No abstract

Cytoplasmic dynein plays critical roles within the developing and mature nervous systems, including effecting nuclear migration, and retrograde transport of various cargos. Unsurprisingly, mutations in dynein are causative of various developmental neuropathies and motor neuron diseases. These ‘dyneinopathies’ define a broad spectrum of diseases with no known correlation between mutation identity and disease state. To circumvent complications associated with dynein studies in human cells, we employed budding yeast as a screening platform to characterize the motility properties of seventeen disease-correlated dynein mutants. Using this system, we determined the molecular basis for several classes of etiologically related diseases. Moreover, by engineering compensatory mutations, we alleviated the mutant phenotypes in two of these cases, one of which we confirmed with recombinant human dynein. In addition to revealing molecular insight into dynein regulation, our data provide additional evidence that the type of disease may in fact be dictated by the degree of dynein dysfunction.

45Cytoplasmic dynein is a minus end-directed microtubule motor that transports myriad 46 cargos in various cell types and contexts. How dynein is regulated to perform all these 47 62Cytoplasmic dynein is an enormous minus end-directed microtubule motor 63 complex that transports numerous cargoes. At first glance, this motor seems 64 exceedingly complex in terms of its architecture, size, and reliance on accessories and 65 regulators for proper activity. For instance, processive single molecule motility of human 66 dynein -itself comprised of 4 to 6 subunits -requires the 11 subunit dynactin complex 67 in addition to an adaptor that links them together 1,2 . Although yeast dynein does not 68 require dynactin for in vitro single molecule motility 3 , it does require this complex for in 69 vivo activity 4,5 . Recent studies have yielded invaluable insight into the underlying 70 reasons for the complexity of the dynein motor. For instance, the reliance on adaptors 71 (e.g., BicD2, Spindly, Hook3 1,2 ) to link dynein to dynactin ensures that cytoplasmic 72 dynein-1 -which effects motility of numerous and varied cargoes throughout the cell 73 cycle 6 -and dynactin are linked together at the right place (and presumably time) for 74 appropriate motility. Additionally, recent studies have revealed that dynactin helps to 75 orient the motor domains in a parallel manner that is conducive for motility 7 , thus 76 revealing the mechanistic basis for dynein's reliance on this large complex. Thus, the 77 complexity of this molecular motor ensures that cargoes are transported to their target 78 destinations in accordance with the needs of the cell. 79In addition to its regulation by extrinsic factors, several studies have 80 demonstrated that human dynein-1 and dynein-2 can also be auto-regulated by intra-81 complex interactions. Specifically, intermolecular interactions between the motor 82 domains have been shown to stabilize an autoinhibited conformation of human dynein 83 called the phi particle (named for its resemblance to the Greek letter) 7-10 . In the case of 84 4 dynein-2 (responsible for intraflagellar transport), the phi particle conformation -which 85 has been observed in its native context 10 -reduces its velocity, ATPase activity and 86 microtubule landing rate 9 . Similarly, the autoinhibited dynein-1 conformation has been 87 shown to reduce its microtubule landing rate and motility properties 7,11 . Moreover, unlike 88 dynein-2 which is not regulated by dynactin 12 , uninhibited dynein-1 mutants interact 89 more readily with dynactin and the adaptor BicD2 7 . 90Although it is well established that human dynein adopts the autoinhibited phi 91 particle conformation (both dynein-1 and dynein-2), it is unclear if this conformational 92 state is evolutionarily conserved. Yeast dynein is of particular interest due to two 93 notable in vitro discrepancies with human dynein. In particular, unlike human dynein, 94 yeast dynein is processive in single molecule assays without the need for other factors, 95 such as dynactin...

Cytoplasmic dynein plays critical roles within the developing and mature nervous systems, including effecting nuclear migration, and retrograde transport of various cargos. Unsurprisingly, mutations in dynein are causative of various developmental neuropathies and motor neuron diseases. These "dyneinopathies" define a broad spectrum of diseases with no known correlation between mutation identity and disease state. To overcome complications associated with studying dynein function in human cells, we employed budding yeast as a screening platform to characterize the motility properties of seventeen disease-correlated dynein mutants. Using this system, we have determined the molecular basis for several broad classes of etiologically related diseases. Moreover, by engineering compensatory mutations, we have alleviated the mutant phenotypes in two of these cases, one of which we confirmed with recombinant human dynein complexes. In addition to revealing molecular insight into dynein regulation, our data reveal an unexpected correlation between the degree of dynein dysfunction and disease type.3

As a human services educator and practitioner, I have experienced the stress that often leads to burnout in my own life, and I have observed it in my colleagues and students as well. I am often reminded of the importance of self-care and of taking time to recharge my batteries. As a human services practitioner and educator, I believe that burnout is one of the biggest issues I see in this fi eld. Human services work is often emotionally and physically draining because of the nature of the fi eld. Whether one works with victims of domestic violence, formerly incarcerated individuals, individuals with mental illness, addiction, or survivors of catastrophic events, the work involves dealing with individuals in crisis. Burnout comes from being overworked and underpaid, and most important, not practicing selfcare. A literature review, coupled with my own experiences in the human services fi eld, supports the notion that individuals working in the helping professions are at high risk for job burnout. Students in human services programs are often concerned with others and their problems, are already stretched thin with commitments to others, are in touch with human suffering, and quite often lack the skills to care for themselves.The human services philosophy views the individual from a holistic, integrated perspective. In order to better serve the individuals with whom we work in the helping professions and teach them self-care skills, we fi rst need to develop those skills in ourselves. As human services professionals, we believe in caring for the whole person, body, mind, and spirit. We also