WNT4及其抑制因子SFRP1在糖尿病肾病大鼠肾组织中的表达

目的观察WNT4/β-catenin信号通路及其抑制因子分泌型卷曲相关蛋白1(SFRP1)在糖尿病肾病(DN)大鼠肾组织中的表达变化,探讨其在肾脏纤维化发生发展中的可能作用。方法将大鼠随机分为正常对照(NC)组和DN组,8只/组。尾静脉注射STZ 55 mg/kg复制IDDM模型。HE、PAS及Masson染色观察肾组织形态学结构和纤维化病变;免疫组织化学法观察WNT4和β-catenin蛋白在肾组织的表达部位;Western blot检测WNT4、SFRP1、β-catenin、p-GSK-3β、GSK-3β、CollagenⅠ、α-SMA和E-cadherin蛋白在肾组织中的表达;Real-time PCR检测WNT4及SFRP1 mRNA在肾组织中的表达。结果与NC组相比,DN组大鼠肾组织纤维化病变明显;WNT4蛋白和mRNA表达显著增多(P<0.05);β-catenin、p-GSK-3β、α-SMA和CollagenⅠ蛋白的表达显著增多(P<0.05);E-cadherin蛋白表达显著减少(P<0.05);SFRP1蛋白和mRNA表达显著下降(P<0.05)。结论在DN发病中,WNT4/β-catenin信号通路异常活化;SFRP1表达减少可能抑制该通路,促进了DN肾纤维化的发生发展。     

Hedgehog signaling in hematopoiesis

The Hedgehog signaling pathway is highly conserved and plays an essential role in the embryonic development of a wide variety of organs. In adult tissues, such as the central nervous system, it may also be required for homeostasis and repair following injury. The role of Hedgehog signaling in regulating hematopoiesis is not entirely clear. Evidence has shown that Hedgehog signaling is required for both primitive hematopoiesis in the developing embryo, as well as for definitive hematopoiesis in the adult. However, several studies also suggest that Hedgehog pathway activity is completely dispensable in postnatal hematopoiesis. In this review, we discuss the current understanding of Hedgehog signaling in vertebrate hematopoiesis, as well as the contradictory findings that have been reported.     

The Wnt signaling antagonist Kremen1 is required for development of thymic architecture

Wnt signaling has been reported to regulate thymocyte proliferation and selection at several stages during T cell ontogeny, as well as the expression of FoxN1 in thymic epithelial cells (TECs). Kremen1 (Krm1) is a negative regulator of the canonical Wnt signaling pathway, and functions together with the secreted Wnt inhibitor Dickkopf (Dkk) by competing for the lipoprotein receptor-related protein (LRP)-6 co-receptor for Wnts. Here krm1 knockout mice were used to examine krm1 expression in the thymus and its function in thymocyte and TEC development. Krm1 expression was detected in both cortical and medullary TEC subsets, as well as in immature thymocyte subsets, beginning at the CD25+CD44+ (DN2) stage and continuing until the CD4+CD8+(DP) stage. Neonatal mice show elevated expression of krm1 in all TEC subsets. krm1(-/-) mice exhibit a severe defect in thymic cortical architecture, including large epithelial free regions. Much of the epithelial component remains at an immature Keratin 5+ (K5) Keratin 8(+)(K8) stage, with a loss of defined cortical and medullary regions. A TOPFlash assay revealed a 2-fold increase in canonical Wnt signaling in TEC lines derived from krm1(-/-) mice, when compared with krm1(+/+) derived TEC lines. Fluorescence activated cell sorting (FACS) analysis of dissociated thymus revealed a reduced frequency of both cortical (BP1(+)EpCAM(+)) and medullary (UEA-1(+) EpCAM(hi)) epithelial subsets, within the krm1(-/-) thymus. Surprisingly, no change in thymus size, total thymocyte number or the frequency of thymocyte subsets was detected in krm1(-/-) mice. However, our data suggest that a loss of Krm1 leads to a severe defect in thymic architecture. Taken together, this study revealed a new role for Krm1 in proper development of thymic epithelium.     

Hedgehog signaling and congenital malformations

The Hedgehog (Hh)-signaling pathway is essential for numerous developmental processes in Drosophila and vertebrate embryos. Hh signal transduction encompasses a complex series of regulatory events, including the generation of the mature Hh ligand, propagation of the ligand from source of production as well as the reception and interpretation of the signal in Hh-receiving cells. Many congenital malformations in humans are known to involve mutations in various components of the Hh-signaling pathway. This mini review summarizes some recent findings about the regulation of Hh signal transduction and describes the spectrum of human congenital malformations that are associated with aberrant Hh signaling. Based on a comparison of mouse-mutant phenotypes and human syndromes, we discuss how Hh-dependent Gli activator and repressor functions contribute to some of the congenital malformations.     

The expression of SFRP1, SFRP3, DVL1, and DVL2 proteins in testicular germ cell tumors

Germ cell tumors of the testis are a heterogeneous group of neoplasms that affect male adolescents and young adults. Wnt signaling pathway components have been shown to be actively involved in normal and malignant germ cell differentiation and progression. In this study, we aimed to explore the expression patterns of the secreted frizzled‐related protein (SFRP) and Disheveled protein family (DVL) in a subset of testicular germ cell tumors. Eighty‐five formalin‐fixed, paraffin‐embedded tissue samples of the primary germ cell tumors of the testis were stained against SFRP1, SFRP3, DVL1, and DVL2 proteins using immunohistochemistry. SFRP1 and SFRP3 exhibited lower expression in both seminomas and mixed/non‐seminomatous tumors, compared with atrophic/benign tissue (p < 0.001). SFRP3 expression was lower than SFRP1 expression within the seminoma group (p = 0.004), but not within the mixed/non‐seminomatous group (p = 0.409). The majority of the tested cases (27/28, 96%) exhibited low DVL1 protein expression (median 0%, range 0–90%). In contrast, 20 out of 22 tested cases (91%) exhibited strong expression of DVL2 protein (median 80%, range 0–100%). No significant difference in DVL1 and DVL2 protein expression was observed between seminomas and mixed/non‐seminomatous tumors (p = 0.68 and 0.29). The secreted frizzled‐related protein and disheveled protein family members appear to be actively involved in the pathogenesis of primary testicular germ cell tumors.     

Canonical WNT signaling pathway and human AREG

AREG (Amphiregulin), BTC (beta-cellulin), EGF, EPGN (Epigen), EREG (Epiregulin), HBEGF, NRG1, NRG2, NRG3, NRG4 and TGFA (TGFalpha) constitute EGF family ligands for ERBB family receptors. Cetuximab (Erbitux), Pertuzumab (Omnitarg) and Trastuzumab (Herceptin) are anti-cancer drugs targeted to EGF family ligands, while Gefitinib (Iressa), Erlotinib (Tarceva) and Lapatinib (GW572016) are anti-cancer drugs targeted to ERBB family receptors. AREG and TGFA are biomarkers for Gefitinib non-responders. The TCF/LEF binding sites within the promoter region of human EGF family members were searched for by using bioinformatics and human intelligence (Humint). Because three TCF/LEF-binding sites were identified within the 5'-promoter region of human AREG gene, comparative genomics analyses on AREG orthologs were further performed. The EPGN-EREG-AREG-BTC cluster at human chromosome 4q13.3 was linked to the PPBP-CXCL segmental duplicons. AREG was the paralog of HBEGF at human chromosome 5q31.2. Chimpanzee AREG gene, consisting of six exons, was located within NW_105918.1 genome sequence. Chimpanzee AREG was a type I transmembrane protein showing 98.0% and 71.4% total amino-acid identity with human AREG and mouse Areg, respectively. Three TCF/LEF-binding sites within human AREG promoter were conserved in chimpanzee AREG promoter, but not in rodent Areg promoters. Primate AREG promoters were significantly divergent from rodent Areg promoters. AREG mRNA was expressed in a variety of human tumors, such as colorectal cancer, liver cancer, gastric cancer, breast cancer, prostate cancer, esophageal cancer and myeloma. Because human AREG was characterized as potent target gene of WNT/beta-catenin signaling pathway, WNT signaling activation could lead to Gefitinib resistance through AREG upregulation. AREG is a target of systems medicine in the field of oncology.     

Hedgehog signaling regulates proliferation of prostate cancer cells via stathmin1

Hedgehog (Hh) signaling is an essential pathway in embryonic development of prostate. Hh also plays roles in the proliferation of progenitor cells and cancer cells of adult prostate. However, how Hh signaling contributes to carcinogenesis of prostate is poorly understood. Stathmin1 is a microtubule-regulating protein that plays an important role in the assembly and disassembly of the mitotic spindle. Stathmin1 is expressed in normal developing mouse prostate and in prostate cancer. The expression pattern of stathmin1 is similar to that of Shh in prostate development and cancer, suggesting a connection between these two proteins. In this study, we examined the relationship between stathmin1 and Hh signaling. Here, we show that stathmin1 expression is regulated by Hh signaling in prostate cancer cells. Cyclopamine, a specific inhibitor of Hh signaling, reduced the expression of stathmin1 in prostate cancer cells. However, the Shh peptide induced stathmin1 expression. Overexpression of Gli1 further confirmed the relationship. Co-expression of stathmin1 and Patched 1, a receptor for Hh signaling was observed in prostate cancer tissues. Cyclopamine and stathmin1 siRNA both decreased proliferation of prostate cancer cells but did not produce an additive effect, suggesting a common pathway. These results suggest that Hh signaling regulates proliferation of prostate cancer cells by controlling stathmin1 expression.     

Hedgehog信号通路与骨发育

背景：Hedgehog作为骨发育中一种重要调控因子,近几年其在骨生长中作用机制的研究备受关注。 目的：介绍Hedgehog在软骨组织和骨组织发育中的作用机制及其与骨疾病的关系,从而分析Hedgehog信号通路与骨发育的研究现状及发展趋势。 方法：应用计算机检索中国期刊全文数据库和PubMed 数据库,以“Hedgehog,骨发育,间充质干细胞,软骨,成骨,骨缺陷”和“Hedgehog,bone development,mesenchymal stem cells,cartilage,osteogenesis,bone defects”为检索词。最终共纳入31篇文献进行综述。 结果与结论：Hedgehog信号与骨发育各阶段密切相关,包括间充质细胞向骨细胞分化,软骨组织和骨组织形成等各方面。其信号通路传导异常会导致各种骨畸形或骨缺陷。但是Hedgehog信号在骨发育中的详细作用机制体系尚未完善,相关动物实验技术尚未成熟,国内外尚未出现相关临床实验。由于Hedgehog即参与骨发育,又参与某些胚胎组织的血管重新形成和成年哺乳动物的血管发生,因而有望在修复骨缺损的同时解决骨组织工程血管化的问题。Hedgehog信号通路的研究在骨组织工程及临床基因干预治疗等领域有广阔的前景。     

Frizzled10 mediates WNT1 and WNT3A signaling in the dorsal spinal cord of the developing chick embryo

Background: WNT1 and WNT3A drive a dorsal to ventral gradient of β‐catenin‐dependent Wnt signaling in the developing spinal cord. However, the identity of the receptors mediating downstream functions remains poorly understood. Results: In this report, we show that the spatiotemporal expression patterns of FZD10 and WNT1/WNT3A are highly correlated. We further show that in the presence of LRP6, FZD10 promotes WNT1 and WNT3A signaling using an 8xSuperTopFlash reporter assay. Consistent with a functional role for FZD10, we demonstrate that FZD10 is required for proliferation in the spinal cord. Finally, by using an in situ proximity ligation assay, we observe an interaction between FZD10 and WNT1 and WNT3A proteins. Conclusions: Together, our results identify FZD10 as a receptor for WNT1 and WNT3A in the developing chick spinal cord. Developmental Dynamics 243:833–843, 2014. © 2014 Wiley Periodicals, Inc.     

Hedgehog signaling regulates sebaceous gland development

Epithelial progenitor cells in skin give rise to multiple lineages, comprising the hair follicle, an associated sebaceous gland, and overlying epidermis; however, the signals that regulate sebocyte development are poorly understood. We tested the potential involvement of the Hedgehog pathway in sebaceous gland development using transgenes designed to either block or stimulate Hedgehog signaling in cutaneous keratinocytes in vivo. Whereas inhibition of the Hedgehog pathway selectively suppressed sebocyte development, Hedgehog pathway activation led to a striking increase both in size and number of sebaceous glands. Remarkably, ectopic Hedgehog signaling also triggered the formation of sebaceous glands from footpad epidermis, in regions normally devoid of hair follicles and associated structures. These ectopic sebaceous glands expressed molecular markers of sebocyte differentiation and were functional, secreting their contents directly onto the skin's surface instead of into a hair canal. The Hedgehog pathway thus plays a key role in sebocyte cell fate decisions and is a potential target for treatment of skin disorders linked to abnormal sebaceous gland function, such as acne.