| Research Abstract |
Functional structures of gap junctions were analyzed by immunohistochemical, biochemical and molecular biological methods to examine the molecular diversity and distribution patterns of connexin protein family in various tissue and cell types as well as in different functional states.
1) During ameloblast development of the rat upper incisor, connexin 43 in undifferentiated cells once disappears just before enamel formation and reappears after maturation of secretion activity.
2) In granulosa cells of developing rat ovary, gap junctions are composed of Cx43 and Cx45 in various phosphorylation states. While Cx45 remains constant, Cx43 increases during maturations but disappears soon after ovulation. In addition, Cx40 detected in RNA blot in ovary is localized only in blood vessel wall.
3) In rat mammary glands, Cx26 and Cx32 are colocalized between secretory acinar cells and Cx43 is localized between myoepithels. They gradually increase during pregnancy. Cx32 and Cx43 are induced dramatica
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lly just after delivery, and reach a maximum at the early lactation period. There seems to bea gap between mRNA and protein expression levels as well as the additional shift from P1 to P2 phosphorylation state of Cx43.
4) In rat endocardium and blood vessels, endothelial cells can be classified as Cx40 dominant or Cx37 dominant type according to their connexin expression patterns.
5) In rat trachea Cx37 is expressed in smooth muscle cells after 3weeks after birth and increases thereafter and colocalized with Cx43, but not with Cx40.
6) In guinea pig, Cx43 is localized between fibroblast like cells in the outer layr of circular smooth muscles and deep muscular plexus of the small intestine and between submuscular plexus in the large intestine. These Cx43 containing cells are also c-Kit positive and interconnect the interstitial cells with intestinal pacemaker activity.
This research project has successfully elucidated the diverse aspects of gap junction functions in the light of composite protein connexin family with specific physiological properties ; Gap junction protein expressions are characteristically regulated during developmental stages, in different functional states and between different tissues. They are controlled by various mechanisms such as expression levels or phosphorylation states. Finally, specific connexin molecules are identified in specialized functional cells such as pacemaker cells in heart and intestinal movement. Less
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