Protein kinase A-mediated phosphorylation of naked cuticle homolog 2 stimulates cell-surface delivery of transforming growth factor-α for epidermal growth factor receptor transactivation

Electrodeposited magnetic nanoporous membrane for high-yield and high-throughput immunocapture of extracellular vesicles and lipoproteins

Superparamagnetic nanobeads offer several advantages over microbeads for immunocapture of nanocarriers (extracellular vesicles, lipoproteins, and viruses) in a bioassay: high-yield capture, reduction in incubation time, and higher capture capacity. However, nanobeads are difficult to "pull-down" because their superparamagnetic feature requires high nanoscale magnetic field gradients. Here, an electrodeposited track-etched membrane is shown to produce a unique superparamagnetic nano-edge ring with multiple edges around nanopores. With a uniform external magnetic field, the induced monopole and dipole of this nano edge junction combine to produce a 10× higher nanobead trapping force. A dense nanobead suspension can be filtered through the magnetic nanoporous membrane (MNM) at high throughput with a 99% bead capture rate. The yield of specific nanocarriers in heterogeneous media by nanobeads/MNM exceeds 80%. Reproducibility, low loss, and concentration-independent capture rates are also demonstrated. This MNM material hence expands the application of nanobead immunocapture to physiological samples.

AKAP12 ameliorates liver injury via targeting PI3K/AKT/PCSK6 pathway

A kinase anchor protein 12（AKAP12）is a scaffold protein that is critical for cell structure maintenance and signal transduction. However, the role of AKAP12 in liver injury remains unclear. Here, we attempt to explore the potential contribution of AKAP12 in liver injury and elucidate its underlying molecular mechanism. We found that AKAP12 deletion in acute liver injury (ALI) activates the PI3K/AKT phosphorylation signaling pathway, induces the increased expression of PCSK6 and its downstream inflammation-related genes, and prompts macrophages to produce a large number of inflammatory factors. And knockdown of PCSK6 by in vivo siRNA assay reversed in liver injury AKAP12^Δhep mice, demonstrating that PCSK6 has an important role in ALI. Furthermore, we found that signal transducer and activator of transcription 3 (STAT3) and serine/threonine kinase Akt (AKT) were upregulated in AKAP12^Δhep mice of chronic liver injury. To sum up, our study here demonstrates that AKAP12 has a protective role in ALI and chronic liver fibrosis, at least in part through inhibition of the PI3K/AKT/PCSK6 pathway. Our findings provide a new potential treatment for liver injury with important clinical implications.

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The PI3K-AKT pathway is activated in the liver of AKAP12^Δhep mice upon ALI.

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Increased PCSK6 expression is the main cause of aggravated ALI in AKAP12^Δhep mice.

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Increased phosphorylation levels of STAT3 and AKT promote liver fibrosis in AKAP12^Δhep mice.

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AKAP12 ameliorates liver injury through reprogramming PI3K/AKT/PCSK6 pathway.

Pituitary adenylate cyclase-activating polypeptide/vasoactive intestinal peptide [Part 1]: biology, pharmacology, and new insights into their cellular basis of action/signaling which are providing new therapeutic targets

PURPOSE OF REVIEW

To discuss recent advances of vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase-activating polypeptide (PACAP) receptors in pharmacology, cell biology, and intracellular signaling in cancer.

RECENT FINDINGS

Recent studies provide new insights into the pharmacology, cell biology of the VIP/PACAP system and show they play important roles in a number of human cancers, as well as in tumor growth/differentiation and are providing an increased understanding of their signaling cascade that is suggesting new treatment targets/approaches.

SUMMARY

Recent insights from studies of VIP/PACAP and their receptors in both central nervous system disorders and inflammatory disorders suggest possible new treatment approaches. Elucidation of the exact roles of VIP/PACAP in these disorders and development of new therapeutic approaches involving these peptides have been limited by lack of specific pharmacological tools, and exact signaling mechanisms involved, mediating their effects. Reviewed here are recent insights from the elucidation of structural basis for VIP/PACAP receptor activation as well as the signaling cascades mediating their cellular effects (using results primarily from the study of their effects in cancer) that will likely lead to novel targets and treatment approaches in these diseases.

Bombesin, endothelin, neurotensin and pituitary adenylate cyclase activating polypeptide cause tyrosine phosphorylation of receptor tyrosine kinases

Numerous peptides including bombesin (BB), endothelin (ET), neurotensin (NTS) and pituitary adenylate cyclase-activating polypeptide (PACAP) are growth factors for lung cancer cells. The peptides bind to G protein-coupled receptors (GPCRs) resulting in elevated cAMP and/or phosphatidylinositol (PI) turnover. In contrast, growth factors such as epidermal growth factor (EGF) or neuregulin (NRG)-1 bind to receptor tyrosine kinases (RTKs) such as the EGFR or HER3, increasing tyrosine kinase activity, resulting in the phosphorylation of protein substrates such as PI3K or phospholipase (PL)C. Peptide GPCRs can transactivate numerous RTKs, especially members of the EGFR/HER family resulting in increased phosphorylation of ERK, leading to cellular proliferation or increased phosphorylation of AKT, leading to cellular survival. GRCR antagonists and tyrosine kinase inhibitors are useful agents to prevent RTK transactivation and inhibit proliferation of cancer cells.

AKAP12 Signaling Complex: Impacts of Compartmentalizing cAMP-Dependent Signaling Pathways in the Heart and Various Signaling Systems

Heart failure is a complex clinical syndrome, represented as an impairment in ventricular filling and myocardial blood ejection. As such, heart failure is one of the leading causes of death in the United States. With a mortality rate of 1 per 8 individuals and a prevalence of 6.2 million Americans, it has been projected that heart failure prevalence will increase by 46% by 2030. Cardiac remodeling (a general determinant of heart failure) is regulated by an extensive network of intertwined intracellular signaling pathways. The ability of signalosomes (molecular signaling complexes) to compartmentalize several cellular pathways has been recently established. These signalosome signaling complexes provide an additional level of specificity to general signaling pathways by regulating the association of upstream signals with downstream effector molecules. In cardiac myocytes, the AKAP12 (A‐kinase anchoring protein 12) scaffolds a large signalosome that orchestrates spatiotemporal signaling through stabilizing pools of phosphatases and kinases. Predominantly upon β‐AR (β₂‐adrenergic‐receptor) stimulation, the AKAP12 signalosome is recruited near the plasma membrane and binds tightly to β‐AR. Thus, one major function of AKAP12 is compartmentalizing PKA (protein kinase A) signaling near the plasma membrane. In addition, it is involved in regulating desensitization, downregulation, and recycling of β‐AR. In this review, the critical roles of AKAP12 as a scaffold protein in mediating signaling downstream GPCRs (G protein–coupled receptor) are discussed with an emphasis on its reported and potential roles in cardiovascular disease initiation and progression.

Plant natural products with anti-thyroid cancer activity

Thyroid cancer is the most frequent endocrine malignancy, with more than 500,000 cases per year worldwide. Differentiated thyroid cancers are the most common forms with best prognosis, while poorly/undifferentiated ones are rare (2% of all thyroid cancer), aggressive, frequently metastasize and have a worse prognosis. For aggressive, metastatic and advanced thyroid cancer novel antitumor molecules are urgently needed and phytochemical products can be a rational and extensive source, since secondary plant metabolites can guarantee the necessary biochemical variability for therapeutic purpose. Among bioactive molecules that present biological activity on thyroid cancer, resveratrol, curcumin, isoflavones, glucosinolates are the most common and used in experimental model. Most of them have been studied both in vitro and in vivo on this cancer, but rarely in clinical trial. This review summarizes phytochemicals, phytotherapeutics and plant derived compounds used in thyroid cancer.

Protein kinase A-mediated phosphorylation of naked cuticle homolog 2 stimulates cell-surface delivery of transforming growth factor-α for epidermal growth factor receptor transactivation

The classic mode of G protein-coupled receptor (GPCR)-mediated transactivation of the receptor tyrosine kinase epidermal growth factor receptor (EGFR) transactivation occurs via matrix metalloprotease (MMP)-mediated cleavage of plasma membrane-anchored EGFR ligands. Herein, we show that the Gαs-activating GPCR ligands vasoactive intestinal peptide (VIP) and prostaglandin E2 (PGE2 ) transactivate EGFR through increased cell-surface delivery of the EGFR ligand transforming growth factor-α (TGFα) in polarizing madin-darby canine kidney (MDCK) and Caco-2 cells. This is achieved by PKA-mediated phosphorylation of naked cuticle homolog 2 (NKD2), previously shown to bind TGFα and direct delivery of TGFα-containing vesicles to the basolateral surface of polarized epithelial cells. VIP and PGE2 rapidly activate protein kinase A (PKA) that then phosphorylates NKD2 at Ser-223, a process that is facilitated by the molecular scaffold A-kinase anchoring protein 12 (AKAP12). This phosphorylation stabilized NKD2, ensuring efficient cell-surface delivery of TGFα and increased EGFR activation. Thus, GPCR-triggered, PKA/AKAP12/NKD2-regulated targeting of TGFα to the cell surface represents a new mode of EGFR transactivation that occurs proximal to ligand cleavage by MMPs.