Legouis R, Hardelin J P, Petit C, Ayer-Le Lièvre C
Unité de Génétique Moléculaire Humaine (CNRS URA 1445), Institut Pasteur, Paris, France.
Anat Embryol (Berl). 1994 Dec;190(6):549-62. doi: 10.1007/BF00190105.
The human KAL gene is responsible for the X chromosome-linked Kallmann syndrome, which consists of the association of hypogonadotropic hypogonadism and anosmia. The human and chicken KAL genes have been isolated. Using in situ hybridization, we studied KAL gene expression during development of the chick. We have previously reported that, from embryonic day 8, the expression is almost restricted to definite neuronal populations in the central nervous system, most of which still express the gene after hatching. Here we report that the KAL gene is also expressed during early embryonic development (days 2-8) in various endodermal, mesodermal, and neurectodermal derivatives. In most endodermal and mesodermal derivatives, the expression is transient and precedes cell differentiation. In contrast, the expression in the nervous system concerns postmitotic central neuroblastic populations, most of which still express the gene after differentiation. In accordance with such a spatio-temporal pattern of expression, we suggest that the KAL gene is involved both in morphogenetic events and in neuronal late differentiation. In addition, the absence of detectable expression of the KAL gene either in the embryonic olfactory epithelium or in the surrounding nasal mesenchyme reinforces the hypothesis that Kallmann's syndrome results from a central olfactory target cell defect.
人类KAL基因与X染色体连锁的卡尔曼综合征有关，该综合征表现为低促性腺激素性性腺功能减退和嗅觉缺失。人类和鸡的KAL基因已被分离出来。我们利用原位杂交技术研究了鸡发育过程中KAL基因的表达情况。我们之前报道过，从胚胎第8天开始，该基因的表达几乎局限于中枢神经系统中特定的神经元群体，其中大多数在孵化后仍表达该基因。在此我们报道，KAL基因在胚胎早期发育阶段（第2 - 8天）也在各种内胚层、中胚层和神经外胚层衍生物中表达。在大多数内胚层和中胚层衍生物中，这种表达是短暂的，且先于细胞分化。相比之下，在神经系统中的表达涉及有丝分裂后的中枢神经母细胞群体，其中大多数在分化后仍表达该基因。根据这种时空表达模式，我们认为KAL基因既参与形态发生事件，也参与神经元的后期分化。此外，在胚胎嗅觉上皮或周围鼻间充质中未检测到KAL基因的表达，这进一步支持了卡尔曼综合征是由中枢嗅觉靶细胞缺陷导致的假说。
