Pure platelet-rich plasma promotes semaphorin-3A expression: a novel insight to ameliorate intervertebral disk degeneration in vitro.

INTRODUCTION: Intervertebral disk degeneration (IVDD) can be effectively treated using platelet-rich plasma (PRP). While the exact process is fully understood, it is believed that using pure PRP (P-PRP) without leukocytes is a better option for preventing IVDD. Semaphorin-3A (Sema3A), an inhibitor of angiogenesis and innervation, is essential for preserving IVDD's homeostasis. Whether PRP prevents IVDD by modifying Sema3A has yet to receive much research. This work aims to clarify how P-PRP affects Sema3A when IVDD develops in vitro. METHODS: Nucleus pulposus cells (NPCs) isolated from 8-week-old male Sprague-Dawley rats were exposed to 10 ng/ml IL-1ß and then treated with P-PRP or leukocyte platelet-rich plasma (L-PRP) in vitro, followed by measuring cell proliferation, apoptosis and microstructures, inflammatory gene and Sema3A expression, as well as anabolic and catabolic protein expression by immunostaining, quantitative real-time polymerase chain reaction (qPCR), western blot, and enzyme-linked immunosorbent assay (ELISA). RESULTS: In comparison with L-PRP, P-PRP had a higher concentration of growth factors but a lower concentration of inflammatory substances. P-PRP increased the proliferation of NPCs, while IL-1 relieved the amount of apoptosis due to its intervention. Anabolic genes, aggrecan, and collagen II had higher expression levels. MMP-3 and ADAMTS-4, two catabolic or inflammatory genes, showed lower expression levels. Sema3A activity was enhanced after P-PRP injection, whereas CD31 and NF200 expression levels were suppressed. CONCLUSIONS: P-PRP enhanced the performance of NPCs in IVDD by modifying the NF-κB signaling pathway and encouraging Sema3A expression, which may offer new therapy options for IVDD. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: The findings provide a new therapeutic target for the treatment of IVDD and show a novel light on the probable mechanism of PRP and the function of Sema3A in the progression of IVDD.

Semaphorin-3A Promotes Degradation of Fragile X Mental Retardation Protein in Growth Cones via the Ubiquitin-Proteasome Pathway.

Fragile X mental retardation protein (FMRP) is an RNA-binding protein that regulates local translation in dendrites and spines for synaptic plasticity. In axons, FMRP is implicated in axonal extension and axon guidance. We previously demonstrated the involvement of FMRP in growth cone collapse via a translation-dependent response to Semaphorin-3A (Sema3A), a repulsive axon guidance factor. In the case of attractive axon guidance factors, RNA-binding proteins such as zipcode binding protein 1 (ZBP1) accumulate towards the stimulated side of growth cones for local translation. However, it remains unclear how Sema3A effects FMRP localization in growth cones. Here, we show that levels of FMRP in growth cones of hippocampal neurons decreased after Sema3A stimulation. This decrease in FMRP was suppressed by the ubiquitin-activating enzyme E1 enzyme inhibitor PYR-41 and proteasome inhibitor MG132, suggesting that the ubiquitin-proteasome pathway is involved in Sema3A-induced FMRP degradation in growth cones. Moreover, the E1 enzyme or proteasome inhibitor suppressed Sema3A-induced increases in microtubule-associated protein 1B (MAP1B) in growth cones, suggesting that the ubiquitin-proteasome pathway promotes local translation of MAP1B, whose translation is mediated by FMRP. These inhibitors also blocked the Sema3A-induced growth cone collapse. Collectively, our results suggest that Sema3A promotes degradation of FMRP in growth cones through the ubiquitin-proteasome pathway, leading to growth cone collapse via local translation of MAP1B. These findings reveal a new mechanism of axon guidance regulation: degradation of the translational suppressor FMRP via the ubiquitin-proteasome pathway.

Semaphorin 3A (SEMA3A), protocadherin 9 (PCdh9), and S100 calcium binding protein A3 (S100A3) as potential biomarkers of carcinogenesis and chemoresistance of different neoplasms, including ovarian cancer - review of literature.

Ovarian cancer is the fifth leading cause of cancer-related deaths in women. Its high mortality rate results from lack of adequate and sensitive methods allowing for the detection of the early stages of the disease, as well as low efficiency of the treatment, caused by the cytotoxic drug resistance of cancer cells. Unfortunately, tumours are able to develop new pathways and protective mechanisms that allow them to survive toxic conditions of chemotherapy. Therefore, intensive search for new genes and proteins involved in resistance to cytotoxic drugs is still needed, especially from a clinical point of view. The article presents an overview of the available literature on the role of semaphorin 3A (SEMA3A), protocadherin 9 (PCDH9), and S100 calcium binding protein A3 (S100A3) in carcinogenesis and chemoresistance of various tumors including ovarian cancer. As it turns out, the role of described genes/proteins is not limited only to their native biological activity but they function also as an oncogenic or suppressor factors in the tumor development. Moreover, they can also play an important role in development of drug resistance, as it was shown in ovarian cancer cell lines.

Wnt/ß-catenin signaling, which is activated in odontomas, reduces Sema3A expression to regulate odontogenic epithelial cell proliferation and tooth germ development.

Odontomas, developmental anomalies of tooth germ, frequently occur in familial adenomatous polyposis patients with activated Wnt/ß-catenin signaling. However, roles of Wnt/ß-catenin signaling in odontomas or odontogenic cells are unclear. Herein, we investigated ß-catenin expression in odontomas and functions of Wnt/ß-catenin signaling in tooth germ development. ß-catenin frequently accumulated in nucleus and/or cellular cytoplasm of odontogenic epithelial cells in human odontoma specimens, immunohistochemically. Wnt/ß-catenin signaling inhibited odontogenic epithelial cell proliferation in both cell line and tooth germ development, while inducing immature epithelial bud formation. We identified Semaphorin 3A (Sema3A) as a downstream molecule of Wnt/ß-catenin signaling and showed that Wnt/ß-catenin signaling-dependent reduction of Sema3A expression resulted in suppressed odontogenic epithelial cell proliferation. Sema3A expression is required in appropriate epithelial budding morphogenesis. These results suggest that Wnt/ß-catenin signaling negatively regulates odontogenic epithelial cell proliferation and tooth germ development through decreased-Sema3A expression, and aberrant activation of Wnt/ß-catenin signaling may associate with odontoma formation.

Semaphorin 3A Inhibits Nerve Regeneration During Early Stage after Inferior Alveolar Nerve Transection.

Neuroma formation at sites of injury can impair peripheral nerve regeneration. Although the involvement of semaphorin 3A has been suggested in neuroma formation, this detailed process after injury is not fully understood. This study was therefore undertaken to examine the effects of semaphorin 3A on peripheral nerve regeneration during the early stage after injury. Immunohistochemistry for semaphorin 3A and PGP9.5, a general neuronal marker, was carried out for clarify chronological changes in their expressions after transection of the mouse inferior alveolar nerve thorough postoperative days 1 to 7. At postoperative day 1, the proximal stump of the damaged IAN exhibited semaphorin 3A, while the distal stump lacked any immunoreactivity. From this day on, its expression lessened, ultimately disappearing completely in all regions of the transected inferior alveolar nerve. A local administration of an antibody to semaphorin 3A into the nerve transection site at postoperative day 3 inhibited axon sprouting at the injury site. This antibody injection increased the number of trigeminal ganglion neurons labeled with DiI (paired t-test, p < 0.05). Immunoreactivity of the semaphorin 3A receptor, neuropilin-1, was also detected at the proximal stump at postoperative day 1. These results suggest that nerve injury initiates semaphorin 3A production in ganglion neurons, which is then delivered through the nerve fibers to the proximal end, thereby contributes to the inhibition of axonal sprouting from the proximal region of injured nerves in the distal direction. To our knowledge, this is the first report to reveal the involvement of Sema3A in the nerve regeneration process at its early stage.

Substance P restores normal skin architecture and reduces epidermal infiltration of sensory nerve fiber in TNCB-induced atopic dermatitis-like lesions in NC/Nga mice.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disorder characterized by intense pruritus and eczematous lesion. Substance P (SP) is an 11-amino-acid endogenous neuropeptide that belongs to the tachykinin family and several reports recently have supported the anti-inflammatory and tissue repairing roles of SP. OBJECTIVE: In this study, we investigated whether SP can improve AD symptoms, especially the impaired skin barrier function, in 2, 4, 6-trinitrochlorobenzene (TNCB)-induced chronic dermatitis of NC/Nga mice or not. METHOD: AD-like dermatitis was induced in NC/Nga mice by repeated sensitization with TNCB for 5 weeks. The experimental group designations and topical treatments were as follows: vehicle group (AD-VE); SP group (AD-SP); and SP with NK1R antagonist CP99994 (AD-SP-A) group. Histological analysis was performed to evaluate epidermal differentiation, dermal integrity, and epidermal nerve innervation in AD-like lesions. The skin barrier functions and pruritus of NC/Nga mice were evaluated by measuring transepidermal water loss (TEWL) and scratching behavior, respectively. RESULT: Topical SP treatment resulted in significant down-regulation of Ki67 and the abnormal-type keratins (K) K6, K16, and K17, restoration of filaggrin and claudin-1, marked reduction of TEWL, and restoration of basement membrane and dermal collagen deposition, even under continuous sensitization of low dose TNCB. In addition, SP significantly reduced innervation of itch-evoking nerve fibers, gelatinase activity and nerve growth factor (NGF) expression in the epidermis but upregulated semaphorin-3A (Sema3A) expression in the epidermis, along with reduced scratching behavior in TNCB-treated NC/Nga mice. All of these effects were completely reversed by co-treatment with the NK1R antagonist CP99994. In cultured human keratinocytes, SP treatment reduced expression of TGF-α, but upregulated TGF-ß and Sema3A. CONCLUSION: Topically administered SP can restore normal skin barrier function, reduce epidermal infiltration of itch-evoking nerve fibers in the AD-like skin lesions, and alleviate scratching behavior. Thus, SP may be proposed as a potential medication for chronic dermatitis and AD.

Association of Plasma Semaphorin 3A With Phenotypes of Diabetic Retinopathy and Nephropathy.

PURPOSE: To investigate whether diabetic retinopathy phenotypes and albuminuria are associated with the overexpression of plasma semaphorin 3A (Sema3A). METHODS: The study group with severe nonproliferative diabetic retinopathy (NPDR) or proliferative diabetic retinopathy (PDR), the diabetes without diabetic retinopathy group, and the control group without diabetes consisted of all consecutive patients who were scheduled to undergo intravitreal bevacizumab injection for treatment-naïve diabetic macular edema (DME) and senile cataract surgery, respectively. In all subjects, the plasma Sema3A levels before intravitreal bevacizumab injections or cataract surgery were measured by enzyme-linked immunosorbent assay. In the patients with DME, the capillary nonperfusion area (measured by fluorescein angiography), total macular volume (measured by spectral-domain optical coherence tomography), and the urine albumin-to-creatinine ratio were determined. RESULTS: Severe NPDR (57 eyes) and PDR groups (51 eyes) both had significantly higher Sema3A levels than the control (58 eyes) and diabetes without diabetic retinopathy groups (54 eyes) (P < 0.001). Moreover, the PDR group had higher Sema3A levels than the severe NPDR group (P < 0.001). Plasma Sema3A levels correlated positively with the retinal nonperfusion area size (r = 0.844, P = 0.004), total macular volume (r = 0.765, P = 0.005), and the urine albumin-to-creatinine ratio (r = 0.752, P < 0.001). When DME patients were divided into normo-, micro-, and macroalbuminuria groups, the macroalbuminuria group had significantly higher plasma Sema3A levels than the microalbuminuria group or the normoalbuminuria group (P = 0.002 and P < 0.001, respectively). CONCLUSIONS: The plasma Sema3A levels correlated significantly with the phenotypes of diabetic retinopathy and albuminuria. This suggests that Sema3A may be a potential biomarker for diabetic retinopathy and nephropathy.

miR-30c and semaphorin 3A determine adult neurogenesis by regulating proliferation and differentiation of stem cells in the subventricular zones of mouse.

OBJECTIVES: Mechanisms that regulate proliferation of adult neural stem cells are largely unknown. Here, we have investigated the role of microR-30c (miR-30c) and its target, semaphoring 3A (sema3A), in regulating adult neurogenesis and mechanisms underlying this process. MATERIALS AND METHODS: In situ hybridization, immunofluorescence and quantitative real-time PCR were used to assess complementary expression patterns of miR-30c and sema3A in mice. Effects of miR-30c in the subventricular zone (SVZ) were examined by stereotaxic injection of up- and down-regulating lentiviruses. 5'-bromo-2'-deoxyuridine labelling was performed to investigate effects of miR-30c and sema3A on adult neurogenesis. Real-time cell assays, morphological analysis and cell cycle measurements were used to reveal the mechanisms by which miR-30c and sema3A regulate adult neurogenesis. RESULTS: Expression of miR-30c negatively correlated with that of sema3A in neurons, and levels of miR-30c and sema3A correlated positively with numbers of newborn cells in the SVZ and rostral migration stream. miR-30c and sema3A affected adult neurogenesis by regulating proliferation and differentiation, as well as cycles of stem cells in the SVZ. CONCLUSIONS: miR-30c and sema3A regulate adult neurogenesis by controlling proliferation and differentiation of stem cells in the SVZ. This finding reveals a novel regulatory mechanism of adult neurogenesis.

Effects of angiotensin II type I receptor blocker losartan on orthodontic tooth movement.

INTRODUCTION: Drugs that block the renin-angiotensin system (RAS) are widely used for treating hypertension, heart and kidney failure, and the harmful effects of diabetes. Components of the RAS have been identified in various organs, but little is known of their effects on bone remodeling. The aim of this study was to evaluate whether the blockage of the RAS influences strain-induced bone remodeling in a model of orthodontic tooth movement. METHODS: An orthodontic appliance was placed in C57BL6/J mice that were randomly divided into 2 groups: vehicle-treated mice (VH) and mice treated with losartan (an angiotensin II receptor blocker). Orthodontic tooth movement and the number of tartrate-resistant acid phosphatase-positive cells were determined by histopathologic analysis. The expression of mediators involved in bone remodeling was evaluated by quantitative real-time polymerase chain reaction. Blood pressure was measured before and during the experimental period. RESULTS: Orthodontic tooth movement and tartrate-resistant acid phosphatase-positive cells were significantly reduced in the losartan group compared with the VH group. mRNA levels of osteoclast markers (RANK, RANKL, cathepsin K, and metalloproteinase 13) were lower in the losartan mice than in the VH group, whereas the expressions of osteoblast markers and negative regulators of bone resorption (periostin, dentin matrix protein, alkaline phosphatase, collagen 1A1, semaphorin 3A3, metalloproteinase 2, and osteoprotegerin) were higher in the VH group. CONCLUSIONS: Blockage of the RAS system decreases osteoclast differentiation and activity and, consequently, results in decreased strain-induced bone remodeling in orthodontic tooth movement.

The Involvement of Immune Semaphorins in the Pathogenesis of Inflammatory Bowel Diseases (IBDs).

BACKGROUND AND AIMS: Immune semaphorins are a large family of proteins involved in the pathogenesis of inflammatory diseases through the regulation of immune homeostasis and tissue inflammation. We aim to assess the possible involvement of semaphorin3A (sema3A) and 4A (sema4A) in peripheral immune responses and bowel tissue inflammation of patients suffering from Crohn's disease (CD) and ulcerative colitis (UC). PATIENTS AND METHODS: Twenty-seven CD patients and 10 UC patients were studied and compared to 10 patients followed for acute diverticulitis (disease control) and 12 healthy individuals. All were evaluated for sema3A expression on T regulatory cells (Tregs), serum levels of sema3A and sema4A, and tissue expression of sema3A and sema4A in bowel biopsies. RESULTS: The percentage (%) of T regulatory cells (Tregs) expressing sema3A in patients with active CD (64.5% ± 14.49%) and active UC (49.8% ± 16.45%) was significantly lower when compared to that of healthy controls (88.7% ± 3.6%, p< 0.001 and p< 0.0001, respectively). This expression was seen to be in negative correlation with CD activity. Serum levels of Sema4A were significantly lower in patients with CD and UC when compared to that of controls (5.69 ± 1 .48 ng\ml for CD, 5.26 ± 1.23 ng/ml for UC patients vs 9.74 ± 2.73 ng/ml for normal controls, P<0.001). Sema4A was highly expressed in lymphocytes of the lamina propria of CD and UC patients but absent in patients with diverticulitis or in normal individuals. CONCLUSIONS: Altered % of Tregs expressing sema3A in patients with inflammatory bowel diseases (IBD) is partially responsible for their failure in preventing CD4+ effector T cell induced inflammation in IBD in peripheral blood. The increased expression of sema4A in bowel biopsies from CD and UC patients is suggestive of its central role in regulating local tissue inflammation in the bowel.

[The effect of semaphorin 3A in the process of apoptosis in oxygen induced retinopathy in rats].

OBJECTIVE: To observe the change of semaphorin 3A (SEMA3A) expression in the retina of oxygen induced retinopathy (OIR) in rats and to investigate its influence on retinal degeneration in OIR. METHODS: Experimental study. Forty-eight newborn pups were randomly classified into four groups and only one eye was examined in each pup. Thirty-six pups was induced into OIR model through aspirating 50% and 10% oxygen every 24 hours alternatively while the control group (12 pups) was raised under normal atmosphere. OIR+SEMA3Aab group accepted intravitreous injection of rabbit anti-rat SEMA3A antibody (Abcam Co.LTD, 40 mg/L, 2 µl) while OIR+IgG group was injected the same amount of non-active rabbit IgG at postnatal day 7. And the OIR group had no injections. All the pups were executed at postnatal day 18. Histological changes of retinas were examined through HE stain while Immunoflurecence staining and TUNEL procedure were used to detect focal expression of SEMA3A and apoptosis respectively. Total tissue protein was extracted and the expression of SEMA3A and Caspase-3 p17subunit were examined by Western blot. The data including retinal thickness, cell counting of retinal ganglion cells layers (RGCL) , endothelia outside inner limiting membrane, retinal apoptosis index (AI), the relative expression of SEMA3A and Caspase3 p17 subunit were analyzed by One-way ANOVA and followed LSD-t test to compare group differences. RESULTS: There were significant differences of retinal thickness, cell counting of RGCL and endothelia outside inner limiting membrane among each groups respectively (F = 13.222, F = 22.537, F = 14.478;P < 0.01) . The retinal thickness was (117.07 ± 8.13) µm in normal control group, (70.93 ± 5.68) µm in OIR group, (91.28 ± 4.58) µm in OIR+SEMA3Aab group, and (67.27 ± 10.15) µm in OIR+IgG group; the cell counting of RGCL was 42.7 ± 3.6 in normal control group, 24.3 ± 3.1 in OIR group, 35.0 ± 6.2 in OIR+SEMA3Aab group, and 22.8 ± 4.3 in OIR+IgG group while the endothelia outside inner limiting membrane was 1.0 ± 0.3 in normal control group, 14.2 ± 3.2 in OIR group, 9.6 ± 1.1 in OIR+SEMA3Aab group, and 10.8 ± 1.6 in OIR+IgG group. The retinal thickness and cell counting of RGCL in OIR+SEMA3Aab group were significantly lower than those in the normal control group (P < 0.01) , but were apparently higher than the data of OIR group and OIR+IgG group respectively (P < 0.01) . There were no more endothelia on the vitreal side of the inner limiting membrane in OIR+SEMA3Aab group than OIR group or OIR+IgG group (P > 0.05) although these three groups had much more endothelia than it in the normal control group (P < 0.01). The retinal AI detected by TUNEL staining was 27.67 ± 2.51 in normal control, 58.33 ± 8.50 in OIR group, 37.33 ± 5.03 in OIR+SEMA3Aab group and 61.67 ± 6.65 in OIR+IgG group. There was significant difference of the retinal AI among the four groups (F = 19.250, P = 0.001) . Apoptotic cells were significantly reduced in OIR+SEMA3Aab group compared with OIR + IgG group or OIR group (P < 0.01). The difference of SEMA3A protein expression among the groups detected by Western blot was significant (F = 38.59, P = 0.000) . SEMA3A expression in OIR group was 0.97 ± 0.05, which was significantly upregulated compared with the normal control group (0.64 ± 0.03) ( P < 0.01) . And its expression was successfully neutralized in OIR + SEMA3Aab group (0.41 ± 0.02) with comparison with OIR+IgG group (1.03 ± 0.15) through Western blot (P < 0.01) . SEMA3A was detected apparently in the photoreceptors layer in the normal control while its fluorescence was stronger and much more scattered in the whole retina. However, anti-SEMA3Aab intravitreous injection successfully reduced its fluorescence compared with the IgG injection. The cleavage of Caspase-3 was not detected in the normal control while the relative expression of Caspase-3 p17 subunit was significantly different in the other three groups (F = 304.619, P < 0.01). OIR + SEMA3Aab group had much less Caspase-3 p17 subunit (0.12 ± 0.01) than OIR group (0.30 ± 0.02) or OIR +IgG group (0.27 ± 0.02) (P < 0.01) . CONCLUSIONS: The over regulation of SEMA3A probably enhances the aggravation of apoptosis in OIR rats. Inhibition of SEMA3A is helpful to protect neuroretina.

Urinary semaphorin 3A correlates with diabetic proteinuria and mediates diabetic nephropathy and associated inflammation in mice.

Semaphorin 3A (sema3A) was recently identified as an early diagnostic biomarker of acute kidney injury. However, its role as a biomarker and/or mediator of chronic kidney disease (CKD) related to diabetic nephropathy is unknown. We examined the expression of sema3A in diabetic animal models and in humans and tested whether sema3A plays a pathogenic role in the development of diabetic nephropathy. The expression of sema3A was localized to podocytes and epithelial cells in distal tubules and collecting ducts in control animals, and its expression was increased following the induction of diabetes. Quantification of sema3A urinary excretion in three different diabetic mouse models showed that excretion was increased as early as 2 weeks after the induction of diabetes and increased over time, in conjunction with the development of nephropathy. Consistent with the mouse data, increased sema3A urinary excretion was detected in diabetic patients with albuminuria, particularly in those with macroalbuminuria. Genetic ablation of sema3A or pharmacological inhibition with a novel sema3A inhibitory peptide was protected against diabetes-induced albuminuria, kidney fibrosis, inflammation, oxidative stress, and renal dysfunction. We conclude that sema3A is both a biomarker and a mediator of diabetic kidney disease and could be a promising therapeutic target in diabetic nephropathy. Key messages Diabetes induced sema3A excretion in urine. Increased semaphorin 3A was associated with severity of albuminuria. Seme3A-mediated diabetes induced glomerulosclerosis. Peptide-based inhibition of semaphorin3A suppressed diabetic nephropathy.

Decreased semaphorin3A expression correlates with disease activity and histological features of rheumatoid arthritis.

BACKGROUND: Rheumatoid arthritis (RA) is an autoimmune disease of which the pathogenetic mechanisms are not fully understood. Semaphorin3A (Sema3A) has an immune regulatory role. Neuropilin1 (NRP1), the primary receptor for Sema3A, is also a receptor for vascular endothelial growth factor 165 (VEGF 165). It has been shown that Sema3A competitively antagonizes VEGF 165 signaling. This study investigated whether Sema3A is expressed in synovial tissues, and is associated with disease activity and the histological features of synovial tissues from RA patients. METHODS: Human synovial tissues samples were obtained from RA and osteoarthritis (OA) patients. Disease activity of RA patients was calculated using the 28-joint Disease Activity Score based on C-reactive protein (DAS28-CRP). The histological features of RA synovial tissues were evaluated using Rooney's inflammation scoring system. The localization of Sema3A, VEGF 165 and NRP1 positive cells was immunohistochemically determined in synovial tissues. Expression levels of Sema3A, VEGF-A and NRP1 mRNA were determined using quantitative real-time polymerase chain reaction (qPCR). RESULTS: In OA specimens, Sema3A, VEGF 165 and NRP1 proteins were expressed in the synovial lining and inflammatory cells beneath the lining. Immunohistochemistry revealed the protein expression of Sema3A in synovial lining cells was decreased in RA tissues compared with OA samples. qPCR analysis demonstrated a significant reduction of Sema3A mRNA levels in RA synovial tissue samples than in OA and a significant correlation of the ratio of Sema3A/VEGF-A mRNA expression levels with DAS28-CRP (R = -0.449, p = 0.013). Sema3A mRNA levels also correlated with Rooney's inflammation score, especially in perivascular infiltrates of lymphocytes (R = -0.506, p = 0.004), focal aggregates of lymphocytes (R = -0.501, p = 0.005) and diffuse infiltrates of lymphocytes (R = -0.536, p = 0.002). CONCLUSIONS: Reduction of Sema3A expression in RA synovial tissues may contribute to pathogenesis of RA.

Interplay of neuropilin-1 and semaphorin 3A after partial hepatectomy in rats.

AIM: To elucidate the role of neuropilin-1 (Nrp-1) and semaphorin 3A (Sema3A) in sinusoidal remodeling during liver regeneration in rats. METHODS: Male Wistar/ST rats at 7 wk of age, weighing about 200 g, were used for all animal experiments. In vivo, at 24, 48, 72, 96, 144 and 192 h after two-thirds partial hepatectomy (PHx), the remnant livers were removed. Liver tissues were immunohistochemically stained for Nrp-1, Sema3A and SE-1, a liver sinusoidal endothelial cell (SEC) marker. Total RNA of the liver tissue was extracted and reversely transcribed into cDNA. The mRNA expression of Sema3A was analyzed by quantitative real-time polymerase chain reaction and normalized to that of ribosomal protein S18. In vitro, SECs were isolated from rat liver and cultured in endothelial growth medium containing 20 ng/mL vascular endothelial cell growth factor. Migration of SECs in primary culture was assessed by cell transwell assay with or without recombinant Sema3A. Apoptotic cells were determined by a terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick end labeling method. RESULTS: In vitro, immunohistochemistry study revealed that Sema3A and Nrp-1 were constitutively expressed in hepatocytes and SECs, respectively, in normal rat liver tissues. Nrp-1 expression in SECs was quantified by the percentage of immunostained area with anti-Nrp-1 antibody in relation to the area stained with SE-1. Between 24 h and 96 h following resection of liver, Nrp-1 expression in SECs was transiently increased. Compared with the baseline (5.2% ± 0.1%), Nrp-1 expression in SECs significantly increased at 24 h (17.3% ± 0.7%, P < 0.05), 48 h (39.1% ± 0.6%, P < 0.01), 72 h (46.9% ± 4.5%, P < 0.01) and 96 h (29.9% ± 3.8%, P < 0.01) after PHx, then returned to the basal level at termination of liver regeneration. Interestingly, the expression of Sema3A was inversely associated with that of Nrp-1 in liver after PHx. Sema3A mRNA expression was significantly reduced by about 75% over the period 24-144 h after PHx (P < 0.05), and returned to basal levels at 192 h after PHx. In vitro, SECs isolated from rats after PHx (PHx-SECs) were observed to migrate to the lower chamber of the cell transwell system after incubation for 24 h, but not cells from normal rats (CONT-SECs), indicating that mobility of PHx-SECs increases as compared with that of CONT-SECs. Moreover, recombinant Sema3A significantly attenuated migration in PHx-SECs in primary culture (vehicle-treated 100% ± 7.9% vs Sema3A-treated 42.6% ± 5.4%, P < 0.01), but not in CONT-SECs. Compared with CONT-SECs, the apoptotic rate of PHx-SECs decreased by 78.3% (P < 0.05). There was no difference in apoptosis between CONT-SECs that were treated with vehicle and Sema3A. However, in PHx-SECs, apoptosis was induced by the presence of 5 nmol Sema3A for 24 h (vehicle-treated 21.7% ± 7.6% vs Sema3A-treated 104.3% ± 8.9%, P < 0.05). In addition, immunohistochemistry confirmed the increased expression of Nrp-1 in PHx-SECs, while it was noted to a lesser extent in CONT-SECs. CONCLUSION: The interplay of Nrp-1 and Sema3A shown in our results may lead to a better understanding of interaction between sinusoidal remodeling and SECs during liver regeneration.

Decreased expression of semaphorin-3A, a neurite-collapsing factor, is associated with itch in psoriatic skin.

Pruritus is a common symptom of psoriasis, which affects quality of life. This symptom accompanies the hyper-innervation of sensory C-fibres in psoriatic lesions. Two extracellular molecules, nerve growth factor (NGF) and semaphorin-3A, regulate C-fibre extension. In this study, the expression levels of these 2 molecules in biopsy specimens from psoriatic and healthy skin were quantified by immunohistochemistry and quantitative reverse-transcription PCR. Semaphorin-3A expression was lower in the psoriatic samples compared with the healthy samples, whereas NGF was higher. C-fibre innervation in the epidermis was also increased in psoriatic skin. Semaphorin-3A mRNA expression was negatively correlated with itch intensity and severity of psoriasis. We propose that decreased semaphorin-3A and increased NGF expression levels may trigger the outgrowth of C-fibres, leading to pruritus.

Modifying neurorepair and neuroregenerative factors with tPA and edaravone after transient middle cerebral artery occlusion in rat brain.

Changes in expression of neurorepair and neuroregenerative factors were examined after transient cerebral ischemia in relation to the effects of tissue plasminogen activator (tPA) and the free radical scavenger edaravone. Physiological saline or edaravone was injected twice during 90 min of transient middle cerebral artery occlusion (tMCAO) in rats, followed by the same saline or tPA at reperfusion. Sizes of the infarct and protein factors relating to neurorepair and neuroregeneration were examined at 4d after tMCAO. The protein factors examined were: a chondroitin sulfate proteoglycan neurocan, semaphorin type 3A (Sema3A), a myelin-associated glycoprotein receptor (Nogo receptor, Nogo-R), a synaptic regenerative factor (growth associated protein-43, GAP43), and a chemotropic factor netrin receptor (deleted in colorectal cancer, DCC). Two groups treated by edaravone only or edaravone plus tPA showed a reduction in infarct volume compared to the two groups treated by vehicle only or vehicle plus tPA. Immunohistochemistry and western blot analyses indicated that protein expression of neurocan, Sema3A, Nogo-R, GAP43, and DCC was decreased with tPA, but recovered with edaravone. Additive edaravone prevented the reductions of these five proteins induced by tPA. The present study demonstrates for the first time that exogenous tPA reduced protein factors involved in inhibiting and promoting axonal growth, but that edaravone ameliorated such damage in brain repair after acute ischemia.

Autocrine semaphorin 3A signaling promotes glioblastoma dispersal.

Glioblastoma multiforme (GBM) is the most malignant glioma type with diffuse borders due to extensive tumor cell infiltration. Therefore, understanding the mechanism of GBM cell dispersal is critical for developing effective therapies to limit infiltration. We identified neuropilin-1 as a mediator of cancer cell invasion by a functional proteomic screen and showed its role in GBM cells. Neuropilin-1 is a receptor for semaphorin3A (Sema3A), a secreted chemorepellent that facilitates axon guidance during neural development. Although neuropilin-1 expression in GBMs was previously shown, its role as a Sema3A receptor remained elusive. Using fluorophore-assisted light inactivation and RNA interference , we showed that neuropilin-1 is required for GBM cell migration. We also showed that GBM cells secrete Sema3A endogenously, and RNA interference-mediated downregulation of Sema3A inhibits migration and alters cell morphology that is dependent on Rac1 activity. Sema3A depletion also reduces dispersal, which is recovered by supplying Sema3A exogenously. Extracellular application of Sema3A decreases cell-substrate adhesion in a neuropilin-1-dependent manner. Using immunohistochemistry, we showed that Sema3A is overexpressed in a subset of human GBMs compared with the non-neoplastic brain. Together, these findings implicate Sema3A as an autocrine signal for neuropilin-1 to promote GBM dispersal by modulating substrate adhesion and suggest that targeting Sema3A-neuropilin-1 signaling may limit GBM infiltration.

Pontocerebellar axon guidance: neuropilin-1- and semaphorin 3A-sensitivity gradients across basilar pontine nuclei and semaphorin 3A variation across cerebellum.

To assess the role of semaphorin 3A (Sema3A) and its receptor component neuropilin-1 (Npn-1) in pontocerebellar axon guidance, we compared the distributions of Sema3A, Npn-1, and DiI-labeled pontocerebellar axons in neonatal mouse cerebellum. Between embryonic day 18 and birth there was a large increase in Npn-1 expression in the basilar pontine nuclei (BPN), the major source of pontocerebellar axons. Sema3A expression in cerebellum also increased at this time. In the BPN, Npn-1 and the response of axons to Sema3A were graded with high Npn-1 and Sema3A responsiveness rostrally and lower levels caudally. The Npn-1 gradient was not smooth and cells with higher and lower expression were interspersed. Between birth and postnatal day 5, pontocerebellar axons projected to lobules of the hemispheres, including those with low to moderate levels of Sema3A, but did not enter regions with high levels of Sema3A, including the flocculus and much of the vermis. These results suggest that varying neuropilin levels on BPN axons, which correlated with their varying responses to Sema3A, combined with varying Sema3A levels across cerebellum, may contribute to guiding subsets of BPN axons to their distinct target regions within cerebellum.