Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2011 Aug 3;14(2):208-18.
doi: 10.1016/j.cmet.2011.06.007.

Expression of the splicing factor gene SFRS10 is reduced in human obesity and contributes to enhanced lipogenesis

Jussi Pihlajamäki  1 , Carles Lerin, Paula Itkonen, Tanner Boes, Thomas Floss, Joshua Schroeder, Farrell Dearie, Sarah Crunkhorn, Furkan Burak, Josep C Jimenez-Chillaron, Tiina Kuulasmaa, Pekka Miettinen, Peter J Park, Imad Nasser, Zhenwen Zhao, Zhaiyi Zhang, Yan Xu, Wolfgang Wurst, Hongmei Ren, Andrew J Morris, Stefan Stamm, Allison B Goldfine, Markku Laakso, Mary Elizabeth Patti
Affiliations

Expression of the splicing factor gene SFRS10 is reduced in human obesity and contributes to enhanced lipogenesis

Jussi Pihlajamäki et al. Cell Metab. .

Abstract

Alternative mRNA splicing provides transcript diversity and may contribute to human disease. We demonstrate that expression of several genes regulating RNA processing is decreased in both liver and skeletal muscle of obese humans. We evaluated a representative splicing factor, SFRS10, downregulated in both obese human liver and muscle and in high-fat-fed mice, and determined metabolic impact of reduced expression. SFRS10-specific siRNA induces lipogenesis and lipid accumulation in hepatocytes. Moreover, Sfrs10 heterozygous mice have increased hepatic lipogenic gene expression, VLDL secretion, and plasma triglycerides. We demonstrate that LPIN1, a key regulator of lipid metabolism, is a splicing target of SFRS10; reduced SFRS10 favors the lipogenic β isoform of LPIN1. Importantly, LPIN1β-specific siRNA abolished lipogenic effects of decreased SFRS10 expression. Together, our results indicate that reduced expression of SFRS10, as observed in tissues from obese humans, alters LPIN1 splicing, induces lipogenesis, and therefore contributes to metabolic phenotypes associated with obesity.

PubMed Disclaimer

Conflict of interest statement

The authors declare no competing financial interests.

Figures

Figure 1
Figure 1. RNA processing gene expression is downregulated in obesity
(A) Top-ranking downregulated pathways in obese humans identified through GO-based pathway analysis (MAPPFinder) of microarray data from liver and muscle. (B) Heatmap of 13 RNA processing genes with decreased gene expression in both tissues. Blue indicates lower and red higher gene expression. NGT, normal glucose tolerance; IGT, impaired glucose tolerance; T2D, type 2 diabetes. (C) Expression of RNA processing genes was determined by RT-PCR from mouse liver and muscle after 4 month of HFD (black bars) compared to chow diet (white bars). Data are mean±SEM. *, p<0.05 vs. chow (n=6). (D) Protein levels of SFRS10, SFPQ and HNRPK were measured by Western blot from liver nuclear extracts. See Fig S1.
Figure 2
Figure 2. SFRS10 knockdown increases expression of lipogenic genes and leads to TAG accumulation in hepatic cells
HepG2 cells were transfected with scramble (SCR) or SFRS10 siRNA and analyzed 4 days later. (A) SFRS10 mRNA and protein levels were analyzed by RT-PCR and Western blot. (B) mRNA levels were determined by RT-PCR. (C) Lipogenesis (from 14C-acetate), (D) TAG levels, (E) TAG synthesis, and (F) fatty acid oxidation were measured as described in Methods. Data are mean±SEM of triplicates, representative of 3 independent experiments. *, p<0.05 vs. SCR siRNA. See Fig S2.
Figure 3
Figure 3. Sfrs10 heterozygous (Het) mice show increased lipogenic gene expression and hypertriglyceridemia
Wild-type (WT) and Sfrs10 Het mice were fasted for 16 hours and then refed for 10 hours before sacrifice. (A) Liver Sfrs10 mRNA and protein levels were determined by RT-PCR and Western blot. (B) Liver mRNA was quantified by RT-PCR. (C) Liver TAG and (D) plasma TAG were measured as in Methods. (E) Plasma lipoprotein profile was determined by FPLC. (F) VLDL secretion was calculated by quantifying plasma TAG after Tyloxapol administration. Data are mean±SEM of at least 5 mice/group and are representative of 2 independent cohorts. *, p<0.05 vs. WT. See Fig S4.
Figure 4
Figure 4. SFRS10 regulates LPIN1 splicing
(A) The putative binding site of SFRS10, GGAA, is highlighted in gray within alternatively spliced exon 6 sequence (Ensembl release 61) of human and mouse LPIN1. The U1 snRNA binding site at the 5’ splice site is underlined. (B) SFRS10 cotransfection increases exclusion of LPIN1 exon 6 in a minigene system (left), while SFRS10 siRNA increases inclusion (right). PCR primers are shown as arrows. (C–D) Expression of total LPIN1, LPIN1β and LPIN1α isoforms was determined (RT-PCR) in: (C) HepG2 cells after SCR (white bars) or SFRS10 siRNA (black bars), and (D) liver samples from WT (white, n=7) and Sfrs10 heterozygous (black, n=5) mice. (E–G) Expression of Lpin1β relative to Lpin1α was measured by RT-PCR in liver from: (E) HFD (black, n=6) and chow (white, n=6) mice, (F) lean (white, n=6) or obese (black, n=14) humans, and (G) Hepa1c cells after GFP (white, n=5) or SFRS10 (black, n=5) overexpression. Data are mean±SEM. *, p<0.05 vs. control. See Fig S2.
Figure 5
Figure 5. Increased expression of lipogenic genes and lipogenesis in response to SFRS10 siRNA is reversed with LPIN1β knockdown
HepG2 cells were transfected with the indicated siRNA and analyzed 4 days later. (A) mRNA levels were determined by RT-PCR. (B) Lipogenesis, (C) TAG accumulation and (D) lysophosphatidic acid levels were measured as in Methods. Data are mean±SEM of triplicates, representative of 3 independent experiments. *, p<0.05 vs. SCR siRNA. #, p<0.05 vs. SFRS10 siRNA. See Fig S5.
Figure 6
Figure 6. Human obesity is associated with decreased expression of RNA processing genes and can influence metabolic phenotypes
Reduced expression of the splicing factor SFRS10 alters splicing of LPIN1, leading to dysregulation of lipogenic pathways and contributing to hypertriglyceridemia. Other alterations in RNA processing in human obesity should be identified (dashed arrows).
See this image and copyright information in PMC

Comment in

  • SFRS10--a splicing factor gene reduced in human obesity?
    Brosch M, von Schönfels W, Ahrens M, Nothnagel M, Krawczak M, Laudes M, Sipos B, Becker T, Schreiber S, Röcken C, Schafmayer C, Hampe J. Brosch M, et al. Cell Metab. 2012 Mar 7;15(3):265-6; author reply 267-9. doi: 10.1016/j.cmet.2012.02.002. Cell Metab. 2012. PMID: 22405059 No abstract available.

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Agarwal AK, Garg A. Genetic disorders of adipose tissue development, differentiation, and death. Annu Rev Genomics Hum Genet. 2006;7:175–99. - PubMed
    1. Biddinger SB, Hernandez-Ono A, Rask-Madsen C, Haas JT, Aleman JO, Suzuki R, Scapa EF, Agarwal C, Carey MC, Stephanopoulos G, et al. Hepatic insulin resistance is sufficient to produce dyslipidemia and susceptibility to atherosclerosis. Cell Metab. 2008;7:125–134. - PMC - PubMed
    1. Bland CS, Wang ET, Vu A, David MP, Castle JC, Johnson JM, Burge CB, Cooper TA. Global regulation of alternative splicing during myogenic differentiation. Nucleic Acids Res. 2010;38:7651–7664. - PMC - PubMed
    1. Blencowe BJ. Alternative splicing: new insights from global analyses. Cell. 2006;126:37–47. - PubMed
    1. Bou KM, Blais A, Figeys D, Yao Z. Lipin - The bridge between hepatic glycerolipid biosynthesis and lipoprotein metabolism. Biochim Biophys Acta. 2010;1801:1249–1259. - PubMed

Publication types

MeSH terms

Associated data