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Epithelial sodium channel abundance is decreased by an unfolded protein response induced by hyperosmolality.

Crambert G, Ernandez T, Lamouroux C, Roth I, Dizin E, Martin PY, Féraille E, Hasler U - Physiol Rep (2014)

Bottom Line: Hyperosmotic stress profoundly challenges cellular homeostasis and induces endoplasmic reticulum (ER) stress.Both hyperosmolality and chemical induction of ER stress decreased ENaC expression in vitro.ENaC depletion by either stimulus was abolished by transcriptional inhibition and by the chemical chaperone 4-phenylbutyric acid and was partly abrogated by either PERK or ATF6 silencing.

View Article: PubMed Central - PubMed

Affiliation: UPMC/INSERM/Paris Descartes U1138 CNRS ERL 8228, Equipe 3 Métabolisme et Physiologie Rénale, Centre de Recherche des Cordeliers, Paris, France.

No MeSH data available.


Related in: MedlinePlus

ER stress decreases ENaC abundance via a transcriptionally mediated mechanism. (A and B) mCCDcl1 (A) and mpkCCDcl4 (B) cells were challenged with either actinomycin D (5 μmol/L) or NaCl (500 mOsmol/kg) alone or simultaneously challenged with both actinomycin D and NaCl for 30 min to 6 h. mRNA of all time points were extracted at the same time and ENaC abundance was analyzed by Q‐PCR. Data is represented as fold difference over values obtained in unstimulated cells (0 min) and is expressed as the mean ± SEM of four independent experiments. (C) mRNA abundance of ENaC and AQP2 in cells challenged or not (Ctl) with NaCl, thapsigargin (Tg, 1 μmol/L), tunicamycin (Tun, 3 μmol/L) or both NaCl and either chemical agent for 6 h. (D) mRNA abundance of ENaC in cells challenged or not with actinomycin D with or without (Ctl) NaCl, Tg or Tun for 6 h. Data is represented as fold difference over values obtained in unstimulated cells and is expressed as the mean ± SEM of four independent experiments.
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fig03: ER stress decreases ENaC abundance via a transcriptionally mediated mechanism. (A and B) mCCDcl1 (A) and mpkCCDcl4 (B) cells were challenged with either actinomycin D (5 μmol/L) or NaCl (500 mOsmol/kg) alone or simultaneously challenged with both actinomycin D and NaCl for 30 min to 6 h. mRNA of all time points were extracted at the same time and ENaC abundance was analyzed by Q‐PCR. Data is represented as fold difference over values obtained in unstimulated cells (0 min) and is expressed as the mean ± SEM of four independent experiments. (C) mRNA abundance of ENaC and AQP2 in cells challenged or not (Ctl) with NaCl, thapsigargin (Tg, 1 μmol/L), tunicamycin (Tun, 3 μmol/L) or both NaCl and either chemical agent for 6 h. (D) mRNA abundance of ENaC in cells challenged or not with actinomycin D with or without (Ctl) NaCl, Tg or Tun for 6 h. Data is represented as fold difference over values obtained in unstimulated cells and is expressed as the mean ± SEM of four independent experiments.

Mentions: We investigated ENaC mRNA stability under hyperosmotic conditions by treating mCCDcl1 (Fig. 3A) and mpkCCDcl4 (Fig. 3B) cells with actinomycin D, which halts de novo mRNA gene transcription. Cells were challenged with either actinomycin D or NaCl alone or were simultaneously challenged with both actinomycin D and NaCl for various periods of time (30 min to 6 h). Each experimental point was compared to the same control (untreated cells). Under control isosmotic conditions, actinomycin D decreased ENaCα and ENaCγ mRNA expression. Unexpectedly, actinomycin D increased expression of ENaCβ mRNA. This implies the loss of short‐lived repressive element(s) that are quickly depleted in the presence of actinomycin D. Decreased ENaC mRNA abundance by hyperosmolality was blunted by actinomycin D, indicating that the effects of NaCl on ENaC abundance are transcriptionally mediated.


Epithelial sodium channel abundance is decreased by an unfolded protein response induced by hyperosmolality.

Crambert G, Ernandez T, Lamouroux C, Roth I, Dizin E, Martin PY, Féraille E, Hasler U - Physiol Rep (2014)

ER stress decreases ENaC abundance via a transcriptionally mediated mechanism. (A and B) mCCDcl1 (A) and mpkCCDcl4 (B) cells were challenged with either actinomycin D (5 μmol/L) or NaCl (500 mOsmol/kg) alone or simultaneously challenged with both actinomycin D and NaCl for 30 min to 6 h. mRNA of all time points were extracted at the same time and ENaC abundance was analyzed by Q‐PCR. Data is represented as fold difference over values obtained in unstimulated cells (0 min) and is expressed as the mean ± SEM of four independent experiments. (C) mRNA abundance of ENaC and AQP2 in cells challenged or not (Ctl) with NaCl, thapsigargin (Tg, 1 μmol/L), tunicamycin (Tun, 3 μmol/L) or both NaCl and either chemical agent for 6 h. (D) mRNA abundance of ENaC in cells challenged or not with actinomycin D with or without (Ctl) NaCl, Tg or Tun for 6 h. Data is represented as fold difference over values obtained in unstimulated cells and is expressed as the mean ± SEM of four independent experiments.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4255800&req=5

fig03: ER stress decreases ENaC abundance via a transcriptionally mediated mechanism. (A and B) mCCDcl1 (A) and mpkCCDcl4 (B) cells were challenged with either actinomycin D (5 μmol/L) or NaCl (500 mOsmol/kg) alone or simultaneously challenged with both actinomycin D and NaCl for 30 min to 6 h. mRNA of all time points were extracted at the same time and ENaC abundance was analyzed by Q‐PCR. Data is represented as fold difference over values obtained in unstimulated cells (0 min) and is expressed as the mean ± SEM of four independent experiments. (C) mRNA abundance of ENaC and AQP2 in cells challenged or not (Ctl) with NaCl, thapsigargin (Tg, 1 μmol/L), tunicamycin (Tun, 3 μmol/L) or both NaCl and either chemical agent for 6 h. (D) mRNA abundance of ENaC in cells challenged or not with actinomycin D with or without (Ctl) NaCl, Tg or Tun for 6 h. Data is represented as fold difference over values obtained in unstimulated cells and is expressed as the mean ± SEM of four independent experiments.
Mentions: We investigated ENaC mRNA stability under hyperosmotic conditions by treating mCCDcl1 (Fig. 3A) and mpkCCDcl4 (Fig. 3B) cells with actinomycin D, which halts de novo mRNA gene transcription. Cells were challenged with either actinomycin D or NaCl alone or were simultaneously challenged with both actinomycin D and NaCl for various periods of time (30 min to 6 h). Each experimental point was compared to the same control (untreated cells). Under control isosmotic conditions, actinomycin D decreased ENaCα and ENaCγ mRNA expression. Unexpectedly, actinomycin D increased expression of ENaCβ mRNA. This implies the loss of short‐lived repressive element(s) that are quickly depleted in the presence of actinomycin D. Decreased ENaC mRNA abundance by hyperosmolality was blunted by actinomycin D, indicating that the effects of NaCl on ENaC abundance are transcriptionally mediated.

Bottom Line: Hyperosmotic stress profoundly challenges cellular homeostasis and induces endoplasmic reticulum (ER) stress.Both hyperosmolality and chemical induction of ER stress decreased ENaC expression in vitro.ENaC depletion by either stimulus was abolished by transcriptional inhibition and by the chemical chaperone 4-phenylbutyric acid and was partly abrogated by either PERK or ATF6 silencing.

View Article: PubMed Central - PubMed

Affiliation: UPMC/INSERM/Paris Descartes U1138 CNRS ERL 8228, Equipe 3 Métabolisme et Physiologie Rénale, Centre de Recherche des Cordeliers, Paris, France.

No MeSH data available.


Related in: MedlinePlus