Decreasing Txnip mRNA and protein levels in pancreatic MIN6 cells reduces reactive oxygen species and restores glucose regulated insulin secretion.
OBJECTIVE
Recently, thioredoxin-interacting protein (Txnip) expression has been implicated in a number of cellular events associated with diabetes, with increased Txnip levels associated with reduced glucose uptake into peripheral tissues, increased reactive oxygen species (ROS) in endothelial cells, beta cell glucotoxicity and apoptosis. The potential relevance of Txnip with regards to glucose-regulated insulin secretion (GSIS), a fundamentally important characteristic of beta cells and insulin-producing cells being considered as a possible cell therapy for diabetes, has not yet been investigated.


METHODS
Here, studying glucose-responsive MIN6 B1(GSIS) and cells which had significantly reduced response to glucose after time in culture i.e. MIN6 B1(Non-GSIS), using ELISAs; qRT-PCR; immunoprecipitation and Western blotting; transient and stable (siRNA/shRNA and cDNA) approaches to achieve Txnip knock-down or over-expression, respectively,we established a direct association between Txnip expression and GSIS.


RESULTS
Specifically, increasing Txnip levels correlate with increased intracellular ROS levels and with significant GSIS loss.Conversely, both transient and stable knock-down of Txnip expression was associated with GSIS recovery.


CONCLUSIONS
This, we believe, is another reason in favour of targeting Txnip as a novel approach for diabetes-related therapy.
School of Pharmacy & Pharmaceutical Sciences, Trinity College Dublin, Dublin 2, Ireland.
Sweta
S
Rani
Jai Prakash
JP
Mehta
Niall
N
Barron
Padraig
P
Doolan
Per Bendix
PB
Jeppesen
Martin
M
Clynes
Lorraine
L
O'Driscoll
D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation; D005786:Gene Expression Regulation; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism*; D010179:Pancreas / Q000166:cytology; D012333:RNA, Messenger / Q000235:genetics*; D034741:RNA, Small Interfering / Q000235:genetics; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013879:Thioredoxins / Q000235:genetics* / Q000378:metabolism
D007328:Insulin; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D017382:Reactive Oxygen Species; D013879:Thioredoxins; D005947:Glucose