Cellular mechanisms underlying pituitary adenylate cyclase activating polypeptide-stimulated secretion in the adrenal medulla.

The adrenal medulla is a key effector of the sympathetic nervous system in the periphery. Its primary function is to translate variations in sympathetic activity into hormone outputs that modify end organ function throughout the body. These hormones include epinephrine, norepinephrine, and a variety of vasoactive peptides.

Roles for PKC signaling in chromaffin cell exocytosis.

Chromaffin cells of the adrenal medulla have an important role in the sympathetic stress response. They secrete catecholamines and other hormones into the bloodstream upon stimulation by the neurotransmitter pituitary adenylate cyclase-activating polypeptide (PACAP). PACAP causes a long-lasting and robust secretory response from chromaffin cells.

A PACAP-activated network for secretion requires coordination of Ca influx and Ca mobilization.

Chromaffin cells of the adrenal medulla transduce sympathetic nerve activity into stress hormone secretion. The two neurotransmitters principally responsible for coupling cell stimulation to secretion are acetylcholine and pituitary adenylate activating polypeptide (PACAP). In contrast to acetylcholine, PACAP evokes a persistent secretory response from chromaffin cells.

A PACAP-activated network for secretion requires coordination of Ca influx and Ca mobilization.

Chromaffin cells of the adrenal medulla transduce sympathetic nerve activity into stress hormone secretion. The two neurotransmitters principally responsible for coupling cell stimulation to secretion are acetylcholine and pituitary adenylate activating polypeptide (PACAP). In contrast to acetylcholine, PACAP evokes a persistent secretory response from chromaffin cells.

Hair cell morphological patterns and polarity organization in the sea lamprey vestibular cristae.

The inner ear of the sea lamprey was examined by scanning electron microscopy, antibody labeling with tubulin, Myo7a, Spectrin, and Phalloidin stain to elucidate the canal cristae organization and the morphology and polarity of the hair cells. We characterized the hair cell stereocilia bundles and their morphological polarity with respect to the kinocilia. We identified three types of hair cells.

PACAP and acetylcholine cause distinct Ca2+ signals and secretory responses in chromaffin cells.

The adrenomedullary chromaffin cell transduces chemical messages into outputs that regulate end organ function throughout the periphery. At least two important neurotransmitters are released by innervating preganglionic neurons to stimulate exocytosis in the chromaffin cell-acetylcholine (ACh) and pituitary adenylate cyclase activating polypeptide (PACAP). Although PACAP is widely acknowledged as an important secretagogue in this system, the pathway coupling PACAP stimulation to chromaffin cell secretion is poorly understood.

Selection and characterization of structure-switching DNA aptamers for the salivary peptide histatin 3.

In this study, single-stranded DNA aptamers that switch structural conformation upon binding to the salivary peptide histatin 3 have been reported for the first time. Histatin 3 is an antimicrobial peptide that possesses the capability of being a therapeutic agent against oral candidiasis and has recently been linked as a novel biomarker for acute stress. The aptamers were identified through a library immobilization version of an iterative in vitro process known as the Systematic Evolution of Ligands by EXponential enrichment (SELEX).

Synaptotagmin-7 enhances calcium-sensing of chromaffin cell granules and slows discharge of granule cargos.

Synaptotagmin-7 (Syt-7) is one of two major calcium sensors for exocytosis in adrenal chromaffin cells, the other being synaptotagmin-1 (Syt-1). Despite a broad appreciation for the importance of Syt-7, questions remain as to its localization, function in mediating discharge of dense core granule cargos, and role in triggering release in response to physiological stimulation. These questions were addressed using two distinct experimental preparations-mouse chromaffin cells lacking endogenous Syt-7 (KO cells) and a reconstituted system employing cell-derived granules expressing either Syt-7 or Syt-1.

CACNB2 is associated with aberrant RAS-MAPK signaling in hypertensive Dahl Salt-Sensitive rats.

Several independent genome-wide association studies (GWAS) have indicated that calcium (Ca) voltage-gated channel auxiliary subunit beta 2 (CACNB2) an L-type Ca channel (LTCC) associated protein has strong association with hypertension. However, the molecular mechanism of CACNB2 and its role in the pathophysiology of hypertension is not clear. To address this knowledge gap, we utilized in vitro and in vivo approaches using HEK293 cells and genetically hypertensive, Dahl Salt-Sensitive (SS) rats.

Role of NAADP for calcium signaling in the salivary gland.

Coordination of intracellular Ca signaling in parotid acini is crucial for controlling the secretion of primary saliva. Previous work from our lab has demonstrated acidic-organelle Ca release as a participant in agonist-evoked signaling dynamics of the parotid acinar cell. Furthermore, results implicated a potential role for the potent Ca releasing second messenger NAADP in these events.

Arachidonic acid-induced Ca entry and migration in a neuroendocrine cancer cell line.

Background: Store-operated Ca entry (SOCE) has been implicated in the migration of some cancer cell lines. The canonical SOCE is defined as the Ca entry that occurs in response to near-maximal depletion of Ca within the endoplasmic reticulum. Alternatively, arachidonic acid (AA) has been shown to induce Ca entry in a store-independent manner through Orai1/Orai3 hetero-multimeric channels.

Synaptotagmin isoforms confer distinct activation kinetics and dynamics to chromaffin cell granules.

Adrenomedullary chromaffin cells respond to sympathetic nervous system activation by secreting a cocktail of potent neuropeptides and hormones into the circulation. The distinct phases of the chromaffin cell secretory response have been attributed to the progressive fusion of distinct populations of dense core granules with different activation kinetics. However, it has been difficult to define what distinguishes these populations at the molecular level.

Salivary protein changes in response to acute stress in medical residents performing advanced clinical simulations: a pilot proteomics study.

Context: Quantitative changes of salivary proteins due to acute stress were detected.

Objective: To explore protein markers of stress in saliva of eight medical residents who performed emergency medicine simulations.

Materials And Methods: Saliva was collected before the simulations, after the simulations, and following morning upon waking.

cAMP-dependent recruitment of acidic organelles for Ca2+ signaling in the salivary gland.

Autonomic neural activation of intracellular Ca release in parotid acinar cells induces the secretion of the fluid and protein components of primary saliva critical for maintaining overall oral homeostasis. In the current study, we profiled the role of acidic organelles in shaping the Ca signals of parotid acini using a variety of imaging and pharmacological approaches. Results demonstrate that zymogen granules predominate as an apically polarized population of acidic organelles that contributes to the initial Ca release.

Nicotinic Acid Adenine Dinucleotide Phosphate Plays a Critical Role in Naive and Effector Murine T Cells but Not Natural Regulatory T Cells.

Nicotinic acid adenine dinucleotide phosphate (NAADP), the most potent Ca(2+) mobilizing second messenger discovered to date, has been implicated in Ca(2+) signaling in some lymphomas and T cell clones. In contrast, the role of NAADP in Ca(2+) signaling or the identity of the Ca(2+) stores targeted by NAADP in conventional naive T cells is less clear. In the current study, we demonstrate the importance of NAADP in the generation of Ca(2+) signals in murine naive T cells.

Increased Glucose-induced Secretion of Glucagon-like Peptide-1 in Mice Lacking the Carcinoembryonic Antigen-related Cell Adhesion Molecule 2 (CEACAM2).

Carcinoembryonic antigen-related cell adhesion molecule 2 (CEACAM2) regulates food intake as demonstrated by hyperphagia in mice with the Ceacam2 null mutation (Cc2(-/-)). This study investigated whether CEACAM2 also regulates insulin secretion. Ceacam2 deletion caused an increase in β-cell secretory function, as assessed by hyperglycemic clamp analysis, without affecting insulin response.

Crosstalk between purinergic receptors and canonical signaling pathways in the mouse salivary gland.

Isolated clusters of mouse parotid acinar cells in combination with live cell imaging were used to explore the crosstalk in molecular signaling between purinergic, cholinergic and adrenergic pathways that integrate to control fluid and protein secretion. This crosstalk was manifested by (1) β-adrenergic receptor activation and amplification of P2X4R evoked Ca(2+) signals, (2) β-adrenergic-induced amplification of P2X7R-evoked Ca(2+) signals and (3) muscarinic receptor induced activation of P2X7Rs via exocytotic activity. The findings from our study reveal that purinoceptor-mediated Ca(2+) signaling is modulated by crosstalk with canonical signaling pathways in parotid acinar cells.

Gastro-Enteropancreatic Neuroendocrine Tumor Cell Dynamics in Liver Microvasculature.

For many cancers, liver metastasis is common and usually indicates poor prognosis. Gastro-enteropancreatic neuroendocrine tumors (GEPNETs) of the midgut are a heterogeneous group of cancers that typically remain asymptomatic until they metastasize to the liver. However, the mechanisms by which these usually indolent cancers establish distal metastasis remain unclear.

Activity of nicotinic acid substituted nicotinic acid adenine dinucleotide phosphate (NAADP) analogs in a human cell line: difference in specificity between human and sea urchin NAADP receptors.

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the most potent Ca2+ mobilizing second messenger that has been identified. We have previously shown that NAADP analogs substituted at the 5-position of nicotinic acid were recognized by the sea urchin receptor at low concentration, whereas the 4- substituted analogs were not as potent. However, to date the structure-activity relationship (SAR) of these analogs has not been addressed in mammalian systems.

Different roles of the cardiac Na+/Ca2+-exchanger in ouabain-induced inotropy, cell signaling, and hypertrophy.

Previous studies have shown that digitalis drugs, acting as specific inhibitors of cardiac Na(+)/K(+)-ATPase, not only cause positive inotropic effects, but also activate cell signaling pathways that lead to cardiac myocyte hypertrophy. A major aim of this work was to assess the role of Na(+)/Ca(2+)-exchanger, NCX1, in the above two seemingly related drug effects. Using a mouse with ventricular-specific knockout (KO) of NCX1, ouabain-induced positive inotropy that was evident in isolated wild-type (Wt) hearts was clearly reduced in KO hearts.

Human heat shock protein 105/110 kDa (Hsp105/110) regulates biogenesis and quality control of misfolded cystic fibrosis transmembrane conductance regulator at multiple levels.

Heat shock protein 105/110-kDa (Hsp105/110), a member of the Hsp70 super family of molecular chaperones, serves as a nucleotide exchange factor for Hsc70, independently prevents the aggregation of misfolded proteins, and functionally relates to Hsp90. We investigated the roles of human Hsp105α, the constitutively expressed isoform, in the biogenesis and quality control of the cystic fibrosis transmembrane conductance regulator (CFTR). In the endoplasmic reticulum (ER), Hsp105 facilitates CFTR quality control at an early stage in its biosynthesis but promotes CFTR post-translational folding.

Distinct contributions by ionotropic purinoceptor subtypes to ATP-evoked calcium signals in mouse parotid acinar cells.

There is emerging consensus that P2X₄ and P2X₇ ionotropic purinoceptors (P2X₄R and P2X₇R) are critical players in regulating [Ca²⁺]i dynamics and fluid secretion in the salivary gland. In contrast, details regarding their compartmentalization and selective activation, contributions to the spatiotemporal properties of intracellular signals and roles in regulating protein exocytosis and ion channel activity have remained largely undefined. To address these concerns, we profiled mouse parotid acinar cells using live-cell imaging to follow the spatial and temporal features of ATP-evoked Ca²⁺ dynamics and exocytotic activity.

FKBP38 peptidylprolyl isomerase promotes the folding of cystic fibrosis transmembrane conductance regulator in the endoplasmic reticulum.

FK506-binding protein 38 (FKBP38), a membrane-anchored, tetratricopeptide repeat (TPR)-containing immunophilin, associates with nascent plasma membrane ion channels in the endoplasmic reticulum (ER). It promotes the maturation of the human ether-à-go-go-related gene (HERG) potassium channel and maintains the steady state level of the cystic fibrosis transmembrane conductance regulator (CFTR), but the underlying mechanisms remain unclear. Using a combination of steady state and pulse-chase analyses, we show that FKBP38 knockdown increases protein synthesis but inhibits the post-translational folding of CFTR, leading to reduced steady state levels of CFTR in the ER, decreased processing, and impaired cell surface functional expression in Calu-3 human airway epithelial cells.

Molecular and functional characterization of non voltage-operated Ca entry in gastrointestinal neuroendocrine tumor cells.

Ca(2+) entry through non-voltage operated channels serves as a key signaling component for tumor progression in a variety of cancers including prostate, colon and breast. As a starting point for an inquiry into the role of Ca(2+) signaling pathways in gastroenteropancreatic neuroendocrine cancers, including carcinoid, we characterized Ca(2+) entry in a set of human carcinoid cell lines originating in the foregut, midgut and hindgut. In the current study, we provide molecular and functional evidence for store-operated and other non-voltage operated Ca(2+) permeable channels in carcinoid tumor cell lines.

The cardiotonic steroid hormone marinobufagenin induces renal fibrosis: implication of epithelial-to-mesenchymal transition.

We recently demonstrated that the cardiotonic steroid marinobufagenin (MBG) induced fibrosis in rat hearts through direct stimulation of collagen I secretion by cardiac fibroblasts. This stimulation was also responsible for the cardiac fibrosis seen in experimental renal failure. In this study, the effect of MBG on the development of renal fibrosis in rats was investigated.