[
International Worm Meeting,
2017]
Microtubule organization is critical for cell function. Nearly all dividing animal cells use the centrosome as a microtubule organizing center (MTOC), where microtubules tether chromosomes to the spindle poles to facilitate the correct segregation of DNA between daughter cells. By contrast, differentiated cells organize their microtubules in a wide variety of patterns, and establish specific noncentrosomal locations as MTOCs to achieve these microtubule arrangements. While much is known about how centrosomes organize microtubules, little is known about the composition of noncentrosomal MTOCs (ncMTOCs), how these sites are designated, or how they organize microtubules. A simple hypothesis is that an ncMTOC is essentially the MTOC features of a centrosome targeted to a different cellular location. Our studies suggest that the ncMTOC that forms at the apical surface of the polarized C. elegans intestine is in fact different in its composition and protein requirements for microtubule organization than the centrosome. We have examined the localization of several CRISPR-tagged microtubule- and MTOC-associated proteins in the intestinal ncMTOC, and observe three classes of proteins: (1) only at the centrosome (SPD-2/Cep192, SPD-5), (2) only at the ncMTOC (PTRN-1/CAMSAP, NOCA-1/Ninein), and (3) at whichever location is the active MTOC (?-TuRC proteins, AIR-1/Aurora A). To test the requirement of several factors in intestinal ncMTOCs, including AIR-1 and the ?-TuRC components GIP-1 and Mozart, we have optimized the ZIF-1/ZF protein degradation system to allow for the removal of early essential proteins from tissues of interest. We find evidence that the microtubule nucleation complex ?-TuRC must be intact for the recruitment of ?-TuRC components to the ncMTOC. Surprisingly, microtubules are still made and correctly localized to the apical ncMTOC even when ?-TuRC and AIR-1 are compromised, and we are currently analyzing the dynamics of these microtubules. These results suggest that differentiated cells use novel mechanisms to create a functional ncMTOC that organizes their microtubules.
[
International Worm Meeting,
2005]
Lithium the element was discovered over 188 years ago. Seminal work by John Cade, over 50 years ago and then subsequent clinical studies by Mogens Schou, lead to lithium being recognized as an effective treatment for manic-depressive/bipolar disorder. Lithium has remained the mainstay of treatment for this illness for more than three decades in North America. Advances in cellular and molecular biology have led to the identification of several targets of lithiums actions, however, the exact mechanism of action in bipolar is unknown. A growing body of evidence demonstrates that lithium can exert neuroprotective effects both in vitro and in vivo. These effects may in part be due to action on two molecular targets, the cytoprotective BCL-2 (the mammalian ortholog of CED-9, cell death abnormal-9) and GSK-346; (glycogen synthase kinase-346;). These discoveries may have major impact on the use of this interesting cation in medicine and biology. We have begun the examination of the lifespan and stress effects of lithium chloride in C. elegans. We discovered that post-developmental treatment with lithium chloride has robust effects on lifespan in a dose dependent manner. Wild type population treated with LiCl and cultured at 25oC showed up to a 45% increase in median lifespan and 16% in maximal lifespan. From examination of different genetic backgrounds we have found this effect to be DAF-16 independent. We are investigating the possibility that lithium is having neuroprotective effects that slow aging in adult nematodes. We also observe that lithium markedly decreases fertility and embryonic viability and are examining the role of the germ line and gonad in the modulation of lifespan by lithium.