An ent-Kaurene That Inhibits Mitotic Chromosome Movement and Binds the Kinetochore Protein Ran-Binding Protein 2

Abstract

Using a chemical genetics screen, we have identified ent-15-oxokaurenoic acid (EKA) as a chemical that causes prolonged mitotic arrest at a stage resembling prometaphase. EKA inhibits the association of the mitotic motor protein centromeric protein E with kinetochores and inhibits chromosome movement. Unlike most antimitotic agents, EKA does not inhibit the polymerization or depolymerization of tubulin. To identify EKA-interacting proteins, we used a cell-permeable biotinylated form that retains biological activity to isolate binding proteins from living cells. Mass spectrometric analysis identified six EKA-binding proteins, including Ran-binding protein 2, a kinetochore protein whose depletion by small interfering RNA causes a similar mitotic arrest phenotype.

Kinesin-1 and mitochondrial motility control by discrimination of structurally equivalent but distinct subdomains in Ran-GTP-binding domains of Ran-binding protein 2

“…For example, the activation of kinesin-1 by RanBP2 mediates adenoviral infection by promoting viral capsid disruption and uncoating at the nuclear pore and outward dispersion of capsid and selective nucleoporins, such as RanBP2 [27]. Collectively, these data support that RanBP2 mediates the tight coordination of pleiotropic motor and energy-driven trafficking processes at distinct cell cycles and between various cell types [24,25,27,88]. Future studies on the physiological effects of RBD 2 , RBD 3 and KBD of RanBP2 with animal models should help to tease out the multi-functional activities associated with the interplay between kinesin-1, Ran GTPase and RanBP2 in mitochondrial motility and other transport events.…”

Cytotoxic and apoptosis-inducing effect of ent-15-oxo-kaur-16-en-19-oic acid, a derivative of grandiflorolic acid from Espeletia schultzii

“…This finding is in agreement with recently reported activities for other kauranoids such as ent-16b-17a-dihidroxykaurene (Morales et al, 2005), ent-15-oxo-1,7,14,20-tetrahydroxykaur-16-ene or Kamebakaurin (Lee et al, 2002), and ent-16-kaur-16-en-19-oic acid (Castrillo et al, 2001), derivatives from kaura-9(11),16-dien-19-oic acid (Alonso, 2006), among many others, where they are sensitizing the tumoral cells to undergo apoptosis. Rundle et al (2006) recently reported that EOKA (1c) induces mitotic arrest on human epithelial cell lines at early drug exposure times. This group did not find evidence of apoptosis induction; however, other compounds such as mebendazole (methyl 5-benzoyl-2-benzimidazole-carbamate) (Sasaki et al, 2002), or arsenic trioxide (Ling et al, 2002), besides inducing mitotic arrest, also provoked apoptosis in human tumor cell lines.…”

“…Since each one of these compounds can similarly induce apoptosis, it could be inferred that the enone moiety might be responsible for the biological activity. Moreover, although EOKA (1c) has been proven to cause mitotic arrest by inhibiting RanBP2 function at early drug exposure times (Rundle et al, 2006), the specific mechanisms of action of this compound to unchain apoptosis still remain to be elucidated.…”

“…Nagashima et al (2003) have studied the biological properties of ent-11a-hydroxykaur-16-en-15-one in a human leukemia cell line and found evidence that this compound was able to induce apoptosis. More recently, Rundle et al (2006) described the ability of EOKA (1c) to irreversibly prolong the mitotic arrest on human epithelial tumoral cell lines, a characteristic effect that sometimes precedes apoptosis (Sasaki et al, 2002;Ling et al, 2002).…”

Unraveling the Role of Peptidyl-Prolyl Isomerases in Neurodegeneration

“…While the bulk of the protein is gray, several residues are color-coded: yellow: aa interacting with FK506; red: aa interacting with calcineurin; blue: aa responsible for catalytic activity; orange: aa interacting with FK506 and calcineurin; light green: catalytic aa interacting with FK506; dark green: catalytic aa interacting with calcineurin and FK506. Images were made in PyMOL (DeLano Scientific LLC, Palo Alto, CA, USA) based on PDB ID: 1TCO [161] [198,199] Human parvulins 1 Pin1 Nuclear 1 WW Cell cycle regulation [200,201] [63]…”