The “8-kD” Cytoplasmic Dynein Light Chain Is Required for Nuclear Migration and for Dynein Heavy Chain Localization in Aspergillus nidulans

Abstract

The heavy chain of cytoplasmic dynein is required for nuclear migration in Aspergillus nidulans and other fungi. Here we report on a new gene required for nuclear migration, nudG, which encodes a homologue of the “8-kD” cytoplasmic dynein light chain (CDLC). We demonstrate that the temperature sensitive nudG8 mutation inhibits nuclear migration and growth at restrictive temperature. This mutation also inhibits asexual and sexual sporulation, decreases the intracellular concentration of the nudG CDLC protein and causes the cytoplasmic dynein heavy chain to be absent from the mycelial tip, where it is normally located in wild-type mycelia. Coimmunoprecipitation experiments with antibodies against the cytoplasmic dynein heavy chain (CDHC) and the nudG CDLC demonstrated that some fraction of the cytoplasmic dynein light chain is in a protein complex with the CDHC. Sucrose gradient sedimentation analysis, however, showed that not all of the NUDG protein is complexed with the heavy chain. A double mutant carrying a cytoplasmic dynein heavy chain deletion plus a temperature-sensitive nudG mutation grew no more slowly at restrictive temperature than a strain with only the CDHC deletion. This result demonstrates that the effect of the nudG mutation on nuclear migration and growth is mediated through an interaction with the CDHC rather than with some other molecule (e.g., myosin-V) with which the 8-kD CDLC might theoretically interact.

The DISC locus in psychiatric illness

“…The Aspergillus orthologue of LIS1, NUDF, 145 functions within a complex of NUD proteins, including NUDA (dynein heavy chain), NUDG (dynein light chain), NUDK (dynactin subunit Arp1) and NUDE. [145][146][147][148][149] The composition of this complex is conserved in mammals, demonstrating that nuclear positioning is an indispensable function. Aspergillus NUDE has two mammalian orthologues termed NUDE and NUDE-like (NDE1 and NDEL1), which interact with LIS1.…”

LIS1—no more no less

“…16 Several of the nud genes (nudA, nudI and nudG) are subunits of cytoplasmic dynein, a microtubule-based motor protein, and nudK is a part of the dynein regulatory complex dynactin. [17][18][19] Recently, it has been shown that the Aspergillus nidulans cytoplasmic dynein heavy chain and NUDF localize to microtubule ends. 20 Furthermore, microtubules of nudA and nudF loss-of-function mutants were less dynamic; They showed a lower frequency of microtubule catastrophe events, a lower rate of shrinkage during catastrophe, and a lower frequency of rescue.…”

Dynein Light Chain 1 Regulates Dynamin-mediated F-Actin Assembly during Sperm Individualization inDrosophila

“…In addition, cytoplasmic dynein is shown to move isolated nuclei along the astral microtubules in a cell free system (Reinsch and Karsenti, 1997) and facilitate nuclear fusion after fertilization in vivo (Payne et al, 2003). Although DLC1 is an integral component of the cytoplasmic dynein complex and its homologue plays a key role in both dynein localization and nuclear migration processes in Aspergillus (Beckwith et al, 1998), its role in nuclear positioning process was unknown in higher eukaryotes.…”