Stress-induced corneal epithelial apoptosis mediated by K+ channel activation.

One of the functional roles of the corneal epithelial layer is to protect the cornea, lens and other underlying ocular structures from damages caused by environmental insults. It is important for corneal epithelial cells to maintain this function by undergoing continuous renewal through a dynamic process of wound healing. Previous studies in corneal epithelial cells have provided substantial evidence showing that environmental insults, such as ultraviolet (UV) irradiation and other biohazards, can induce stress-related cellular responses resulting in apoptosis and thus interrupt the dynamic process of wound healing.

Effect of CTCF-binding motif on regulation of PAX6 transcription.

Purpose: Previous studies indicate that the CCCTC binding transcription factor (CTCF) regulates homeobox PAX6 gene transcription in corneal epithelial cells. In the present study, the effect was investigated of CTCF activity on PAX6 transcription through interaction with five essential motifs located in an 80-bp region upstream from the PAX6 P0 promoter.

Methods: An electrophoretic mobility shift assay (EMSA) was used to determine the interaction between CTCF and DNA binding motifs.

"Cultural fit": individual and societal discrepancies in values, beliefs, and subjective well-being.

The author examined the relationship between cultural values, beliefs, and subjective well-being (SWB) in the context of the "cultural fit" proposition with 3 diverse Chinese samples from Taiwan and Mainland China (N = 581). The author found that beliefs regarding the independent self, the interdependent self, active control, and relationship harmony as forming individual-level culture were consistently related to SWB. Furthermore, the author found that the magnitude of cultural fit was associated with SWB for certain groups of the Chinese people.

Estrogen receptor alpha mediates acute potassium channel stimulation in human coronary artery smooth muscle cells.

The pleiotropic effects of estrogen are mediated via stimulation of two estrogen receptor (ER) subtypes, ERalpha and ERbeta. Although a number of studies have identified expression of one or both subtypes in estrogen target tissues, fewer studies have correlated ER expression with a functional role of these proteins in regulating cellular excitability. In the present study, we have combined cellular fluorescence, immunocytochemistry, and molecular expression techniques with single-channel patch-clamp studies to determine which ER mediates estrogen-stimulated potassium channel activity in human coronary artery smooth muscle cells (HCASMC).

TNF-alpha promotes cell survival through stimulation of K+ channel and NFkappaB activity in corneal epithelial cells.

Tumor necrosis factor (TNF-alpha) in various cell types induces either cell death or mitogenesis through different signaling pathways. In the present study, we determined in human corneal epithelial cells how TNF-alpha also promotes cell survival. Human corneal epithelial (HCE) cells were cultured in DMEM/F-12 medium containing 10% FBS.

TRPC4 knockdown suppresses epidermal growth factor-induced store-operated channel activation and growth in human corneal epithelial cells.

Epidermal growth factor (EGF) in corneal epithelial cells stimulates proliferation by inducing capacitative calcium entry (CCE). However, neither the identity nor the mechanism of activation of the plasma membrane influx pathway that mediates CCE is known. Accordingly, we determined, in human corneal epithelial cells, whether or not (i) CCE is dependent upon stimulation of storeoperated channel (SOC) activity, (ii) the canonical transient receptor potential (TRP) protein isoform TRPC4 is a component of such channels, and (iii) suppression of TRPC4 protein expression decreases EGF-induced stimulation of SOC activity and proliferation.

K+ channel KVLQT1 located in the basolateral membrane of distal colonic epithelium is not essential for activating Cl- secretion.

The cellular mechanism for Cl(-) and K(+) secretion in the colonic epithelium requires K(+) channels in the basolateral and apical membranes. Colonic mucosa from guinea pig and rat were fixed, sectioned, and then probed with antibodies to the K(+) channel proteins K(V)LQT1 (Kcnq1) and minK-related peptide 2 (MiRP2, Kcne3). Immunofluorescence labeling for Kcnq1 was most prominent in the lateral membrane of crypt cells in rat colon.

Insulin-activated, K+-channel-sensitive Akt pathway is primary mediator of ML-1 cell proliferation.

Voltage-gated K(+) channel activities are involved in regulating growth factor-stimulated cell proliferation in a variety of cell types. Here we report that suppression of a voltage-gated K(+) channel with 4-aminopyridine (4-AP), barium, and tetraethylammonium inhibited both EGF- and insulin-stimulated myeloblastic leukemia ML-1 cell proliferation in a concentration-dependent manner. Both MAPK/ERK and Akt pathways are known to mediate cell proliferative signals of a variety of growth factors including insulin.

Ultraviolet irradiation-induced K(+) channel activity involving p53 activation in corneal epithelial cells.

Recent studies from our lab found that ultraviolet (UV) irradiation induces a voltage-gated potassium (Kv) channel activation and subsequently activates JNK signaling pathway resulting in apoptosis. The present study in rabbit corneal epithelial (RCE) cells is to investigate mechanisms of UV irradiation-induced Kv channel activity involving p53 activation in parallel to DNA damage-induced signaling pathway. UV irradiation-induced signaling events were characterized by measurements of JNK activation and further downstream p53 phosphorylation.

Epidermal growth factor-induced proliferation requires down-regulation of Pax6 in corneal epithelial cells.

Growth factors play important roles in regulating corneal epithelial cell proliferation/differentiation during wound healing. It is suggested that PAX6 involves corneal epithelium lineage-specific differentiation (Liu, J. J.

Asiaticoside induction for cell-cycle progression, proliferation and collagen synthesis in human dermal fibroblasts.

Asiaticoside, isolated from Centella asiatica, promotes fibroblast proliferation and extracullar matrix synthesis in wound healing. The precise mechanism, however, in molecular and gene expression levels still remains partially understood. Using cDNA microarray technology, the alternation of genes expression profiles was determined in a human dermal fibroblast in vitro in the presence of asiaticoside (30 microg/ml).

K(+) channel activity and redox status are differentially required for JNK activation by UV and reactive oxygen species.

Upon exposure to ultraviolet (UV) radiation, osmotic changes or the presence of reactive oxygen species (ROS) c-Jun N-terminal kinases (JNKs) are rapidly activated. Extensive studies have elucidated molecular components that mediate the activation of JNKs. However, it remains unclear whether activation of JNKs by various stress signals involves different pathways.

Identification of a Kv3.4 channel in corneal epithelial cells.

Purpose: Voltage-gated K(+) channels maintain salt and water balance and normal function of corneal epithelial cells. To determine their identity, Kv channel types were sought in cultured rabbit corneal epithelial cells and in the intact rat corneal epithelium.

Methods: Immunohistochemistry and Western blot analysis were performed to detect K(+) channels in the membrane and cell lysates of rat and SV-40-transformed rabbit corneal epithelial (RCE) cells, using specific antibodies.

Regulation of eye development by transcription control of CCCTC binding factor (CTCF).

CCCTC binding factor (CTCF), a transcriptional regulator, plays important roles in epigenetics and development. In the present study, we report that overexpression of CTCF in transgenic mice during embryonic development suppresses Pax6 gene expression. This effect causes defects in ocular development that result in microophthalmia.

Volume-regulated anion conductance in cultured rat cerebral astrocytes requires calmodulin activity.

We examined the calmodulin dependence of anion channel activation during hypo-osmotic swelling in rat cerebral astrocytes. Control cells bathed in iso-osmotic (290 mOsm) phosphate-buffered saline (PBS) and recorded using a patch electrode containing 140 mM KCl increased membrane conductance threefold over basal levels after 12 min in hypo-osmotic (200 mOsm) PBS. Cells injected with monoclonal anticalmodulin antibody demonstrated no increase in membrane conductance during a subsequent exposure to hypo-osmotic PBS.

[Distribution and expression of transforming growth factor beta and their receptors in hypertrophic scar].

Objective: To explore the role of transforming growth factor beta (TGF beta) and their receptors (TGF beta-R) in the pathogenesis of hypertrophic scar.

Methods: Specimens of normal skin and hypertrophic scar were harvested and the distribution and the expression of the TGF beta and TGF beta-R were determined by immunohistochemistry and in situ hybridization method.

Results: The expressions of TGF beta and TGF beta-RII in normal skin were higher than the expression of TGF beta 1, TGF beta 2 and TGF-RI.

UV-induced signaling pathways associated with corneal epithelial cell apoptosis.

Purpose: UV-C irradiation of corneal epithelial cells elicits K+ channel activation, which in turn causes them to undergo apoptosis. In the present study, the intermediary role played by mitogen-activated protein kinase (MAPK) signaling pathways in mediating this response was investigated.

Methods: Western blot and kinase assays were used to measure UV-induced activation (i.

UV-induced corneal epithelial cell death by activation of potassium channels.

Purpose: The purpose of the present study is to determine the role of K+ channel activity as an early event in UV-induced corneal epithelial cell apoptosis.

Method: Both cell-attached and nystatin-perforated patch-clamping were performed to record K+ channel activity in rabbit corneal epithelial (RCE) and primary cultured rabbit corneal epithelial (PRCE) cells exposed to UV irradiation. On exposure of corneal epithelial cells or intact corneas to UV-C irradiation or treatment of corneal epithelial cells with etoposide, cell apoptosis was determined by DNA fragmentation, ethidium bromide-acridine orange nuclear stain and TdT-mediated dUTP nick-end labeling (TUNEL).

Function of gamma-aminobutyric acid receptor/channel rho 1 subunits in spinal cord.

gamma-Aminobutyric acid (GABA) receptor/channel rho 1 subunits are important components in inhibitory pathways in the central nervous system. However, the precise locations and roles of these receptors in the central nervous system are unknown. We studied the expression localization of GABA receptor/channel rho 1 subunit in mouse spinal cord and dorsal root ganglia (DRG).

[An observation of the effects of recombinant human transforming growth factor beta3 on fibroblast].

Objective: To investigate the role of recombinant human transforming growth factor beta3 (rhTGFbeta3) on fibroblast and its possible mechanism.

Methods: Normal skin fibroblast (NSFb) and hypertrophic scar fibroblast (HSFb) were cultured in vitro, and were processed by different concentrations of rhTGFbeta3. NSFb and HSFb in DMEM solution without rhTGFbeta3 were employed as control.

Proteasome-dependent downregulation of p21(Waf1/Cip1) induced by reactive oxygen species.

After hydrogen peroxide (H(2)O(2)) treatment, the p21 (p21(Waf1/Cip1)) protein level in GM00637 fibroblast cells was rapidly decreased, reaching its nadir around 3 h. However, it rebounded within 5 hours to a level higher than that before treatment. Fluorescence microscopic analyses revealed that nuclear p21 was downregulated during the initial oxidative stress.

Interaction of GABA receptor/channel rho(1) and gamma(2) subunit.

Purpose: To determine whether protein-protein and functional interactions can occur between gamma-aminobutyric acid (GABA)(A) receptor/channels gamma(2) subunit and the retina-specific GABA(C) rho(1) subunit.

Methods: Protein-protein interaction was characterized by immunocoprecipitation of these subunits in brain and spinal cord with anti-gamma(2) subunit antibody and by Western blot analysis with anti-rho(1) subunit antibody. The rho(1) and gamma(2) subunits were detected in the adult rat brain and spinal cord lysates that had been previously precipitated with the specific antibodies against the rho(1) and gamma(2) subunits, respectively.

Ultraviolet-induced junD activation and apoptosis in myeloblastic leukemia ML-1 cells.

The exposure of mammalian cells to UV irradiation induces the expression of immediate early genes such as c-jun and c-fos and activates the transcription factors AP-1 and NF-kappaB. JunD is one of the three members of the Jun family and shares some functional characteristics with c-Jun. In the present study, we found that the exposure of myeloblastic leukemia ML-1 cells to UV light (UVC) caused a significant increase in junD mRNA expression within 5 min that persisted for a period of 3 h.

Traditional and modern characteristics across the generations: similarities and discrepancies.

The authors examined, through an analysis of self-construals and beliefs about social interaction, the traditional and modern orientations of younger and older generations of Taiwanese people. The authors surveyed 169 pairs of parent-child dyads with a battery of structured questionnaires. Within-subjects analyses revealed high generational correlations as well as discrepancies in both traditional and modern characteristics.

Demographic Variables, Control, Stress, Support and Health among the Elderly.

This article examines possible psychosocial factors that are expected to influence the health of community elderly people. A probability random sample of 240 Chinese elderly people living in a metropolitan Taiwanese city were interviewed at home. They answered questionnaires including measures for demographic variables (gender, age, marital status and education), locus of control, life stress, perceived social support and various indicators of physical and mental health.