배양된 간 세포의 세포 주기 변화(G1-S)와 간극 연접의 기능 조절

학위논문(박사) - 한국과학기술원 : 생물과학과, 1996.8, [ viii, 121 p. ]Gap junctional communication during the progression of cell cycle from quiescent $G_0$ to S phase was examined in cultured clone 9 rat liver cells. The transfer of scrape-loaded fluorescent dye was suppressed immediately after the stimulation of cell cycle progression in a synchronized cell population. Intracellular pHs in clone 9 cells during $G_0$ / S progression were not virtually altered and thus acidification might be not the cause of gap junctional modulation. Northern blot analysis showed that the temporal disturbance of gap junctional communication in cells passing from $G_0$ to S phase did not result from transcriptional down- regulation of connexin 43. It was also found that the PKC inhibitor, calphostin C, was able to restore intercellular communication in serum stimulated cells. Data suggest a control mechanism by PKC mediated phosphorylation in the regulation of gap junction function which is vulnerable to cell cycling. The loss of gap junctional communication correlated with the increased phosphorylation of connexin 43 on serine residues in clone 9 cells. In an attempt to provide an evidence that phosphorylation of gap junction protein is directly related with the gating of gap junction protein, a single gap junction channel was reconstituted into an artificial liposome. The opening of gap junction channel was examined by means of sedimentation velocities in iso-osmolar density gradient. It was found that connexin phosphorylation by PKC gated the channels and dephosphorylation by CIP restored the gap junction permeability.한국과학기술원 : 생물과학과

K562 세포에서의 단백질 인산화와 세포성장과의 관계

학위논문(석사) - 한국과학기술원 : 생명과학과, 1993.2, [ v, 39 p. ]Protein phosphorylation in K562 cells(human pre-erythrocyte leukemia) transitting from $G_0$ to S phase of cell cycle was examined. The 100 kDa and 120 kDa protein of molecular weight were specifically phosphorylated in 30 minutes after serum addition and remained phosphorylated for 4 hours. Cellular levels of second messenger molecules during the progresseion of cell cycle from G0 to S phase were monitored. Rapid increase of $IP_3$ contents were observed in 30 minutes after the addition of serum to the culture media. There were temporary elevation of calcium concentration in parallel with the increase of $IP_3$ contents. The phosphorylation of 100 kDa and 120 kDa proteins were inhibited by addition of CaM kinase inhibitor, calmidazolium. Data indicates that CaM kinase is the major kinase responsible for the phosphorylation of the 100kDa and 120 kDa proteins, which might be involved with the initiation of DNA synthesis in S phase of the cell cycle.한국과학기술원 : 생명과학과