Pannexins form gap junctions with electrophysiological and pharmacological properties distinct from connexins.
Stable expression of pannexin 1 (Panx1) and pannexin 3 (Panx3) resulted in functional gap junctions (GJs) in HeLa cells, but not in Neuro-2a (N2a) or PC-12 cells. The glycosylation pattern of expressed Panx1 varied greatly among different cell lines. In contrast to connexin (Cx) containing GJs (Cx-GJs), junctional conductance (Gj) of pannexin GJs (Panx-GJs) is very less sensitive to junctional voltage. Both Panx1 and Panx3 junctions favoured anionic dyes over cations to permeate. Though, carbenoxolone (CBX) and probenecid blocked Panx1 hemichannel activity, they had no effect on Panx1-GJs or Panx3-GJs. Extracellular loop 1 (E1) of Panx1 possibly bears the binding pocket. The Cx-GJ blocker heptanol blocked neither Panx1 hemichannel nor Panx-GJs. Unlike the GJs formed by most Cxs, CO2 did not uncouple Panx-GJs completely. Oxygen and glucose deprivation (OGD) caused lesser uncoupling of Panx-GJs compared to Cx43-GJs. These findings demonstrate properties of Panx-GJs that are distinctly different from Cx-GJs.
1] Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Chennai - 600036, Tamil Nadu, India [2].
Giriraj
G
Sahu
Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Chennai - 600036, Tamil Nadu, India.
Sunitha
S
Sukumaran
Department of Biotechnology, Indian Institute of Technology Madras, Sardar Patel Road, Chennai - 600036, Tamil Nadu, India.
Amal Kanti
AK
Bera
D000138:Acidosis / Q000378:metabolism; D000818:Animals; D000838:Anions / Q000378:metabolism; D016466:CHO Cells; D002412:Cations / Q000378:metabolism; D002460:Cell Line; D018031:Connexin 43 / Q000378:metabolism; D017630:Connexins / Q000378:metabolism*; D003412:Cricetulus; D017629:Gap Junctions / Q000187:drug effects* / Q000502:physiology*; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D007511:Ischemia / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009928:Organ Specificity; D010539:Permeability
D000838:Anions; D002412:Cations; D018031:Connexin 43; D017630:Connexins; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; C492766:PANX3 protein, human