title: Tat-enhanced delivery of metallothionein can partially prevent the development of diabetes.
abstract: Metallothioneins (MTs) are intracellular low-molecular-weight, cysteine-rich proteins with potent metal-binding and redox functions, but with limited membrane permeativity. The aim of this study was to investigate whether we could enhance delivery of MT-1 to pancreatic islets or β cells in vitro and in vivo. The second goal was to determine whether increased MT-1 could prevent cellular toxicity induced by high glucose and free fatty acids in vitro (glucolipotoxicity) and ameliorate the development of diabetes induced by streptozotocin in mice or delay the development of diabetes by improving insulin secretion and resistance in the OLETF rat model of type 2 diabetes. Expression of HIV-1 Tat-MT-1 enabled efficient delivery of MT into both INS-1 cells and rat islets. Intracellular MT activity increased in parallel with the amount of protein delivered to cells. The formation of reactive oxygen species, glucolipotoxicity, and DNA fragmentation due to streptozotocin decreased after treating pancreatic β cells with Tat-MT in vitro. Importantly, in vivo, intraperitoneal injection resulted in delivery of the Tat-MT protein to the pancreas as well as liver, muscle, and white adipose tissues. Multiple injections increased radical-scavenging activity, decreased apoptosis, and reduced endoplasmic reticulum stress in the pancreas. Treatment with Tat-MT fusion protein delayed the development of diabetes in streptozotocin-induced mice and improved insulin secretion and resistance in OLETF rats. These results suggest that in vivo transduction of Tat-MT may offer a new strategy to protect pancreatic β cells from glucolipotoxicity, may improve insulin resistance in type 2 diabetes, and may have a protective effect in preventing islet destruction in type 1 diabetes.
authors.affiliation: Department of Internal Medicine and Bioengineering, College of Medicine and Engineering, Hanyang University, Seoul 471-020, Korea.
authors.forename: Leejin
authors.initials: L
authors.lastname: Park
authors.forename: Dongsoo
authors.initials: D
authors.lastname: Min
authors.forename: Hyunok
authors.initials: H
authors.lastname: Kim
authors.forename: Hee-Yong
authors.initials: HY
authors.lastname: Chung
authors.forename: Chul-Hoon
authors.initials: CH
authors.lastname: Lee
authors.forename: In-Sun
authors.initials: IS
authors.lastname: Park
authors.forename: Yonghee
authors.initials: Y
authors.lastname: Kim
authors.forename: Yongsoo
authors.initials: Y
authors.lastname: Park
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D003924:Diabetes Mellitus, Type 2 / Q000139:chemically induced / Q000378:metabolism / Q000517:prevention & control*; D004195:Disease Models, Animal; D015696:Gene Products, tat / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018014:Gene Transfer Techniques; D015497:HIV-1 / Q000378:metabolism*; D007328:Insulin / Q000378:metabolism; D007333:Insulin Resistance; D000078790:Insulin Secretion; D008297:Male; D008668:Metallothionein / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D051381:Rats; D020334:Rats, Inbred OLETF; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D013311:Streptozocin
chemical_list: D015696:Gene Products, tat; D007328:Insulin; C491055:Mt2A protein, rat; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D013311:Streptozocin; D008668:Metallothionein