Sfrp1 and Sfrp2 are required for normal male sexual development in mice

AbstractSecreted frizzled-related proteins (Sfrps) are antagonists of WNT signalling implicated in a variety of biological processes. However, there are no reports of a direct role for Sfrps in embryonic organogenesis in mammals. Using in vivo loss-of-function studies we report here for the first time a redundant role for Sfrp1 and Sfrp2 in embryonic sexual development of the mouse. At 16.5 dpc, male embryos lacking both genes exhibit multiple defects in gonad morphology, reproductive tract maturation and gonad positioning. Abnormal positioning of the testis appears to be due to failed gubernaculum development and an unusually close association between the cranial end of the reproductive tract and the kidney. The testes of double homozygotes are smaller than controls, contain fewer cords from the earliest stages, but still express Insl3, which encodes the hormone required for gubernacular masculinisation. Lgr8, which encodes the Insl3 receptor, is also expressed in the mutant gubernaculum, suggesting that Sfrp1/Sfrp2 signalling is not required for expression of the ligand or receptor that controls transabdominal testicular descent. Similarities between the abnormalities of embryonic sexual development in Sfrp1−/− Sfrp2−/− embryos with those exhibited by the Looptail and Wnt5a mutants suggest that disrupted non-canonical Wnt signalling may cause these defects

Sfrp Controls Apicobasal Polarity and Oriented Cell Division in Developing Gut Epithelium

Epithelial tubular morphogenesis leading to alteration of organ shape has important physiological consequences. However, little is known regarding the mechanisms that govern epithelial tube morphogenesis. Here, we show that inactivation of Sfrp1 and Sfrp2 leads to reduction in fore-stomach length in mouse embryos, which is enhanced in the presence of the Sfrp5 mutation. In the mono-cell layer of fore-stomach epithelium, cell division is normally oriented along the cephalocaudal axis; in contrast, orientation diverges in the Sfrps-deficient fore-stomach. Cell growth and apoptosis are not affected in the Sfrps-deficient fore-stomach epithelium. Similarly, cell division orientation in fore-stomach epithelium diverges as a result of inactivation of either Stbm/Vangl2, an Fz/PCP component, or Wnt5a. These observations indicate that the oriented cell division, which is controlled by the Fz/PCP pathway, is one of essential components in fore-stomach morphogenesis. Additionally, the small intestine epithelium of Sfrps compound mutants fails to maintain proper apicobasal polarity; the defect was also observed in Wnt5a-inactivated small intestine. In relation to these findings, Sfrp1 physically interacts with Wnt5a and inhibits Wnt5a signaling. We propose that Sfrp regulation of Wnt5a signaling controls oriented cell division and apicobasal polarity in the epithelium of developing gut

Numerical Simulation of Solidification in Additive Manufacturing of Ti Alloy by Multi-Phase Field Method

The multi-phase field method (MPFM) coupled with the database of calculation of phase diagrams (CALPHAD) is a powerful tool for simulation of solidification microstructure evolution in engineering casting conditions. MPFM equations have been introduced assuming quasi-equilibrium at the interface. However, few attempts have been made adopting MPFM for solidification in additive manufacturing (AM) conditions because the process is considered to be in a strongly non-equilibrium condition. In other words, the classical solidification theory based on the local equilibrium assumption was not considered to be applicable to this process. However, some researchers have reported experimental observations of the columnar-to-equiaxed transition in the solidification of AM. These suggest MPFM can be adopted for solidification simulation of the AM process. We tackled the issue of applicability of MPFM for solidification simulation in AM of Ti alloys. It was confirmed that solidification simulation using MPFM can provide observation of the columnar-to-equiaxed transition and establish a solidification map for the AM process conditions.Mechanical Engineerin

Método de diagnóstico de la enfermedad de Alzheimer que emplea SFRP1 como biomarcador

La presente invención se refiere a un método de diagnóstico de la enfermedad de Alzheimer que comprende (a) detectar y/o cuantificar el producto de expresión de una secuencia nucleotídica de un gen sfrp1 en una muestra aislada; (b) comparar la cantidad detectada y/o cuantificada con una cantidad de referencia; (c) identificar cualquier desviación significativa en la comparación de datos de la etapa (b); y, (d) atribuir la desviación significativa identificada a la presencia de la enfermedad de Alzheimer. Así mismo, la presente invención se refiere al uso de un kit que comprende cebadores y/o sondas que hibridan con la secuencia nucleotídica de un gen sfrp1 o anticuerpos que se unen específicamente a una secuencia aminoacídica codificada por la secuencia nucleotídica de un gen sfrp1 para determinar la presencia de una enfermedad de Alzheimer.Peer reviewedConsejo Superior de Investigaciones Científicas, Vall D'hebron Institut de Recerca, Vall D'hebron Institute of Oncology, Institució Catalana de Recerca I Estudis Avançats, National University of SingaporeA1 Solicitud de patente con informe sobre el estado de la técnic

Secreted frizzled-related proteins are required for Wnt/beta-catenin signalling activation in the vertebrate optic cup.

Secreted frizzled-related proteins (Sfrps) are considered Wnt signalling antagonists but recent studies have shown that specific family members enhance Wnt diffusion and thus positively modulate Wnt signalling. Whether this is a general and physiological property of all Sfrps remains unexplored. It is equally unclear whether disruption of Sfrp expression interferes with developmental events mediated by Wnt signalling activation. Here, we have addressed these questions by investigating the functional consequences of Sfrp disruption in the canonical Wnt signalling-dependent specification of the mouse optic cup periphery. We show that compound genetic inactivation of Sfrp1 and Sfrp2 prevents Wnt/-catenin signalling activation in this structure, which fails to be specified and acquires neural retina characteristics. Consistent with a positive role of Sfrps in signalling activation, Wnt spreading is impaired in the retina of Sfrp1–/–;Sfrp2–/– mice. Conversely, forced expression of Sfrp1 in the wing imaginal disc of Drosophila, the only species in which the endogenous Wnt distribution can be detected, flattens the Wg gradient, suppresses the expression of high-Wg target genes but expands those typically activated by low Wg concentrations. Collectively, these data demonstrate that, in vivo, the levels of Wnt signalling activation strongly depend on the tissue distribution of Sfrps, which should be viewed as multifunctional regulators of Wnt signalling.Spanish MICINN, BFU2007-61774, Fundación Mutual Madrileña (2006-0916), Comunidad Autonoma de Madrid (CAM, P-SAL-0190-2006) CIBERER intramural funds to P.B.Peer Reviewe

Mice Deficient in <i>Sfrp1</i> Exhibit Increased Adiposity, Dysregulated Glucose Metabolism, and Enhanced Macrophage Infiltration

<div><p>The molecular mechanisms involved in the development of obesity and related complications remain unclear. Wnt signaling plays an important role in preadipocyte differentiation and adipogenesis. The expression of a Wnt antagonist, secreted frizzled related protein 1 (SFRP1), is increased in response to initial weight gain, then levels are reduced under conditions of extreme obesity in both humans and animals. Here we report that loss of <i>Sfrp1</i> exacerbates weight gain, glucose homeostasis and inflammation in mice in response to diet induced obesity (DIO). Sfrp1^-/- mice fed a high fat diet (HFD) exhibited an increase in body mass accompanied by increases in body fat percentage, visceral white adipose tissue (WAT) mass, and adipocyte size. Moreover, <i>Sfrp1</i> deficiency increases the mRNA levels of key <i>de novo</i> lipid synthesis genes (<i>Fasn</i>, <i>Acaca</i>, <i>Acly</i>, <i>Elovl</i>, <i>Scd1</i>) and the transcription factors that regulate their expression (<i>Lxr-α, Srebp1, Chreb</i>, and <i>Nr1h3</i>) in WAT. Fasting glucose levels are elevated, glucose clearance is impaired, hepatic gluconeogenesis regulators are aberrantly upregulated (<i>G6pc</i> and <i>Pck1</i>), and glucose transporters are repressed (<i>Slc2a2</i> and <i>Slc2a4</i>) in Sfrp1^-/- mice fed a HFD. Additionally, we observed increased steatosis in the livers of Sfrp1^-/- mice. When there is an expansion of adipose tissue there is a sustained inflammatory response accompanied by adipokine dysregulation, which leads to chronic subclinical inflammation. Thus, we assessed the inflammatory state of different tissues and revealed that Sfrp1^-/- mice fed a HFD exhibited increased macrophage infiltration and expression of pro-inflammatory markers including <i>IL-6, Nmnat, Tgf-β2</i>, and <i>SerpinE1</i>. Our findings demonstrate that the expression of <i>Sfrp1</i> is a critical factor required for maintaining appropriate cellular signaling in response to the onset of obesity.</p> </div

Analysis of de novo lipid synthesis and the inflammatory signature in the gonadal fat pad.

<p>(A) Total RNA from the gonadal fat pad in each group (n=6) was utilized for real-time PCR analysis of <i>Fasn</i>, Acly, and <i>Acaca, Elov</i>16, and <i>Scd</i>1 gene expression. The results shown represent experiments performed in duplicate and normalized to the amplification of β-actin mRNA. Bars represent mean ± SEM of the difference in fold change compared with control ND fed mice. (B) Real-time PCR was carried out utilizing RNA from the gonadal fat pad of control mice and Sfrp1^-/- mice on a ND to measure the relative mRNA expression of the following transcription factors: <i>Srebp1, Chrebp-α</i>, <i>Chrebp</i>-β, and <i>Nr1h3</i>. The experiments were carried out as described above and bars represent mean ± SEM of the difference in fold change compared with control ND fed mice. (C) <i>Left </i><i>panel</i>, gonadal fat pad sections were subjected to immunohistochemical analysis, stained for F4/80 (brown chromogen), and representative images were captured at 100X and are displayed for mice in each treatment group (scale bar 200 μm). <i>Right </i><i>upper </i><i>panel</i>, gondal fat pad RNA was used for real-time PCR analysis of F4/80 mRNA, experiments were carried out as described, and bars represent mean ± SEM of the relative expression with respect to ND fed mice. <i>Right </i><i>lower </i><i>panel</i>, The total number of CLSs (see arrow inset) were counted in F4/80 stained gonadal fat pad sections (n=4/genotype) (D) Real-time PCR analysis of liver Il-6<i>, Tnf</i>-α, Il-1β, and <i>Nampt</i> gene expression was carried out as described above. Bars represent mean ± SEM of the difference in fold change compared with control ND fed mice. (*p<0.05, **p<0.01, ***p<0.001 significantly different from control mice fed a ND using Bonferroni’s <i>t</i> test after a two-way ANOVA; ^#p<0.05, ^##p<0.01, significantly different from respective ND fed mice using student’s <i>t</i> test.).</p