Mitotic exit network and human cancer

描述（由申请人提供）：癌症遗传不稳定性的主要原因之一是有丝分裂错误，导致子细胞之间遗传物质的不均匀分离。许多有丝分裂事件和监测这些事件的检查点尚未在分子水平上被理解。这对于有丝分裂后期到末期的转变中发生的事件尤其如此，当细胞解除其姐妹染色单体的致密并重新组装其细胞核时。In S.在酿酒酵母中，介导这些事件的途径被称为有丝分裂出口网络（MEN）。在人类细胞中，MEN途径尚未被表征。然而，人蛋白激酶Lats 1与酵母MEN激酶具有高度的序列相似性。Lats 1与有丝分裂有关，但其确切功能尚不清楚。尽管如此，Latsl与癌症发展明显相关;在苍蝇，小鼠和人类中，Lats 1是一种公认的肿瘤抑制蛋白。我们假设Lats 1在人类细胞中的MEN通路中起作用，并且该通路的失调导致遗传不稳定性（如通过杂合性丢失分析所测量的）。将通过执行以下特定目标来解决该假设： 1.确定Lats 1是S.酿酒酵母Dbf 2 MEN激酶。我们将研究Lats 1是否与Dbf 2共享受Mob蛋白调控的能力。我们将使用siRNA方法和显性失活突变体进一步研究Lats 1是否在人类细胞的MEN通路中起作用。 2.确定Lats 1受hDmal调控。In S.在粟酒裂殖酵母中，MEN激酶受DmaI（一种推定的泛素连接酶）调节。我们将研究人类Lats 1是否受hDmal的调控，hDmal是一种与酵母Dmal具有高度序列相似性的泛素连接酶。 3.确定LATS 1和hDmal的失调增加了杂合性丢失（洛）的频率。洛缺失明显参与了癌症的发生和发展。因此，这些研究将有助于确定Lats 1肿瘤抑制功能的分子基础。

DESCRIPTION (provided by applicant): One of the major causes of genetic instability in cancer is errors in mitosis leading to unequal segregation of the genetic material between daughter cells. Many of the mitotic events and the checkpoints that monitor these events are yet to be understood at the molecular level. This is particularly true for the events that occur in late mitosis at the anaphase to telophase transition, when cells decondense their sister chromatids and reassemble their nuclei. In S. cerevisiae, the pathway that mediates these events is referred to as the mitotic exit network (MEN). In human cells a MEN pathway has not been characterized. However, a human protein kinase, Lats 1, has high sequence similarity to a yeast MEN kinase. Lats 1 has been implicated in mitosis, but its precise function is unclear. Nevertheless, Latsl is clearly linked to cancer development; in flies, mice and humans, Lats 1 is a well-established tumor suppressor protein. We hypothesize that Lats 1 functions in a MEN pathway in human cells and that deregulation of this pathway leads to genetic instability (as measured by loss-of-heterozygosity analysis). This hypothesis will be addressed by performing the following Specific Aims: 1. Establish that Lats 1 is the human ortholog of the S. cerevisiae Dbf2 MEN kinase. We will examine if Lats 1 shares with Dbf2 the ability to be regulated by Mob proteins. We will further examine whether Lats 1 functions in the MEN pathway in human cells using an siRNA approach and dominant negative mutants. 2. Establish that Lats 1 is regulated by hDmal. In S. pombe the MEN kinases are regulated by Dmal, a putative ubiquitin ligase. We will examine if human Lats 1 is regulated by hDmal, a ubiquitin ligase that has high sequence similarity with yeast Dmal. 3. Establish that deregulation of LATS 1 and hDmal increases the frequency of loss-of-heterozygosity (LOH). LOH is clearly involved in cancer development and progression. Thus, these studies will help identify the molecular basis for the tumor suppressor function of Lats 1.