Merck
  • Home
  • Search Results
  • Differential signaling by regulatory subunits of phosphoinositide-3-kinase influences cell survival in INS-1E insulinoma cells.

Differential signaling by regulatory subunits of phosphoinositide-3-kinase influences cell survival in INS-1E insulinoma cells.

Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association (2014-11-14)
J Schrader, P Niebel, A Rossi, E Archontidou-Aprin, D Hörsch
ABSTRACT

Class 1A phosphoinositide 3-kinase (PI3K) is essential for beta-cell growth and survival. Although PI3K has been studied extensively in diabetes the effect of alternatively spliced isoforms of the catalytic subunit p85α on beta cell proliferation and survival remains to be defined.We examined expression and signaling of alternatively spliced PI3K regulatory subunits p85α, p55α and p50α in insulinoma cells (INS-1E), an insulin-producing beta cell line. PI3K regulatory isoforms were knocked down by siRNA transfection or overexpressed by adenoviral gene delivery.Knockdown of p85α elevated PI3K activation determined by Akt phosphorylation at baseline and after stimulation with growth factors. In contrast, Akt phosphorylation was inhibited by overexpression of all isoforms of p85α. Correspondingly, p55α and p85α overexpression decreased downstream kinase GSK-3 phosphorylation as well, whereas p50α overexpression resulted in an activation of GSK-3. Moreover, overexpression of p50α and p85α lead to retinoblastoma protein hyperphosphorylation and S-phase entry. Upon challenge of INS-1E cells with a cytotoxic cytokine cocktail, levels of p85α were reduced and p50α was upregulated. Selective overexpression of p50α prevented cytokine induced apoptosis in INS-1E cells.In conclusion, signalling of p50α, p55α and p85α is similar at the level of Akt, but differentially influence downstream GSK-3 activation and cell cycle entry. PI3K isoform p50α induction by cytokines provides a link between regeneration and cell survival under cytotoxic stress in insulin-producing pancreatic beta-cells.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Propidium iodide solution, solution (1.0 mg/ml in water)
Sigma-Aldrich
Glycerol, tested according to Ph. Eur., anhydrous
Sigma-Aldrich
Ethylenediaminetetraacetic acid, ≥98.0% (KT)
Supelco
Fluoride ion solution for ISE, 0.1 M F-, analytical standard (for ion-selective electrodes)
Sigma-Aldrich
Sodium fluoride, BioXtra, ≥99%
Sigma-Aldrich
Sodium fluoride, 99.99% trace metals basis
Sigma-Aldrich
Glycerol, FCC, FG
Sigma-Aldrich
Ethylenediaminetetraacetic acid disodium salt solution, BioUltra, for molecular biology, pH 8.0, ~0.5 M in H2O
Sigma-Aldrich
Glycerol, BioUltra, for molecular biology, anhydrous, ≥99.5% (GC)
Sigma-Aldrich
Ethylenediaminetetraacetic acid, BioUltra, ≥99.0% (KT)
Sigma-Aldrich
Ethylenediaminetetraacetic acid solution, 0.02% in DPBS (0.5 mM), sterile-filtered, BioReagent, suitable for cell culture
Sigma-Aldrich
Glycerol, BioReagent, suitable for cell culture, suitable for insect cell culture, suitable for electrophoresis, ≥99% (GC)
Sigma-Aldrich
Glycerol, for molecular biology, ≥99.0%
Sigma-Aldrich
Ethylenediaminetetraacetic acid, ACS reagent, 99.4-100.6%, powder
Sigma-Aldrich
Sodium fluoride, BioReagent, suitable for insect cell culture, ≥99%
Sigma-Aldrich
Ethylenediaminetetraacetic acid, purified grade, ≥98.5%, powder
Sigma-Aldrich
Ethylenediaminetetraacetic acid, anhydrous, crystalline, BioReagent, suitable for cell culture
Sigma-Aldrich
Ethylenediaminetetraacetic acid, BioUltra, anhydrous, ≥99% (titration)
Sigma-Aldrich
Triton X-100, laboratory grade
Sigma-Aldrich
Glycerol, BioXtra, ≥99% (GC)
Sigma-Aldrich
Glycerol, ≥99.5%
Sigma-Aldrich
Sodium fluoride, anhydrous, powder, 99.99% trace metals basis
Sigma-Aldrich
Ethylenediaminetetraacetic acid, 99.995% trace metals basis
Sigma-Aldrich
Sodium fluoride 0.5 M solution
Sigma-Aldrich
Glycerol, Vetec, reagent grade, 99%
Sigma-Aldrich
Glycerol, ReagentPlus®, ≥99.0% (GC)
Sigma-Aldrich
Glycerol, puriss. p.a., ACS reagent, anhydrous, dist., ≥99.5% (GC)
Sigma-Aldrich
Glycerol, ACS reagent, ≥99.5%
Supelco
Glycerol, analytical standard
Supelco
Sodium Fluoride, Pharmaceutical Secondary Standard; Certified Reference Material