animal Resources Conference
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• 2004.05a
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• pp.177-180
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• 2004

본 연구는 PCR-RFLP 및 PCR-SSCP 기법을 이용하여 PSE 돈육을 생산하는 PSS 돼지 유전자 진단 기술을 개발하고 이를 이용한 국내 종돈 및 교잡 비육돈의 PSS 유전자 출현 빈도를 파악하고자 수행하였다. 돼지 PSS의 원인이 되는 ryanodine receptor 유전자의 단일염기 돌연변이 $C{\rightarrow}T$ ; $Arg\;{\rightarrow}\;Cys$)를 포함하는 134 bp 영역을 PCR로 증폭한 후 RFLP 및 SSCP 기법으로 분석한 결과 동형접합체의 정상(N/N), 이형접합체의 잠재성 개체 (N/n) 그리고 돌연변이 유전자를 동형접합체 상태로 갖는 PSS 감수성 개체(n/n)에 각각 특이적인 유전자형이 검출되었다. 특히, PCR-SSCP기법을 이용한 RYR1 유전자 돌연변이 검출 방법은 보다 신속 간편하면서도 상대적으로 분석비용이 저렴한 정확성이 높은 PSS 돼지 진단기술로서 대규모 돼지집단검색이나 RFLP 방법으로 판정이 불확실한 시료의 재검에 효율적으로 이용할 수 있을 것으로 판단된다.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.25-25
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• 2003

Atrial myocytes have two functionally separate $Ca^{2+}$ release sites: those in peripheral sarcoplasmic reticulum (SR) adjacent to the $Ca^{2+}$ channels of surface membrane and those in central SR not associated with $Ca^{2+}$ channels. Study on the spatio-temporal properties of focal $Ca^{2+}$ releases (“sparks”) occurring spontaneously in central and peripheral sites of voltage-clamped rat atrial myocytes, using rapid two-dimensional (2-D) confocal $Ca^{2+}$ imaging revealed that peripheral and central sparks were similar in size and release time (~300,000 $Ca^{2+}$ ions for=12 ms), but significantly larger and longer than ventricular sparks. Both sites were resistant to Cd$^{2+}$ and inhibited by ryanodine. Peripheral sparks were brighter and flattened against surface membrane, had ~5-fold higher frequency, ~2 times faster diffusion coefficient, and dissipated abruptly. Central sparks, in contrast, occurred less frequently, were elongated along the cellular longitudinal axis, and dissipated slowly. Compound sparks (composed of 2-5 unitary focal releases) aligned longitudinally, occurred more frequently at the center.at the center.

• Proceedings of the Korean Biophysical Society Conference
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• 2003.06a
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• pp.53-53
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• 2003

Calumenin was previously identified as a high affinity Ca$\^$2+/ binding protein in mouse cardiac sarcoplasmic reticulum (SR). For the present study, a 48 kDa skeletal homologue of calumenin was identified by sucrose-density gradient of rabbit skeletal SR membranes, concanavalin A treatment, 2D-gel electrophoresis, $\^$45/Ca$\^$2+/ overlay, Stains-all staining, and MALDI-TOF analysis. We attempted to clone the skeletal calumenin by RT-PCR based on mouse cardiac and human calumenin sequences. The deduced amino acid sequence (315 residues) of the skeletal calumenin showed high identity to mouse cardiac calumenin (90％). As seen in the cardiac calumenin, the deduced sequence contains a 19 amino acid N-terminal signal sequence and a HDEF C-terminal sequence, a putative retrieval signal to ER. Also, the skeletal calumenin contains one N-glycosylation site, three PKC phosphorylation sites, eight casein kinase 2 phosphorylation sites, and 6 EF-hand domains. GST-calumenin showed a conformational change and increased mobility in the presence of Ca$\^$2+/ in SDS-PAGE. Three calumenin interacting proteins (ryanodine receptor 1, glycogen phosphorylase, and phosphofructo kinase) were identified by pull-down assay with GST-calumenin and solubilized SR. All the interactions were Ca$\^$2+/dependent. The present results suggest that calumenin plays an important role in Ca$\^$2+/ homeostasis of muscle cells.

• The Korean Journal of Physiology
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• v.23 no.2
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• pp.313-328
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• 1989

The electrophysiological properties of the inward current contributing to the late plateau phase of the action potential were investigated using the whole cell clamp technique and intracellular dialysis in single atrial cells isolated from the rabbit heart. The inward current was activated by various repolarizing pulses after a brief depolarizing pulse to +40 mV for 2 ms and its time course was similar to that of the late plateau of the action potential. The current was fully activated above the potential of -40 mV and abolished by intracellular EGTA. Ryanodine of $1{\mu}M$ also abolished the late plateau and the inward current. Reduced $Na_o\;to\;30%\;and\;20\;mM\;Na_1$ diminished the late plateau together with the inward current. Diltiazem blocked the activation of the current and Ni in the concentration of $40{\sim}200\;{\mu}M$ decreased the development of the late plateau and the inward current. Fully activated current-voltage relation of the inward current showed exponential voltage dependency which was steeper in more hyperplarizing range. The above findings suggest that the inward current was activated by intracellular calcium and contribute the late plateau phase of the action potential. It could be concluded that the inward current would be the inward component of Na-Ca exchange.

• YAKHAK HOEJI
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• v.58 no.4
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• pp.245-249
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• 2014

Murrayafoline-A (1-methoxy-3-methylcarbazole) is a monomeric carbazole alkaloid found in Murraya euchrestifolia HAYATA and Glycosmis stenocarpa. We have recently shown that murrayafoline-A has positive inotropic effect in isolated rat ventricular myocytes. To know possible mechanisms for the positive inotropic effect of murrayafoline-A we examined the effects of murrayafoline-A on in situ behavior of cardiac $Ca^{2+}$ release units ('$Ca^{2+}$ sparks') and sarcoplasmic reticulum (SR) $Ca^{2+}$ loading using confocal $Ca^{2+}$ imaging method in single rat ventricular myocytes. Murrayafoline-A significantly increased the frequency (events/($10^3{\mu}m^2{\cdot}s$)) of $Ca^{2+}$ sparks in a concentration-dependent manner, with an $EC_{50}$ of $28{\pm}6.4{\mu}M$ and a maximal ~twofold change. The $Ca^{2+}$ content in the SR, measured as caffeine (10 mM)-induced $Ca^{2+}$ transient, was significantly increased by murrayafoline-A (${\approx}$116% and ${\approx}$123% of control at 25 and 100 ${\mu}M$, respectively). In addition, murrayafoline-A significantly increased the fractional $Ca^{2+}$ release, suggesting increase in the efficacy of $Ca^{2+}$ release at given SR $Ca^{2+}$ loading. These results suggest that murrayafoline-A may enhance contractility via increase in $Ca^{2+}$ release from the SR through the ryanodine receptors in ventricular myocytes.

• Reproductive and Developmental Biology
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• v.29 no.1
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• pp.15-18
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• 2005

This study was carried out to analyze the structure of the gene related to porcine stress syndrome (PSS) through cloning from PSS heterozygous pigs and to examine hereditary type associated with PSS. The results obtained from the study were summarized as follows: Amino acid arginine and cysteine exist in dominant gene, N and harmfully recessive gene, n, respectively. It was confirmed that such genes exists as alleles in the sixth chromosome related to PSS. These allelic genes might be inherited according to Mendelian law.

• The Korean Journal of Physiology
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• v.28 no.2
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• pp.159-167
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• 1994

The contraction of rabbit basilar artery was examined as a function of changes in the $Na^+$ electrochemical gradient in order to determine the contribution of $Na^+/Ca^{2+}$ exchange to the modulation of contractility. Ouabain $(10^{-5}\;M)$ or $K^+-free$ Tyrode solution caused an increase in tonic tension even in the presence of a $Ca^{2+}$ channel blocker $(10^{-6}\;M\;verapamil)$ and an ${\alpha}-receptor$ blocker $(10^{-5}\;M\;phentolamine)$. After treatment with ouabain $(10^{-5}\;M)$, contractions were augmented by reduction of external $Na^+$ concentration. The longer the treatment with ouabain $(10^{-5}\;M)$ was, the larger the amplitude of $Na^+-free$ contracture was. $Na^+-free$ contracture wag induced by either substitution of equimolar Tris for $Na^+$ or substitution of equimolar $Li^+\;for\;Na^+$. The competition between $Na^+\;and\;Ca^{2+}$ for the $Na^+/Ca^{2+}$ exchange carrier would exist, because it was observed that contractility was dependent on the $Na^+$ electrochemical gradient or the extracellular $Ca^{2+}$ concentration (2 mM, 4 mM). Ryanodine $(10^{-7}\;M)$, the blocker of intracellular $Ca^{2+}$ release from the sarcoplasmic reticulum, did not suppress the development of $Na^+-free$ contracture. The contractile response to norepinephrine $(10^{-6}\;M)$ was augmented by reducing the extracellular $Na^+$ concentration. The relaxation rate from caffeine-induced contraction was dependent on the extracellular $Na^+$ concentration (0 mM, 140 mM). From the above results, it could be suggested that $Na^+/Ca^{2+}$ exchange can move $Ca^{2+}$ either into or out of rabbit basilar arterial smooth muscle. $Ca^{2+}$ entry or extrusion is dependent upon the $Na^+$ electrochemical gradient. $Na^+/Ca^{2+}$ exchange plays a significant role in the regulation of contractility in rabbit basilar arterial smooth muscle.

• Biomedical Science Letters
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• v.8 no.3
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• pp.195-202
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• 2002

Osteoarthritis (OA), the most common form of arthritis, involves the destabilization of the normal balance between the degradation and the synthesis of articular cartilage and subchondral bone within a joint. As articular cartilage degrades over time, its smooth surface roughens and bone-against-bone contact ensues, producing the inflammation response symptomatic of this 'wear and tear' disease. Although a variety of genetic, developmental, metabolic, and traumatic factors may initiate the development of osteoarthritis, its symptoms (joint pain, stiffness, and curtailed function) typically evolve slowly, and patients experience periods of relative calm alternation with episodes of inflammation and pain. Rheumatoid arthritis (RA), an autoimmune disease of unknown etiology characterized by chronic synovitis and cartilage destruction, affect 1% of the total population. Cartilage is a specialized connective tissue in which the chondrocytes occupy only 5% of the volume. Cartilage is particularly rich in extracellular matrix, with matrix making up 90% of the dry weight of the tissue chondrocytes have cell processes that extend a short distance into the matrix, but do not touch other cells thus in cartilage, cell-matrix interactions are essential for the maintenance of the extracellular matrix. In this study, subtractive hybridization method was utilized to detect genes differentially expressed in chondrocytes treated with methylprednisolone. We have isolated 57 genes that expressed differentially in the chondreocytes by methylprednisolone. 13 clones of them were analyzed with sequencing and their homologies were searched. 8 cDNAS included KIAA 0368, upregulated during skeletal muscle growth 5 (usmg 5), ribosomal protein S 18 (RPS 18), skeletal muscle ryanodine receptor, radial spoke protein 3 (RSP 3), ribosomal protein QM, ribosomal protein L37a (RPL37A), cytochrome coxidase subunit VIII (COX8).

• YAKHAK HOEJI
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• v.48 no.6
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• pp.352-357
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• 2004

Atrial myocytes have two functionally separate groups of ryanodine receptors (RyRs): those at the periphery colocalized with L-type $Ca^{2+}$channels (DHPRS) and those a t the cell interior not associated with DHPRs. $Ca^{2+}$ current ($I_{ca}$) directly gates peripheral RyRs on action potential and the subsequent peripheral $Ca^{2+}$ release propagates into the center of atrial myocytes. The mechanisms that regulate the $Ca^{2+}$+ propagation wave remain Poorly understood. Using 2-D confocal$Ca^{2+}$ imaging, we examined the role of inositol 1,4,5-trisphosphate receptor (IP $_3R$) and mitochondria on ($I_{ca}$)- gated local $Ca^{2+}$ signaling in rat atrial myocytes. Blockade of IP $_3R$ by xestospongin C (XeC) partially suppressed the magnitudes of I ca-gated central and peripheral $Ca^{2+}$ releases with no effect on $I_{ca}$. Mitochondrial staining revealed that mitochondria were aligned with ${\thickapprox}2-{\mu}m$ separations in the entire cytoplasm of ventricular and atrial myocytes. Membrane depolarization induced rapid mitochondrial $Ca^{2+}$ rise and decay in the cell periphery with slower rise in the center, suggesting that mitochondria may immediately uptake cytosolic $Ca^{2+}$, released from the peripheral SR on depolarization, and re-release the $Ca^{2+}$ into the cytosol to activate neighboring central RyRs. Our data suggest that the activation of IP $_3R$ and mitochondrial $Ca^{2+}$ handing on action potential may serve as a cofactor for the $Ca^{2+}$ propagation from the DHPR-coupled RyRs to the DHPR-uncoupled RyRs with large gaps between them.