RAB23 mutations in Carpenter syndrome imply an unexpected role for hedgehog signaling in cranial-suture development and obesity

Carpenter syndrome is a pleiotropic disorder with autosomal recessive inheritance, the cardinal features of which include craniosynostosis, polysyndactyly, obesity, and cardiac defects. Using homozygosity mapping, we found linkage to chromosome 6p12.1-q12 and, in 15 independent families, identified five different mutations (four truncating and one missense) in RAB23, which encodes a member of the RAB guanosine triphosphatase (GTPase) family of vesicle transport proteins and acts as a negative regulator of hedgehog (HH) signaling. In 10 patients, the disease was caused by homozygosity for the same nonsense mutation, L145X, that resides on a common haplotype, indicative of a founder effect in patients of northern European descent. Surprisingly, nonsense mutations of Rab23 in open brain mice cause recessive embryonic lethality with neural-tube defects, suggesting a species difference in the requirement for RAB23 during early development. The discovery of RAB23 mutations in patients with Carpenter syndrome implicates HH signaling in cranial-suture biogenesis--an unexpected finding, given that craniosynostosis is not usually associated with mutations of other HH-pathway components--and provides a new molecular target for studies of obesity.     

A long unidentifiable extra chromosomal segment--a possible duplication of human 7q

Limitation of current techniques in identifying extra chromosomal segments arising de novo is illustrated by a putative case of a duplication of the long arm of chromosome 7. The propositus, demonstrating multiple congenital anomalies and severe mental retardation, had a large extra segment of chromatin on chromosome 7q that was absent in his parents. The banding pattern of this segment resembled that of the long arm of chromosomes 7, 8, or 9. Various procedures indicated that the additional material did not include the secondary constriction of 9q. The phenotype of the propositus did not fit well with that of trisomy 8.     

In vitro selection for salt tolerance in crop plants: Theoretical and practical considerations

Summary In recent years attempts have been made to supplement traditional breeding for the production of salt-tolerant plants with variability existing in cell culture. The potential causes suggested as an explanation for the limited success of the in vitro approach include: a) lack, or loss during selection, of regeneration capability; b) the development of epigenetically adapted cells; c) lack of correlation between the mechanisms of tolerance operating in cultured cells and mechanisms that operate in cells in the intact plant; and d) multigenicity of salt tolerance. The recent successful production of healthy, fertile, and genetically stable salt-tolerant regenerants from cells obtained from highly morphogenic explants which are selected early in culture (using one-step or short-term strategies) for salt tolerance, together with the demonstration that salt-sensitive plants can become tolerant by mutations in one or few genes, suggest that some of the potential limitations can be overcome and that some of them may not exist at all.     

Urinalysis of patients suffering from climatic heat stress (Sharav)

Hot dry winds (Sharav in Israel) are notorious for causing controversial symptoms such as depression, discomfort, headaches, irritability and exacerbation of respiratory ailments. Daily urinalysis combined with study of the complaints of two hundred weather-sensitive patients suffering from Sharav have shown that there exist at least three different patterns of reaction: serotonin hypersecretion causing a general "Irritation Syndrome", catecholamine deficiency resulting in the "Exhaustion Syndrome", histamine and creatinine overproduction combined with clinical "Hyperthyroidism - Forme Fruste" and typical thyroid complaints. These syndromes are amenable to appropriate treatment controlled by urinalysis.

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Zusammenfassung Trockene heisse Wüstenwinde (Sharav in Israel) rufen eine seltsame Mischung von Symptomen hervor wie Depression, Unwohlsein, Kopfschmerzen, Reizbarkeit und Verschlimmerung respiratorischer Beschwerden. Tägliche Urinuntersuchungen kombiniert mit dem Studium der verschiedenen Beschwerden von 200 Sharav-gefühligen Personen haben gezeigt, dass drei verschiedene Reaktionsformen vorliegen: Serotonin-Ausschüttung, die zu einem allgemeinen Irritationssyndrom führt; Katecholamin-Mangel, der zu einem typischen Erschöpfungssyndrom führt; Histamin- und Kreatinin-Ausschüttung, die mit leichtem Hyperthyreoidismus einhergehen. Letzteres Syndrom bereitet dem Patienten nur an Sharav-Tagen Beschwerden. Die Syndrome sind durch gezielte und Urin-kontrollierte Behandlung heilbar.

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Resume Des vents chauds et secs provenant du désert (le Charav en Israël par exemple) sont connus pour provoquer un ensemble de symptômes particuliers tels que dépression nerveuse, indisposition, céphalées, irritabilité et aggravation des troubles respiratoires. L'analyse journalière de l'urine et l'étude des divers symptômes que présentaient 200 personnes sensibles au Charav ont montré la présence de trois formes différentes de réactions: sécrétion accrue de sérotonine qui conduit à un syndrome d'irritabilité générale; une carence en catécholamine qui se traduit par un syndrome typique d'épuisement; une sécrétion d'histamine et de créatinine parallèle à un faible hyperthyréoïdisme. Ce dernier syndrome ne provoque des troubles aux patients que durant les jours où le Charav souffle. Ces trois syndromes sont guérissables par une médication appropriée et dont l'effet est contrôlé par des analyses d'urine.

     

An evolutionary space-time model with varying among-site dependencies

It is now widely accepted that sites in a protein do not undergo independent evolutionary processes. The underlying assumption is that proteins are composed of conserved and variable linear domains, and thus rates at neighboring sites are correlated. In this paper, we comprehensively examine the performance of an autocorrelation model of evolutionary rates in protein sequences. We further develop a model in which the level of correlation between rates at adjacent sites is not equal at all sites of the protein. High correlation is expected, for example, in linear functional domains. On the other hand, when we consider nonlinear functional regions (e.g., active sites), low correlation is expected because the interaction between distant sites imposes independence of rates in the linear sequence. Our model is based on a hidden Markov model, which accounts for autocorrelation at certain regions of the protein and rate independence at others. We study the differences between the novel model and models which assume either independence or a fixed level of dependence throughout the protein. Using a diverse set of protein data sets we show that the novel model better fits most data sets. We further analyze the potassium-channel protein family and illustrate the relationship between the dependence of rates at adjacent sites and the tertiary structure of the protein.     

Alternate AChE-R variants facilitate cellular metabolic activity and resistance to genotoxic stress through enolase and RACK1 interactions

Tumorogenic transformation is a multifaceted cellular process involving combinatorial protein-protein interactions that modulate different cellular functions. Here, we report apparent involvement in two independent tumorogenic processes by distinct partner protein interactions of the stress-induced acetylcholinesterase AChE-R and N-AChE-R variants. Human testicular tumors showed elevated levels of N-terminally extended N-AChE-R compared with healthy tissue, indicating alternate promoter usage in the transformed cells. Two-hybrid screens demonstrate that the C-terminus common to both N-AChE-R and AChE-R interacts either with the glycolytic enzyme enolase or with the scaffold protein RACK1. In vitro, the AChE-R C-terminal peptide ARP elevated enolase's activity by 12%, suggesting physiological relevance for this interaction. Correspondingly, CHO cells expressing either human AChE-R or N-AChE-R but not AChE-S showed a 25% increase in cellular ATP levels, indicating metabolic significance for this upregulation of enolase activity. ATP levels could be reduced by AChE-targeted siRNA in CHO cells expressing AChE-R but not AChE-S, attributing this elevation to the AChE-R C-terminus. Additionally, transfected CHO cells expressing AChE-R but not N-AChE-R showed resistance to up to 60muM of the common chemotherapeutic agent, cis-platinum, indicating AChE-R involvement in another molecular pathway. cis-Platinum elevates the expression of the apoptosis-regulator p53-like protein, p73, which is inactivated by interaction with the scaffold protein RACK1. In co-transfected cells, AChE-R competed with endogenous RACK1 for p73 interaction. Moreover, AChE-R-transfected CHO cells presented higher levels than control cells of the pro-apoptotic TAp73 as well as the anti-apoptotic dominant negative DeltaNp73 protein, leading to an overall decrease in the proportion of pro-apoptotic p73. Together, these findings are compatible with the hypothesis that in cancer cells, both AChE-R and N-AChE-R elevate cellular ATP levels and that AChE-R modifies p73 gene expression by facilitating two independent cellular pathways, thus conferring both a selective metabolic advantage and a genotoxic resistance.