Modulation of L-type Ca²⁺ channel activity by neuronal nitric oxide synthase and myofilament Ca²⁺ sensitivity in cardiac myocytes from hypertensive rat

Neuronal nitric oxide synthase (nNOS) is important in cardiac protection in diseased heart. Recently, we have reported that nNOS is associated with myofilament Ca(2+) desensitization in cardiac myocytes from hypertensive rats. So far, the effect of myofilament Ca(2+) desensitization or nNOS on L-type Ca(2+) channel activity (I(Ca)) in cardiac myocyte is unclear. Here, we examined nNOS regulation of I(Ca) in left ventricular (LV) myocytes from sham and angiotensin II (Ang II)-induced hypertensive rats. Our results showed that basal I(Ca) was not different between sham and hypertension (from -60 to +40 mV, 0.1 Hz). S-methyl-L-thiocitrulline (SMTC), a selective nNOS inhibitor, increased peak I(Ca) similarly in both groups. However, chelation of intracellular Ca(2+) [Ca(2+)]i with BAPTA increased I(Ca) and abolished SMTC-augmentation of I(Ca) only in hypertension. Myofilament Ca(2+) desensitization with butanedione monoxime (BDM), a myosin ATPase inhibitor, decreased I(Ca) in both groups but to a greater extent in hypertension. Intracellular BAPTA or nNOS inhibition reinstated I(Ca) in the presence of BDM to the basal level, suggesting Ca(2+)-dependent inactivation of I(Ca) by nNOS and greater vulnerability in hypertension. Increasing stimulation frequencies (2, 4 and 8 Hz) attenuated myofilament Ca(2+) sensitivity in sham and reduced peak ICa in both groups. Nevertheless, SMTC or BAPTA exerted no effect on I(Ca) at high frequencies in either group. These results suggest that nNOS attenuates I(Ca) via Ca(2+)-dependent mechanism and the vulnerability is greater in hypertension subject to myofilament Ca(2+) desensitization. nNOS or [Ca(2+)]i does not affect I(Ca) at high stimulation frequencies. The results were recapitulated with computer simulation.

First Report of Cherry necrotic rusty mottle virus Infecting Sweet Cherry Trees in Korea

Cherry necrotic rusty mottle virus (CNRMV), an unassigned member in the family Betaflexiviridae, has been reported in sweet cherry in North America, Europe, New Zealand, Japan, China, and Chile. The virus causes brown, angular necrotic spots, shot holes on the leaves, gum blisters, and necrosis of the bark in several cultivars (1). During the 2012 growing season, 154 sweet cherry trees were tested for the presence of CNRMV by RT-PCR. Samples were randomly collected from 11 orchards located in Gyeonggi and Gyeongsang provinces in Korea. RNA was extracted from leaves using the NucliSENS easyMAG system (bioMérieux, Boxtel, The Netherlands). The primer pair CGRMV1/2 (2) was used to amplify the coat protein region of CNRMV. Although none of the collected samples showed any notable symptoms, CNRMV PCR products of the expected size (949 bp) were obtained from three sweet cherry samples from one orchard in Gyeonggi province. The PCR products were cloned into a pGEM-T easy vector (Promega, Madison, WI) and sequenced. BLAST analyses of the three Korean sequences obtained (GenBank Accession Nos. AB822635, AB822636, and AB822637) showed 97% nucleotide sequence identity with a flowering cherry isolate from Japan (EU188439), and shared 98.8 to 99.6% nucleotide and 99.6 to 100% amino acid similarities to each other. The CNRMV positive samples were also tested for Apple chlorotic leaf spot virus (ACLSV), Cherry mottle leaf virus (CMLV), Cherry rasp leaf virus (CRLV), Cherry leafroll virus (CLRV), Cherry virus A (CVA), Little cherry virus 1 (LChV-1), Prune dwarf virus (PDV), and Prunus necrotic ringspot virus (PNRSV) by RT-PCR. One of the three CNRMV-positive samples was also infected with CVA. To confirm CNRMV infection by wood indexing, Prunus serrulata cv. Kwanzan plants were graft-inoculated with chip buds from the CNRMV-positive sweet cherry trees. At 3 to 4 weeks post-inoculation, the Kwanzan plants showed quick decline with leaves wilting and dying; CNRMV infection of the indicators was confirmed by RT-PCR. To our knowledge, this is the first report of CNRMV infection of sweet cherry trees in Korea. Screening for CNRMV in propagation nurseries should minimize spread of this virus within Korea. References: (1) R. Li and R. Mock. Arch. Virol. 153:973, 2008. (2) R. Li and R. Mock. J. Virol. Methods 129:162, 2005.

Microarray analysis reveals increased expression of ΔNp63α in seborrhoeic keratosis

BACKGROUND

Seborrhoeic keratoses (SKs) are very common benign epidermal lesions without malignant potential. Ultraviolet radiation, old age and viruses are well-known risk factors for disease development. However, the pathomechanisms of SK are not fully understood.

OBJECTIVES

To detect and characterize the genes that are involved in the pathogenesis of SK.

METHODS

We performed a gene expression study using paired lesional and nonlesional skin samples from patients with SK.

RESULTS

We identified and validated 19 differentially expressed genes in SK. Of these 19 genes, we focused on p63 transcription factor, which plays a pivotal role in epidermal development by regulating its transcriptional programme. We found by immunofluorescence that the expression of ΔNp63α, the most abundantly expressed p63 isoform, was significantly increased in SK as compared with normal skin. Moreover, siRNA-mediated knockdown of ΔNp63 led to the downregulation of 11 genes, including a member of the tensin family TNS4. Chromatin immunoprecipitation assay revealed that TNS4 was a target gene of p63.

CONCLUSIONS

We identified upregulated genes in SK using genome-wide cDNA microarray and elucidated the functional contribution of p63 to the disease transcriptome by gene-silencing assay. Taken together, these data may provide a novel insight into the molecular basis of these benign skin lesions.

Inhibition of Ca2+-release-activated Ca2+ channel (CRAC) and K+ channels by curcumin in Jurkat-T cells

The increase in cytoplasmic Ca(2+) concentration (Δ[Ca(2+)](c)) mediated by the Ca(2+)-release-activated Ca(2+) channel (CRAC) is a critical signal for the activation of lymphocytes. Also, the voltage-gated K(+) channel (K(v)) and intermediate-conductance Ca(2+)-activated K(+) channel (IKCa1/SK4) have drawn attention as pharmacological targets for regulating immune responses. Since polyphenolic agents have various immunomodulatory effects, here we compared the effects of curcumin, rosmarinic acid, resveratrol, and epigallocatechin gallate on the ionic currents through CRAC (I(CRAC)), K(v) (I(Kv)), SK4 (I(SK4)) and on the Δ[Ca(2+)](c) of Jurkat-T cells using the patch clamp technique and fura-2 spectrofluorimetry. Curcumin (10 µM) inhibited store-operated Ca(2+) entry (SOCE). Consistently, dose-dependent inhibition of I(CRAC) by curcumin was confirmed in Jurkat-T (IC(50), 5.9 µM) and the HEK293 cells overexpressing Orai1 and STIM1 (IC(50), 0.6 µM). Also, curcumin inhibited both I(Kv) (IC(50), 11.9 µM) and I(SK4) (IC(50), 4.2 µM). The other polyphenols (rosmarinic acid, resveratrol, and epigallocatechin gallate at 10 - 30 µM) had no effect on SOCE and showed only a partial inhibition of the K(+) currents. In summary, among the tested polyphenolic agents, curcumin showed prominent inhibition of major ion channels in lymphocytes, which might contribute to the anti-inflammatory effects of curcumin. [Supplementary Figures: available only at http://dx.doi.org/10.1254/jphs.10209FP].

Exercise training increases inwardly rectifying K(+) current and augments K(+)-mediated vasodilatation in deep femoral artery of rats

AIMS

A moderate increase in extracellular [K(+)] ([K(+)](e)) induces relaxation of small arteries by activating inwardly rectifying K(+) current (I(Kir)). The K(+)-induced vasodilatation is an important mechanism for exercise-induced hyperaemia in skeletal muscle. We investigated whether I(Kir) and K(+)-induced vasodilatation are enhanced in deep femoral arteries (DFAs) from exercise-trained rats (ET rats; treadmill running for 20 min at 20 m/min, 3 days/week for 2 weeks). The effects of exercise training on K(+)-induced vasodilatation and I(Kir) were also investigated in cerebral (CA) and mesenteric arteries.

METHODS AND RESULTS

The K(+)-induced vasodilatation of DFAs and the density of I(Kir) and voltage-gated K(+) current (I(Kv)) were increased in DFA myocytes of ET rats. The myogenic tone of the DFA was unchanged by exercise. Although similar functional up-regulations of I(Kir) and I(Kv) were observed in CA myocytes, the K(+)-induced vasodilatation was not increased in the CA of ET rats. Interestingly, concomitant to the increases in I(Kir) and I(Kv), background Na(+) conductance was also increased in the CA myocytes. However, such an effect was not observed in DFA myocytes from ET rats. Neither I(Kir) nor K(+)-induced vasodilatation was observed in mesenteric arteries of ET rats.

CONCLUSION

The present study provides evidence that regular exercise up-regulates I(Kir) in DFA and CA myocytes. Although the increase in I(Kir) was observed in two types of arteries, augmentation of K(+)-induced relaxation was observed only in the DFA of ET rats, possibly due to the increased Na(+) conductance in CA myocytes. The increases in I(Kir) and K(+)-induced vasodilatation of the arteries of skeletal muscle suggest novel mechanisms of improved exercise hyperaemia with physical training.

Tob is a potential marker gene for the basal layer of the epidermis and is stably expressed in human primary keratinocytes

BACKGROUND

Epidermis consists of multiple layers, from the proliferating basal layer to terminal differentiated cornified layers, and these layers are defined by differentiation status. Tob gene product is known to be a member of the BTG antiproliferative protein family. We investigated the expression pattern of Tob gene product to understand the possible role in differentiation of keratinocytes and epidermis.

OBJECTIVES

In this study, we examined the expression of Tob gene product in the primary cultured human keratinocytes and in the in vivo epidermis.

METHODS

The expression of Tob gene product was assessed by Western blotting analysis. Cellular localization of Tob was detected using the green fluorescent protein-tagged Tob cDNA expression construct. In vivo expression of Tob gene product in the epidermis was determined by immunohistochemistry with paraffin sections.

RESULTS

Tob family members are degraded by the ubiquitine-proteasome system triggered by the growth signal. Tob is stably and abundantly expressed in primary cultured human keratinocytes. Furthermore, the expression of Tob in the keratinocytes persists during the differentiation induced by calcium; however, it was not detected in primary cultured fibroblasts. Also, the subcellular localization of Tob is mainly in the cellular membrane in the primary human keratinocytes. We evaluated Tob expression in normal skin, oral mucosa and different diseases, such as psoriasis, X-linked ichthyosis and squamous cell carcinoma (SCC). Using immunohistochemical analysis, we observed that Tob was selectively expressed in the basal layer of X-linked ichythyosis and the hyperproliferative basal layer of psoriasis and oral mucosa as well as in normal epidermis. In SCC, the expression of Tob gene product was relatively decreased.

CONCLUSIONS

Tob is stably expressed in primary human keratinocytes and it is specifically expressed in the basal layer of in vivo epidermis.

Analysis of genes responding to ultraviolet B irradiation of HaCaT keratinocytes using a cDNA microarray

BACKGROUND

Ultraviolet (UV) B irradiation causes many important biological changes in skin, which lead to pathophysiological alterations of the homeostatic environment.

OBJECTIVES

To gain more insight into the molecular events provoked by UVB irradiation, we performed cDNA microarray analysis.

METHODS

Immortalized HaCaT keratinocytes were irradiated with a high cytotoxic dose of UVB (50 mJ cm(-2)), and total RNA was isolated. Fluorescently labelled probes were prepared by reverse transcription and were hybridized with cDNA microarray slides made using 840 cDNA clones.

RESULTS

Time-course cDNA microarray analysis revealed the global gene expression profile after UVB exposure. Of 840 genes tested, 192 genes showed changes in their expression levels at one or more of four time points. The genes were clustered into four groups according to their expression patterns in a self-organizing maps analysis. Classification of these genes into nine functional categories revealed that UVB irradiation affected several biological processes. The genes that were first upregulated and then returned to normal levels included several genes related to the inhibition of cell growth and the proteasome pathway. Conversely, the expressions of many genes involved in the cytoskeleton, signal transduction, metabolism and transcription were first downregulated or unchanged and then upregulated later, reflecting the recovery of UVB-damaged cellular activities.

CONCLUSIONS

These results demonstrate the complexity of the transcriptional profile of the UVB response, and provide a basis for the global characterization of UV-regulated gene expression.