Lipid kinase PIP5K1A regulates let-7 microRNA biogenesis through interacting with nuclear export protein XPO5.

MicroRNAs (miRNAs) are small non-coding RNAs first discovered in Caenorhabditis elegans. The let-7 miRNA is highly conserved in sequence, biogenesis and function from C. elegans to humans. During miRNA biogenesis, XPO5-mediated nuclear export of pre-miRNAs is a rate-limiting step and, therefore, might be critical for the quantitative control of miRNA levels, yet little is known about how this is regulated. Here we show a novel role for lipid kinase PPK-1/PIP5K1A (phosphatidylinositol-4-phosphate 5-kinase) in regulating miRNA levels. We found that C. elegans PPK-1 functions in the lin-28/let-7 heterochronic pathway, which regulates the strict developmental timing of seam cells. In C. elegans and human cells, PPK-1/PIP5K1A regulates let-7 miRNA levels. We investigated the mechanism further in human cells and show that PIP5K1A interacts with nuclear export protein XPO5 in the nucleus to regulate mature miRNA levels by blocking the binding of XPO5 to pre-let-7 miRNA. Furthermore, we demonstrate that this role for PIP5K1A is kinase-independent. Our study uncovers the novel finding of a direct connection between PIP5K1A and miRNA biogenesis. Given that miRNAs are implicated in multiple diseases, including cancer, this new finding might lead to a novel therapeutic opportunity.

Immunological, Cognitive, and Psychiatric Outcomes After Initiating Efavirenz- and Dolutegravir-based Antiretroviral Therapy During Acute Human Immunodeficiency Virus Infection.

BACKGROUND: Efavirenz (EFV)- and dolutegravir (DTG)-based antiretroviral therapy (ART) is the former and current recommended regimen for treatment-naive individuals with human immunodeficiency virus type 1 (HIV-1). Whether they impact the immunological and neuropsychiatric profile differentially remains unclear. METHODS: This retrospective analysis included 258 participants enrolled during acute HIV-1 infection (AHI). Participants initiated 1 of 3 ART regimens during AHI: EFV-based (n = 131), DTG-based (n = 92), or DTG intensified with maraviroc (DTG/MVC, n = 35). All regimens included 2 nucleoside reverse-transcriptase inhibitors and were maintained for 96 weeks. CD4+ and CD8+ T-cell counts, mood symptoms, and composite score on a 4-test neuropsychological battery (NPZ-4) were compared. RESULTS: At baseline, the median age was 26 years, 99% were male, and 36% were enrolled during Fiebig stage I-II. Plasma viral suppression at weeks 24 and 96 was similar between the groups. Compared with the EFV group, the DTG group showed greater increments of CD4+ (P < .001) and CD8+ (P = .015) T-cell counts but a similar increment of CD4/CD8 ratio at week 96. NPZ-4 improvement was similar between the 2 groups at week 24 but greater in the DTG group at week 96 (P = .005). Depressive mood and distress symptoms based on the Patient Health Questionnaire and distress thermometer were similar between the 2 groups at follow-up. Findings for the DTG/MVC group were comparable to those for the DTG group vs the EFV group. CONCLUSIONS: Among individuals with AHI, 96 weeks of DTG-based ART was associated with greater increments of CD4+ and CD8+ T-cell counts and improvement in cognitive performance.

A High-Throughput Small Molecule Screen Identifies Ouabain as Synergistic with miR-34a in Killing Lung Cancer Cells.

MicroRNA-34 (miR-34) is one of the major families of tumor suppressor miRNAs often lost in cancers. Delivery of miR-34a mimics to affected tumors as a therapeutic strategy has been tried in pre-clinical studies and in a phase I clinical trial. One approach to increase efficacy and reduce toxicity is to rationally identify drug combinations with small molecules that synergize with miR-34a. In this study we performed a high-throughput screen of a large panel of small molecules with known biological activity and identified ouabain as a candidate small molecule that synergized with miR-34a in killing lung cancer cells. We elucidated autophagy activation as a key mechanism by which miR-34a and ouabain causes increased cytotoxicity in cells. We posit that this combinatorial approach could reduce the active dose of miR-34a needed in vivo to observe tumor shrinkage and potentiate the development of miR-34a combination therapies in the future.

Adiponectin deficit during the precarious glucose economy of early lactation in dairy cows.

In rodents and primates, insulin resistance develops during pregnancy and fades after parturition. In contrast, dairy cows and other ruminants maintain insulin resistance in early lactation (EL). This adaptation favors mammary glucose uptake, an insulin-independent process, at a time when the glucose supply is scarce. Reduction in circulating levels of the insulin-sensitizing hormone adiponectin promotes insulin resistance in other species, but whether it contributes to insulin resistance in EL dairy cows is unknown. To address this question, plasma adiponectin was measured in high-yielding dairy cows during the transition from late pregnancy (LP) to EL. Plasma adiponectin varied in quadratic fashion with the highest levels in LP, a maximal reduction of 45% on the day after parturition and a progressive return to LP values over the next 8 wk. Adiponectin circulated nearly exclusively in high molecular weight complexes in LP, and this distribution remained unaffected in EL. The reduction of plasma adiponectin in EL occurred without changes in adiponectin mRNA in adipose tissue but was associated with repression of the expression of proteins associated with the endoplasmic reticulum and involved in assembly of adiponectin oligomers. Finally, EL increased the expression of the adiponectin receptor 1 in muscle and adiponectin receptor 2 in liver but had no effect on the expression of these receptors in adipose tissue and in the mammary gland. These data suggest that reduced plasma adiponectin belongs to the subset of hormonal adaptations in EL dairy cows facilitating mammary glucose uptake via promotion of insulin resistance.