Kindr Motors Drive in Meiosis.

The discovery of neocentromere activity by maize knobs heralded the field of meiotic drive, in which selfish genetic elements exploit meiotic asymmetry to enhance their propagation. A new study reveals the long-awaited basis of this meiotic drive: cytoskeletal motors enable neocentromeric knobs to achieve favorable meiotic positioning and preferential inheritance.

Assembly of nuclear dimers of PI3K regulatory subunits is regulated by the Cdc42-activated tyrosine kinase ACK.

Activated Cdc42-associated kinase (ACK) is an oncogenic nonreceptor tyrosine kinase associated with poor prognosis in several human cancers. ACK promotes proliferation, in part by contributing to the activation of Akt, the major effector of class 1A phosphoinositide 3-kinases (PI3Ks), which transduce signals via membrane phosphoinositol lipids. We now show that ACK also interacts with other key components of class 1A PI3K signaling, the PI3K regulatory subunits. We demonstrate ACK binds to all five PI3K regulatory subunit isoforms and directly phosphorylates p85α, p85ß, p50α, and p55α on Tyr607 (or analogous residues). We found that phosphorylation of p85ß promotes cell proliferation in HEK293T cells. We demonstrate that ACK interacts with p85α exclusively in nuclear-enriched cell fractions, where p85α phosphorylated at Tyr607 (pTyr607) also resides, and identify an interaction between pTyr607 and the N-terminal SH2 domain that supports dimerization of the regulatory subunits. We infer from this that ACK targets p110-independent p85 and further postulate that these regulatory subunit dimers undertake novel nuclear functions underpinning ACK activity. We conclude that these dimers represent a previously undescribed mode of regulation for the class1A PI3K regulatory subunits and potentially reveal additional avenues for therapeutic intervention.

An investigation of preceptors' perceptions of behavioral elements of "professionalism" among genetic counseling students.

Professionalism in health care is a loosely defined but increasingly studied concept. In genetic counseling, "professional development" expectations for entry-level genetic counselors are described in the "Practice-Based Competencies for Genetic Counselors," but the teaching and evaluation of "professionalism" among genetic counseling students is relatively unexplored. This study investigated program leaders' and clinical supervisors' perceptions of professionalism demonstrated by genetic counseling graduate students to learn about their associated strengths and lapses. Members of program leadership and clinical supervisors at Accreditation Council for Genetic Counseling (ACGC) accredited genetic counseling graduate programs in the United States and Canada were surveyed regarding their observations of genetic counseling students for the years 2017-2019 regarding four domains of professional behavior: integrity, accountability/conscientiousness, teamwork, and patient care, with the Merriam-Webster definition of each behavior provided for each domain. Participants also provided open-text descriptions. Descriptive results showed that the 263 participants found all facets of these professional behaviors to be essential. Patient care had the highest importance and was the domain with the most strengths observed among genetic counseling students. Lapses in professional behavior were identified for self-awareness, time management, and thoroughness. Free responses noted that suggestions or strategies for education about professional behavior from ACGC may improve the professional behavior of genetic counseling students and in turn, genetic counselors. Participants voiced the importance of consideration of diverse professional and cultural backgrounds in setting the expectations for professional behavior among genetic counseling students and genetic counselors so that "professionalism" in genetic counseling is not defined through a White lens. Further investigation into challenges that genetic counseling students face regarding professional behavior during their graduate training and strategies for education about these behaviors will aid in the growth and improvement of the training of genetic counselors. Given the sensitive nature of this topic, portions of this discussion may be triggering for some readers.

A Burst of Genetic Innovation in Drosophila Actin-Related Proteins for Testis-Specific Function.

Many cytoskeletal proteins perform fundamental biological processes and are evolutionarily ancient. For example, the superfamily of actin-related proteins (Arps) specialized early in eukaryotic evolution for diverse cellular roles in the cytoplasm and the nucleus. Despite its strict conservation across eukaryotes, we find that the Arp superfamily has undergone dramatic lineage-specific diversification in Drosophila. Our phylogenomic analyses reveal four independent Arp gene duplications that occurred in the common ancestor of the obscura group of Drosophila and have been mostly preserved in this lineage. All four obscura-specific Arp paralogs are predominantly expressed in the male germline and have evolved under positive selection. We focus our analyses on the divergent Arp2D paralog, which arose via a retroduplication event from Arp2, a component of the Arp2/3 complex that polymerizes branched actin networks. Computational modeling analyses suggest that Arp2D can replace Arp2 in the Arp2/3 complex and bind actin monomers. Together with the signature of positive selection, our findings suggest that Arp2D may augment Arp2's functions in the male germline. Indeed, we find that Arp2D is expressed during and following male meiosis, where it localizes to distinct locations such as actin cones-specialized cytoskeletal structures that separate bundled spermatids into individual mature sperm. We hypothesize that this unprecedented burst of genetic innovation in cytoskeletal proteins may have been driven by the evolution of sperm heteromorphism in the obscura group of Drosophila.

How Dynein Moves Along Microtubules.

Cytoplasmic dynein, a member of the AAA (ATPases Associated with diverse cellular Activities) family of proteins, drives the processive movement of numerous intracellular cargos towards the minus end of microtubules. Here, we summarize the structural and motile properties of dynein and highlight features that distinguish this motor from kinesin-1 and myosin V, two well-studied transport motors. Integrating information from recent crystal and cryoelectron microscopy structures, as well as high-resolution single-molecule studies, we also discuss models for how dynein biases its movement in one direction along a microtubule track, and present a movie that illustrates these principles.

Clinically significant germline pathogenic variants are missed by tumor genomic sequencing.

A germline pathogenic variant may be present even if the results of tumor genomic sequencing do not suggest one. There are key differences in the assay design and reporting of variants between germline and somatic laboratories. When appropriate, both tests should be completed to aid in therapy decisions and determining optimal screening and risk-reduction interventions.

Evolutionary diversification reveals distinct somatic versus germline cytoskeletal functions of the Arp2 branched actin nucleator protein.

Branched actin networks are critical in many cellular processes, including cell motility and division. Arp2, a protein within the seven-membered Arp2/3 complex, is responsible for generating branched actin. Given its essential roles, Arp2 evolves under stringent sequence conservation throughout eukaryotic evolution. We unexpectedly discovered recurrent evolutionary diversification of Arp2 in Drosophila, yielding independently arising paralogs Arp2D in obscura species and Arp2D2 in montium species. Both paralogs are unusually testis-enriched in expression relative to Arp2. We investigated whether their sequence divergence from canonical Arp2 led to functional specialization by replacing Arp2 in D. melanogaster with either Arp2D or Arp2D2. Despite their divergence, we surprisingly found that both complement Arp2's essential function in somatic tissue, suggesting they have preserved the ability to polymerize branched actin even in a non-native species. However, we found that Arp2D- and Arp2D2-expressing males display defects throughout sperm development, with Arp2D resulting in more pronounced deficiencies and subfertility, suggesting the Arp2 paralogs are cross-species incompatible in the testis. We focused on Arp2D and pinpointed two highly diverged structural regions-the D-loop and C terminus-and found that they contribute to germline defects in D. melanogaster sperm development. However, while the Arp2D C terminus is suboptimal in the D. melanogaster testis, it is essential for Arp2D somatic function. Testis cytology of the paralogs' native species revealed striking differences in germline actin structures, indicating unique cytoskeletal requirements. Our findings suggest canonical Arp2 function differs between somatic versus germline contexts, and Arp2 paralogs may have recurrently evolved for species-specialized actin branching in the testis.

Evolutionary diversification reveals distinct somatic versus germline cytoskeletal functions of the Arp2 branched actin nucleator protein.

Branched actin networks are critical in many cellular processes, including cell motility and division. Arp2, a protein within the 7-membered Arp2/3 complex, is responsible for generating branched actin. Given its essential roles, Arp2 evolves under stringent sequence conservation throughout eukaryotic evolution. We unexpectedly discovered recurrent evolutionary diversification of Arp2 in Drosophila, yielding independently arising paralogs Arp2D in obscura species and Arp2D2 in montium species. Both paralogs are unusually testis-enriched in expression relative to Arp2. We investigated whether their sequence divergence from canonical Arp2 led to functional specialization by replacing Arp2 in D. melanogaster with either Arp2D or Arp2D2. Despite their divergence, we surprisingly found both complement Arp2's essential function in the soma, suggesting they have preserved the ability to polymerize branched actin even in a non-native species. However, we found that Arp2D-expressing males are subfertile and display many defects throughout sperm development. We pinpointed two highly diverged structural regions in Arp2D that contribute to these defects: subdomain 2 and the C-terminus. We expected that germline function would be rescued by replacing Arp2D's long and charged C-terminus with Arp2's short C-terminus, yet surprisingly, the essential somatic function of Arp2D was lost. Therefore, while Arp2D's structural divergence is incompatible with D. melanogaster sperm development, its unique C-terminus has evolved a critical role in actin polymerization. Our findings suggest canonical Arp2's function differs between somatic versus germline contexts, and Arp2 paralogs have recurrently evolved and specialized for actin branching in the testis.

Exploratory Study of Advance Care Discussions Among Chinese American and White Stage IV Cancer Patients at an American Tertiary Medical Center.

PURPOSE: Timely advance care discussions are essential components of quality care for diverse populations; however, little is known about these conversations among Chinese American cancer patients. This exploratory study describes differences in advance care discussions and planning between Chinese American and White advanced cancer patients. METHODS: We collected data for 63 Chinese American and 63 White stage IV cancer patients who died between 2013 and 2018. We compared: frequency and timing of prognosis, goals of care (GOC), and end-of-life care (EOLC) discussions in the final year of life; family inclusion in discussions; healthcare proxy (HCP) identification; do not resuscitate (DNR) order, do not intubate (DNI) order, and other advance directive (AD) completion. We did not conduct statistical tests due to the study's exploratory nature. RESULTS: Among Chinese American and White patients, respectively, 76% and 71% had prognosis, 51% and 56% had GOC, and 89% and 84% had EOLC discussions. Prognosis, GOC, and EOLC discussions were held a median of 34.0, 15.5, and 34.0 days before death among Chinese American and 17.0, 13.0, and 24.0 days before death among White patients. Documentation rates among Chinese American and White patients were 79% and 76% for DNRs, 81% and 71% for DNIs, 79% and 81% for HCPs, and 52% and 40% for other ADs. CONCLUSIONS: Findings suggest that Chinese Americans had similar rates of advance care discussions, completed conversations earlier, and had similar to higher rates of AD documentation compared to White patients. Further studies are needed to confirm our preliminary findings.

Mutational and splicing landscape in a cohort of 43,000 patients tested for hereditary cancer.

DNA germline genetic testing can identify individuals with cancer susceptibility. However, DNA sequencing alone is limited in its detection and classification of mRNA splicing variants, particularly those located far from coding sequences. Here we address the limitations of splicing variant identification and interpretation by pairing DNA and RNA sequencing and describe the mutational and splicing landscape in a clinical cohort of 43,524 individuals undergoing genetic testing for hereditary cancer predisposition.