PMID- 24810050
OWN - NLM
STAT- MEDLINE
DCOM- 20141021
LR  - 20220410
IS  - 2041-4889 (Electronic)
VI  - 5
IP  - 5
DP  - 2014 May 8
TI  - Rapamycin reverses insulin resistance (IR) in high-glucose medium without causing 
      IR in normoglycemic medium.
PG  - e1214
LID - 10.1038/cddis.2014.178 [doi]
AB  - Mammalian target of rapamycin (mTOR) is involved in insulin resistance (IR) and 
      diabetic retinopathy. In retinal pigment epithelial (RPE) cells, insulin 
      activates the mTOR pathway, inducing hypoxia-inducible factor-1alpha (HIF-1alpha) and 
      HIF-dependent transcription in serum-free minimum essential medium Eagle (MEM). 
      Serendipitously, we found that insulin failed to induce the HIF-1alpha-dependent 
      response, when RPE cells were cultured in Dulbecco's modification of Eagle's 
      medium (DMEM). Whereas concentration of glucose in MEM corresponds to normal 
      glucose levels in blood (5.5 mM), its concentration in DMEM corresponds to severe 
      diabetic hyperglycemia (25 mM). Addition of glucose to MEM also caused IR. 
      Glucose-mediated IR was characterized by basal activation of mTORC1 and its poor 
      inducibility by insulin. Basal levels of phosphorylated S6 kinase (S6K), S6 and 
      insulin receptor substrate 1 (IRS1) S635/639 were high, whereas their 
      inducibilities were decreased. Insulin-induced Akt phosphorylation was decreased 
      and restored by rapamycin and an inhibitor of S6K. IR was associated with 
      de-phosphorylation of IRS1 at S1011, which was reversed by rapamycin. Both short 
      (16-40 h) and chronic (2 weeks) treatment with rapamycin reversed IR. 
      Furthermore, rapamycin did not impair Akt activation in RPE cells cultured in 
      normoglycemic media. In contrast, Torin 1 blocked Akt activation by insulin. We 
      conclude that by activating mTOR/S6K glucose causes feedback IR, preventable by 
      rapamycin. Rapamycin does not cause IR in RPE cells regardless of the duration of 
      treatment. We confirmed that rapamycin also did not impair phosphorylation of Akt 
      at T308 and S473 in normal myoblast C2C12 cells. Our work provides insights in 
      glucose-induced IR and suggests therapeutic approaches to treat patients with IR 
      and severe hyperglycemia and to prevent diabetic complications such as 
      retinopathy. Also our results prompt to reconsider physiological relevance of 
      numerous data and paradigms on IR given that most cell lines are cultured with 
      grossly super-physiological levels of glucose.
FAU - Leontieva, O V
AU  - Leontieva OV
AD  - Department of Cell Stress Biology, Roswell Park Cancer Institute, Elm and Carlton 
      Streets, Buffalo, NY, USA.
FAU - Demidenko, Z N
AU  - Demidenko ZN
AD  - Department of Cell Stress Biology, Roswell Park Cancer Institute, Elm and Carlton 
      Streets, Buffalo, NY, USA.
FAU - Blagosklonny, M V
AU  - Blagosklonny MV
AD  - Department of Cell Stress Biology, Roswell Park Cancer Institute, Elm and Carlton 
      Streets, Buffalo, NY, USA.
LA  - eng
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
DEP - 20140508
PL  - England
TA  - Cell Death Dis
JT  - Cell death & disease
JID - 101524092
RN  - 0 (Hypoglycemic Agents)
RN  - 0 (Insulin)
RN  - 0 (Insulin Receptor Substrate Proteins)
RN  - 0 (Irs1 protein, mouse)
RN  - 0 (Multiprotein Complexes)
RN  - 0 (Oligonucleotides)
RN  - 0 (Protein Kinase Inhibitors)
RN  - EC 2.7.1.1 (mTOR protein, mouse)
RN  - EC 2.7.11.1 (Mechanistic Target of Rapamycin Complex 1)
RN  - EC 2.7.11.1 (Proto-Oncogene Proteins c-akt)
RN  - EC 2.7.11.1 (Ribosomal Protein S6 Kinases)
RN  - EC 2.7.11.1 (TOR Serine-Threonine Kinases)
RN  - IY9XDZ35W2 (Glucose)
RN  - W36ZG6FT64 (Sirolimus)
SB  - IM
MH  - Animals
MH  - Cell Line
MH  - Enzyme Activation
MH  - Glucose/*metabolism
MH  - Hyperglycemia/*metabolism
MH  - Hypoglycemic Agents/*pharmacology
MH  - Insulin/metabolism
MH  - Insulin Receptor Substrate Proteins/metabolism
MH  - *Insulin Resistance
MH  - Mechanistic Target of Rapamycin Complex 1
MH  - Mice
MH  - Multiprotein Complexes/metabolism
MH  - Myoblasts, Skeletal/*drug effects/metabolism
MH  - Oligonucleotides/genetics/metabolism
MH  - Phosphorylation
MH  - Protein Kinase Inhibitors/*pharmacology
MH  - Proto-Oncogene Proteins c-akt/metabolism
MH  - Retinal Pigment Epithelium/*drug effects/metabolism
MH  - Ribosomal Protein S6 Kinases/antagonists & inhibitors/metabolism
MH  - Signal Transduction/drug effects
MH  - Sirolimus/*pharmacology
MH  - TOR Serine-Threonine Kinases/antagonists & inhibitors/metabolism
MH  - Time Factors
MH  - Transfection
PMC - PMC4047870
EDAT- 2014/05/09 06:00
MHDA- 2014/10/22 06:00
PMCR- 2014/05/01
CRDT- 2014/05/10 06:00
PHST- 2014/02/17 00:00 [received]
PHST- 2014/03/17 00:00 [revised]
PHST- 2014/03/26 00:00 [accepted]
PHST- 2014/05/10 06:00 [entrez]
PHST- 2014/05/09 06:00 [pubmed]
PHST- 2014/10/22 06:00 [medline]
PHST- 2014/05/01 00:00 [pmc-release]
AID - cddis2014178 [pii]
AID - 10.1038/cddis.2014.178 [doi]
PST - epublish
SO  - Cell Death Dis. 2014 May 8;5(5):e1214. doi: 10.1038/cddis.2014.178.