Multi-omic analysis reveals VEGFR2, PI3K, and JNK mediate the small molecule induction of human iPSC-derived cardiomyocyte proliferation.

Mammalian hearts lose their regenerative potential shortly after birth. Stimulating the proliferation of preexisting cardiomyocytes is a potential therapeutic strategy for cardiac damage. In a previous study, we identified 30 compounds that induced the bona-fide proliferation of human iPSC-derived cardiomyocytes (hiPSC-CM).

An Epilepsy-Associated CILK1 Variant Compromises KATNIP Regulation and Impairs Primary Cilia and Hedgehog Signaling.

Mutations in human (ciliogenesis associated kinase 1) are linked to ciliopathies and epilepsy. Homozygous point and nonsense mutations that extinguish kinase activity impair primary cilia function, whereas mutations outside the kinase domain are not well understood. Here, we produced a knock-in mouse equivalent to the human A615T variant identified in juvenile myoclonic epilepsy (JME).

An epilepsy-associated CILK1 variant compromises KATNIP regulation and impairs primary cilia and Hedgehog signaling.

Mutations in human (ciliogenesis associated kinase 1) are linked to ciliopathies and epilepsy. Homozygous point and nonsense mutations that extinguish kinase activity impair primary cilia function, whereas mutations outside the kinase domain are not well understood. Here, we produced a knock-in mouse equivalent of the human A615T variant identified in juvenile myoclonic epilepsy (JME).

The Scaffold Protein KATNIP Enhances CILK1 Control of Primary Cilia.

The primary cilium functions as a cellular sensory organelle and signaling antenna that detects and transduces extracellular signals. Mutations in the human gene (ciliogenesis associated kinase 1) cause abnormal cilia elongation and faulty Hedgehog signaling, associated with developmental disorders and epilepsy. CILK1 is a protein kinase that requires dual phosphorylation of its TDY motif for activation and its extended C-terminal intrinsically disordered region (IDR) mediates targeting to the basal body and substrate recognition.

Phosphorylase phosphatase and flash activation of skeletal muscle glycogen phosphorylase-A tribute to Edmond H. Fischer.

Glycogen is a polymerized form of glucose that serves as an energy reserve in all types of organisms. In animals glycogen synthesis and degradation, especially in liver and skeletal muscle, are regulated by hormonal and physiological signals that reciprocally control the opposing activities of glycogen synthase and glycogen phosphorylase. These enzymes are under allosteric control by binding of metabolites (e.

Modulation of Primary Cilia by Alvocidib Inhibition of CILK1.

The primary cilium provides cell sensory and signaling functions. Cilia structure and function are regulated by ciliogenesis-associated kinase 1 (CILK1). Ciliopathies caused by mutations show longer cilia and abnormal Hedgehog signaling.

Animal Models of Hepatocellular Carcinoma for Local-Regional Intraarterial Therapies.

Animal models play a crucial role in developing and testing new therapies for hepatocellular carcinoma (HCC), providing preclinical evidence prior to exploring human safety and efficacy outcomes. The interventional radiologist must weigh the advantages and disadvantages of various animal models available when testing a new local-regional therapy. This review highlights the currently available animal models for testing local-regional therapies for HCC and details the importance of considering animal genetics, tumor biology, and molecular mechanisms when ultimately choosing an animal model.

Renal AT Receptors Mediate Natriuresis via Protein Phosphatase PP2A.

Background: How signals from activated angiotensin type-2 receptors (ATR) mediate inhibition of sodium ion (Na) reabsorption in renal proximal tubule cells is currently unknown. Protein phosphatases including PP2A (protein phosphatase 2A) have been implicated in ATR signaling in tissues other than kidney. We investigated whether inhibition of protein phosphatase PP2A reduced ATR-mediated natriuresis and evaluated changes in PP2A activity and localization after renal ATR activation in normal 4- and 10-week-old control Wistar-Kyoto rats and 4-week-old prehypertensive and 10-week-old hypertensive spontaneously hypertensive rats.

A non-canonical, interferon-independent signaling activity of cGAMP triggers DNA damage response signaling.

Cyclic guanosine monophosphate-adenosine monophosphate (cGAMP), produced by cyclic GMP-AMP synthase (cGAS), stimulates the production of type I interferons (IFN). Here we show that cGAMP activates DNA damage response (DDR) signaling independently of its canonical IFN pathways. Loss of cGAS dampens DDR signaling induced by genotoxic insults.

Targeting protein phosphatase PP2A for cancer therapy: development of allosteric pharmaceutical agents.

Tumor initiation is driven by oncogenes that activate signaling networks for cell proliferation and survival involving protein phosphorylation. Protein kinases in these pathways have proven to be effective targets for pharmaceutical inhibitors that have progressed to the clinic to treat various cancers. Here, we offer a narrative about the development of small molecule modulators of the protein Ser/Thr phosphatase 2A (PP2A) to reduce the activation of cell proliferation and survival pathways.

Phosphosite T674A mutation in kinesin family member 3A fails to reproduce tissue and ciliary defects characteristic of CILK1 loss of function.

Background: Kinesin family member 3A (KIF3A) is a molecular motor protein in the heterotrimeric kinesin-2 complex that drives anterograde intraflagellar transport. This process plays a pivotal role in both biogenesis and maintenance of the primary cilium that supports tissue development. Ciliogenesis associated kinase 1 (CILK1) phosphorylates human KIF3A at Thr672.

Selective PP2A Enhancement through Biased Heterotrimer Stabilization.

Impairment of protein phosphatases, including the family of serine/threonine phosphatases designated PP2A, is essential for the pathogenesis of many diseases, including cancer. The ability of PP2A to dephosphorylate hundreds of proteins is regulated by over 40 specificity-determining regulatory "B" subunits that compete for assembly and activation of heterogeneous PP2A heterotrimers. Here, we reveal how a small molecule, DT-061, specifically stabilizes the B56α-PP2A holoenzyme in a fully assembled, active state to dephosphorylate selective substrates, such as its well-known oncogenic target, c-Myc.

Functional Alterations in Ciliogenesis-Associated Kinase 1 (CILK1) that Result from Mutations Linked to Juvenile Myoclonic Epilepsy.

Ciliopathies are a group of human genetic disorders associated with mutations that give rise to the dysfunction of primary cilia. Ciliogenesis-associated kinase 1 (CILK1), formerly known as intestinal cell kinase (ICK), is a conserved serine and threonine kinase that restricts primary (non-motile) cilia formation and length. Mutations in CILK1 are associated with ciliopathies and are also linked to juvenile myoclonic epilepsy (JME).

Protein kinase CK2 phosphorylation of SAPS3 subunit increases PP6 phosphatase activity with Aurora A kinase.

Protein Ser/Thr phosphatase-6 (PP6) regulates pathways for activation of NF-kB, YAP1 and Aurora A kinase (AURKA). PP6 is a heterotrimer comprised of a catalytic subunit, one of three different SAPS subunits and one of three different ankyrin-repeat ANKRD subunits. Here, we show FLAG-PP6C expressed in cells preferentially binds endogenous SAPS3, and the complex is active with the chemical substrate DiFMUP.

Aurora B Kinase Promotes CHIP-Dependent Degradation of HIF1α in Prostate Cancer Cells.

Hypoxia is a major factor in tumor progression and resistance to therapies, which involves elevated levels of the transcription factor HIF1α. Here, we report that prostate tumor xenografts express high levels of HIF1α and show greatly enhanced growth in response to knockdown of the E3 ligase CHIP (C-terminus of Hsp70-interacting protein). In multiple human prostate cancer cell lines under hypoxia, taxol treatment induces the degradation of HIF1α, and this response is abrogated by knockdown of CHIP, but not by E3 ligase VHL or RACK1.

Deletion of the SAPS1 subunit of protein phosphatase 6 in mice increases radiosensitivity and impairs the cellular DNA damage response.

Cellular responses to DNA damage include activation of DNA-dependent protein kinase (DNA-PK) through, among others, the serine/threonine protein phosphatase 6 (PP6). We previously showed that recognition of DNA-PKcs is mediated by the SAPS1 PP6 regulatory subunit. Here, we report and characterize a SAPS1 null mouse and investigate the effects of deletion on DNA damage signaling and repair.

Inactivation of PP2A by a recurrent mutation drives resistance to MEK inhibitors.

The serine/threonine Protein Phosphatase 2A (PP2A) functions as a tumor suppressor by negatively regulating multiple oncogenic signaling pathways. The canonical PP2A holoenzyme comprises a scaffolding subunit (PP2A Aα/β), which serves as the platform for binding of both the catalytic C subunit and one regulatory B subunit. Somatic heterozygous missense mutations in PPP2R1A, the gene encoding the PP2A Aα scaffolding subunit, have been identified across multiple cancer types, but the effects of the most commonly mutated residue, Arg-183, on PP2A function have yet to be fully elucidated.

Ciliogenesis associated kinase 1: targets and functions in various organ systems.

Ciliogenesis associated kinase 1 (CILK1) was previously known as intestinal cell kinase because it was cloned from that origin. However, CILK1 is now recognized as a widely expressed and highly conserved serine/threonine protein kinase. Mutations in the human CILK1 gene have been associated with ciliopathies, a group of human genetic disorders with defects in the primary cilium.

Ciliopathy-Associated Protein Kinase ICK Requires Its Non-Catalytic Carboxyl-Terminal Domain for Regulation of Ciliogenesis.

Loss-of-function mutations in the human (intestinal cell kinase) gene cause dysfunctional primary cilia and perinatal lethality which are associated with human ciliopathies. The enzyme that we herein call CAPK (ciliopathy-associated protein kinase) is a serine/threonine protein kinase that has a highly conserved MAPK-like N-terminal catalytic domain and an unstructured C-terminal domain (CTD) whose functions are completely unknown. In this study, we demonstrate that truncation of the CTD impairs the ability of CAPK to interact with and phosphorylate its substrate, kinesin family member 3A (KIF3A).

Protein phosphatase 1α interacts with a novel ciliary targeting sequence of polycystin-1 and regulates polycystin-1 trafficking.

Autosomal dominant polycystic kidney disease (ADPKD) is the most common genetic disorder causing renal failure. Mutations of polycystic kidney disease 1 () account for most ADPKD cases. Defective ciliary localization of polycystin-1 (PC1), a large integral membrane protein encoded by , underlies the pathogenesis of a subgroup of patients with ADPKD.

High-content phenotypic assay for proliferation of human iPSC-derived cardiomyocytes identifies L-type calcium channels as targets.

Over 5 million people in the United States suffer from heart failure, due to the limited ability to regenerate functional cardiac tissue. One potential therapeutic strategy is to enhance proliferation of resident cardiomyocytes. However, phenotypic screening for therapeutic agents is challenged by the limited ability of conventional markers to discriminate between cardiomyocyte proliferation and endoreplication (e.

Modulation of NKG2D, NKp46, and Ly49C/I facilitates natural killer cell-mediated control of lung cancer.

Natural killer (NK) cells play a critical role in controlling malignancies. Susceptibility or resistance to lung cancer, for example, specifically depends on NK cell function. Nevertheless, intrinsic factors that control NK cell-mediated clearance of lung cancer are unknown.

Selective toxicity of caffeic acid in hepatocellular carcinoma cells.

Caffeic acid is a natural phytochemical structurally similar to other cinnamic acids. In this study we found caffeic acid (CA) but not ferulic, sinapic or cinnamic acids inhibited proliferation of hepatocellular carcinoma cells (HCC) and reduced cell numbers by inducing apoptosis. Only transient exposure to CA was required for these lethal effects that are associated with disruption of mitochondrial membrane potential and induction of reactive oxygen species.

Protein Serine/Threonine Phosphatases: Keys to Unlocking Regulators and Substrates.

Protein serine/threonine phosphatases (PPPs) are ancient enzymes, with distinct types conserved across eukaryotic evolution. PPPs are segregated into types primarily on the basis of the unique interactions of PPP catalytic subunits with regulatory proteins. The resulting holoenzymes dock substrates distal to the active site to enhance specificity.

Modulation of GSK3β autoinhibition by Thr-7 and Thr-8.

Glycogen synthase kinase 3β (GSK-3β) is a pivotal signaling node that regulates a myriad of cellular functions and is deregulated in many pathological conditions, making it an attractive therapeutic target. Inhibitory Ser-9 phosphorylation of GSK3β by AKT is an important mechanism for negative regulation of GSK3β activity upon insulin stimulation. Here, we report that Thr-7 and Thr-8 residues located in the AKT/PKB substrate consensus sequence on GSK3β are essential for insulin-stimulated Ser-9 phosphorylation in vivo and for GSK3β inactivation.