Cx31.1 expression is modulated in HaCaT cells exposed to UV‐induced damage and scrape‐wounding

Abstract

Connexin31.1 (Cx31.1) is a gap junction protein associated with apoptosis. In the skin, apoptosis is modulated by diabetes. A HaCaT skin model investigated whether normal (NGI) and high glucose and insulin (HGI; diabetic) conditions altered Cx31.1 expression, and if these were apoptosis linked. Cx31.1 was found in HaCaT and HeLa Ohio cells, with HaCaT Cx31.1 protein increased in HGI conditions, and around apoptotic cells. HeLa Cx31.1 channels were noncommunicative. Post scrapewounding, Cx31.1 increased at wound edges. Caspase 3/7 in scrape-wounds media (containing cells) elevated in HGI. UV exposure raised Cx31.1, and caspase 3/7, in NGI and HGI. UV reduced cell viability in NGI cells, although not significantly in HGI. Cx31.1 is modulated during HaCaT cell wound closure, and associated with 'diabetic' conditions. Cx31.1 expression matched apoptosis levels, higher in HGI cultures. Cx31.1 is noncommunicating, modulated after wounding, linked to apoptosis, and may be associated with tissue turnover around diabetic wounds.

A Quantitative Assay for Ca2+ Uptake through Normal and Pathological Hemichannels

“…Supplementing ECM with 2 mM Ca 2+ , which reduces the open probability of HCs [11][12][13][14][15][16][17][18][19][20], inhibited DAPI uptake (Figure 3A). In contrast, in prior work with parental HaCaT cells that are known to express low levels of Cxs [59] and mainly Cx43 [83][84][85], DAPI uptake Cells pre-exposed to dox for 24 h showed a significant increase of DAPI fluorescence emission when bathed in an extracellular medium (ECM) containing a low [Ca 2+ ] ex (60 µM). HaCaT cells and isolated primary keratinocytes can be cultured in this and even lower [Ca 2+ ] ex values [63][64][65][80][81][82] (which increase the open probability of HCs [11][12][13][14][15][16][17][18][19][20]).…”

“…Supplementing ECM with 2 mM Ca 2+ , which reduces the open probability of HCs [11][12][13][14][15][16][17][18][19][20], inhibited DAPI uptake (Figure 3A). In contrast, in prior work with parental HaCaT cells that are known to express low levels of Cxs [59] and mainly Cx43 [83][84][85], DAPI uptake lacked the sensitivity required to discriminate between low and high [Ca 2+ ] ex conditions [59].…”

Single cell expression profile of connexins in the mouse substantia nigra pars compacta

“…Likewise previous reports in rats (Leung et al, 2002;Vandecasteele et al, 2006), we were able to identify the expression of Cx26 ,Cx30 , Cx31.1 , Cx43 in pure DA neurons, but not the expression of Cx32 , Cx36 nor Cx45 . Since no expression of Cx36 or Cx45 was detected and given that Cx31.1 can only form nonfunctional gap junctions (Harris, 2001;Nugent et al, 2021), and Cx26, Cx30 and Cx43 are essentially gap junction forming connexins in glial cells (Bennett & Zukin, 2004;Nagy et al, 2018), it could be considered the connexin responsible for the electric coupling between DA neurons (Vandecasteele et al, 2005) is still missing in mice. Nevertheless, in our experiments we identified the presence of adult cells of double DA/GABA phenotype that expressedCx45 , which given their DA phenotype, are very likely to be account simply as DA cells in patch clamp experiments using the electrophysiological signature method of identification (Margolis et al, 2006).…”

Cx31.1 can selectively intermix with co-expressed connexins to facilitate its assembly into gap junctions

“…Consequently, keratinocyte connexins oligomerize into homomeric or heteromeric connexons en route to the plasma membrane, where they proceed to form homotypic or heterotypic channels that can exhibit distinct permeabilities and biophysical properties, which uniquely contribute to the maintenance of epidermal homeostasis and physiological function through GJIC ( Lucaciu et al, 2023b ; Martin et al, 2014 ; Scott et al, 2012 ; Martin and van Steensel, 2015 ; Koval et al, 2014 ). However, several reports suggest that Cx31.1 (encoded by GJB5 ) fails to assemble into functional gap junction channels in Xenopus oocytes and HeLa cells, but it is not known whether this is the case in connexin-rich keratinocytes where Cx31.1 is endogenously expressed in mammals and, in some cases, seen as puncta at the cell membrane ( Hennemann et al, 1992 ; Bruzzone et al, 1994 ; Manthey et al, 1999 ; Manthey et al, 2001 ; Harris, 2001 ; Nugent et al, 2021 ; Goliger and Paul, 1994 ; Di et al, 2001 ; Chang et al, 2009 ).…”

“…Cx31.1 also appears to be regulated in rodent skin as Cx31.1 levels are reduced at the edge of rat tail wounds ( Goliger and Paul, 1994 ). Conversely, Cx31.1 is elevated at scrape-wounded edges of HaCaT human keratinocyte cultures at 24 h following wounding ( Goliger and Paul, 1994 ; Nugent et al, 2021 ). Cx31.1 might additionally have a role in skin cancer as regions of hyperplastic skin and papillomas exhibit reduced levels of Cx31.1 in various chemically induced mouse models of skin cancer ( Budunova et al, 1996a , b ).…”