Referenced in: none

Automatically associated channels: Kir2.3

Title: Membrane channel connexin 32 maintains Lin(-)/c-kit(+) hematopoietic progenitor cell compartment: analysis of the cell cycle.

Authors: Yoko Hirabayashi, Byung-Il Yoon, Isao Tsuboi, Yan Huo, Yukio Kodama, Jun Kanno, Thomas Ott, James E Trosko, Tohru Inoue

Journal, date & volume: J. Membr. Biol., 2007 Jun , 217, 105-13

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/17629738

Abstract
Membrane channel connexin (Cx) forms gap junctions that are implicated in the homeostatic regulation of multicellular systems; thus, hematopoietic cells were assumed not to express Cxs. However, hematopoietic progenitors organize a multicellular system during the primitive stage; thus, the aim of the present study was to determine whether Cx32, a member of the Cx family, may function during the primitive steady-state hematopoiesis in the bone marrow (BM). First, the numbers of mononuclear cells in the peripheral blood and various hematopoietic progenitor compartments in the BM decreased in Cx32-knockout (KO) mice. Second, on the contrary, the number of primitive hematopoietic progenitor cells, specifically the Lin(-)/c-kit(+)/Scal(+ )fraction, the KSL progenitor cell compartment, also increased in Cx32-KO mice. Third, expression of Cx32 was detected in Lin(-)/c-kit(+) hematopoietic progenitor cells of wild-type mice (0.27% in the BM), whereas it was not detected in unfractionated wild-type BM cells. Furthermore, cell-cycle analysis of the fractionated KSL compartment from Cx32-KO BM showed a higher ratio in the G(2)/M fraction. Taken together, all these results imply that Cx32 is expressed solely in the primitive stem cell compartment, which maintains the stemness of the cells, i.e., being quiescent and noncycling; and once Cx32 is knocked out, these progenitor cells are expected to enter the cell cycle, followed by proliferation and differentiation for maintaining the number of peripheral blood cells.