Pulmonary vascular development goes awry in congenital lung abnormalities

Pulmonary vascular diseases of the newborn comprise a wide range of pathological conditions with developmental abnormalities in the pulmonary vasculature. Clinically, pulmonary arterial hypertension (PH) is characterized by persistent increased resistance of the vasculature and abnormal vascular response. The classification of PH is primarily based on clinical parameters instead of morphology and distinguishes five groups of PH. Congenital lung anomalies, such as alveolar capillary dysplasia (ACD) and PH associated with congenital diaphragmatic hernia (CDH), but also bronchopulmonary dysplasia (BPD), are classified in group three. Clearly, tight and correct regulation of pulmonary vascular development is crucial for normal lung development. Human and animal model systems have increased our knowledge and make it possible to identify and characterize affected pathways and study pivotal genes. Understanding of the normal development of the pulmonary vasculature will give new insights in the origin of the spectrum of rare diseases, such as CDH, ACD, and BPD, which render a significant clinical problem in neonatal intensive care units around the world. In this review, we describe normal pulmonary vascular development, and focus on four diseases of the newborn in which abnormal pulmonary vascular development play a critical role in morbidity and mortality. In the future perspective, we indicate the lines of research that seem to be very promising for elucidating the molecular pathways involved in the origin of congenital pulmonary vascular disease. Birth Defects Research (Part C) 102:343–358, 2014. © 2014 Wiley Periodicals, Inc.     

Neuronal defects in the hindbrain of Hoxa1, Hoxb1 and Hoxb2 mutants reflect regulatory interactions among these Hox genes

Hox genes are instrumental in assigning segmental identity in the developing hindbrain. Auto-, cross- and para-regulatory interactions help establish and maintain their expression. To understand to what extent such regulatory interactions shape neuronal patterning in the hindbrain, we analysed neurogenesis, neuronal differentiation and motoneuron migration in Hoxa1, Hoxb1 and Hoxb2 mutant mice. This comparison revealed that neurogenesis and differentiation of specific neuronal subpopulations in r4 was impaired in a similar fashion in all three mutants, but with different degrees of severity. In the Hoxb1 mutants, neurons derived from the presumptive r4 territory were re-specified towards an r2-like identity. Motoneurons derived from that territory resembled trigeminal motoneurons in both their migration patterns and the expression of molecular markers. Both migrating motoneurons and the resident territory underwent changes consistent with a switch from an r4 to r2 identity. Abnormally migrating motoneurons initially formed ectopic nuclei that were subsequently cleared. Their survival could be prolonged through the introduction of a block in the apoptotic pathway. The Hoxa1 mutant phenotype is consistent with a partial misspecification of the presumptive r4 territory that results from partial Hoxb1 activation. The Hoxb2 mutant phenotype is a hypomorph of the Hoxb1 mutant phenotype, consistent with the overlapping roles of these genes in facial motoneuron specification. Therefore, we have delineated the functional requirements in hindbrain neuronal patterning that follow the establishment of the genetic regulatory hierarchy between Hoxa1, Hoxb1 and Hoxb2.     

Juvenoid-induced effects on the growth and differentiation of testis in the rice moth, Corcyra cephalonica

The juvenoid hydroprene or altozar (ZR-0512), when applied to larvae and pupae of Corcyra cephalonica at doses of 100 μg and 10 μg per individual, produced abnormalities in the growth and differentiation of imaginal testicular structures. In all the resultant larval-imaginal intermediates each testis contained a compact mass of cysts at various developmental stages with a comparatively higher number of spermatid cysts denoting a potentiality for increased fertility. Delayed differentiation of spermatozoa may also be inferred from this finding. On rare occasions the two larval testes failed to become enclosed in a single sac. Conversely, in the adultoids obtained from pupal treatment, the production of a normal quantity of testicular cysts of different kinds was inhibited. Moreover, malformed and sometimes degenerating spermatozoan cysts were formed. In a few extreme cases differentiation of even the spermatid cysts had been almost entirely prevented. Spermatogonia and the degenerating cell masses were the chief components of the testis of such adultoids. All observations indicated a sort of male sterility induced by the juvenoid when applied to pupae, especially at 12 hours age. The effect of the juvenoid on spermatogenesis could not be shown to be direct.     

Auto/cross-regulation of Hoxb3 expression in posterior hindbrain and spinal cord

The complex and dynamic pattern of Hoxb3 expression in the developing hindbrain and the associated neural crest of mouse embryos is controlled by three separate cis-regulatory elements: element I (region A), element IIIa, and the r5 enhancer (element IVa). We have examined the cis-regulatory element IIIa by transgenic and mutational analysis to determine the upstream trans-acting factors and mechanisms that are involved in controlling the expression of the mouse Hoxb3 gene in the anterior spinal cord and hindbrain up to the r5/r6 boundary, as well as the associated neural crest which migrate to the third and posterior branchial arches and to the gut. By deletion analysis, we have identified the sequence requirements within a 482-bp element III482. Two Hox binding sites are identified in element III482 and we have shown that in vitro both Hoxb3 and Hoxb4 proteins can interact with these Hox binding sites, suggesting that auto/cross-regulation is required for establishing the expression of Hoxb3 in the neural tube domain. Interestingly, we have identified a novel GCCAGGC sequence motif within element III482, which is also required to direct gene expression to a subset of the expression domains except for rhombomere 6 and the associated neural crest migrating to the third and posterior branchial arches. Element III482 can direct a higher level of reporter gene expression in r6, which led us to investigate whether kreisler is involved in regulating Hoxb3 expression in r6 through this element. However, our transgenic and mutational analysis has demonstrated that, although kreisler binding sites are present, they are not required for the establishment or maintenance of reporter gene expression in r6. Our results have provided evidence that the expression of Hoxb3 in the neural tube up to the r5/r6 boundary is auto/cross-regulated by Hox genes and expression of Hoxb3 in r6 does not require kreisler.     

Hoxb8 is required for normal grooming behavior in mice.

Repertoires of grooming behaviors critical to survival are exhibited by most animal species, including humans. Genes that influence this complex behavior are unknown. We report that mice with disruptions of Hoxb8 show, with 100% penetrance, excessive grooming leading to hair removal and lesions. Additionally, these mice excessively groom normal cagemates. We have been unable to detect any skin or PNS abnormalities in Hoxb8 mutants. These observations suggest that the excessive, pathological grooming exhibited by these mice results from CNS abnormalities. Consistent with this interpretation, we demonstrate Hoxb8 expression in regions of the adult mouse CNS previously implicated in the control of grooming. The aberrant behavior observed in Hoxb8 mutants is not unlike that of humans suffering from the OC-spectrum disorder, trichotillomania. Interestingly, Hoxb8 is expressed in regions of the CNS known as the "OCD-circuit."     

Hippo信号通路在肺发育、再生和疾病中的功能

哺乳动物肺对于血液与外部环境之间的气体交换至关重要。而肺相关的疾病是现代人死亡的主要原因之一。肺的发育、再生和相关疾病的研究对临床治疗具有重要的指导作用。研究发现,Hippo信号通路参与细胞增殖与分化的调控、器官大小的控制,以及机械力的感应和传递。Hippo信号通路中的核心转录调控分子YAP/TAZ在肺部的多种细胞中均有表达,其表达及定位的变化在肺发育与再生中发挥着重要的调控作用。本文主要介绍了Hippo信号通路在肺生长发育中的功能及其与肺纤维化、肺癌的关系,并从肺泡力学和肺泡相关免疫两个角度对Hippo信号通路潜在的功能进行了展望。     

Hoxb13 up-regulates transglutaminase activity and drives terminal differentiation in an epidermal organotypic model

Hox genes act to differentiate and pattern embryonic structures by promoting the proliferation of specific cell types. An exception is Hoxb13, which functions as a proapoptotic and antiproliferative protein during development of the caudal spinal cord and tail vertebrae and has also been implicated in adult cutaneous wound repair. The adult epidermis, which expresses several Hox genes including Hoxb13, is continually renewed in a program of growth arrest, differentiation, and a specialized form of apoptosis (cornification). Yet little is known about the function(s) of these genes in skin. Based on its role during embryogenesis, Hoxb13 is an attractive candidate to be involved in the regulation of epidermal differentiation. Here, we demonstrate that Hoxb13 overexpression in an adult organotypic epidermal model recapitulates actions of Hoxb13 reported in embryonic development. Epidermal cell proliferation is decreased, apoptosis increased, and excessive terminal differentiation observed, as characterized by enhanced transglutaminase activity and excessive cornified envelope formation. Overexpression of Hoxb13 also produces abnormal phenotypes in the epidermal tissue that resemble certain pathological features of dysplastic skin diseases. Our results suggest that Hoxb13 functions to promote epidermal differentiation, a critical process for skin regeneration and for the maintenance of normal barrier function.     

Oncogene amplification and chromosomal abnormalities in small cell lung cancer

Twelve cell lines isolated from patients with small cell lung cancer have been studied for amplification of the three characterised members of the myc proto-oncogene family (c-myc, N-myc, and L-myc) and for abnormalities of chromosome 3. Ten of these lines were being studied for the first time. Ten of the 12 small cell lung cancer cell lines had amplification of one member of the myc proto-oncogene family. Amplification of c-myc was observed in only one small cell lung line--a "morphological variant". One "classic" small cell lung cancer line expressed c-myc but had no obvious amplification of the gene. N-myc and L-myc were more commonly amplified than c-myc. Chromosomal abnormalities (mainly deletions) in chromosome 3 were observed in all small cell lung carcinoma cell lines examined. When the small cell lung carcinoma lines were grouped according to "classic" or "variant" characteristics, it was found that the "classics" had deletions of the short arm of chromosome 3, whereas the "biochemical variants" had deletions of the long arm of chromosome 3. The extent of the deletions varied between cell lines. For the deletion in the short arm of chromosome 3 the minimum common region of overlap was assigned to bands 3p23-3p24.     

Reversals in two dextral flounder species, Microstomus achne and Cleisthenes pinetorum (Pleuronectida; Teleostei), from Japan

Reversals are described in Microstomus achne (three specimens) and Cleisthenes pinetorum (one specimen) collected from the Pacific coast of northern Japan, being the first published records of reversals in these genera.     

Hoxb13 mutations cause overgrowth of caudal spinal cord and tail vertebrae

To address the expression and function of Hoxb13, the 5' most Hox gene in the HoxB cluster, we have generated mice with loss-of-function and beta-galactosidase reporter insertion alleles of this gene. Mice homozygous for Hoxb13 loss-of-function mutations show overgrowth in all major structures derived from the tail bud, including the developing secondary neural tube (SNT), the caudal spinal ganglia, and the caudal vertebrae. Using the beta-galactosidase reporter allele of Hoxb13, also a loss-of-function allele, we found that the expression patterns of Hoxb13 in the developing spinal cord and caudal mesoderm are closely associated with overgrowth phenotypes in the tails of homozygous mutant animals. These phenotypes can be explained by the observed increased cell proliferation and decreased levels of apoptosis within the tail of homozygous mutant mice. This analysis of Hoxb13 function suggests that this 5' Hox gene may act as an inhibitor of neuronal cell proliferation, an activator of apoptotic pathways in the SNT, and as a general repressor of growth in the caudal vertebrae.     

Effects on spermiogenesis in the mouse of a male sterile neurological mutation,Purkinje cell degeneration

Purkinje cell degeneration (pcd) is a neurological mutation in the mouse that causes male sterility, but not female sterility. In order to assess the effects of this mutation on spermiogenesis, the structure of the testis and of epididymal spermatozoa was examined by transmission and scanning electron microscopy. In the mutant males, the sperm count was reduced, sperm were nonmotile, and 93% of the sperm were characterized by structural abnormalities of the head, the tail, or both. In the testes of mutant mice, Sertoli cell structure was normal, as were also the early stages of spermiogenesis. However, the elongating and maturing spermatids were characterized by abnormally shaped heads and tails with extraneous and ectopic outer dense fibers. These defects were common in the testes of the mutant mice and rare in the testes of the littermate control mice. It was concluded that the structural abnormalities of the pcd sperm occurred during spermiogenesis and were not due to degeneration of the sperm in the epididymis. These structural abnormalities are similar to those found in all other reported male sterile mutants of the mouse; therefore, although they are caused by the expression of the pcd gene, they are not unique to the expression of this gene.