Heparan Sulfate Regulates Hair Follicle and Sebaceous Gland Morphogenesis and Homeostasis

Hair follicle (HF) morphogenesis and cycling are a result of intricate autonomous epithelial-mesenchymal interactions. Once the first HF cycle is complete it repeatedly undergoes cyclic transformations. Heparan sulfate (HS) proteoglycans are found on the cell surface and in the extracellular matrix where they influence a variety of biological processes by interacting with physiologically important proteins, such as growth factors. Inhibition of heparanase (an HS endoglycosidase) in in vitro cultured HFs has been shown to induce a catagen-like process. Therefore, this study aimed to elucidate the precise role of HS in HF morphogenesis and cycling. An inducible tetratransgenic mouse model was generated to excise exostosin glycosyltransferase 1 (Ext1) in keratin 14-positive cells from P21. Interestingly, EXT1^{StEpiΔ/StEpiΔ} mice presented solely anagen HFs. Moreover, waxing the fur to synchronize the HFs revealed accelerated hair regrowth in the EXT1^{StEpiΔ/StEpiΔ} mice and hindered cycling into catagen. The ablation of HS in the interfollicular epidermal cells of mature skin led to the spontaneous formation of new HFs and an increase in Sonic Hedgehog expression resembling wild-type mice at P0, thereby indicating that the HS/Sonic Hedgehog signaling pathway regulates HF formation during embryogenesis and prevents HF formation in mature skin. Finally, the knock-out of HS also led to the morphogenesis and hyperplasia of sebaceous glands and sweat glands in mature mice, leading to exacerbated sebum production and accumulation on the skin surface. Therefore, our findings clearly show that an intricate control of HS levels is required for HF, sebaceous gland, and sweat gland morphogenesis and HF cycling.     

BMP signaling in vascular biology and dysfunction

The vascular system is critical for developmental growth, tissue homeostasis and repair but also for tumor development. Bone morphogenetic protein (BMP) signaling has recently emerged as a fundamental pathway of the endothelium by regulating cardiovascular and lymphatic development and by being causative for several vascular dysfunctions. Two vascular disorders have been directly linked to impaired BMP signaling: pulmonary arterial hypertension and hereditary hemorrhagic telangiectasia. Endothelial BMP signaling critically depends on the cellular context, which includes among others vascular heterogeneity, exposure to flow, and the intertwining with other signaling cascades (Notch, WNT, Hippo and hypoxia). The purpose of this review is to highlight the most recent findings illustrating the clear need for reconsidering the role of BMPs in vascular biology.     

Timing of Expression of r and Its Encoding mRNAs in the Developing Cerebral Neocortex and Cerebellum of the Mouse

The expression of tau mRNA and of the corresponding encoded protein variants was studied during postnatal development in two brain regions differing in their timing of differentiation: the cerebral neocortex and the cerebellum. (a) The expression of tau mRNA was different in the two regions. Maximal contents were found at early stages in the cerebral neocortex, with a 10-fold decrease at later stages. In the cerebellum, two peaks of tau mRNA were observed soon after birth and in adulthood, with minimal values at postnatal day 6. (b) The expression of total tau proteins was similar to that of their encoding mRNAs in the cerebral neocortex, i.e., high concentrations after birth and low contents at later stages. In contrast, two peaks of tau proteins were observed in the cerebellum: the first perinatally and the second with a maximum at postnatal day 15. (c) Both in the cerebral neocortex and especially in the cerebellum, increasing concentrations of mature tau variants were expressed at late developmental stages, i.e., when total tau protein contents were decreased. In conclusion, the fluctuations in expression of tau and of its encoding mRNA seen in the cerebellum seem to reflect differences in the timing of differentiation of the various cell types, i.e., the macroneurons and the interneurons, present in this brain region. The adult tau variants appear in both the neocortex and the cerebellum only at late developmental stages, i.e., when most of the circuitry has been established, although these two regions markedly differ in their timing of differentiation.     

Simple But Efficacious Enrichment of Integral Membrane Proteins and Their Interactions for In-Depth Membrane Proteomics

Membrane proteins play essential roles in various cellular processes, such as nutrient transport, bioenergetic processes, cell adhesion, and signal transduction. Proteomics is one of the key approaches to exploring membrane proteins comprehensively. Bottom–up proteomics using LC–MS/MS has been widely used in membrane proteomics. However, the low abundance and hydrophobic features of membrane proteins, especially integral membrane proteins, make it difficult to handle the proteins and are the bottleneck for identification by LC–MS/MS. Herein, to improve the identification and quantification of membrane proteins, we have stepwisely evaluated methods of membrane enrichment for the sample preparation. The enrichment methods of membranes consisted of precipitation by ultracentrifugation and treatment by urea or alkaline solutions. The best enrichment method in the study, washing with urea after isolation of the membranes, resulted in the identification of almost twice as many membrane proteins compared with samples without the enrichment. Notably, the method significantly enhances the identified numbers of multispanning transmembrane proteins, such as solute carrier transporters, ABC transporters, and G-protein–coupled receptors, by almost sixfold. Using this method, we revealed the profiles of amino acid transport systems with the validation by functional assays and found more protein–protein interactions, including membrane protein complexes and clusters. Our protocol uses standard procedures in biochemistry, but the method was efficient for the in-depth analysis of membrane proteome in a wide range of samples.     

Glutathione Reductase-null Malaria Parasites Have Normal Blood Stage Growth but Arrest during Development in the Mosquito

Malaria parasites contain a complete glutathione (GSH) redox system, and several enzymes of this system are considered potential targets for antimalarial drugs. Through generation of a γ-glutamylcysteine synthetase (γ-GCS)-null mutant of the rodent parasite Plasmodium berghei, we previously showed that de novo GSH synthesis is not critical for blood stage multiplication but is essential for oocyst development. In this study, phenotype analyses of mutant parasites lacking expression of glutathione reductase (GR) confirmed that GSH metabolism is critical for the mosquito oocyst stage. Similar to what was found for γ-GCS, GR is not essential for blood stage growth. GR-null parasites showed the same sensitivity to methylene blue and eosin B as wild type parasites, demonstrating that these compounds target molecules other than GR in Plasmodium. Attempts to generate parasites lacking both GR and γ-GCS by simultaneous disruption of gr and γ-gcs were unsuccessful. This demonstrates that the maintenance of total GSH levels required for blood stage survival is dependent on either de novo GSH synthesis or glutathione disulfide (GSSG) reduction by Plasmodium GR. Our studies provide new insights into the role of the GSH system in malaria parasites with implications for the development of drugs targeting GSH metabolism.     

Interference by the mantispid Mantispa uhleri with the development of the spider Lycosa rabida

Abstract. 1. The larvae of Mantispa uhleri Banks (Neuroptera: Mantispidae) board spiders to await the production of an egg sac containing their obligate developmental food. While aboard the spider, larvae maintain themselves by feeding on spider blood. This parasitic behaviour was investigated by allowing larvae to board sixth instar Lycosa rabida Walckenaer (Araneae: Lycosidae). Larval parasitism has a direct and indirect effect on the developmental physiology of the spider.
2. The direct effect, equal in both spider sexes, is an increase in development time and a decrease in adult size.
3. The indirect effect on development time and adult size is brought about by the loss of an instar in female spiders only. Parasitized females were mature at nine or ten instars; control females at ten or eleven. Male instar number was not affected; both control and parasitized males were mature at nine or ten instars.
4. The net result is that parasitized female spiders are even smaller than would be predicted from the direct effect alone, but actually mature faster than control females. In males there is only the direct effect. The adaptive significance of this sexually dimorphic response is discussed.     

Adaptive strategies in natural populations of Drosophila

Summary Adult tolerance of ethanol vapour in a closed system containing 12% ethanol in solution, decreases in a cline from southern to northern Australia. However a Darwin population is more tolerant than predicted from its latitude. Ethanol tolerance races in Australia have almost certainly evolved within the last 100–150 years, because of resource unavailability prior to that time. Within populations, variation among isofemale strains is lowest in the climatically extreme southern Melbourne (37°S) and northern Darwin and Melville I. (11–12°S) populations. This suggests low resource diversity within extreme populations compared with the climatically less extreme Brisbane (28°S) and especially Townsville (19°S) populations. For desiccation resistance, the population rankings are: Darwin Melbourne > Townsville > Brisbane Melville I. and for development time, rankings are similar: Darwin Melbourne < Townsville < Brisbane Melville I.Therefore resource utilization heterogeneity is greatest in populations not greatly stressed by desiccation and where development times are extended. In total therefore, the utilization of a diversity of resources is a feature of populations tending somewhat towards a K-strategy; this is emphasized by the relative heterogeneity among isofemale strains of these populations for desiccation resistance and to a lesser extent development times.The D. melanogaster gene pool can be viewed as made up of climate-associated races. Since the ethanol tolerances of adjacent (and climatically similar) Darwin and Melville I. are very different, resource utilization races may occur within climatic races. Such a mosaic of resource utilization races are more likely in climatically extreme than in optimal habitats.     

Developmental Changes in Polypeptide Composition of, and Precursor Incorporation into, Cellular and Subcellular Fractions of Rat Cerebral Cortex

Abstract: Neuronal-enriched and glial-enriched fractions from rat cerebral cortex at 2. 5, 9, 14 and 23 days postnatally, and subcellular fractions from 2, 14 and 46 day old rat were prepared. The polypeptide composition of all fractions was analysed by sodium dodecyl sulphate (SDS) polyacrylamide gel electro-phoresis and quantified by densitometry. Fifty-nine polypeptides (mol. wts., 13,200–251,000) were resolved in the cell fractions of which the majority remained unchanged throughout postnatal development. Three polypeptides (mol. wts., 102,000, 56,000, 53,700) were found to increase in amount devel-opmentally in both cellular fractions, the latter two showing a peak in relative amount on day 14 and a subsequent decline. Three polypeptides (mol. wts., 47,000, 28,200, 17,400) were found to be common to the glial-enriched fraction as well as the myelin fraction, and all showed a developmental increase. The neuronal-enriched fraction was found to be enriched in five polypeptides of which one (mol. wt., 51,900) showed a developmental increase after ten days postnatally, the others (mol. wts., 178,700, 142,000, 109,000, 24,000) showing a decrease. In vitro incorporation of [³⁵S]-methionine into the glial-enriched fraction was carried out, and a developmental decline was observed in the labelling of a polypeptide of 42,000 mol. wt.