Targeting DNAJB9, a novel ER luminal co-chaperone, to rescue ΔF508-CFTR.

The molecular mechanism of Endoplasmic Reticulum-associated degradation (ERAD) of Cystic fibrosis transmembrane-conductance regulator (CFTR) is largely unknown. Particularly, it is unknown what ER luminal factor(s) are involved in ERAD. Herein, we used ProtoArray to identify an ER luminal co-chaperone, DNAJB9, which can directly interact with CFTR.

Altered cGMP dynamics at the plasma membrane contribute to diarrhea in ulcerative colitis.

Ulcerative colitis (UC) belongs to inflammatory bowel disorders, a group of gastrointestinal disorders that can produce serious recurring diarrhea in affected patients. The mechanism for UC- and inflammatory bowel disorder-associated diarrhea is not well understood. The cystic fibrosis transmembrane-conductance regulator (CFTR) chloride channel plays an important role in fluid and water transport across the intestinal mucosa.

Capturing the Direct Binding of CFTR Correctors to CFTR by Using Click Chemistry.

Cystic fibrosis (CF) is a lethal genetic disease caused by the loss or dysfunction of the CF transmembrane conductance regulator (CFTR) channel. F508del is the most prevalent mutation of the CFTR gene and encodes a protein defective in folding and processing. VX-809 has been reported to facilitate the folding and trafficking of F508del-CFTR and augment its channel function.

The autotaxin-LPA2 GPCR axis is modulated by γ-irradiation and facilitates DNA damage repair.

In this study we characterized the effects of radiation injury on the expression and function of the autotaxin (ATX)-LPA2 GPCR axis. In IEC-6 crypt cells and jejunum enteroids quantitative RT-PCR showed a time- and dose-dependent upregulation of lpa2 in response to γ-irradiation that was abolished by mutation of the NF-κB site in the lpa2 promoter or by inhibition of ATM/ATR kinases with CGK-733, suggesting that lpa2 is a DNA damage response gene upregulated by ATM via NF-κB. The resolution kinetics of the DNA damage marker γ-H2AX in LPA-treated IEC-6 cells exposed to γ-irradiation was accelerated compared to vehicle, whereas pharmacological inhibition of LPA2 delayed the resolution of γ-H2AX.

PKA and actin play critical roles as downstream effectors in MRP4-mediated regulation of fibroblast migration.

Multidrug resistance protein 4 (MRP4), a member of the ATP binding cassette transporter family, functions as a plasma membrane exporter of cyclic nucleotides. Recently, we demonstrated that fibroblasts lacking the Mrp4 gene migrate faster and contain higher cyclic-nucleotide levels. Here, we show that cAMP accumulation and protein kinase A (PKA) activity are higher and polarized in Mrp4(-/-) fibroblasts, versus Mrp4(+/+) cells.

Förster resonance energy transfer - an approach to visualize the spatiotemporal regulation of macromolecular complex formation and compartmentalized cell signaling.

Background: Signaling messengers and effector proteins provide an orchestrated molecular machinery to relay extracellular signals to the inside of cells and thereby facilitate distinct cellular behaviors. Formations of intracellular macromolecular complexes and segregation of signaling cascades dynamically regulate the flow of a biological process.

Scope Of Review: In this review, we provide an overview of the development and application of FRET technology in monitoring cyclic nucleotide-dependent signalings and protein complexes associated with these signalings in real time and space with brief mention of other important signaling messengers and effector proteins involved in compartmentalized signaling.

Compartmentalization of cyclic nucleotide signaling: a question of when, where, and why?

Preciseness of cellular behavior depends upon how an extracellular cue mobilizes a correct orchestra of cellular messengers and effector proteins spatially and temporally. This concept, termed compartmentalization of cellular signaling, is now known to form the molecular basis of many aspects of cellular behavior in health and disease. The cyclic nucleotides cyclic adenosine monophosphate and cyclic guanosine monophosphate are ubiquitous cellular messengers that can be compartmentalized in three ways: first, by their physical containment; second, by formation of multiple protein signaling complexes; and third, by their selective depletion.

MAST205 competes with cystic fibrosis transmembrane conductance regulator (CFTR)-associated ligand for binding to CFTR to regulate CFTR-mediated fluid transport.

The PDZ (postsynaptic density-95/discs large/zona occludens-1) domain-based interactions play important roles in regulating the expression and function of the cystic fibrosis transmembrane conductance regulator (CFTR). Several PDZ domain-containing proteins (PDZ proteins for short) have been identified as directly or indirectly interacting with the C terminus of CFTR. To better understand the regulation of CFTR processing, we conducted a genetic screen and identified MAST205 (a microtubule-associated serine/threonine kinase with a molecular mass of 205 kDa) as a new CFTR regulator.

Multi-drug resistance protein 4 (MRP4)-mediated regulation of fibroblast cell migration reflects a dichotomous role of intracellular cyclic nucleotides.

It has long been known that cyclic nucleotides and cyclic nucleotide-dependent signaling molecules control cell migration. However, the concept that it is not just the absence or presence of cyclic nucleotides, but a highly coordinated balance between these molecules that regulates cell migration, is new and revolutionary. In this study, we used multidrug resistance protein 4 (MRP4)-expressing cell lines and MRP4 knock-out mice as model systems and wound healing assays as the experimental system to explore this unique and emerging concept.

Unique profile of ordered arrangements of repetitive elements in the C57BL/6J mouse genome implicating their functional roles.

The entirety of all protein coding sequences is reported to represent a small fraction (~2%) of the mouse and human genomes; the vast majority of the rest of the genome is presumed to be repetitive elements (REs). In this study, the C57BL/6J mouse reference genome was subjected to an unbiased RE mining to establish a whole-genome profile of RE occurrence and arrangement. The C57BL/6J mouse genome was fragmented into an initial set of 5,321 units of 0.

KLF4 positively regulates human ghrelin expression.

Ghrelin, an endogenous ligand of the GH (growth hormone) secretagogue receptor, influences many metabolic processes including GH secretion, food intake, energy balance, insulin secretion and adipogenesis. Although ghrelin exhibits a variety of biological functions, the mechanism by which ghrelin expression is regulated is unknown. Ghrelin is expressed in the gastrointestinal tract, predominantly in the stomach, as is KLF4 (Krüppel-like factor 4).

Association of the Src homology 2 domain-containing leukocyte phosphoprotein of 76 kD (SLP-76) with the p85 subunit of phosphoinositide 3-kinase.

To investigate additional functions of the T cell adaptor, Src homology 2 (SH2) domain-containing leukocyte protein of 76 kD (SLP-76), we performed a yeast two-hybrid assay using the N-terminal region of SLP-76 fused with the kinase domain of Syk. By screening a human leukemia cDNA library, we identified the p85 subunit of phosphoinositide 3-kinase (PI3K) as one of the interacting molecules. Unlike the SH2 domain of Vav or Nck, tyrosine phosphorylation of SLP-76 at position 113 or 128 was sufficient for it to associate with the N-terminal SH2 of p85.