Isolation and mapping of a human gene (RABL) encoding a small GTP-binding protein homologous to the Ras-related RAB gene

Early Pregnancy Exposure to Ambient Air Pollution among Late-Onset Preeclamptic Cases Is Associated with Placental DNA Hypomethylation of Specific Genes and Slower Placental Maturation

Exposure to ambient air pollution during pregnancy has been associated with an increased risk of preeclampsia (PE). Some suggested mechanisms behind this association are changes in placental DNA methylation and gene expression. The objective of this study was to identify how early pregnancy exposure to ambient nitrogen oxides (NO_x) among PE cases and normotensive controls influence DNA methylation (EPIC array) and gene expression (RNA-seq). The study included placentas from 111 women (29 PE cases/82 controls) in Scania, Sweden. First-trimester NO_x exposure was assessed at the participants’ residence using a dispersion model and categorized via median split into high or low NO_x. Placental gestational epigenetic age was derived from the DNA methylation data. We identified six differentially methylated positions (DMPs, q < 0.05) comparing controls with low NO_x vs. cases with high NO_x and 14 DMPs comparing cases and controls with high NO_x. Placentas with female fetuses showed more DMPs (N = 309) than male-derived placentas (N = 1). Placentas from PE cases with high NO_x demonstrated gestational age deceleration compared to controls with low NO_x (p = 0.034). No differentially expressed genes (DEGs, q < 0.05) were found. In conclusion, early pregnancy exposure to NO_x affected placental DNA methylation in PE, resulting in placental immaturity and showing sexual dimorphism.

Genome-Wide Association Transethnic Meta-Analyses Identifies Novel Associations Regulating Coagulation Factor VIII and von Willebrand Factor Plasma Levels

BACKGROUND

Factor VIII (FVIII) and its carrier protein von Willebrand factor (VWF) are associated with risk of arterial and venous thrombosis and with hemorrhagic disorders. We aimed to identify and functionally test novel genetic associations regulating plasma FVIII and VWF.

METHODS

We meta-analyzed genome-wide association results from 46 354 individuals of European, African, East Asian, and Hispanic ancestry. All studies performed linear regression analysis using an additive genetic model and associated ≈35 million imputed variants with natural log-transformed phenotype levels. In vitro gene silencing in cultured endothelial cells was performed for candidate genes to provide additional evidence on association and function. Two-sample Mendelian randomization analyses were applied to test the causal role of FVIII and VWF plasma levels on the risk of arterial and venous thrombotic events.

RESULTS

We identified 13 novel genome-wide significant ( P≤2.5×10^-8) associations, 7 with FVIII levels ( FCHO2/TMEM171/TNPO1, HLA, SOX17/RP1, LINC00583/NFIB, RAB5C-KAT2A, RPL3/TAB1/SYNGR1, and ARSA) and 11 with VWF levels ( PDHB/PXK/KCTD6, SLC39A8, FCHO2/TMEM171/TNPO1, HLA, GIMAP7/GIMAP4, OR13C5/NIPSNAP, DAB2IP, C2CD4B, RAB5C-KAT2A, TAB1/SYNGR1, and ARSA), beyond 10 previously reported associations with these phenotypes. Functional validation provided further evidence of association for all loci on VWF except ARSA and DAB2IP. Mendelian randomization suggested causal effects of plasma FVIII activity levels on venous thrombosis and coronary artery disease risk and plasma VWF levels on ischemic stroke risk.

CONCLUSIONS

The meta-analysis identified 13 novel genetic loci regulating FVIII and VWF plasma levels, 10 of which we validated functionally. We provide some evidence for a causal role of these proteins in thrombotic events.

A de novo 17q21.2 duplication in a boy with developmental delay and dysmorphic features

We report a boy with severe developmental delay, microcephaly and characteristic facial dysmorphism consisting in round face, hypertelorism, upslanted palpebral fissures, small nose, large mouth, micrognathia, sparse hair and eyelashes. Array-CGH revealed a de novo duplication of 103 kb within 17q21.2 not reported to date. The duplication includes 8 genes: DHX58, KAT2A, HSPB9, RAB5C, KCNH4, HCRT, GHDC and STAT5B. Three genes (KATA2, KCNH4, and STAT5B) may contribute to intellectual deficiency. Further observations will be necessary to confirm the specificity of the facial Gestalt.

Refined mapping of Naegeli-Franceschetti- Jadassohn syndrome to a 6 cM interval on chromosome 17q11.2-q21 and investigation of candidate genes

Naegeli-Franceschetti-Jadassohn syndrome and dermatopathia pigmentosa reticularis are autosomal dominant ectodermal dysplasias characterized by the absence of dermatoglyphics, reticulate hyper pigmentation of the skin, hypohidrosis, and heat intolerance. Palmoplantar keratoderma, nail dystrophy, and enamel defects are common in Naegeli-Franceschetti-Jadassohn syndrome, whereas diffuse alopecia is only seen in dermatopathia pigmentosa reticularis. We studied a large Swiss family with Naegeli-Franceschetti-Jadassohn syndrome originally described by Naegeli in 1927 and assessed linkage to chromosome 17q, which was proposed to harbor the Naegeli-Franceschetti-Jadassohn syndrome gene. Our results considerably narrow the Naegeli-Franceschetti-Jadassohn syndrome gene region from 27 cM to 6 cM flanked by D17S933 and D17S934 with a maximum multipoint LOD score of 2.7 at marker locus D17S800. In addition, we studied a small family with dermatopathia pigmentosa reticularis, and our linkage data suggest that dermatopathia pigmentosa reticularis may map to the same chromosomal region. The Naegeli-Franceschetti-Jadassohn syndrome critical interval spans approximately 5.4 Mb and contains a minimum of 45 distinct genes. We scrutinized 13 new prime candidates in addition to five genes previously examined, established the genomic organization of 10 of these genes, and excluded all of them by mutation analysis. Moreover, we identified a cDNA (KRT24) encoding a new keratin protein that bears high similarity to the type I keratins and displays a unique expression profile. No pathogenic mutations were identified in this novel gene either, however. In summary, our results substantially refine the Naegeli-Franceschetti-Jadassohn syndrome region and will aid in identifying a gene that is critical for ontogenesis of multiple ectodermal tissues.

Deviant expression of Rab5 on phagosomes containing the intracellular pathogens Mycobacterium tuberculosis and Legionella pneumophila is associated with altered phagosomal fate

The intracellular human pathogens Legionella pneumophila and Mycobacterium tuberculosis reside in altered phagosomes that do not fuse with lysosomes and are only mildly acidified. The L. pneumophila phagosome exists completely outside the endolysosomal pathway, and the M. tuberculosis phagosome displays a maturational arrest at an early endosomal stage along this pathway. Rab5 plays a critical role in regulating membrane trafficking involving endosomes and phagosomes. To determine whether an alteration in the function or delivery of Rab5 could play a role in the aberrant development of L. pneumophila and M. tuberculosis phagosomes, we have examined the distribution of the small GTPase, Rab5c, in infected HeLa cells overexpressing Rab5c. Both pathogens formed phagosomes in HeLa cells with molecular characteristics similar to their phagosomes in human macrophages and multiplied in these host cells. Phagosomes containing virulent wild-type L. pneumophila never acquired immunogold staining for Rab5c, whereas phagosomes containing an avirulent mutant L. pneumophila (which ultimately fused with lysosomes) transiently acquired staining for Rab5c after phagocytosis. In contrast, M. tuberculosis phagosomes exhibited abundant staining for Rab5c throughout its life cycle. To verify that the overexpressed, recombinant Rab5c observed on the bacterial phagosomes was biologically active, we examined the phagosomes in HeLa cells expressing Rab5c Q79L, a fusion-promoting mutant. Such HeLa cells formed giant vacuoles, and after incubation with various particles, the giant vacuoles acquired large numbers of latex beads, M. tuberculosis, and avirulent L. pneumophila but not wild-type L. pneumophila, which consistently remained in tight phagosomes that did not fuse with the giant vacuoles. These results indicate that whereas Rab5 is absent from wild-type L. pneumophila phagosomes, functional Rab5 persists on M. tuberculosis phagosomes. The absence of Rab5 on the L. pneumophila phagosome may underlie its lack of interaction with endocytic compartments. The persistence of functional Rab5 on the M. tuberculosis phagosomes may enable the phagosome to retard its own maturation at an early endosomal stage.

Abnormal frequencies of alleles in polymorphic markers of the 17q21 region is associated with breast cancer

This study was carried out to evaluate the frequencies of alleles of four polymorphic markers in the 17q21 region in breast cancer patients, and their relation to seven pathological parameters. One hundred and sixty-four patients with breast cancer and 102 controls were analyzed. D17S856, D17S855, D17S1323 and D17S1327 polymorphic markers were studied, and used to investigate loss of heterozygosity in this region. The frequencies of alleles at marker D17S856 differed significantly in breast cancer patients and controls, and were related to histologic features considered to indicate a poor prognosis. When present, the pathophenotype of tumors associated with LOH in the 17q21 region is modified.

Molecular cloning and expression of an avian rab5 homolog

A chicken rab5 cDNA was isolated that contains the complete open reading frame for a protein of 216 amino acids, which, by comparison with available rab5 sequences from other species, is most closely related to the rab5c isoform. Two rab5 transcripts of 1.3 and 1.8 kb were detectable in various chicken tissues; they are abundant in tissues with high endocytic activity, such as brain, ovary, and testis. Similarly, high levels of rab5 protein expression were found in endocytotically active tissues and were increased upon estrogen treatment of roosters.