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Gland Acinar Cells (gland + acinar_cell)
Selected AbstractsTissue-engineered tear secretory system: Functional lacrimal gland acinar cells cultured on matrix protein-coated substrataJOURNAL OF BIOMEDICAL MATERIALS RESEARCH, Issue 1 2007Shivaram Selvam Abstract Dry eye is a general term that refers to a myriad of ophthalmic disorders resulting in the inadequate wetting of the corneal surface by the tear film. Dry eyes are typically treated by the application of artificial tears. However, patients with lacrimal insufficiencies such as Stevens-Johnson syndrome, chemical and thermal injuries, or ocular cicatricial pemphigoid have very limited options because of the short duration and action of lubricating agents. As a therapeutic strategy, we are working to develop a bioengineered tear secretory system for such patients. This article describes the growth and physiological properties of purified rabbit lacrimal gland acinar cells (pLGACs) on several matrix protein-coated polymers such as silicone, collagen I, copolymers of poly- D,L -lactide- co -glycolide (PLGA; 85:15 and 50:50), poly- L -lactic acid (PLLA), and Thermanox® plastic cell culture coverslips. Monolayers of acinar cells were established on all of the polymeric substrata. An assay of ,-hexosaminidase activity in the supernatant medium showed significant increases in protein secretion, following stimulation with 100 ,M carbachol on matrix protein-coated and uncoated polymers such as silicone, PLGA 85:15, and PLLA. Our study demonstrates that PLLA supported the morphological and physiological properties of purified rabbit lacrimal gland epithelial cells more successfully than the others. © 2006 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2007 [source] Novel biphasic traffic of endocytosed EGF to recycling and degradative compartments in lacrimal gland acinar cellsJOURNAL OF CELLULAR PHYSIOLOGY, Issue 1 2004Jiansong Xie The purpose of this study was to delineate the traffic patterns of EGF and EGF receptors (EGFR) in primary cultured acinar epithelial cells from rabbit lacrimal glands. Uptake of [125I]-EGF exhibited saturable and non-saturable, temperature-dependent components, suggesting both receptor-mediated and fluid phase endocytosis. Accumulation of [125I] was time-dependent over a 120-min period, but the content of intact [125I]-EGF decreased after reaching a maximum at 20 min. Analytical fractionation by sorbitol density gradient centrifugation and phase partitioning indicated that within 20 min at 37°C [125I] reached an early endosome, basal,lateral recycling endosome, pre-lysosome, and lysosome. Small components of the label also appeared to reach the Golgi complex and trans -Golgi network. Intact [125I]-EGF initially accumulated in the recycling endosome; the content in the recycling endosome subsequently decreased, and by 120 min increased amounts of [125I]-labeled degradation products appeared in the pre-lysosomes and lysosomes. Confocal microscopy imaging of FITC-EGF and LysoTrackerRed revealed FITC enriched in a dispersed system of non-acidic compartments at 20 min and in acidic compartments at 120 min. Both confocal immunofluorescence microscopy and analytical fractionation indicated that the intracellular EGFR pool was much larger than the plasma membrane-expressed pool at all times. Cells loaded with [125I]-EGF released a mixture of intact EGF and [125I]-labeled degradation products. The observations indicate that in lacrimal acinar cells, EGFR and EGF,EGFR complexes continually traffic between the plasma membranes and a system of endomembrane compartments; EGF-stimulation generates time-dependent signals that initially decrease, then increase, EGF,EGFR traffic to degradative compartments. J. Cell. Physiol. 199: 108,125, 2004© 2003 Wiley-Liss, Inc. [source] Odorants as cell-type specific activators of a heat shock response in the rat olfactory mucosaTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2001Virginian McMillan Carr Abstract Heat shock, or stress, proteins (HSPs) are induced in response to conditions that cause protein denaturation. Activation of cellular stress responses as a protective and survival mechanism is often associated with chemical exposure. One interface between the body and the external environment and chemical or biological agents therein is the olfactory epithelium (OE). To determine whether environmental odorants affect OE HSP expression, rats were exposed to a variety of odorants added to the cage bedding. Odorant exposure led to transient, selective induction of HSP70, HSC70, HSP25, and ubiquitin immunoreactivities (IRs) in supporting cells and subepithelial Bowman's gland acinar cells, two OE non-neuronal cell populations involved with inhalant biotransformation, detoxification, and maintenance of overall OE integrity. Responses exhibited odor specificity and dose dependency. HSP70 and HSC70 IRs occurred throughout the apical region of supporting cells; ubiquitin IR was confined to a supranuclear cone-shaped region. Electron microscopic examination confirmed these observations and, additionally, revealed odor-induced formation of dense vesicular arrays in the cone-like regions. HSP25 IR occurred throughout the entire supporting cell cytoplasm. In contrast to classical stress responses, in which the entire array of stress proteins is induced, no increases in HSP40 and HSP90 IRs were observed. Extended exposure to higher odorant doses caused prolonged activation of the same HSP subset in the non-neuronal cells and severe morphological damage in both supporting cells and olfactory receptor neurons (ORNs), suggesting that non-neuronal cytoprotective stress response mechanisms had been overwhelmed and could no longer adequately maintain OE integrity. Significantly, ORNs showed no stress responses in any of our studies. These findings suggest a novel role for these HSPs in olfaction and, in turn, possible involvement in other normal neurophysiological processes. J. Comp. Neurol. 432:425,439, 2001. © 2001 Wiley-Liss, Inc. [source] Regulation of membrane potential and fluid secretion by Ca2+ -activated K+ channels in mouse submandibular glandsTHE JOURNAL OF PHYSIOLOGY, Issue 2 2007Victor G. Romanenko We have recently shown that the IK1 and maxi-K channels in parotid salivary gland acinar cells are encoded by the KCa3.1 and KCa1.1 genes, respectively, and in vivo stimulated parotid secretion is severely reduced in double-null mice. The current study tested whether submandibular acinar cell function also relies on these channels. We found that the K+ currents in submandibular acinar cells have the biophysical and pharmacological footprints of IK1 and maxi-K channels and their molecular identities were confirmed by the loss of these currents in KCa3.1- and KCa1.1 -null mice. Unexpectedly, the pilocarpine-stimulated in vivo fluid secretion from submandibular glands was essentially normal in double-null mice. This result and the possibility of side-effects of pilocarpine on the nervous system, led us to develop an ex vivo fluid secretion assay. Fluid secretion from the ex vivo assay was substantially (about 75%) reduced in animals with both K+ channel genes ablated , strongly suggesting systemic complications with the in vivo assay. Additional experiments focusing on the membrane potential in isolated submandibular acinar cells revealed mechanistic details underlying fluid secretion in K+ channel-deficient mice. The membrane potential of submandibular acinar cells from wild-type mice remained strongly hyperpolarized (,55 ± 2 mV) relative to the Cl, equilibrium potential (,24 mV) during muscarinic stimulation. Similar hyperpolarizations were observed in KCa3.1- and KCa1.1 -null mice (,51 ± 3 and ,48 ± 3 mV, respectively), consistent with the normal fluid secretion produced ex vivo. In contrast, acinar cells from double KCa3.1/KCa1.1 -null mice were only slightly hyperpolarized (,35 ± 2 mV) also consistent with the ex vivo (but not in vivo) results. Finally, we found that the modest hyperpolarization of cells from the double-null mice was maintained by the electrogenic Na+,K+ -ATPase. [source] Secretion and cell volume regulation by salivary acinar cells from mice lacking expression of the Clcn3 Cl, channel geneTHE JOURNAL OF PHYSIOLOGY, Issue 1 2002Jorge Arreola Salivary gland acinar cells shrink when Cl, currents are activated following cell swelling induced by exposure to a hypotonic solution or in response to calcium-mobilizing agonists. The molecular identity of the Cl, channel(s) in salivary cells involved in these processes is unknown, although ClC-3 has been implicated in several tissues as a cell-volume-sensitive Cl, channel. We found that cells isolated from mice with targeted disruption of the Clcn3 gene undergo regulatory volume decrease in a fashion similar to cells from wild-type littermates. Consistent with a normal regulatory volume decrease response, the magnitude and the kinetics of the swell-activated Cl, currents in cells from ClC-3-deficient mice were equivalent to those from wild-type mice. It has also been suggested that ClC-3 is activated by Ca2+ -calmodulin-dependent protein kinase II; however, the magnitude of the Ca2+ -dependent Cl, current was unchanged in the Clcn3,/- animals. In addition, we observed that ClC-3 appeared to be highly expressed in the smooth muscle cells of glandular blood vessels, suggesting a potential role for this channel in saliva production by regulating blood flow, yet the volume and ionic compositions of in vivo stimulated saliva from wild-type and null mutant animals were comparable. Finally, in some cells ClC-3 is an intracellular channel that is thought to be involved in vesicular acidification and secretion. Nevertheless, the protein content of saliva was unchanged in Clcn3,/- mice. Our results demonstrate that the ClC-3 Cl, channel is not a major regulator of acinar cell volume, nor is it essential for determining the secretion rate and composition of saliva. [source] | ||||||||||