Correction: Synergistic drug combinations designed to fully suppress SARS-CoV-2 in the lung of COVID-19 patients.

[This corrects the article DOI: 10.1371/journal.pone.

Myrtleciclib, a CDK4/6/9 Inhibitor for the Treatment of Aggressive Cancers.

Background: Selective Cyclin-Dependent Kinase 4/6 inhibitors (CDK4/6i) have revolutionized the treatment of breast cancer and have potential in other cancers, being manageable drugs yet with some bone marrow toxicity. Selective CDK9 inhibitors (CDK9i) never advanced into clinical use, partly due to side effects, including gastrointestinal toxicity, and a small window between activity and cytotoxicity, which results in a narrow therapeutic index (TI).

Method: To overcome the drawbacks of CDK4/6 and CDK9 inhibitors, we have developed myrtleciclib, a selective CDK4/6/9 inhibitor with few non-critical molecular off-targets.

Synergistic drug combinations designed to fully suppress SARS-CoV-2 in the lung of COVID-19 patients.

Despite new antivirals are being approved against SARS-CoV-2 they suffer from significant constraints and are not indicated for hospitalized patients, who are left with few antiviral options. Repurposed drugs have previously shown controversial clinical results and it remains difficult to understand why certain trials delivered positive results and other trials failed. Our manuscript contributes to explaining the puzzle: this might have been caused by a suboptimal drug exposure and, consequently, an incomplete virus suppression, also because the drugs have mostly been used as add-on monotherapies.

Evaluation of the expression and intracellular localization of a 44-kDa calmodulin binding protein during exponential growth and quiescence (G0).

We have previously demonstrated that changes in calmodulin (CaM) levels are associated with G1/S transition of the cell cycle and entry into and release from quiescence (G0). CaM mediates its regulation through the specific interaction with different intracellular proteins called calmodulin binding proteins (CaMBPs). This study was designed to evaluate the expression of the CaMBPs during the cell cycle.

A potent peptidomimetic inhibitor of HSV ribonucleotide reductase with antiviral activity in vivo.

Herpes simplex viruses (HSV) types 1 and 2 encode their own ribonucleotide reductases (RNRs) (EC 1.17.4.

The phospholipase A2 of human spermatozoa; purification and partial sequence.

In view of its proposed key role in the acrosome reaction, phospholipase A2 has been isolated and purified from human spermatozoa. Following SDS-PAGE, a single major band was obtained with an estimated molecular mass of 16.7 kDa.

Decrease in calmodulin concentrations during heparin-induced capacitation in bovine spermatozoa.

Concentrations of the intracellular Ca(2+)-mediator calmodulin (CaM), were measured by radioimmunoassay during heparin-induced capacitation of bull spermatozoa. Heparin reduced sperm CaM concentrations in a dose-dependent manner corresponding with an increase in in-vitro fertilization rates. Such reductions were observed after heparin treatment for 4-6 h, which is in agreement with the length of the capacitation period in bulls and was concomitant with an increase in CaM concentration in the incubation medium, suggesting translocation of CaM from the spermatozoa to the surrounding milieu.

Activation of bovine rod outer segment phosphatidylinositol-4,5-bisphosphate phospholipase C by calmodulin antagonists does not depend on calmodulin.

Calmodulin antagonists stimulated phosphatidylinositol-4,5-bisphosphate phospholipase C in soluble and particulate fractions of bovine rod outer segments. Antagonists tested include trifluoperazine, melittin, calmidazolium, compound 48/80, W-13 [N-(4-aminobutyl)-5-chloro-1-naphthalenesulfonamide], and W-7 [N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide]. All were effective, but W-7 was chosen for further characterization of the effect, which was most pronounced in the soluble fraction.

Increased sensitivity to Vinca alkaloids in cells overexpressing calmodulin by gene transfection.

Mouse C127 cells, transfected with the chicken calmodulin (CaM) gene and overexpressing CaM protein, were used to evaluate the effect of elevated levels of CaM on the sensitivity of these cells to various anticancer drugs. Clones C2 and C3 overexpress CaM mRNA by 40- and 80-fold, respectively, and CaM protein 3- and 8-fold, respectively. These cell lines were tested for their sensitivity to vincristine, vinblastine, bleomycin, and Adriamycin by comparing the 50% inhibitory concentration in a 72-h growth inhibition assay.

Identification of a 51-kilodalton calmodulin binding protein that changes during estrogen-stimulated cell growth.

Calmodulin-binding proteins (CaMBPs) were analyzed during estrogen-stimulated growth in the human breast cancer cell line ZR-75-1. A variety of Ca2(+)-dependent and -independent CaMBPs were observed to be present in these cells. Calmodulin (CaM) binding to a 51-kilodalton protein was shown to be Ca2(+)-dependent.

Decreased binding of calmodulin to bull sperm proteins during heparin-induced capacitation.

The 125I-calmodulin gel overlay procedure was used to evaluate the effect of a heparin treatment on the calmodulin-binding proteins of bull spermatozoa. At concentrations that increase the in vitro fertilization rate of in vitro-matured oocytes, heparin induced a decrease in the binding to calmodulin (CaM) in 3 sperm proteins of 28, 30, and 49 kDa. The binding of these proteins to CaM was higher when Ca2+ was absent from the overlay procedure, and this binding was negatively correlated to the fertilization rate.

In vitro interactions of calmodulin with the ovine proacrosin-acrosin system.

The authors studied the interaction of calmodulin (CaM) with proacrosin and acrosin from ram spermatozoa. CaM binding evaluated by the [125I]-CaM overlay procedure was shown to occur preferentially with both proacrosin and acrosin in the presence of EGTA; in the presence of Ca2+, the interaction was less intense. Further studies with native proenzyme preparations showed that proacrosin activation at pH 7.

Effect of heparin on the expression of calmodulin-binding proteins in bull spermatozoa.

A 125I-labelled calmodulin gel overlay procedure in the presence and the absence of Ca2+ was used to evaluate bull spermatozoa calmodulin-binding proteins. Frozen spermatozoa were thawed, washed and incubated for 6 h before being processed for SDS polyacrylamide gel electrophoresis and the 125I-labelled calmodulin gel overlay procedure. In non-incubated spermatozoa, up to 14 binding proteins were detected.

Developmental appearance of the Ca2+-binding proteins parvalbumin, calbindin D-28K, S-100 proteins and calmodulin during testicular development in the rat.

Calcium and intracellular Ca2+-binding proteins are possibly involved in hormone production and spermatogenesis in rat testis. Parvalbumin, calbindin D-28K, S-100 proteins and calmodulin were localized in the Leydig cells, which are sites of testosterone synthesis. Only the appearance of parvalbumin-immunoreactivity is closely correlated to testosterone production during development of the testes.

Calmodulin may mediate 1,25-dihydroxyvitamin D-stimulated intestinal calcium transport.

1,25-Dihydroxyvitamin D (1,25(OH)2D stimulated an increase in calmodulin content in chick duodenal brush border membranes in parallel with an increase in duodenal calcium transport in vivo and calcium uptake by brush border membrane vesicles (BBMV) in vitro. The increase in calcium uptake by BBMV was blocked by specific calmodulin antagonists. These results suggest that calmodulin mediates 1,25(OH)2D-stimulated calcium movement across the brush border membrane.

Estrogen stimulates the transient association of calmodulin and myosin light chain kinase with the chicken liver nuclear matrix.

Previous work has demonstrated that estrogen administration to immature chickens results in a rapid but transient increase in nuclear estrogen receptor content, a large portion of which is associated with the nuclear matrix. The present studies were undertaken to determine whether estrogen produced a more generalized change in the protein composition of the nuclear matrix. High-resolution two-dimensional gel analysis of the matrix revealed a very complex protein pattern, but several major qualitative differences were observed after estrogen treatment.

Potentiation of bleomycin lethality by anticalmodulin drugs: a role for calmodulin in DNA repair.

Treatment of exponentially growing Chinese hamster ovary cells with bleomycin causes a dose-dependent decrease in cell survival due to DNA damage. This lethal effect can be potentiated by the addition of a nonlethal dose of the anticalmodulin drug N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide ( W13 ) but not its inactive analog N-(4-aminobutyl)-2-naphthalenesulfonamide ( W12 ). By preventing the repair of damaged DNA, W13 also inhibits recovery from potentially lethal damage induced by bleomycin.

Mechanisms subserving calcium's modulation of luteinizing hormone action in isolated swine granulosa cells.

We studied the mechanism(s) by which calcium ions modulate progesterone biosynthesis by isolated swine granulosa cells incubated in chemically defined medium in vitro. In selectively calcium-deficient incubations, the capacity of 8-bromo-cAMP to stimulate pregnenolone synthesis from endogenous sterol substrate was significantly impeded. This effect of calcium ions was specific, because calcium ions did not influence basal pregnenolone production or alter progesterone production in response to exogenously supplied cholesterol substrate.

Changes in calmodulin and its mRNA accompany reentry of quiescent (G0) cells into the cell cycle.

Release of CHO-K1 cells from plateau or stationary phase and reentry into the cell cycle is specifically and reversibly blocked at two distinct sites by the anticalmodulin drug W13. The first block occurs early during release while the cells are still at G0/G1, whereas the second occurs later in reentry during early S phase. As determined by radioimmunoassay, calmodulin levels undergo changes at three distinct steps in plateau-phase entry and release.

Calmodulin-binding proteins in a cloned rat insulinoma cell line.

Calmodulin concentrations were measured in isolated hamster islets or in a cloned rat insulin-secreting cell line RIN-m-5F treated with high glucose. There was no change in the cellular calmodulin content of either islets or RIN-m-5F cells despite increases of insulin concentrations in the media. Treatment of cells with the anti-calmodulin drug W13 inhibited insulin-stimulated glucose release, whereas a small effect on insulin accumulation in the media was observed with W12, the dechlorinated, less active analogue of W13.

Calmodulin and the cell cycle: involvement in regulation of cell-cycle progression.

Calmodulin levels are elevated twofold at late G1 and/or early S phases during the growth cycle of CHO-K1 cells. These levels are maintained throughout the remainder of the cell cycle unit cytokinesis. The G1 daughter cells then contain half the intracellular calmodulin level found prior to cell division.