Sonic hedgehog: restricted expression and limb dysmorphologies

Sonic hedgehog, SHH, is required for patterning the limb. The array of skeletal elements that compose the hands and feet, and the ordered arrangement of these bones to form the pattern of fingers and toes are dependent on SHH. The mechanism of action of SHH in the limb is not fully understood; however, an aspect that appears to be important is the localized, asymmetric expression of Shh. Shh is expressed in the posterior margin of the limb bud in a region defined as the zone of polarizing activity (ZPA). Analysis of mouse mutants which have polydactyly (extra toes) shows that asymmetric expression of Shh is lost due to the appearance of an ectopic domain of expression in the anterior limb margin. One such polydactylous mouse mutant, sasquatch (Ssq), maps to the corresponding chromosomal region of the human condition pre-axial polydactyly (PPD) and thus represents a model for this condition. The mutation responsible for Ssq is located 1 Mb away from the Shh gene; however, the mutation disrupts a long-range cis-acting regulator of Shh expression. By inference, human pre-axial polydactyly results from a similar disruption of Shh expression. Other human congenital abnormalities also map near the pre-axial polydactyly locus, suggesting a major chromosomal region for limb dysmorphologies. The distinct phenotypes range from loss of all bones of the hands and feet to syndactyly of the soft tissue and fusion of the digits. We discuss the role played by Shh expression in mouse mutant phenotypes and the human limb dysmorphologies.     

Preaxial polydactyly caused by Gli3 haploinsufficiency is rescued by Zic3 loss of function in mice

Limb anomalies are important birth defects that are incompletely understood genetically and mechanistically. GLI3, a mediator of hedgehog signaling, is a genetic cause of limb malformations including pre- and postaxial polydactyly, Pallister-Hall syndrome and Greig cephalopolysyndactyly. A closely related Gli (glioma-associated oncogene homolog)-superfamily member, ZIC3, causes X-linked heterotaxy syndrome in humans but has not been investigated in limb development. During limb development, post-translational processing of Gli3 from activator to repressor antagonizes and posteriorly restricts Sonic hedgehog (Shh). We demonstrate that Zic3 and Gli3 expression overlap in developing limbs and that Zic3 converts Gli3 from repressor to activator in vitro. In Gli3 mutant mice, Zic3 loss of function abrogates ectopic Shh expression in anterior limb buds, limits overexpression in the zone of polarizing activity and normalizes aberrant Gli3 repressor/Gli3 activator ratios observed in Gli3+/- embryos. Zic3 null;Gli3+/- neonates show rescue of the polydactylous phenotype seen in Gli3+/- animals. These studies identify a previously unrecognized role for Zic3 in regulating limb digit number via its modifying effect on Gli3 and Shh expression levels. Together, these results indicate that two Gli superfamily members that cause disparate human congenital malformation syndromes interact genetically and demonstrate the importance of Zic3 in regulating Shh pathway in developing limbs.     

Hedgehog signaling is involved in differentiation of normal colonic tissue rather than in tumor proliferation

The Hedgehog (Hh) pathway is a main regulation cascade in embryonic differentiation. It is also present in adult tissues and unusual expression has been associated with formation of benign and malignant lesions. We examined the presence of the Hedgehog pathway in normal and pathological human colon tissue. Components investigated include Sonic (Shh), Indian (Ihh), and Desert Hedgehog (Dhh), Gli1, Gli2, Gli3, and Patched (Ptch). Pathological tissue samples comprised 23 benign and 20 malignant lesions of human colon. The influence of the Hedgehog pathway on differentiation and proliferation has been investigated by analyzing the effect of the pathway inhibitor Cyclopamine on human colon cancer cell lines HT29 and CaCo2. In normal colon, we detected expression of Shh and Dhh within the lining epithelium and Patched, Gli1, and Gli2 along the whole crypts. Within all benign lesions, positive staining of Shh, Dhh, Gli1, Gli2, and Ptch was detected. Expression of Shh and Dhh was restricted to single cell aggregates. Malignant lesions also displayed focal staining pattern for Shh and Dhh but to a much lesser extent. We conclude that Hedgehog signaling is involved rather in constant differentiation and renewing of the colonic lining epithelium than in cancer formation, growth, or proliferation.     

基于Hedgehog通路探讨补肾活血方对实验性膝骨性关节炎兔退变软骨的保护作用

目的:探究补肾活血方(BSHX)对实验性膝骨性关节炎兔退变软骨的保护作用及其可能的机制。方法:将新西兰兔分为对照(control)组、模型(model)组、BSHX(1.86 g/kg)组、Hedgehog通路激活剂SAG(20 mg/kg)组和BSHX+SAG组,每组6只。测定兔膝关节宽度,处死兔后观察膝关节软骨大体情况,对软骨退变情况进行评定;HE染色和番红O染色观察膝关节软骨组织病理形态学变化;ELISA法检测软骨组织中肿瘤坏死因子α(TNF-α)和白细胞介素1β(IL-1β)水平;免疫组化法检测软骨组织中基质金属蛋白酶13(MMP-13)和II型胶原(Col-II)蛋白表达;Western blot法检测软骨组织中Shh、Ptch1、Smo和Gli1蛋白表达。结果:与control组相比,model组膝关节宽度增大,软骨退变评分、软骨分级和Mankin评分升高,软骨组织中TNF-α和IL-1β水平升高,MMP-13阳性表达率升高,Col-II阳性表达率降低,Shh、Ptch1、Smo和Gli1蛋白表达升高(P<0.05)。与model组相比,BSHX组膝关节宽度减小,软骨退变评分、软骨分级和Mankin评分降低,软骨组织中TNF-α和IL-1β水平降低,MMP-13阳性表达降低,Col-II阳性表达升高,Shh、Ptch1、Smo和Gli1蛋白表达降低;SAG组膝关节宽度增大,软骨退变评分、软骨分级和Mankin评分升高,软骨组织中TNF-α和IL-1β水平升高,MMP-13阳性率表达升高,Col-II阳性表达率降低,Shh、Ptch1、Smo和Gli1蛋白表达升高(P<0.05)。BSHX+SAG组膝关节宽度,软骨退变评分,软骨分级,Mankin评分,软骨组织中TNF-α和IL-1β水平,MMP-13阳性表达率,以及Shh、Ptch1、Smo和Gli1蛋白表达均低于SAG组,Col-II阳性表达率高于SAG组(P<0.05)。结论:补肾活血方对实验性膝骨性关节炎兔退变软骨具有保护作用,其机制可能与抑制Hedgehog通路有关。     

Expression of hedgehog pathway components in prostate carcinoma microenvironment: shifting the balance towards autocrine signalling

Tzelepi V, Karlou M, Wen S, Hoang A, Logothetis C, Troncoso P & Efstathiou E
(2011) Histopathology 58, 1037–1047
Expression of hedgehog pathway components in prostate carcinoma microenvironment: shifting the balance towards autocrine signalling Aims: The hedgehog (Hh) signalling pathway has been implicated in the pathogenesis and aggressiveness of prostate cancer through epithelial–mesenchymal interactions. The aim of this study was to elucidate the cell‐type partitioned expression of the Hh pathway biomarkers in the non‐neoplastic and tumour microenvironments and to correlate it with the grade and stage of prostate cancer. Methods and results: Expression of the Hh pathway components (Shh, Smo, Ptch, Gli1) in the microenvironment of non‐neoplastic peripheral zone (n = 119), hormone‐naive primary prostate carcinoma (n = 141) and castrate‐resistant bone marrow metastases (n = 53) was analysed using immunohistochemistry in tissue microarrays and bone marrow sections. Results showed that epithelial Shh, Smo and Ptch expression was up‐regulated, whereas stromal Smo, Ptch, and Gli1 expression was down‐regulated in prostate carcinomas compared to non‐neoplastic peripheral zone tissue. Ptch expression was modulated further in high‐grade and high‐stage primary tumours and in bone marrow metastases. Hh signalling correlated with ki67 and vascular endothelial growth factor (VEGF) but not with CD31 expression. Conclusion: Our results highlight the importance of Hh‐mediated epithelial–mesenchymal interactions in the non‐neoplastic prostate and imply that shifting the balance from paracrine towards autocrine signalling is important in the pathogenesis and progression of prostate carcinoma.     

Isolation of the chicken Lmbr1 coding sequence and characterization of its role during chick limb development.

In the developing amniote limb, anteroposterior (A/P) patterning is controlled through secretion of the Sonic Hedgehog (SHH) protein by cells in the zone of polarizing activity (ZPA) located in the posterior mesoderm. In the chicken mutant oligozeugodactyly (ozd), Shh is expressed normally in the entire embryo with the exception that it is undetectable in the developing limbs; this results in the loss of specific bones in wings and legs. The ozd phenotype is similar to that of humans affected with acheiropodia (ACHR), and the ACHR mutation has been mapped to a deletion of exon 4 and portions of introns 3 and 4 in the LMBR1 gene. We have cloned the chick ortholog of LMBR1, Lmbr1, and report that, in chick, Lmbr1 is expressed within the ZPA. Although the ozd phenotype is similar to ACHR, the open reading frame of Lmbr1 is normal in ozd. Sequence analysis of Lmbr1 intron 3 demonstrated that this particular genomic region segregates with the ozd phenotype. In addition, overexpression of Lmbr1 throughout the developing limb mesoderm resulted in morphologically normal limbs. Collectively, these data suggest that the Lmbr1 coding sequence is not required for normal chick limb development. We propose that the ozd mutation is linked to the genomic region containing Shh and Lmbr1.     

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。     

Developmental mechanisms underlying polydactyly in the mouse mutant Doublefoot

The pre-axial polydactylous mouse mutant Doublefoot has 6-9 digits per limb but lacks anteroposterior polarity (there is no biphalangeal digit 1). It differs from other polydactylous mutants in showing normal Shh expression, but polarizing activity (shown by mouse-chick grafting experiments) and hedgehog signalling activity (shown by expression of Ptc1) are present throughout the distal mesenchyme. The Dbf mutation has not yet been identified. Here we review current understanding of this mutant, and briefly report new results indicating (1) that limb bud expansion is concomitant with ectopic lhh expression and with extension of the posterior high cell proliferation rate into the anterior region, and (2) that the Dbf mutation is epistatic to Shh in the limb.     

干扰维生素D3上调蛋白1通过调控Shh影响高糖诱导的肾小管上皮细胞凋亡

目的:探讨维生素D3上调蛋白1(VDUP-1)对高糖诱导的肾小管上皮细胞凋亡的影响及机制。方法:人近端肾小管上皮HK-2细胞用高糖处理后,real-time PCR和Western blot检测细胞中VDUP-1的水平。HK-2细胞转染VDUP-1小干扰RNA,real-time PCR和Western blot检测抑制效果。高糖条件培养VDUP-1表达下调的HK-2细胞,流式细胞术检测细胞凋亡,试剂盒检测细胞中caspase-3和caspase-9的活性,ELISA法测定培养上清液中肿瘤坏死因子α(TNF-α)含量,Western blot检测细胞中音猬因子(Shh)信号通路关键蛋白Patched 1 (Ptch1)、Smoothened (Smo)、锌指蛋白Gli2和Shh的水平。用外源性Shh处理HK-2细胞,Western blot检测Ptch1、Smo和Gli2的水平。用外源性Shh处理VDUP-1表达下调的HK-2细胞,高糖处理后,流式细胞术检测细胞凋亡,试剂盒检测细胞中caspase-3和caspase-9的活性,ELISA法测定培养液上清中TNF-α含量。结果:高糖处理后,HK-2细胞中VDUP-1的mRNA和蛋白水平升高(P 0. 05)。转染VDUP-1小干扰RNA后,HK-2细胞中VDUP-1的mRNA和蛋白水平下降(P 0. 05)。与正常培养的细胞相比,高糖处理后HK-2细胞凋亡率显著升高,细胞中caspase-3和caspase-9活性明显升高,TNF-α含量亦明显升高(P 0. 05);下调VDUP-1表达后的HK-2细胞经高糖处理后细胞凋亡率显著降低,细胞中caspase-3和caspase-9活性也明显降低(P 0. 05)。高糖培养后细胞中Ptch1、Smo、Gli2和Shh的蛋白水平下降,而下调VDUP-1表达部分拮抗高糖对HK-2细胞中Ptch1、Smo、Gli2和Shh表达的影响。外源性Shh可以促进细胞中Ptch1、Smo和Gli2的表达,抑制高糖诱导的HK-2细胞凋亡和分泌TNF-α,与下调VDUP-1共同抑制高糖诱导的肾小管上皮细胞凋亡。结论:干扰VDUP-1表达可能通过激活Shh信号通路抑制高糖诱导的肾小管上皮细胞凋亡和分泌TNF-α。     

Levels of Gli3 repressor correlate with Bmp4 expression and apoptosis during limb development.

Removal of the posterior wing bud leads to massive apoptosis of the remaining anterior wing bud mesoderm. We show here that this finding correlates with an increase in the level of the repressor form of the Gli3 protein, due to the absence of the Sonic hedgehog (Shh) protein signaling. Therefore, we used the anterior wing bud mesoderm as a model system to analyze the relationship between the repressor form of Gli3 and apoptosis in the developing limb. With increased Gli3R levels, we demonstrate a concomitant increase in Bmp4 expression and signaling in the anterior mesoderm deprived of Shh signaling. Several experimental approaches show that the apoptosis can be prevented by exogenous Noggin, indicating that Bmp signaling mediates it. The analysis of Bmp4 expression in several mouse and chick mutations with defects in either expression or processing of Gli3 indicates a correlation between the level of the repressor form of Gli3 and Bmp4 expression in the distal mesoderm. Our analysis adds new insights into the way Shh differentially controls the processing of Gli3 and how, subsequently, BMP4 expression may mediate cell survival or cell death in the developing limb bud in a position-dependent manner.     

阻断Sonic Hedgehog信号对不同人肝癌细胞生长的影响

 目的: 研究阻断Sonic Hedgehog (Shh)信号对不同人肝癌细胞生长的影响,探讨阻断Shh信号抑制肝癌细胞生长的机制。方法: RT-PCR法检测Shh信号分子在3株人肝癌细胞(BEL-7402、Huh7和HepG2)中的表达,并检测Shh阻断抗体作用后BEL-7402细胞Shh信号效应分子表达变化;MTT法检测人肝癌细胞增殖活性;流式细胞术检测人肝癌细胞凋亡;Western blot 检测凋亡相关蛋白表达。结果: Shh信号分子在3株人肝癌细胞中均有表达,Shh阻断抗体可以下调Shh信号效应分子patched (Ptch)、Gli1和Gli2的表达;Shh阻断抗体可以抑制3株肝癌细胞生长,增加G₀/G₁期细胞,并诱导细胞凋亡;Shh阻断抗体作用后,BEL-7402细胞pro-caspase-3、pro-caspase-8和pro-caspase-9蛋白表达水平下降,cleaved caspase-3、cleaved caspase-8和cleaved caspase-9蛋白表达水平升高。结论: 阻断Shh信号可抑制Shh高表达的人肝癌细胞生长,阻滞细胞周期于G₀/G₁期,并诱导肝癌细胞凋亡。