Age-dependent changes of nuclear morphology are uncoupled from longevity in Caenorhabditis elegans IGF/insulin receptor daf-2 mutants.

Nuclear envelope (NE) architecture and aging have been associated since the discovery that certain human progeria diseases are due to perturbations in processing of lamin A protein, generating alterations in NE morphology. However, whether changes in the NE are a causal effect of normal and premature aging is still controversial. Caenorhabditis elegans is a model organism where observations supporting both, dependent and independent roles of nuclear architecture in the aging process, have been reported. We found that the long-lived glp-1 mutant and dietary restriction delayed age-associated nuclear morphology changes. In addition, we observed that the long-lived mutant of the insulin/IGF receptor daf-2 delayed the age-dependent changes of nuclear architecture at 25 °C, as previously described. However, when daf-2 animals were incubated at 20 °C they remained long-lived, but nuclear appearance changed at similar rate as in the wild type. This supports the idea that both phenotypes, longevity and maintenance of nuclear architecture are tightly associated but can be separated and argues that nuclear morphology deterioration is not a cause of the natural aging process.

A multicenter trial evaluating retaspimycin HCL (IPI-504) plus trastuzumab in patients with advanced or metastatic HER2-positive breast cancer.

Heat shock protein 90 (Hsp90) facilitates maturation and stability of HER2. Combining an Hsp90 inhibitor and trastuzumab has demonstrated anti-tumor effects in patients with HER2+ breast cancer. Adults with measurable, locally advanced or metastatic HER2+ breast cancer and prior trastuzumab treatment were enrolled in a phase 2 trial employing weekly 300 mg/m(2) retaspimycin HCl, a potent Hsp90 inhibitor, with 6 mg/kg trastuzumab every 3 weeks. A Simon's two-stage design determined trial expansion by dose-limiting toxicity (DLT) and response rates. Pharmacokinetics and electrocardiograms were evaluated. Twenty-six patients with median age 52.5 years (range 33-72) enrolled with a median of six prior chemotherapeutic regimens (range 2-20). On study, patients received a median of three treatment cycles (range 1-12). No DLTs were observed. Most adverse events (AEs) were grade 1 or 2; common treatment-related AEs included fatigue (46 %), nausea (31 %), and diarrhea (23 %). One patient had treatment-related serious AEs of grade 1 diarrhea and grade 3 hypokalemia. grade 3 transaminase elevation occurred in one patient (4 %) who also had metastatic liver disease. Sixteen patients (62 %) had stable disease, with a median on-study duration of 2.4 months (range 1.1-8.2). No confirmed responses were observed. Retaspimycin HCl at 300 mg/m² weekly in combination with trastuzumab was well tolerated and without significant toxicities. Modest clinical activity was observed, but did not meet criteria for trial expansion. The safety profile for patients on study raises the possibility of retaspimycin HCl underdosing that limited efficacy. Studies employing higher doses are ongoing.

Dissection of the NUP107 nuclear pore subcomplex reveals a novel interaction with spindle assembly checkpoint protein MAD1 in Caenorhabditis elegans.

Nuclear pore complexes consist of several subcomplexes. The NUP107 complex is important for nucleocytoplasmic transport, nuclear envelope assembly, and kinetochore function. However, the underlying molecular mechanisms and the roles of individual complex members remain elusive. We report the first description of a genetic disruption of NUP107 in a metazoan. Caenorhabditis elegans NUP107/npp-5 mutants display temperature-dependent lethality. Surprisingly, NPP-5 is dispensable for incorporation of most nucleoporins into nuclear pores and for nuclear protein import. In contrast, NPP-5 is essential for proper kinetochore localization of NUP133/NPP-15, another NUP107 complex member, whereas recruitment of NUP96/NPP-10C and ELYS/MEL-28 is NPP-5 independent. We found that kinetochore protein NUF2/HIM-10 and Aurora B/AIR-2 kinase are less abundant on mitotic chromatin upon NPP-5 depletion. npp-5 mutants are hypersensitive to anoxia, suggesting that the spindle assembly checkpoint (SAC) is compromised. Indeed, NPP-5 interacts genetically and physically with SAC protein MAD1/MDF-1, whose nuclear envelope accumulation requires NPP-5. Thus our results strengthen the emerging connection between nuclear pore proteins and chromosome segregation.

Early embryonic requirement for nucleoporin Nup35/NPP-19 in nuclear assembly.

Nuclear pore complexes (NPCs) are gateways for transport between the nucleus and cytoplasm of eukaryotic cells and play crucial roles in regulation of gene expression. NPCs are composed of multiple copies of approximately 30 different nucleoporins (nups) that display both ubiquitous and cell type specific functions during development. Vertebrate Nup35 (also known as Nup53) was previously described to interact with Nup93, Nup155 and Nup205 and to be required for nuclear envelope (NE) assembly in vitro. Here, we report the first in vivo characterization of a Nup35 mutation, npp-19(tm2886), and its temperature-dependent effects on Caenorhabditis elegans embryogenesis. At restrictive temperature, npp-19(tm2886) embryos exhibit chromosome missegregation, nuclear morphology defects and die around mid-gastrulation. Depletion of Nup35/NPP-19 inhibits NE localization of Nup155/NPP-8, NPC assembly and nuclear lamina formation. Consequently, nuclear envelope function, including nucleo-cytoplasmic transport, is impaired. In contrast, recruitment of Nup107/NPP-5, LEM-2 and nuclear membranes to the chromatin surface is Nup35/NPP-19-independent, suggesting an uncoupling of nuclear membrane targeting and NPC assembly in the absence of Nup35/NPP-19. We propose that Nup35/NPP-19 has an evolutionary conserved role in NE formation and function, and that this role is particularly critical during the rapid cell divisions of early embryogenesis.