title: The zinc finger protein ZBTB20 regulates transcription of fructose-1,6-bisphosphatase 1 and β cell function in mice.
abstract: OBJECTIVE
  Fructose-1,6-bisphosphatase (FBP)-1 is a gluconeogenic enzyme that regulates glucose metabolism and insulin secretion in β cells, but little is known about how its transcription is controlled. The zinc finger protein ZBTB20 regulates glucose homeostasis, so we investigated its effects on expression of FBP-1.
  
  
  METHODS
  We analyzed gene expression using real-time reverse-transcription polymerase chain reaction, immunoblotting, and immunohistochemistry. We generated mice with β cell-specific disruption of Zbtb20 using Cre/LoxP technology. Expression of Zbtb20 in β cells was reduced using small interfering RNAs, and promoter occupancy and transcriptional regulation were analyzed by chromatin immunoprecipitation and reporter assays.
  
  
  RESULTS
  ZBTB20 was expressed at high levels by β cells and other endocrine cells in islets of normal mice; expression levels were reduced in islets from diabetic db/db mice. Mice with β cell-specific knockout of Zbtb20 had normal development of β cells but had hyperglycemia, hypoinsulinemia, glucose intolerance, and impaired glucose-stimulated insulin secretion. Islets isolated from these mice had impaired glucose metabolism, adenosine triphosphate production, and insulin secretion after glucose stimulation in vitro, although insulin secretion returned to normal levels in the presence of KCl. ZBTB20 knockdown with small interfering RNAs impaired glucose-stimulated insulin secretion in the β cell line MIN6. Expression of Fbp1 was up-regulated in β cells with ZBTB20 knockout or knockdown; impairments to glucose-stimulated insulin secretion were restored by inhibition of FBPase activity. ZBTB20 was recruited to the Fbp1 promoter and repressed its transcription in β cells.
  
  
  CONCLUSIONS
  The transcription factor ZBTB20 regulates β cell function and glucose homeostasis in mice. It might be a therapeutic target for type 2 diabetes mellitus.
authors.affiliation: Department of Pathophysiology, Second Military Medical University, Shanghai, China.
authors.forename: Ye
authors.initials: Y
authors.lastname: Zhang
authors.forename: Zhifang
authors.initials: Z
authors.lastname: Xie
authors.forename: Luting
authors.initials: L
authors.lastname: Zhou
authors.forename: Ling
authors.initials: L
authors.lastname: Li
authors.forename: Hai
authors.initials: H
authors.lastname: Zhang
authors.forename: Guangdi
authors.initials: G
authors.lastname: Zhou
authors.forename: Xianhua
authors.initials: X
authors.lastname: Ma
authors.forename: Pedro L
authors.initials: PL
authors.lastname: Herrera
authors.forename: Zhimin
authors.initials: Z
authors.lastname: Liu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Grusby
authors.forename: Weiping J
authors.initials: WJ
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002460:Cell Line; D006597:Fructose-Bisphosphatase / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D055785:Gene Knockdown Techniques; D005947:Glucose / Q000378:metabolism; D018149:Glucose Intolerance / Q000378:metabolism; D022781:Hepatocytes / Q000378:metabolism; D007328:Insulin / Q000378:metabolism; D000078790:Insulin Secretion; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051379:Mice; D018345:Mice, Knockout; D008822:Mice, Transgenic; D012097:Repressor Proteins / Q000378:metabolism / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014158:Transcription, Genetic; D016335:Zinc Fingers
chemical_list: D007328:Insulin; D012097:Repressor Proteins; C544397:ZBTB2 protein, mouse; D006597:Fructose-Bisphosphatase; D005947:Glucose