title: Identification of a novel gene for diabetic traits in rats, mice, and humans.
abstract: The genetic basis of type 2 diabetes remains incompletely defined despite the use of multiple genetic strategies. Multiparental populations such as heterogeneous stocks (HS) facilitate gene discovery by allowing fine mapping to only a few megabases, significantly decreasing the number of potential candidate genes compared to traditional mapping strategies. In the present work, we employed expression and sequence analysis in HS rats (Rattus norvegicus) to identify Tpcn2 as a likely causal gene underlying a 3.1-Mb locus for glucose and insulin levels. Global gene expression analysis on liver identified Tpcn2 as the only gene in the region that is differentially expressed between HS rats with glucose intolerance and those with normal glucose regulation. Tpcn2 also maps as a cis-regulating expression QTL and is negatively correlated with fasting glucose levels. We used founder sequence to identify variants within this region and assessed association between 18 variants and diabetic traits by conducting a mixed-model analysis, accounting for the complex family structure of the HS. We found that two variants were significantly associated with fasting glucose levels, including a nonsynonymous coding variant within Tpcn2. Studies in Tpcn2 knockout mice demonstrated a significant decrease in fasting glucose levels and insulin response to a glucose challenge relative to those in wild-type mice. Finally, we identified variants within Tpcn2 that are associated with fasting insulin in humans. These studies indicate that Tpcn2 is a likely causal gene that may play a role in human diabetes and demonstrate the utility of multiparental populations for positionally cloning genes within complex loci.
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Shirng-Wern
authors.initials: SW
authors.lastname: Tsaih
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Katie
authors.initials: K
authors.lastname: Holl
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Shuang
authors.initials: S
authors.lastname: Jia
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Mary
authors.initials: M
authors.lastname: Kaldunski
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Michael
authors.initials: M
authors.lastname: Tschannen
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Hong
authors.initials: H
authors.lastname: He
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Jaime Wendt
authors.initials: JW
authors.lastname: Andrae
authors.affiliation: Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Shun-Hua
authors.initials: SH
authors.lastname: Li
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Alex
authors.initials: A
authors.lastname: Stoddard
authors.affiliation: Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Andrew
authors.initials: A
authors.lastname: Wiederhold
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Parrington
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, United Kingdom.
authors.forename: Margarida
authors.initials: M
authors.lastname: Ruas da Silva
authors.affiliation: Department of Pharmacology, University of Oxford, Oxford, OX1 3QT, United Kingdom.
authors.forename: Antony
authors.initials: A
authors.lastname: Galione
authors.affiliation: Department of Medicine, Harvard Medical School, General Medicine Division, Massachusetts General Hospital, Boston, Massachusetts 02114.
authors.forename: James
authors.initials: J
authors.lastname: Meigs
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Raymond G
authors.initials: RG
authors.lastname: Hoffmann
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Pippa
authors.initials: P
authors.lastname: Simpson
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Howard
authors.initials: H
authors.lastname: Jacob
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
authors.forename: Martin
authors.initials: M
authors.lastname: Hessner
authors.affiliation: Human and Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 Department of Pediatrics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 lsolberg@mcw.edu.
authors.forename: Leah C
authors.initials: LC
authors.lastname: Solberg Woods
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000235:genetics; D015220:Calcium Channels / Q000235:genetics* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics*; D005260:Female; D015894:Genome, Human; D006801:Humans; D007328:Insulin / Q000097:blood / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D020641:Polymorphism, Single Nucleotide; D040641:Quantitative Trait Loci; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D001786:Blood Glucose; D015220:Calcium Channels; D007328:Insulin; C530224:TPCN2 protein, human; C546785:TPCN2 protein, mouse
keywords: MPP; Multiparent Advanced Generation Inter-Cross (MAGIC); Multiparental populations; Tpcn2; expression QTL mapping; glucose; heterogeneous stock rats; insulin; type 2 diabetes