Background-Premenstrual dysphoric disorder (PMDD) is a heritable mood disorder that is triggered by gonadal steroids during the luteal phase in susceptible women.

The dynactin complex contains proteins including p150 that interacts with cytoplasmic dynein and an actinrelated protein Arp1 that forms a minifilament. Proteins including Arp11 and p62 locate at the pointed end of the Arp1 filament, but their biochemical functions are unclear (Schroer TA. Dynactin. Annu Rev Cell Dev Biol 2004;20: 759-779). In Aspergillus nidulans, loss of Arp11 or p62 causes the same nuclear distribution (nud) defect displayed by dynein mutants, indicating that these pointed-end proteins are essential for dynein function. We constructed a strain with S-tagged p150 of dynactin that allows us to pull down components of the dynactin and dynein complexes. Surprisingly, while the ratio of pulled-down Arp1 to S-p150 in Arp11-depleted cells is clearly lower than that in wild-type cells, the ratio of pulled-down dynein to S-p150 is significantly higher. We further show that the enhanced dynein-dynactin interaction in Arp11-depleted cells is also present in the soluble fraction and therefore is not dependent upon the affinity of these proteins to the membrane. We suggest that loss of the pointed-end proteins alters the Arp1 filament in a way that affects the conformation of p150 required for its proper interaction with the dynein motor.

No abstract