The Role of Fgf Signaling in Vertebrate Development

这个项目的长期目标是了解一个非常重要的基因产物家族，即成纤维细胞生长因子(FGFs)是如何控制一系列广泛的细胞生物学行为的，如增殖、细胞死亡、迁移、干细胞维持和基因表达。当FGFs调节失调时，它们在各种形式的癌症中起着重要作用，我们研究的特定FGFs在乳腺癌和前列腺癌中发挥着重要作用。为了实现该项目的长期目标，我们将重点放在FGFs在小鼠胚胎发育过程中扮演的正常角色上。因此，我们的短期目标是产生必要的小鼠品系，使我们能够在胚胎发育过程中控制成纤维细胞生长因子基因的表达，并产生和测试关于成纤维细胞生长因子在胚胎中作用的特定假说。例如，我们最近推翻了一个假说，即FGF8在身体发生过程中是必需的，身体的大部分肌肉、真皮和所有脊椎都是通过这个过程产生的(Development 132：3859)。这导致了一种新的假设，即FGF8在这个胚胎过程中的作用是多余的，其他五个FGFs中的一个或多个在该区域表达。这种冗余性的问题对癌症生物学有影响，因为一个给定的肿瘤中可能有超过一个的成纤维细胞生长因子发挥作用。成纤维细胞生长因子(FGFs)是一个由22个成员组成的家族，调控着广泛的细胞生物学行为，如增殖、细胞死亡、迁移和基因表达。在2009财年，作为我们对成纤维细胞生长因子信号的普遍兴趣的一部分，在合作研究中，我们确定了Fgf9在肺发育中的气道平滑肌分化中的作用(&lt；i&gt；dev.动力&lt；/I&gt；，2009 238：123)。另一个我们长期感兴趣的家庭成员是&lt；i&gt；fgf8&lt；/i&gt；，它在乳腺癌和前列腺癌的发展过程中发挥着重要作用。为了了解这种异常表达如何影响癌症中的细胞功能，我们的长期目标是以小鼠为模型系统，确定&lt；i&gt；Fgf8&lt；/i&gt；在脊椎动物胚胎发育过程中的正常作用。&lt；i&gt；Fgf8&lt；/i&gt；在胚胎的多个区域中表达，这些区域可能被称为“组织者”：这些区域是形成图案并因此“组织”周围组织的信号源。在此之前，我们已经在&lt；i&gt；Fgf8&lt；/i&gt；基因座生成了等位基因序列(Meyers et al.1998&lt；i&gt；Natural Genetics&lt；/i&gt；18：136)，以及Cre介导的组织特异性基因敲除(Lewandoski等人。2000&lt；i&gt；Natural Genetics&lt；/i&gt；，26：460；Lewandoski 2001&lt；/i&gt；2：743；Lewandoski 2007&lt；i&gt；Handb Exp Pharmaco&lt；/i&gt；178：235)，并揭示了&lt；i&gt；Fgf8&lt；/i&gt；在控制内脏、肢体和大脑发育的组织者中的作用。我们已经培育出一种有价值的小鼠品系(T-Cre)，它在所有胚胎中胚层谱系中特异表达Cre，从而使我们能够控制这些谱系中的基因表达。这条线有助于绕过影响早期发育的基因的胚胎致死表型，但允许研究这些基因在大部分胚胎中的作用(Verheyden等人，2005；lt；i&gt；Development&lt；/i&gt；，132：4235；Wahl et al，2007&lt；i&gt；Development&lt；/i&gt；，134；4033；Dunty et al&lt；i&gt；Development&lt；/i&gt；135：85；Aulehla，A.I&gt；NAT Cell Biol./i&gt；，10：186；MacDonald S.T.et al 2008&lt；I&gt；Medicovasc Res.&lt；/I&gt；，79：448；Kumar A，et al，2008&lt；I&>；Dev.动态/I&>，237：5391；Tzchori等人，2009&lt；I&>Development&lt；/I&>，136；1375)。用TCre灭活&lt；i&gt；Fgf8&lt；/i&gt；揭示了&lt；i&gt；Fgf8&lt；/i&gt；在肾脏发育过程中对细胞存活和基因表达起着核心作用(Perantoni et al 2005，&lt；i&gt；Development&lt；/i&gt；，132：3859)。从这些研究中发现的另一个令人惊讶的发现是，控制体节形成过程的几个中胚层信号中心并不需要&lt；i&gt；fgf8&lt；/i&gt；被认为在体节形成过程中发挥作用。为了研究这一点，我们正在研究突变体，在这些突变体中，&lt；i&gt；fgf8&lt；/i&gt；以及在这些区域表达的另外五个&lt；i&gt；fgf&lt；/i&gt；中的每一个都同时失活。重要的是，我们发现&lt；i&gt；Fgf4&lt；/i&gt；和&lt；i&gt；Fgf8&lt；/i&gt；在体节形成中扮演了多余的角色。这种功能冗余与癌症有关，因为这两种FGFs在睾丸肿瘤中都被发现异常活跃。此外，这种冗余对进化有影响，因为相同的FGFs在肢体发育中起着补偿作用。

The long term goal of this project is to understand how a very important family of gene products, called Fibroblast Growth Factors (FGFs), control a wide spectrum of cell biological behaviors such as proliferation, cell death, migration, stem cell maintenance and gene expression. FGFs, when dysregulated, are instrumental in various forms of cancer, and the particular FGFs we study play important roles in breast and prostate cancer. To achieve the project's long terms goals, we focus on the normal role FGFs play during mouse embryogenesis. Therefore our short term goals are to generate the necessary mouse strains that will allow us to control FGF gene expression during embryogenesis and to generate and test specific hypotheses concerning FGF action in the embryo. For example, we recently overturned a hypothesis which stated that FGF8 was required for the process of somitogenesis, the process by which much of the body's muscle, dermis and all vertebrae are generated (Development 132: 3859). This lead to a new hypothesis that the role of FGF8 in this embryonic process was redundant with one or more of the other five FGFs expressed in this region. This issue of redundancy has implications for the biology of cancer as more than one FGF can be acting in a given tumor. Fibroblast growth factors (FGFs) comprise a family of 22 members that govern a wide spectrum of cell biological behaviors such as proliferation, cell death, migration and gene expression. In FY 2009, as part of our general interest in FGF signaling, in collaborative studies we have defined the role of Fgf9 in airway smooth muscle differentiation in lung development (<I>Dev. Dyn.</I>, 2009 238:123). Another family member we have a long standing interest in is <I>Fgf8</I>, which plays an important role in the progression of both breast cancer and prostate cancer. To understand how such abnormal <I>Fgf8</I> expression affects cell function in cancer, our long-term goal is to determine the normal role of <I>Fgf8</I>, during vertebrate embryogenesis, using the mouse as a model system. <I>Fgf8</I> is expressed in a variety of regions of the embryo that may be termed "organizers": regions that are a source of signals that pattern and thus "organize" the surrounding tissue. Previously we have generated an allelic series generated at the <I>Fgf8</I> locus (Meyers et al. 1998 <I>Nature Genetics</I> 18:136), as well as Cre-mediated tissue-specific knockouts (Lewandoski et al. 2000 <I>Nature Genetics</I>, 26:460; Lewandoski 2001 <I>Nature Reviews Genet.</I> 2:743; Lewandoski 2007 <I>Handb Exp Pharmaco</I> 178: 235) and revealed a role for <I>Fgf8</I> in organizers that control gastrulation, limb, and brain development. We have produced a valuable mouse line (T-Cre) that expresses Cre specifically throughout all embryonic mesodermal lineages, thus allowing us to control gene expression in these lineages. This line is useful to bypass the embryonic lethal phenotypes of genes that affect early development, yet allows the study of the role of such genes throughout much of the embryo (Verheyden et al, 2005 <I>Development</I>, 132: 4235; Wahl et al, 2007 <I>Development</I>, 134; 4033; Dunty et al <I>Development</I>, 135:85; Aulehla, A. et al, 2008 <I>Nat Cell Biol.</I>, 10:186; MacDonald S.T. et al 2008 <I>Cardiovasc Res. </I>, 79: 448; Kumar A, et al, 2008 <I>Dev. Dyn.</I>, 237:5391; Tzchori et al, 2009 <I>Development</I>, 136; 1375) . Inactivation of <I>Fgf8</I> with TCre has revealed that <I>Fgf8</I> plays a central role in cell survival and gene expression during kidney development (Perantoni et al 2005, <I>Development</I>, 132: 3859). Another surprising insight emerging from these studies is that <I>Fgf8</I> is not required for several mesodermal signaling centers that control the process of somite formation, where it was thought to play a role. To investigate this, we are studying mutants in which <I>Fgf8</I> and each of the other five <I>Fgfs</I> expressed in these regions are simultaneously inactivated. Importantly, we have uncovered a redundant role between <I>Fgf4</I> and <I>Fgf8</I> in somite formation. This functional redundancy has implications for cancer as both FGFs have been found to be aberrantly active in testicular tumors. Furthermore this redundancy has implications for evolution as the same FGFs play compensatory roles in limb development.