Skip to main content
NCBI home page
NIHPA Author Manuscripts logoLink to NIHPA Author Manuscripts
. Author manuscript; available in PMC: 2015 Aug 15.
Published in final edited form as: Gene. 2015 May 12;568(1):112–113. doi: 10.1016/j.gene.2015.05.025

The C57BL/6J Niemann-Pick C1 mouse model with decreased gene dosage is susceptible to increased weight gain when fed a high-fat diet: Confirmation of a gene-diet interaction

David Jelinek 1, Joseph J Castillo 2, Randall A Heidenreich 3, William S Garver 4
PMCID: PMC4483511  NIHMSID: NIHMS701758  PMID: 25979674

Dear Editor

The human Niemann–Pick C1 (NPC1) gene has been primarily investigated in relation to a rare autosomal-recessive lipid-storage disorder characterized by neonatal jaundice, hepatosplenomegaly, and progressive neurological degeneration (Garver et al., 2007, 2010). A number of early studies performed using human NPC1 fibroblasts and the BALB/cJ Npc1 mouse model have determined that the NPC1 protein has a central role in regulating the transport of lipoprotein-derived lipid (cholesterol and fatty acids) from late endosomes/lysosomes to other cellular compartments to maintain cellular, tissue, and whole body lipid homeostasis (Liscum et al., 1989; Pentchev et al., 1986).

Several years ago the first and second waves of genome-wide association studies (GWAS) revealed that common human NPC1 gene risk variants (644A>G encoding His215Arg and 2572A>G encoding Ile858Val) were associated with extreme adult obesity and increased measures of adiposity (Cotsapas et al., 2010; den Hoed et al., 2012; Meyre et al., 2009). These findings were subsequently replicated in other populations and extended to include an additional NPC1 gene risk variant (1926C>G encoding Ile642Met) associated with type 2 diabetes independent of body weight (Al-Daghri et al., 2012; Robiou-du-Pont et al., 2013; Sandholt et al., 2011). Consistent with these results, we have recently reported that the human NPC1 gene risk variants reside in complete linkage-disequilibrium (D′ > 0.99) among certain ethnic groups (non-Hispanic white, Hispanic, and Native American) and associated with maternal overweight or gestational diabetes independent of body weight in our local obstetric population (Garver et al., 2015).

Whether the human NPC1 gene risk variants correspond to an increase or decrease of encoded NPC1 protein function was unknown when initial GWAS and replication studies were performed. To properly address this important question we performed a series of growth studies using different Npc1 mouse models comprised of Npc1 normal mice (Npc1+/+) and Npc1 heterozygous mice (Npc1+/−) with decreased gene dosage resulting from a null mutation and hence proposed to genetically mimic human NPC1 gene loss-of-function variants. As a result of our studies, we were able to clearly demonstrate that male and female pure BALB/cJ or hybrid BALB/cJ-C57BL/6J Npc1+/− mice are susceptible to increased weight gain when fed a high-fat diet (45% kcal fat) but not when fed a low-fat diet (10% kcal fat), consistent with an Npc1 gene-diet interaction responsible for weight gain (Jelinek et al., 2010a,b, 2012).

However, soon after our three studies were published an independent study reported that a C57BL/6J Npc1 mouse model with a loss-of-function variant (3163A>G encoding Asp1005Gly) produced by the potent mutagen ethyl-nitrosourea (Npc1nmf164) was instead susceptible to weight loss starting at approximately 20 weeks of age when fed a normal-fat diet (18% kcal fat) (Borbon et al., 2012). This study also indicated that weight loss occurred in male mice, but not female mice, when fed the normal-fat diet. To examine and clarify this apparent discrepancy, we had produced a novel C57BL/6J Npc1 mouse model by backcrossing the BALB/cJ Npc1 mouse model null mutation into wild-type C57BL/6J mice for 15 generations. We published our first results in this journal (Gene) indicating that C57BL/6J Npc1+/− mice were susceptible to impaired glucose tolerance at 10 weeks of age compared to littermate Npc1+/+ mice when fed a low-fat diet (10% kcal fat) and independent of body weight (Jelinek et al., 2013). This result was highly significant because it confirmed a previous replication study indicating that an additional human NPC1 gene risk variant (1926C>G encoding Ile642Met) predisposes to insulin resistance or type 2 diabetes independent of body weight in certain populations. Finally, we have more recently performed another growth study with our novel C57BL/6J Npc1 mouse model and report results to this journal (Gene) that Npc1+/− mice are predisposed to increased weight gain at approximately 10 weeks of age compared to Npc1+/+ mice when fed a high-fat diet, but not when fed a low-fat diet, thereby confirming our original studies indicating an Npc1 gene-diet interaction responsible for increased weight gain (Fig. 1A). Moreover, our results also indicate that Npc1+/+ and Npc1+/− mice have significantly impaired yet similar glucose tolerance when fed a high-fat diet compared to Npc1+/+ and Npc1+/− mice fed a low-fat diet (Fig. 1B). Nonetheless, the Npc1+/− mice fed a low-fat diet have glucose tolerance that is intermediate compared to Npc1+/+ mice fed the low-fat diet (normal glucose tolerance) and Npc1+/+ and Npc1+/− mice fed a high-fat diet (impaired glucose tolerance).

Fig. 1.

Fig. 1

Open in a new tab

Growth curves and glucose tolerance test for the C57BL/6J Npc1 mouse model fed a low-fat or high-fat diet. (A) The change in body weights for C57BL/6J Npc1+/+ and Npc1+/− mice fed a low-fat diet or high-fat diet and weighed on an approximate weekly basis. (B) The change in blood glucose concentrations for C57BL/6J Npc1+/+ and Npc1+/− mice fed a low-fat diet or high-fat diet measured at 10 weeks of age. Values are represented as mean ± SE (n = 8–10 mice). An asterisk indicates a significant difference (P < 0.05). LFD = low-fat diet. HFD = high-fat diet.

In summary, our Npc1 mouse model studies using different genetic backgrounds (pure BALB/cJ, hybrid BALB/cJ-C57BL/6J, and mostly pure C57BL/6J) indicate that decreased gene dosage predisposes to increased weight gain and impaired glucose tolerance when fed a high-fat diet. These results confirm an Npc1 gene-diet interaction responsible for these common metabolic diseases. Moreover, our combined mouse model studies are consistent with GWAS and subsequent replication studies indicating that the human NPC1 gene ancestral risk variants (644A>G, 1926C>G, and 2572A>G) reported to be in complete linkage-disequilibrium represent loss-of-function variants, or at least are genetically linked with undefined causal variants that impart metabolic thriftiness and therefore enhance energy storage. In contrast, although the C57BL/6J Npc1nmf164 homozygous affected mouse model may be appropriate for investigating classical human NPC1 disease, there are limitations for using this mouse model to investigate common human metabolic diseases (obesity and diabetes). Although speculative, these limitations may have resulted from the general methodology used to induce indiscriminate mutations throughout the mouse genome using ethyl-nitrosourea.

Acknowledgments

These studies were supported in part by a grant received from the National Institues of Health (DK071544), the Tohono O’Oodham Nation and Pima County Health Department, and private donations for the investigation of genetic and metabolic diseases.

Abbreviations

GWAS

genome-wide association study

NPC1

Niemann–Pick C1

Contributor Information

David Jelinek, Department of Biochemistry and Molecular Biology, School of Medicine, The University of New Mexico Health Sciences Center, Albuquerque, NM, USA.

Joseph J. Castillo, Department of Biochemistry and Molecular Biology, School of Medicine, The University of New Mexico Health Sciences Center, Albuquerque, NM, USA

Randall A. Heidenreich, Department of Pediatrics, School of Medicine, The University of New Mexico Health Sciences Center, Albuquerque, NM, USA

William S. Garver, Department of Biochemistry and Molecular Biology, School of Medicine, The University of New Mexico Health Sciences Center, Albuquerque, NM, USA

References

  1. Al-Daghri NM, Cagliani R, Forni D, Alokail MS, Pozzoli U, Alkharfy KM, Sabico S, Clerici M, Sironi M. Mammalian NPC1 genes undergo positive selection and human polymorphisms associate with type 2 diabetes. BMC Med. 2012;10:140. doi: 10.1186/1741-7015-10-140. [DOI] [PMC free article] [PubMed] [Google Scholar]
  2. Borbon I, Campbell E, Ke W, Erickson RP. The role of decreased levels of Niemann-Pick C1 intracellular cholesterol transport on obesity is reversed in the C57BL/6J, metabolic syndrome mouse strain: a metabolic or an inflammatory effect? J Appl Genet. 2012;53:323–330. doi: 10.1007/s13353-012-0099-8. [DOI] [PubMed] [Google Scholar]
  3. Cotsapas C, Speliotes EK, Hatoum IJ, Greenawalt DM, Dobrin R, Lum PY, Suver C, Chudin E, Kemp D, Reitman M, Voight BF, Neale BM, Schadt EE, Hirschhorn JN, Kaplan LM, Daly MJ. Common body mass index-associated variants confer risk of extreme obesity. Hum Mol Genet. 2010;19:3690–3691. doi: 10.1093/hmg/ddp292. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. den Hoed M, Luan J, Langenberg C, Cooper C, Sayer AA, Jameson K, Kumari M, Kivimaki M, Hingorani AD, Grontved A, Khaw KT, Ekelund U, Wareham NJ, Loos RJF. Evaluation of common genetic variants identified by GWAS for early onset and morbid obesity in population-based samples. Int J Obes. 2012;34:1–6. doi: 10.1038/ijo.2012.34. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Garver WS, Francis GA, Jelinek D, Shepherd G, Flynn J, Castro G, Walsh Vockley CM, Coppock DL, Pettit KM, Heidenreich RA, Meaney JF. The National Niemann–Pick C1 disease database: report of clinical features and health problems. Am J Med Genet. 2007;143A:1204–1211. doi: 10.1002/ajmg.a.31735. [DOI] [PubMed] [Google Scholar]
  6. Garver WS, Jelinek D, Meaney JF, Flynn J, Pettit KM, Shepherd G, Heidenreich RA, Walsh Vockley CM, Castro G, Francis GA. The National Niemann–Pick Type C1 disease database: correlation of lipid profiles, mutations, and biochemical phenotypes. J Lipid Res. 2010;51:406–415. doi: 10.1194/jlr.P000331. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Garver WS, de la Torre L, Brennan MC, Luo L, Jelinek D, Castillo JJ, Meyre D, Orlando RA, Heidenreich RA, Rayburn WF. Differential association of Niemann–Pick C1 gene polymorphisms with maternal prepregnancy overweight and gestational diabetes. J Diabetes Obes. 2015;2:1–7. doi: 10.15436/2376-0494.15.007. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Jelinek D, Heidenreich RA, Erickson RP, Garver WS. Decreased Npc1 gene dosage in mice is associated with weight gain. Obesity. 2010a;18:1457–1459. doi: 10.1038/oby.2009.415. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Jelinek D, Millward V, Birdi A, Trouard TP, Heidenreich RA, Garver WS. Npc1 haploinsufficiency promotes weight gain and metabolic features associated with insulin resistance. Hum Mol Genet. 2010b;20:312–321. doi: 10.1093/hmg/ddq466. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. Jelinek D, Baghsoodi B, Borbon IA, Hardwick RN, Cherrington NJ, Erickson RP. Genetic variation in the mouse model of Niemann–Pick C1 affects female, as well as male, adiposity, and hepatic bile transporters but has indeterminant effects on caveolae. Gene. 2012;491:128–134. doi: 10.1016/j.gene.2011.10.010. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Jelinek D, Castillo JJ, Garver WS. The C57BL/6J Niemann–Pick C1 mouse model with decreased gene dosage has impaired glucose tolerance independent of body weight. Gene. 2013;527:65–70. doi: 10.1016/j.gene.2013.05.080. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Liscum L, Ruggiero RM, Faust JR. The intracellular transport of low density lipoprotein-derived cholesterol is defective in Niemann–Pick type C fibroblasts. J Cell Biol. 1989;108:1625–1636. doi: 10.1083/jcb.108.5.1625. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Meyre D, Delplanque J, Chevre JC, Lecoeur C, Lobbens S, Gallina S, Durand E, Vatin V, Degraeve F, Proenca C, Gaget S, Korner A, Kovacs P, Kiess W, Tichet J, Marre M, Hartikainen AL, Horber F, Potoczna N, Hercberg S, Levy-Marchal C, Pattou F, Heude B, Tauber M, McCarthy MI, Blakemore AIF, Montpetit A, Polychronakos C, Weill J, Coin LJM, Asher J, Elliott P, Jarvelin MR, Visvikis-Siest S, Balkau B, Sladek R, Balding D, Walley A, Dina C, Froguel P. Genome-wide association study for early-onset and morbid adult obesity identifies three new risk loci in European populations. Nat Genet. 2009;41:157–159. doi: 10.1038/ng.301. [DOI] [PubMed] [Google Scholar]
  14. Pentchev PG, Kruth HS, Comly ME, Butler JD, Vanier MT, Wenger DA, Patel S. Type C Niemann–Pick disease. A parallel loss of regulatory responses in both the uptake and esterification of low density lipoprotein-derived cholesterol in cultured fibroblasts. J Biol Chem. 1986;261:16775–16780. [PubMed] [Google Scholar]
  15. Robiou-du-Pont S, Bonnefond A, Yengo L, Vaillant E, Lobbens S, Durand E, Weill J, Lantieri O, Balkau B, Charpentier G, Marre M, Froguel P, Meyre D. Contribution of 24 obesity-associated genetic variants to insulin resistance, pancreatic beta-cell function and type 2 diabetes risk in the French population. Int J Obes. 2013;37:980–985. doi: 10.1038/ijo.2012.175. [DOI] [PubMed] [Google Scholar]
  16. Sandholt CH, Vestmar MA, Bille DS, Borglykke A, Almind K, Hansen L, Sandbaek A, Lauritzen T, Witte D, Jorgensen T, Pedersen O, Hansen T. Studies of metabolic phenotypic correlates of 15 obesity associated variants. PLoS One. 2011;6:e23531. doi: 10.1371/journal.pone.0023531. [DOI] [PMC free article] [PubMed] [Google Scholar]

RESOURCES