Shingo Sakai

KIAA1199, a deafness gene of unknown function, is a new hyaluronan binding protein involved in hyaluronan depolymerization

Hyaluronan (HA) has an extraordinarily high turnover in physiological tissues, and HA degradation is accelerated in inflammatory and neoplastic diseases. CD44 (a cell surface receptor) and two hyaluronidases (HYAL1 and HYAL2) are thought to be responsible for HA binding and degradation; however, the role of these molecules in HA catabolism remains controversial. Here we show that KIAA1199, a deafness gene of unknown function, plays a central role in HA binding and depolymerization that is independent of CD44 and HYAL enzymes. The specific binding of KIAA1199 to HA was demonstrated in glycosaminoglycan-binding assays. We found that knockdown of KIAA1199 abolished HA degradation by human skin fibroblasts and that transfection of KIAA1199 cDNA into cells conferred the ability to catabolize HA in an endo-β-N-acetylglucosaminidase–dependent manner via the clathrin-coated pit pathway. Enhanced degradation of HA in synovial fibroblasts from patients with osteoarthritis or rheumatoid arthritis was correlated with increased levels of KIAA1199 expression and was abrogated by knockdown of KIAA1199. The level of KIAA1199 expression in uninflamed synovium was less than in osteoarthritic or rheumatoid synovium. These data suggest that KIAA1199 is a unique hyaladherin with a key role in HA catabolism in the dermis of the skin and arthritic synovium.

The gene responsible for borate cross-linking of pectin Rhamnogalacturonan-II is required for plant reproductive tissue development and fertilization

Deficiencies in boron, a microelement that is essential for the growth and development of higher plants, often cause problems in reproductive growth. Rhamnogalacturonan-II (RG-II) in cell wall pectin acts as the sole receptor for boron in plant cells, forming a borate cross-linked RG-II dimer (dRG-II-B), but the physiological functions of dRG-II-B remain unknown. We have previously shown that the pectin glucuronyltransferase 1 gene NpGUT1, which is involved in the biosynthesis of RG-II sugar chains, is essential for the formation of the RG-II-B complex, resulting in tight intercellular attachment in meristematic tissues. Because NpGUT1 expression was found to be abundant in reproductive organs in addition to meristematic tissues, we analyzed the expression and functions of NpGUT1 in more detail in tobacco reproductive tissues. Specific NpGUT1 expression was detected in the tapetum of flower buds and in the pollen, pollen tube tips, and transmitting tissue of the pistils of flowers. Dexamethasone-induced expression of the NpGUT1 antisense gene in flower buds resulted in the formation of sterile flowers with aberrant development of pollen and transmitting tissue. Pollen tubes could not pass through pistils with aborted transmitting tissue, and expression of an NpGUT1 antisense gene in germinating pollen inhibited pollen tube elongation, accompanied by the absence of pectin RG-II and boron in the pollen tube tip. These results indicate that expression of NpGUT1 is required for the development and functions of male and female tissues.

Induction of differentiation of human myeloid leukemia cells by jasmonates, plant hormones

Some regulators of plant growth and differentiation have been shown to induce the differentiation of several human myeloid leukemia cells, and might be effective as differentiation inducers to control acute myelogenous leukemia cells. In this study, the growth-inhibiting and differentiation-inducing effects of jasmonates on human myeloid leukemia cells were examined. Several myeloid leukemia cells were cultured with methyl jasmonate (MJ) and its derivatives. Cell differentiation was determined by nitroblue tetrazolium-reducing activity, morphological changes, α-naphthyl acetate esterase activity and expression of differentiation-associated surface antigens. MJ induced both monocytic and granulocytic differentiation of HL-60 cells. MJ activated mitogen-activated protein kinase (MAPK) in the cells before causing myelomonocytic differentiation. MAPK activation was necessary for MJ-induced differentiation, since PD98059, an inhibitor of MAPK kinase, suppressed the differentiation induced by MJ. MJ also induced the differentiation of other human leukemia cell lines. Introduction of a double bond at the 4,5-position greatly enhanced the differentiation-inducing activity of MJ. MJ and its derivatives potently induce the differentiation of some myelomonocytic leukemia cells. One novel derivative is a particularly promising therapeutic agent for the treatment of leukemia.

In vivo measurement of the water content in the dermis by confocal Raman spectroscopy

Background/purpose: Dermal water plays an important role in the physical properties of the skin. Recently, researchers have attempted to directly measure the dermal water content in vivo using magnetic resonance imaging, near infrared spectroscopy, and Raman spectroscopy. However, these methods have limitations. Although confocal Raman spectroscopy has been developed to measure the water content in the skin, no reports have suggested that this instrument can measure the dermal water content. This report describes a method for measuring the dermal water content in vivo using confocal Raman spectroscopy.

Automatic characterization and segmentation of human skin using three-dimensional optical coherence tomography

A set of fully automated algorithms that is specialized for analyzing a three-dimensional optical coherence tomography (OCT) volume of human skin is reported. The algorithm set first determines the skin surface of the OCT volume, and a depth-oriented algorithm provides the mean epidermal thickness, distribution map of the epidermis, and a segmented volume of the epidermis. Subsequently, an en face shadowgram is produced by an algorithm to visualize the infundibula in the skin with high contrast. The population and occupation ratio of the infundibula are provided by a histogram-based thresholding algorithm and a distance mapping algorithm. En face OCT slices at constant depths from the sample surface are extracted, and the histogram-based thresholding algorithm is again applied to these slices, yielding a three-dimensional segmented volume of the infundibula. The dermal attenuation coefficient is also calculated from the OCT volume in order to evaluate the skin texture. The algorithm set examines swept-source OCT volumes of the skins of several volunteers, and the results show the high stability, portability and reproducibility of the algorithm.

Characterization of the physical properties of the stratum corneum by a new tactile sensor.

Background/aims: The physical properties of the stratum corneum (SC) change with its water content, which is regulated by the presence of water solutes (natural moisturizing factors) and lipids in the SC, and are considered to be responsible for the induction of desquamation, skin surface roughness, and fine wrinkles. Recently a new type of tactile sensor developed for evaluating the physical properties of objects has been introduced as a simple, non‐invasive method to evaluate them; because the data obtained with this sensor have not yet been characterized in detail, we compared them with other physical parameters of the skin.

In vivo Three-Dimensional Birefringence Analysis Shows Collagen Differences between Young and Old Photo-Aged Human Skin

Polarization-sensitive optical coherence tomography (PS-OCT) permits non-invasive visualization of dermal birefringence, mainly due to collagenous structures. The purpose of this study is to use PS-OCT to assess intrinsic-age-related and photo-age-related differences in three-dimensional dermal birefringence. We measured dermal birefringence of the cheek skin and photo-protected interior upper arm skin from old and young volunteers. The algorithm that we used automatically produces the transversal dermal birefringence map from the polarization-sensitive OCT volume. This allowed quantitative comparison and visualization of the transverse distribution of the dermal birefringence. We found that dermal birefringence of the cheek skin was significantly smaller in the old group than in the young group (young group, 0.295+/-0.037 degrees microm(-1); old group, 0.207+/-0.03 degrees microm(-1); P=0.003), whereas the interior upper arm showed no age-dependent difference. The transversal map of the cheek showed a heterogeneous decrease in dermal birefringence due to photoaging. The maps suggested that the peripheral regions of some infundibula were surrounded by a strong collagen network. Three-dimensional analyses of dermal birefringence using PS-OCT help to quantify the diagnosis of photoaging.

Effects of active oxygen species and methyl jasmonate on expression of the gene for a wound-inducible 1-aminocyclopropane-1-carboxylate synthase in winter squash (Cucurbita maxima)

Abstract. The production of ethylene by mesocarp tissue of winter squash is induced by mechanical wounding. We isolated a cDNA fragment (WSACS2) from the wounded mesocarp tissue of winter-squash (Cucurbita maxima Duch.) fruit by the reverse transcriptase-polymerase chain reaction using primers that corresponded to two conserved amino acid sequences found in 1-aminocyclopropane-1-carboxylate (ACC) synthases. The sequence of WSACS2 cDNA was almost identical to that of the cDNA for a wound-inducible ACC synthase (CM-ACS1) reported by N. Nakajima et␣al. 1990, Plant Cell Physiol 31: 1021–1029, with only one nucleotide difference. The expression of the WSACS2 transcript in tissue disks was examined by Northern blotting analysis. The accumulation of WSACS2 mRNA in the wounded tissue disks was inhibited by treatment with diphenyleneiodonium, which is known as an inhibitor of superoxide-generating NAD(P)H oxidases. The addition of xanthine and xanthine oxidase, which form a superoxide-generating system, strongly induced the accumulation of the WSACS2 transcript within 30 min and the level of the transcript fell thereafter. We measured levels of active oxygen species that were generated in the tissue disks by using chemiluminescence reagents and found that the chemiluminescence signal became apparent within a few seconds after wounding. The synthesis of the WSACS2 transcript was slightly inhibited by inhibitors of lipoxygenase, which is involved in the synthesis of jasmonic acid. Methyl jasmonate stimulated the synthesis of the WSACS2 transcript in the tissue disks.

In vivo evaluation of human skin anisotropy by polarization-sensitive optical coherence tomography

Abstract We performed an in vivo three-dimensional analysis of anisotropic changes in the dermal birefringence of mechanically deformed human skin using polarization-sensitive optical coherence tomography (PS-OCT). The papillary-dermal birefringence of the forehead increased significantly when the skin was shrunk parallel to the body axis, and decreased significantly when the skin was shrunk perpendicular to the body axis. En-face images of the papillary-dermal birefringence revealed variations among individual subjects, and that both shrinking parallel to and stretching in perpendicular to the body axis promoted the formation of macro rope-like birefringent domains. We found that PS-OCT is useful for understanding anisotropic properties of collagen structure in the skin.

Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography

Polarization-sensitive optical coherence tomography (PS-OCT) is known to be advantageous because of its additional tissue-specific contrast of the anterior eye. So far, this advantage has been shown only qualitatively. We evaluate the improved visibility afforded by 3-D PS corneal and anterior eye segment OCT (PS-CAS-OCT) in visualizing the trabecular meshwork (TM) based on statistical evidences. A total of 31 normal subjects participated in this study. The anterior eye segments of both the eyes of the subjects are scanned using a custom-made PS-CAS-OCT and the standard-scattering OCT (S-OCT) and polarization-sensitive phase-retardation OCT (P-OCT) images are obtained. Three graders grade the visibility of the TM using a four-leveled grading system. The intergrader agreement, intermodality differences, and interquadrant dependence of visibility are statistically examined. All three of three combinations of graders show substantial agreement in visibility with P-OCT (ρ = 0.74, 0.70, and 0.68, Spearmans correlation), while only one of three shows substantial agreement with S-OCT (ρ = 0.72). Significant dependence of the visibility on the modality (S-OCT versus P-OCT) and quadrants are found by the analysis of variance. A subsequent Wilcoxon signed-rank test reveals significantly improved visibility. PS-CAS-OCT may become a useful tool for screening angle-closure glaucoma.