Shh mRNA在成年大鼠慢性压迫性脊髓损伤后的表达及其意义

目的:观察成年大鼠慢性压迫性脊髓损伤后与发育相关的重要分子Shh mRNA的表达,探讨其在神经再生过程中的作用.方法:将30只同龄Wistar大鼠置入后路渐进式压迫装置,制作成慢性压迫性脊髓损伤模型.随机分为对照组(5只)和慢性脊髓损伤组(25只).应用原位杂交检测方法,于脊髓损伤后1,3,7,14,28 d对损伤区行Shh mRNA检测.结果:脊髓损伤后7 d,Shh mRNA表达水平达到最大值,在损伤区至远端10 mm处的灰质和白质中均有表达,这种高水平的表达至少维持到损伤后28 d.Shh mRNA在室管膜细胞的表达远远低于在灰质和白质中的表达,其在室管膜区域的表达仅限于损伤区域周围5 mm范围内,分布范围远远小于在灰质和白质中的表达.结论:慢性压迫性脊髓损伤可激活Shh mRNA的表达,其表达对脊髓损伤后神经细胞再生的意义值得进一步探讨.     

Soluble factors from neuronal cultures induce a specific proliferation and resistance to apoptosis of cognate mouse skeletal muscle precursor cells

The mechanisms or the physiological events, which control the regeneration of skeletal muscle through muscle precursor cell multiplication and differentiation, are still largely unknown. To address the question of the involvement of neurons in this process, skeletal muscle progenitors were grown in the presence of conditioned media obtained from 3-day-old cultures of embryonic neurons (derived from either the dorsal or the ventral region of 11-day-old mouse embryos) or media conditioned with satellite cells. Strikingly, only satellite cells cultured in medium conditioned from ventral embryonic neurons exhibited increased proliferation, as well as resistance to staurosporine (STS)-induced apoptosis. Our results suggest the existence of specific anti-apoptogenic neural soluble signals, which could be involved in skeletal muscle regeneration pathways.     

Shh信号通路变化对小鼠胚胎腭突间充质细胞自噬的影响

目的：探讨地塞米松（dexamethasone,DEX）及平滑激动剂（smoothened agonist,SAG）干预下小鼠胚胎腭突间充质细胞Shh信号通路改变后,小鼠胚胎腭突间充质细胞自噬状态的变化。方法：体外培养胚胎14.5 d的C57BL/6J小鼠胚胎腭突间充质细胞,根据干预方式分为4组：对照组、地塞米松组（DEX组）、地塞米松+SAG组（DEX+SAG组）、单独SAG干预组（SAG组）。通过透射电镜观察各组细胞自噬体或自噬溶酶体的数量,Western blot检测各组Shh、Ptch1、Smo、Gli3A/R、Cyclin D1及自噬标志物LC3Ⅱ/Ⅰ和P62、Beclin-1的表达情况。结果：电镜结果显示,对照组和DEX组中自噬体/自噬溶酶体的数量无明显差异,而SAG干预后可观察到大量自噬体/自噬溶酶体。Western blot结果显示,与对照组相比,P62、Ptch1、Smo、Gli3A/R、CyclinD1在DEX组中明显降低（P<0.05）,LC3Ⅱ/Ⅰ、Beclin1表达无明显变化（P>0.05）;DEX+SAG组及SAG组中Ptch1、Smo、Gli3...     

Non-cell-autonomous signaling by Shh in tumors: challenges and opportunities for therapeutic targets

Importance of the field: The Hedgehog (Hh) pathway is required during many developmental events; in adults the Hedgehog pathway is involved in the maintenance of several stem cell niches. It is therefore not surprising that aberrantly regulated Hh pathway activity can cause birth defects in the developing organism, as well as neoplastic disease later in life.

Areas covered in this review: As a consequence of the involvement in pathogenesis, the Hh pathway components are subject to an intense scrutiny as potential targets for therapeutic agents. We aim to provide an overview of the biology of the Hh proteins and the cellular response, in conjunction with potential therapeutic interventions.

What the reader will gain: Specifically, we focus on the recently discovered non-cell-autonomous Shh signaling used by tumors and the implications of this for the design of treatment strategies. This should provide the reader with up-to-date knowledge on the role of the Hh pathway in tumor progression and the options to treat these malignancies.

Take home message: An important concept that we advocate in this review is the need to recognize the need to target both the stromal and the tumor compartment in malignancies that rely on paracrine Shh signaling.     

Regulation of Sox9 by Sonic Hedgehog (Shh) is essential for patterning and formation of tracheal cartilage

We report that Sonic Hedgehog (Shh) regulates both formation and patterning of tracheal cartilage by controlling the expression pattern and level of the chondrogenic gene, Sox9. In Shh^?/? tracheo‐esophageal tubes, Sox9 expression is transient and not restricted ventrally to the site of chondrogenesis, and is absent at the time of chondrogenesis, resulting in the failure of tracheal cartilage formation. Inhibition of Hedgehog signalling with cyclopamine in tracheal cultures prevents tracheal cartilage formation, while treatment of Shh^?/? tracheal explant with exogenous Shh peptide rescues cartilage formation. Both exogenous Bmp4 and Noggin rescue cartilage phenotype in Shh^?/? tracheal culture, while promoting excessive cartilage development in wild‐type trachea through induction of Sox9 expression. The ventral and segmented expression of Sox9 in tracheal primordia under Shh modulated by Bmp4 and Noggin thus determine where and when tracheal cartilage develops. These results indicate that Shh signalling is a critical determinant in tracheal cartilage development. Developmental Dynamics 239:514–526, 2010. © 2009 Wiley‐Liss, Inc.     

Primer and interviews: Diverse connections between primary cilia and Hedgehog signaling

On the surface, the Hedgehog (Hh) pathway and primary cilia make strange bedfellows. Hh is a dynamic regulator of a myriad of developmental processes, ranging from spinal cord and limb patterning to lung branching morphogenesis. By contrast, immotile primary cilia were long considered ancestral holdovers with no known function. Considering the disparate perceptions of these two phenomena, the relatively recent discovery that there is a symbiotic‐like relationship between Hh and cilia was unexpected. This primer covers the basics of primary cilia and Hh signaling, highlighting variations in ways they are connected across species, and also discusses the evolutionary implications of these findings. Roles of cilia in signal transduction are analyzed further in an interview with Søren T. Christensen, PhD, and Andrew S. Peterson, PhD, in the A Conversation With the Experts section. Developmental Dynamics 239:1255–1262, 2010. © 2010 Wiley‐Liss, Inc.     

Dynamic expression pattern of Sonic hedgehog in developing cochlear spiral ganglion neurons

Sonic hedgehog (Shh) signaling plays important roles in the formation of the auditory epithelium. However, little is known about the detailed expression pattern of Shh and the cell sources from which Shh is secreted. By analyzing Shh^CreEGFP/+ mice, we found that Shh was first expressed in all cochlear spiral ganglion neurons by embryonic day 13.5, after which its expression gradually decreased from base to apex. By postnatal day 0, it was not detected in any spiral ganglion neurons. Genetic cell fate mapping results also confirmed that Shh was exclusively expressed in all spiral ganglion neurons and not in surrounding glia cells. The basal‐to‐apical wave of Shh decline strongly resembles that of hair cell differentiation, supporting the idea that Shh signaling inhibits hair cell differentiation. Furthermore, this Shh^CreEGFP/+ mouse is a useful Cre line in which to delete floxed genes specifically in spiral ganglion neurons of the developing cochlea. Developmental Dynamics 239:1674–1683, 2010. © 2010 Wiley‐Liss, Inc.