title: Antisense miR-7 impairs insulin expression in developing pancreas and in cultured pancreatic buds.
abstract: MicroRNAs regulate gene expression by inhibiting translation or inducing target mRNA degradation. MicroRNAs regulate organ differentiation and embryonic development, including pancreatic specification and islet function. We showed previously that miR-7 is highly expressed in human pancreatic  fetal and adult endocrine cells. Here we determined the expression profile of miR-7 in the mouse-developing pancreas by RT-PCR and in situ hybridization. MiR-7 expression was low between embryonic days e10.5 and e11.5, then began to increase at e13.5 through e14.5, and eventually decreased  by e18. In situ hybridization and immunostaining analysis showed that miR-7 colocalizes with endocrine marker Isl1, suggesting that miR-7 is expressed preferentially in endocrine cells. Whole-mount in situ hybridization shows miR-7 highly expressed in the embryonic neural tube. To investigate  the role of miR-7 in development of the mouse endocrine pancreas, antisense miR-7 morpholinos (MO) were delivered to the embryo at an early developmental stage (e10.5 days) via intrauterine fetal heart injection. Inhibition of miR-7 during early embryonic life results in an overall downregulation  of insulin production, decreased β-cell numbers, and glucose intolerance in the postnatal period. This phenomenon is specific for miR-7 and possibly due to a systemic effect on pancreatic development. On the other hand, the in vitro inhibition of miR-7 in explanted pancreatic buds leads  to β-cell death and generation of β-cells expressing less insulin than those in MO control. Therefore, in addition to the potential indirect effects on pancreatic differentiation derived from its systemic downregulation, the knockdown of miR-7 appears to have a β-cell-specific  effect as well. These findings suggest that modulation of miR-7 expression could be utilized in the development of stem cell therapies to cure diabetes.
authors.affiliation: Diabetes Research Institute, University of Miami, Miller School of Medicine, Miami, FL 33136, USA.
authors.forename: Margarita
authors.initials: M
authors.lastname: Nieto
authors.forename: Pedro
authors.initials: P
authors.lastname: Hevia
authors.forename: Enrique
authors.initials: E
authors.lastname: Garcia
authors.forename: Dagmar
authors.initials: D
authors.lastname: Klein
authors.forename: Silvia
authors.initials: S
authors.lastname: Alvarez-Cubela
authors.forename: Valia
authors.initials: V
authors.lastname: Bravo-Egana
authors.forename: Samuel
authors.initials: S
authors.lastname: Rosero
authors.forename: R
authors.initials: R
authors.lastname: Damaris Molano
authors.forename: Nancy
authors.initials: N
authors.lastname: Vargas
authors.forename: Camillo
authors.initials: C
authors.lastname: Ricordi
authors.forename: Antonello
authors.initials: A
authors.lastname: Pileggi
authors.forename: Juan
authors.initials: J
authors.lastname: Diez
authors.forename: Juan
authors.initials: J
authors.lastname: Domínguez-Bendala
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Pastori
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation; D047108:Embryonic Development; D055098:Endocrine Cells / Q000166:cytology / Q000378:metabolism; D005260:Female; D018149:Glucose Intolerance; D007328:Insulin / Q000378:metabolism*; D050417:Insulin-Secreting Cells / Q000166:cytology / Q000378:metabolism; D060850:LIM-Homeodomain Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008810:Mice, Inbred C57BL; D035683:MicroRNAs / Q000378:metabolism*; D060172:Morpholinos / Q000494:pharmacology; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D010179:Pancreas / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D011247:Pregnancy; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
chemical_list: D007328:Insulin; D060850:LIM-Homeodomain Proteins; C549243:MIRN7 microRNA, mouse; D035683:MicroRNAs; D060172:Morpholinos; D016376:Oligonucleotides, Antisense; D014157:Transcription Factors; C063843:insulin gene enhancer binding protein Isl-1