Sonic hedgehog induces the proliferation of primitive human hematopoietic cells via BMP regulation

A pool of stem cells that arise from the mesoderm during embryogenesis initiates hematopoiesis. However, factors that regulate the expansion of blood stem cells are poorly understood. We show here that cytokine-induced proliferation of primitive human hematopoietic cells could be inhibited with antibodies to hedgehog (Hh). Conversely, Sonic hedgehog (Shh) treatment induced the expansion of pluripotent human hematopoietic repopulating cells detected in immunodeficient mice. Noggin, a specific inhibitor of bone morphogenetic protein 4 (BMP-4), was capable of inhibiting Shh-induced proliferation in a similar manner to anti-Hh; however, anti-Hh had no effect on BMP-4-induced proliferation. Our study shows that Shh functions as a regulator of primitive hematopoietic cells via mechanisms that are dependent on downstream BMP signals.     

Sonic Hedgehog蛋白在帕金森病模型大鼠黑质中的表达

目的检测Sonic Hedgehog蛋白(Shh)在帕金森病(Parkinson's disease,PD)大鼠中脑黑质的表达。方法将健康SD大鼠(雌雄不拘)随机分成3组:正常组大鼠不实施任何处理;应用脑立体定位技术,在大鼠右侧纹状体两针道内4点定位注射含0.2g/L抗坏血酸的生理盐水4μL(假手术组)或6-羟基多巴(6-OHDA)12μg/4μL(模型组)。术后1、2、4、6周以阿朴吗啡检测其异常旋转行为,左侧旋转的圈数大于7r/min者为合格的帕金森病模型大鼠。6周后在激光共聚焦显微镜下观察黑质Shh及酪氨酸羟化酶(TH)的免疫荧光双重染色结果,用Leica Confocal Software对Shh的荧光强度进行定量分析。结果Shh蛋白在正常对照组和假手术组大鼠中脑黑质中无明显表达,而在模型组表达显著。结论PD模型大鼠黑质中Shh蛋白的明显表达,提示Shh在PD模型大鼠中脑多巴胺能神经元(DA神经元)修复过程中可能发挥着一定的作用。     

Sonic hedgehog regulates adult neural progenitor proliferation in vitro and in vivo

Neural stem cells exist in the developing and adult nervous systems of all mammals, but the basic mechanisms that control their behavior are not yet well understood. Here, we investigated the role of Sonic hedgehog (Shh), a factor vital for neural development, in regulating adult hippocampal neural stem cells. We found high expression of the Shh receptor Patched in both the adult rat hippocampus and neural progenitor cells isolated from this region. In addition, Shh elicited a strong, dose-dependent proliferative response in progenitors in vitro. Furthermore, adeno-associated viral vector delivery of shh cDNA to the hippocampus elicited a 3.3-fold increase in cell proliferation. Finally, the pharmacological inhibitor of Shh signaling cyclopamine reduced hippocampal neural progenitor proliferation in vivo. This work identifies Shh as a regulator of adult hippocampal neural stem cells.     

Expression of Sonic hedgehog pathway genes is altered in colonic neoplasia

The Hedgehog (Hh) signalling pathway is crucial for normal development and patterning of numerous human organs including the gut. Hh proteins are also expressed during gastric gland development and gastric epithelial differentiation in adults. Recently, dysregulation of these developmentally important genes has been implicated in cancer, leading to the present study of the expression of Hh signalling proteins in colon cancer. In this study, normal colon and colonic lesions (hyperplastic polyp, adenoma, and colonic adenocarcinoma) were examined by immunohistochemistry using antibodies against Hh signalling molecules: the secreted protein Sonic hedgehog (SHH), its receptor Patched (PTCH), and the PTCH-associated transmembrane protein Smoothened (SMOH). The study shows that Hh signalling pathway members are expressed in normal colonic epithelium. SHH was expressed at the top of the crypts and in a few basally located cells, while PTCH was detected in the neuroendocrine cells and SMOH at the brush border of superficial epithelium. RT-PCR analysis of laser-microdissected crypts from normal human colon confirmed that mRNAs encoding these proteins were expressed in colonic epithelium. Expression of SHH, PTCH, and SMOH was up-regulated in hyperplastic polyps, adenomas, and adenocarcinomas of the colon, and SHH expression correlated with increased expression of the proliferation marker Ki-67 in all lesions examined. To address whether the Hh signalling pathway is functional in the gut, the effect of Shh on epithelial cells in vitro was explored by treating primary murine colonocytes with either Shh peptide or neutralizing anti-Shh antibody. The proportion of cells in the S-phase was assessed by bromodeoxyuridine (BrdU) incorporation. It was found that exogenous Shh promotes cell proliferation in colonocytes, while anti-Shh inhibits proliferation, suggesting that Shh is required during proliferation of epithelial cells in vitro. It is suggested that SHH is required during epithelial proliferation in the colon and that there is a possible role for Hh signalling in epithelial colon tumour progression in vivo.     

Sonic hedgehog regulates proliferation of the retinal ciliary marginal zone in posthatch chicks.

The ciliary marginal zone (CMZ) has long been known to be a source of postembryonic neuronal production in the retinas of fish and amphibians, and more recently, birds. However, there is little known about the factors that are required for the maintenance of this neural stem cell zone. The cells of the CMZ respond to mitogens such as endothelial growth factor, insulin-like growth factor-1, and insulin, factors that are also mitogenic for embryonic retinal progenitors, suggesting that the continued expression of embryonic mitogenic factors might be required to maintain the postembryonic proliferative potential of the CMZ. To test this hypothesis, we examined the expression and functional role of a critical embryonic retinal progenitor mitogen, Sonic hedgehog (Shh) in the regulation of proliferation of the cells of the CMZ. We have found that Shh is concentrated at the retinal margin of postembryonic chicks. Moreover, we report that intraocular injection of Shh stimulates proliferation of the CMZ cells, whereas cyclopamine, an inhibitor of the Shh pathway, inhibits CMZ proliferation. We conclude that Shh signaling is an important factor in the maintenance of postembryonic retinal neurogenesis.     

Expression of the Sonic hedgehog (SHH ) gene during early human development and phenotypic expression of new mutations causing holoprosencephaly.

Holoprosencephaly (HPE), the most common developmental defect of the forebrain and the face, is genetically heterogeneous. One of the genes involved, Sonic hedgehog ( SHH ), on 7q36, has been identified as the first HPE-causing gene both in mouse and humans. In order to delineate the phenotype of specific SHH mutations, we described the expression of the SHH gene during early human embryogenesis and investigated the phenotype of novel SHH mutations. In situ hybridization studies were performed on paraffin-embedded human embryo sections at three different development stages. These studies show that SHH is expressed in the notochord, the floorplate, the brain, the zone of polarizing activity and the gut. We also report on the phenotype of four novel mutations identified in 40 HPE families (two in isolated HPE and two in familial HPE). Expressivity ranged from alobar HPE to microcephaly and hypoplasia of the pituitary gland in one family, and from HPE to an asymptomatic form in another family. No SHH mutation was found in six polymalformed cases combining HPE with other defects, such as skeletal, limb, cardiac, anal and/or renal anomalies. This study confirms the genetic heterogeneity of HPE, and further demonstrates that SHH mutations are associated with a broad spectrum of cerebral midline defects.     

Sonic hedgehog mRNA及其蛋白在大肠癌的表达及其临床意义

目的 探讨大肠癌中Hedgehog信号通路相关基因Sonic hedgehog(SHH)的表达及其临床意义.方法 应用RT-PCR及免疫组织化学法(Envison二步法)检测本院2008年12月至2009年4月收集的43例大肠癌组织和距离癌10 cm以上的癌旁组织的SHHmRNA及蛋白的表达情况,并与20例非肠癌患者的正常大肠组织对照,分析其与大肠癌患者临床和病理各变量的相关性.结果 凝胶成像分析显示阳性表达的样本SHH mRNA片段大小为280 bp,与理论值相符,未表达的样本则未见相应条带.大肠癌组织SHHmRNA表达阳性率为27.9%(12/43),与癌旁组织的18.6%(8/43)差异无统计学意义(P＞0.05),但均显著高于正常大肠黏膜的0%(0/20)(均P＜0.05).SHH mRNA在大肠癌组织的表达强度显著高于癌旁组织(P＜0.05),在正常大肠黏膜则未见其表达.免疫组织化学显示SHH蛋白在大肠癌组织和癌旁组织均有阳性表达,细胞膜及胞质内出现棕黄褐色颗粒,背景不着色;正常大肠黏膜阴性表达.SHH蛋白在大肠癌组织的表达阳性率显著高于正常大肠黏膜[25.6%(11/43)比0%(0/20),P＜0.05],在大肠癌组织与癌旁组织、癌旁组织与正常大肠黏膜的表达阳性率差异则无统计学意义(均P＞0.05).SHH蛋白的表达强度大肠癌组织＞癌旁组织＞正常大肠黏膜(均P＜0.05).大肠癌组织中的SHH mRNA和蛋白表达强度与患者的年龄、性别、临床分期、肿瘤部位、肿瘤浸润深度、病理分型等变量均无明显关系(均P＞0.05).结论 SHH mRNA和蛋白在大肠癌组织中表达显著增强,但与临床和病理各变量无关联.     

Left cardiac isomerism in the Sonic hedgehog null mouse

Sonic hedgehog (Shh) is a secreted morphogen necessary for the production of sidedness in the developing embryo. In this study, we describe the morphology of the atrial chambers and atrioventricular junctions of the Shh null mouse heart. We demonstrate that the essential phenotypic feature is isomerism of the left atrial appendages, in combination with an atrioventricular septal defect and a common atrioventricular junction. These malformations are known to be frequent in humans with left isomerism. To confirm the presence of left isomerism, we show that Pitx2c, a recognized determinant of morphological leftness, is expressed in the Shh null mutants on both the right and left sides of the inflow region, and on both sides of the solitary arterial trunk exiting from the heart. It has been established that derivatives of the second heart field expressing Isl1 are asymmetrically distributed in the developing normal heart. We now show that this population is reduced in the hearts from the Shh null mutants, likely contributing to the defects. To distinguish the consequences of reduced contributions from the second heart field from those of left–right patterning disturbance, we disrupted the movement of second heart field cells into the heart by expressing dominant‐negative Rho kinase in the population of cells expressing Isl1. This resulted in absence of the vestibular spine, and presence of atrioventricular septal defects closely resembling those seen in the hearts from the Shh null mutants. The primary atrial septum, however, was well formed, and there was no evidence of isomerism of the atrial appendages, suggesting that these features do not relate to disruption of the contributions made by the second heart field. We demonstrate, therefore, that the Shh null mouse is a model of isomerism of the left atrial appendages, and show that the recognized associated malformations found at the venous pole of the heart in the setting of left isomerism are likely to arise from the loss of the effects of Shh in the establishment of laterality, combined with a reduced contribution made by cells derived from the second heart field.     

Sonic hedgehog信号通路在单侧输尿管梗阻大鼠肾组织中的表达变化及意义

 目的：探讨Sonic hedgehog（Shh）信号通路在单侧输尿管梗阻（UUO）大鼠肾组织中的表达变化及意义。方法：将48只SD大鼠随机分为UUO模型组（n=24）和假手术组（n=24）,梗阻术3、7和14 d后取其梗阻侧肾脏组织。用HE和Masson染色检测肾间质纤维化程度,免疫组织化学染色检测Shh通路分子Shh、Ptch1、Smo、Gli1及III型胶原的蛋白表达,酶联免疫吸附实验（ELISA）检测肾组织中TGF-β₁和Shh含量,real-time RT-PCR检测TGF-β₁、I和III型胶原及Shh通路分子mRNA表达。结果：HE和Masson染色显示,梗阻侧肾组织出现明显的纤维化病变,且随时间延长而加剧。TGF-β₁、I和III型胶原含量在梗阻肾中表达明显增高（P<0.05）。同时,Shh信号通路分子Shh、Smo和Gli mRNA和蛋白在梗阻肾中表达明显升高（P<0.05）,而Ptch1 mRNA和蛋白的表达下调（P<0.01）,提示Shh信号被激活。相关分析表明,Shh信号起始信号Shh水平的升高与TGF-β₁含量增加呈明显的相关。结论：UUO大鼠诱导肾间质纤维化发生过程中,Shh信号通路分子被激活,推测可能的机制是活化的Shh信号通路诱导TGF-β₁表达和释放,导致肾间质纤维化。     

Constitutive hedgehog signaling in chondrosarcoma up-regulates tumor cell proliferation

Chondrosarcoma is a malignant cartilage tumor that may arise from benign precursor lesions, such as enchondromas. Some cases of multiple enchondromas are caused by a mutation that results in constitutive activation of Hedgehog-mediated signaling. We found that chondrosarcomas expressed high levels of the Hedgehog target genes PTCH1 and GLI1. Treatment with parathyroid hormone-related protein down-regulated Indian Hedgehog (IHH) expression in normal growth plates but not in chondrosarcoma or enchondroma organ cultures. Treatment of the chondrosarcoma organ cultures with Hedgehog protein increased cell proliferation rate, whereas addition of chemical inhibitors of Hedgehog signaling decreased the proliferation rate. Chondrosarcoma xenografts from 12 different human tumors were established in NOD-SCID mice. Treatment with triparanol, an inhibitor of Hedgehog signaling, resulted in a 60% decrease in tumor volume, a 30% decrease in cellularity, and a 20% reduction in proliferation rate. These results show that Hedgehog signaling is active in chondrosarcoma and benign cartilage tumors and regulates tumor cell proliferation. Our data raise the intriguing possibility that Hedgehog blockade could serve as an effective treatment for chondrosarcoma, a tumor for which there are currently no universally effective nonsurgical management options.     

The Notch and Sonic hedgehog signalling pathways in immunity

There is an increasing body of knowledge demonstrating that genes involved in cell fate decisions during development also play a role in the continuous cell fate decisions made by the mature immune system in response to foreign antigen. This review concentrates on the role of the Notch and Sonic hedgehog (Shh) signalling pathways in the development and function of CD4+ T lymphocytes.     

Specification of the mammalian cochlea is dependent on Sonic hedgehog

Organization of the inner ear into auditory and vestibular components is dependent on localized patterns of gene expression within the otic vesicle. Surrounding tissues are known to influence compartmentalization of the otic vesicle, yet the participating signals remain unclear. This study identifies Sonic hedgehog (Shh) secreted by the notochord and/or floor plate as a primary regulator of auditory cell fates within the mouse inner ear. Whereas otic induction proceeds normally in Shh(-/-) embryos, morphogenesis of the inner ear is greatly perturbed by midgestation. Ventral otic derivatives including the cochlear duct and cochleovestibular ganglia failed to develop in the absence of Shh. The origin of the inner ear defects in Shh(-/-) embryos could be traced back to alterations in the expression of a number of genes involved in cell fate specification including Pax2, Otx1, Otx2, Tbx1, and Ngn1. We further show that several of these genes are targets of Shh signaling given their ectopic activation in transgenic mice that misexpress Shh in the inner ear. Taken together, our data support a model whereby auditory cell fates in the otic vesicle are established by the direct action of Shh.     

Notochord repression of endodermal Sonic hedgehog permits pancreas development

Notochord signals to the endoderm are required for development of the chick dorsal pancreas. Sonic hedgehog (SHH) is normally absent from pancreatic endoderm, and we provide evidence that notochord, in contrast to its effects on adjacent neuroectoderm where SHH expression is induced, represses SHH expression in adjacent nascent pancreatic endoderm. We identify activin-βB and FGF2 as notochord factors that can repress endodermal SHH and thereby permit expression of pancreas genes including Pdx1 and insulin. Endoderm treatment with antibodies that block hedgehog activity also results in pancreatic gene expression. Prevention of SHH expression in prepancreatic dorsal endoderm by intercellular signals, like activin and FGF, may be critical for permitting early steps of chick pancreatic development.     

Expression of proliferation and apoptotic markers in human placenta during pregnancy

Trophoblast has unique properties in relation to its wide range of metabolic, endocrine and angiogenic functions. Trophoblastic cells invade endometrium and adjacent myometrium in a way that is imitated by malignant tumours. The aim of the present study was to analyse the expression of markers of proliferation and apoptosis in trophoblastic cells in normal human placenta during pregnancy. A total of 22 placentas, 12 of which were obtained from curettage and induced legal abortion and 10 placentas obtained from normal deliveries or caesarean sections were included in this study. Proliferation markers were strongly expressed in cytotrophoblast in early stages of gestation. In late term placentas, a distinct decrease in expression of these markers was observed. Syncytiotrophoblast was negative for proliferation markers in all placentas. Positive immunostaining for bcl-2, an anti-apoptotic marker, was observed only in syncytiotrophoblastic cells in first-trimester but also in third-trimester placentas. Cytotrophoblast and stromal mesenchymal cells of chorionic villi were negative for bcl-2. Expression of bcl-2 protein in syncytiotrophoblast may be one of the major factors preventing these structures from early cell death, which is indispensable for the maintenance of physiological pregnancy.