Toyoko Kawate

Multiple Primary Cilia Modulate the Fluid Transcytosis in Choroid Plexus Epithelium

Functional defects in cilia are associated with various human diseases including congenital hydrocephalus. Previous studies suggested that defects in cilia not only disrupt the flow of cerebrospinal fluid (CSF) generated by motile cilia in ependyma lining the brain ventricles, but also cause increased CSF production at the choroid plexus. However, the molecular mechanisms of CSF overproduction by ciliary dysfunction remain elusive. To dissect the molecular mechanisms, choroid plexus epithelial cells (CPECs) were isolated from porcine brain. These cells expressed clusters of primary cilia on the apical surface. Deciliation of CPECs elevated the intracellular cyclic AMP (cAMP) levels and stimulated basolateral‐to‐apical fluid transcytosis, without detrimental effects on other morphological and physiological features. The primary cilia possessed neuropeptide FF (NPFF) receptor 2. In deciliated cells, the responsiveness to NPFF was reduced at nanomolar concentrations. Furthermore, CPECs expressed NPFF precursor along with NPFFR2. An NPFFR antagonist, BIBP3226, increased the fluid transcytosis, suggesting the presence of autocrine NPFF signaling in CPECs for a tonic inhibition of fluid transcytosis. These results suggest that the clusters of primary cilia in CPECs act as a sensitive chemosensor to regulate CSF production.

Signaling through the primary cilium affects glial cell survival under a stressed environment.

Sensing extracellular milieu is a fundamental requirement of cells. To facilitate and specify sensory reception, mammalian cells develop an antenna‐like structure denoted as the primary cilia. Nearly all interphase and nondividing cells in vertebrates have a single, nonmotile seemingly unspecialized cilium (called a primary cilium). In the central nervous system, astrocytes express primary cilia, but their function in astrocytes has not been examined. Recent studies have shown that primary cilia unite receptors and the machinery of signal‐transduction components, such as Wnt and Hedgehog (Hh) signaling cascades. Although, Hh signaling cascades are known to be activated in various cells during development, their physiological functions in the adult nervous system, especially in glial cells, are still unknown. In this study, we reveal that glial primary cilia receive the Hh signal and regulate the survival of astrocytes under stressed conditions such as starvation. Interestingly, increased astrocyte survival was reversed by knockdown of Ift20, which is one of the main components for building primary cilia. These results collectively indicate that the activation of Hh signaling in the primary cilia plays an important role in the survival of astrocytes under stressed conditions.

Immunohistochemical demonstration of the calcium channel α2 subunit in the chicken dorsal root ganglion and spinal cord : A special reference to colocalization with calbindin-D28k in dorsal root ganglion neurons

We used immunohistochemical methods to examine the distribution of the calcium channel alpha2 (CCalpha2) subunit in the chicken spinal cord and dorsal root ganglion (DRG) neurons and determine its relationship with calbindin-D28k (CB) in the DRG neurons. In the spinal cord, CCalpha2 subunit was detected in nerve terminals, which were observed as dot-like structures, and in laminae I, II, III and Lissauers tract in the dorsal horn. In the DRG neurons, approximately 65% of the total neurons were CCalpha2 subunit positive, and most (86%) of these neurons were small to medium sized, suggesting that the CCalpha2 subunit and/or a complex of the CCalpha2 and delta subunits is possibly localized in a number of nociceptive neurons. A majority (77%) of the positive neurons showed CB immunoreactivity and most (88%) of these neurons were small to medium sized. This may indicate a close correlation between the CCalpha2 subunit and CB in the nociceptive neurons. Thus, it is postulated that the mode of nociceptive transmission may involve a cellular Ca(2+)-regulating system that consists of both Ca(2+) entry via calcium channels with the alpha2delta subunit and intracellular Ca(2+)-binding activity of CB in the nociceptive neurons of the DRG.

Immunohistochemical study of delta and mu opioid receptors on synaptic glomeruli with substance P-positive central terminals in chicken dorsal horn

In an attempt to clarify the mechanism underlying the regulation of the release of substance P (SP) from the central axon terminals of the synaptic glomeruli in lamina II of the dorsal horn, we examined the expression patterns of delta and mu opioid receptors (DOR and MOR) in relation to those of enkephalin (ENK) and SP in the synaptic glomeruli. DOR, MOR, ENK and SP immunoreactivities in lamina II of the dorsal horn in the chicken were examined by confocal laser scanning and electron microscopies. DOR immunoreactivity was localized in both SP-positive central terminals and peripheral elements, while MOR immunoreactivity was only localized in the peripheral elements of the synaptic glomeruli. Both of the peripheral DOR- and MOR-immunoreactive elements were shown to be vesicle-containing dendrites by electron microscopy. Dual immunohistochemistry indicated that DOR, MOR and ENK immunoreactivities were located in distinct peripheral elements. On the basis of present results, the possible roles of DOR and MOR in the regulation of the release of SP from the central axon terminals in the synaptic glomeruli are discussed.

Large-caliber persistent sciatic artery with aneurysm.

Herein is reported a rare case of right persistent sciatic artery (PSA) in the cadaver of a 96-year-old woman who did not have any clinical manifestations related to this anomaly when alive. The anomalous PSA originated from the internal iliac artery, directed toward the infrapiriform foramen, and descended the dorsal side of the thigh. Approximately 20 mm inferior to the infrapiriform foramen, the PSA formed a relatively large aneurysm elongating for approximately 30 mm in length. It then passed under the long head of the femoral biceps muscles, and reached the popliteal fossa, maintaining a constant caliber (approx. 13 mm) as it went down distally. In contrast, the femoral artery was very narrow, and tapered at the level of the knee joint. In addition, the popliteal vein gave rise to two branches, one ran along with the sciatic artery and the other pierced the adductor muscles, and appeared on the ventral side of the thigh. It then drained into the deep femoral vein, which reached the pelvis via the femoral vein. The present case is an interesting example for clinicians who work in pelvic surgery.

Histochemical Analysis of Renal Dysplasia with Ureteral Atresia

Unilateral small kidney with ureteral obstruction was discovered in a 74-year-old female cadaver during an anatomical dissection course. In order to elucidate the histogenesis of renal dysplasia, we carried out histochemical and immunohistochemical analyses. On macroscopic view, the kidney was approximately 3 cm in length, 2 cm in width and weighed only 9 g. Although the ureter ran from the renal hilus to the bladder, its width was under 2 mm. The renal parenchyma was extremely thin and there was a large congested vein in the renal sinus. On microscopic examination of the kidney, we observed that numerous developing renal tubules had cytokeratin-positive epithelia, most of which were surrounded by concentric fibrosis. However, we could not detect any structures resembling the collecting duct, renal tubules, renal pelvis, or glomeruli. The concentric mesencymal fibrous tissue surrounding the immature renal tubules contained the smooth muscles that were positive for h-caldesmon. Serial sections of the ureter revealed several small and discontinuous lacunae lined by cuboidal and transitional epithelium, which did not constitute a patent lumen through the bladder. This case is a rare case of renal dysplasia with defect in recanalization of the ureteral bud during the early developmental stage.

Rare multiple combined anomaly of the vertebral vessels and bronchial artery.

Reported herein is a rare case of multiple vascular anomalies involving the vertebral vessels and the bronchial artery. In the present case the vertebral artery, which normally originates from the subclavian artery, arose directly from the cranial side of the aortic arch, just between the left common carotid and subclavian artery. Furthermore, the bilateral entry of the vertebral artery deviated to the upper level of the transverse foramen of the cervical vertebrae (C5). In addition, the left vertebral vein went through the transverse canal via the 5th and 7th transverse foramen, and drained into the left venous angle. Another conspicuous variation observed in this cadaver was the bronchial artery stemming from the left subclavian artery. This phenotype is an additional branch of bronchial arteries, which in normal cases arises from the descending aorta. These two anomalies could be explained by the deviation of the anlage for the left subclavian artery. The present report should be of interest for the clinician with regard to vascular anomalies in the neck and thoracic region, and may give insight into elucidating the developmental mechanism of angiogenesis.

Physiological role of primary cilia in glial cells as a biosensor for the Hh signaling pathway

Cilia are evolutionary conserved organelles that are classified into either conventional (motile) or primary (nonmotile). Compared with the conventional cilia whose functions are well known, the physiological function and significance of primary cilia are largely unknown, except for its pivotal role in early vertebrate development. Recent studies have shown that primary cilia brought together receptors and signal transduction components, such as Wnt and Hedgehog (Hh) signaling pathway. Although previous studies have shown that molecules for Hh signaling cascade are active in various cells during development, their physiological functions in the nervous system, especially in glial cells, are still enigmatic. In this study, we identified primary cilia in several types of glial cells. Moreover, Hh signaling molecules were accumulated on the primary cilia. Our studies indicate that Hh signaling via primary cilia playa an important role in proliferation and survival of glial cells under stressed condition of the cell.

1925 Immunohistochemical study on leu-enkephalin immunoreactive neurons and nerve fibers in laminae i and ii of the chicken spinal cord

Leu-enkephalin immunoreactive (L-Enk-IR) neurons and nerve fibers in laminae I and nof the chicken dorsal horn were studied using anti-leu-enkephalin antiserum (UC6 Bioproducts) immunohistochemically (PAP technique) by light and electron microscopy. We observed three types of L-Enk-IR neurons and many fibers in laminae I and II. In the lamina 1, large GelIs extended dendrites in rostra-caudal direction. In the lamlna 1 , two kinds of neurons were observed. The one was large and was localized adjacent to the iamina N. The other was small and had dendrites extending rostrocaudally. The latter was scattered throughout the lamina II. L-Enk-IR nerve fibers were different in distribution and size between laminae 1 and II. L-Enk-IR fibers with varicosities in the lamina 1 were larger than those in the lamina n and bui It a network structure in dormlateral direction. In some cases these fibers extended along large unlabeled dendrites, and their varicosities were presynaptic to L-Enk-IR perikarya and dendrites. In the lamina a, smaller L-Enk-IR fibers with varicositiss extended rostrocaudally.