Structural insights into regulation of the PEAK3 pseudokinase scaffold by 14-3-3.

PEAK pseudokinases are molecular scaffolds which dimerize to regulate cell migration, morphology, and proliferation, as well as cancer progression. The mechanistic role dimerization plays in PEAK scaffolding remains unclear, as there are no structures of PEAKs in complex with their interactors. Here, we report the cryo-EM structure of dimeric PEAK3 in complex with an endogenous 14-3-3 heterodimer. Our structure reveals an asymmetric binding mode between PEAK3 and 14-3-3 stabilized by one pseudokinase domain and the SHED domain of the PEAK3 dimer. The binding interface contains a canonical phosphosite-dependent primary interaction and a unique secondary interaction not observed in previous structures of 14-3-3/client complexes. Additionally, we show that PKD regulates PEAK3/14-3-3 binding, which when prevented leads to PEAK3 nuclear enrichment and distinct protein-protein interactions. Altogether, our data demonstrate that PEAK3 dimerization forms an unusual secondary interface for 14-3-3 binding, facilitating 14-3-3 regulation of PEAK3 localization and interactome diversity.

CNPY4 inhibits the Hedgehog pathway by modulating membrane sterol lipids.

The Hedgehog (HH) pathway is critical for development and adult tissue homeostasis. Aberrant HH signaling can lead to congenital malformations and diseases including cancer. Although cholesterol and several oxysterol lipids have been shown to play crucial roles in HH activation, the molecular mechanisms governing their regulation remain unresolved. Here, we identify Canopy4 (CNPY4), a Saposin-like protein, as a regulator of the HH pathway that modulates levels of membrane sterol lipids. Cnpy4-/- embryos exhibit multiple defects consistent with HH signaling perturbations, most notably changes in digit number. Knockdown of Cnpy4 hyperactivates the HH pathway in vitro and elevates membrane levels of accessible sterol lipids, such as cholesterol, an endogenous ligand involved in HH activation. Our data demonstrate that CNPY4 is a negative regulator that fine-tunes HH signal transduction, revealing a previously undescribed facet of HH pathway regulation that operates through control of membrane composition.

Pediatric Paroxysmal Nocturnal Hemoglobinuria Presenting as Acute Kidney Injury.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease characterized by variable and diverse symptoms including the classic triad of hemolytic anemia, thrombosis, and bone marrow failure. It is a disorder primarily seen in the adult population. The authors report a unique case of an 8-year-old girl diagnosed with PNH after initially presenting with a febrile illness and acute kidney injury. Though rare in children, PNH should remain in the differential diagnosis of a child presenting with acute kidney injury. The disease has serious long-term complications, mandating timely diagnosis and appropriate therapy.

Altruism: Scoping review of the literature and future directions for HIV cure-related research.

INTRODUCTION: The question of what motivates people to participate in research is particularly salient in the HIV field. While participation in HIV research was driven by survival in the 1980's and early 1990's, access to novel therapies became the primary motivator with the advent of combination antiretroviral therapy (cART) in the late 1990s. In the HIV cure-related research context, the concept of altruism has remained insufficiently studied. METHODS: We conducted a scoping review to better contextualize and understand how altruism is or could be operationalized in HIV cure-related research. We drew from the fields of altruism in general, clinical research, cancer, and HIV clinical research-including the HIV prevention, treatment, and cure-related research fields. DISCUSSION: Altruism as a key motivating factor for participation in clinical research has often been intertwined with the desire for personal benefit. The cancer field informs us that reasons for participation usually are multi-faceted and complex. The HIV prevention field offers ways to organize altruism-either by the types of benefits achieved (e.g., societal versus personal), or the origin of the values that motivate research participation. The HIV treatment literature reveals the critical role of clinical interactions in fostering altruism. There remains a dearth of in-depth knowledge regarding reasons surrounding research participation and the types of altruism displayed in HIV cure-related clinical research. CONCLUSION: Lessons learned from various research fields can guide questions which will inform the assessment of altruism in future HIV cure-related research.

"My Death Will Not [Be] in Vain": Testimonials from Last Gift Rapid Research Autopsy Study Participants Living with HIV at the End of Life.

End-of-life (EOL) HIV cure-related research provides a novel approach to studying HIV reservoirs. The Last Gift is a rapid autopsy research study at the University of California San Diego that enrolls terminally ill people living with HIV (PLWHIV) with a desire to contribute to HIV cure-related research. We conducted in-depth baseline and follow-up interviews with Last Gift study participants. We analyzed interview data applying conventional content analysis. Since summer 2017, 13 participants have been enrolled (n = 11 males and 2 females; aged 45-89 years) and 8 participants interviewed. Terminal illnesses included cancers, heart diseases, and neurodegenerative illnesses. Our analysis revealed five key themes: (1) The Last Gift study has tremendous meaning for participants at the end of their life. (2) HIV-specific altruism was a primary motivator to join the Last Gift study, nested within the context of community, scientific advancement, and moral obligation. (3) Participants did not expect physical benefits yet they perceived emotional/psychological, financial, and societal/scientific benefits. (4) There were minimal participant-perceived risks and concerns. (5) Last Gift participants expressed immense gratitude toward study staff. The Last Gift study provides a framework for ethical HIV cure-related research at EOL and highlighted participants' perspectives, motivations, and experiences. Knowing how PLWHIV understand and experience such studies will remain critical to designing ethical, fully informed HIV cure research protocols that are acceptable to PLWHIV.

PEAK3/C19orf35 pseudokinase, a new NFK3 kinase family member, inhibits CrkII through dimerization.

Members of the New Kinase Family 3 (NKF3), PEAK1/SgK269 and Pragmin/SgK223 pseudokinases, have emerged as important regulators of cell motility and cancer progression. Here, we demonstrate that C19orf35 (PEAK3), a newly identified member of the NKF3 family, is a kinase-like protein evolutionarily conserved across mammals and birds and a regulator of cell motility. In contrast to its family members, which promote cell elongation when overexpressed in cells, PEAK3 overexpression does not have an elongating effect on cell shape but instead is associated with loss of actin filaments. Through an unbiased search for PEAK3 binding partners, we identified several regulators of cell motility, including the adaptor protein CrkII. We show that by binding to CrkII, PEAK3 prevents the formation of CrkII-dependent membrane ruffling. This function of PEAK3 is reliant upon its dimerization, which is mediated through a split helical dimerization domain conserved among all NKF3 family members. Disruption of the conserved DFG motif in the PEAK3 pseudokinase domain also interferes with its ability to dimerize and subsequently bind CrkII, suggesting that the conformation of the pseudokinase domain might play an important role in PEAK3 signaling. Hence, our data identify PEAK3 as an NKF3 family member with a unique role in cell motility driven by dimerization of its pseudokinase domain.

Feedback regulation of RTK signaling in development.

Precise regulation of the amplitude and duration of receptor tyrosine kinase (RTK) signaling is critical for the execution of cellular programs and behaviors. Understanding these control mechanisms has important implications for the field of developmental biology, and in recent years, the question of how augmentation or attenuation of RTK signaling via feedback loops modulates development has become of increasing interest. RTK feedback regulation is also important for human disease research; for example, germline mutations in genes that encode RTK signaling pathway components cause numerous human congenital syndromes, and somatic alterations contribute to the pathogenesis of diseases such as cancers. In this review, we survey regulators of RTK signaling that tune receptor activity and intracellular transduction cascades, with a focus on the roles of these genes in the developing embryo. We detail the diverse inhibitory mechanisms utilized by negative feedback regulators that, when lost or perturbed, lead to aberrant increases in RTK signaling. We also discuss recent biochemical and genetic insights into positive regulators of RTK signaling and how these proteins function in tandem with negative regulators to guide embryonic development.

Pediatric Nephrology and Rheumatology Practice Patterns in Granulomatosis with Polyangiitis: A Midwest Pediatric Nephrology Consortium Study.

OBJECTIVE: To assess practice pattern similarities and differences amongst pediatric rheumatologists and nephrologists in the management of pediatric Granulomatosis with Polyangiitis (GPA). METHODS: A voluntary survey was distributed to the Midwest Pediatric Nephrology Consortium Group (MWPNC) and an international pediatric rheumatology email listserv in 2016-2017. Data were collected on general practice characteristics and preferences for induction management under three clinical scenarios (A-C): newly diagnosed GPA with glomerulonephritis, GPA with rapidly progressive glomerulonephritis, and GPA with pulmonary hemorrhage. In addition, individual preferences for GPA maintenance medications, disease monitoring, and management of GPA with end-stage renal disease were ascertained. RESULTS: There was a 68% response rate from the MWPNC membership and equal numbers of rheumatology respondents. Survey results revealed Rituximab plus Cyclophosphamide is a more common induction choice for rheumatologists than nephrologists in induction Scenarios A and B, whereas Cyclophosphamide is more commonly chosen by nephrologists in Scenario A. Plasmapheresis rates increased for Scenarios A, B, and C for both specialties, but were overall low. There was no clear consensus on the duration of maintenance therapy nor diagnostic work-up. Rheumatologists more frequently chose Rituximab for maintenance and induction compared to nephrologists. There was also a higher than expected proportion of Mycophenolate Mofetil use for both specialties. CONCLUSION: This survey has revealed important differences in the way that rheumatologists and nephrologists manage this disease. It highlights the need for well-designed clinical trials in pediatric GPA patients and reveals that both specialties must be represented during consensus-building and clinical trial design efforts.