Isolation and characterization of theXenopusHIVEP gene family

Genome-Wide Association Study of Conformation Traits in Brazilian Holstein Cattle

The linear conformation of animals exerts an influence on health, reproduction, production, and welfare, in addition to longevity, which directly affects the profitability of milk-producing farms. The objectives of this study were (1) to perform genome-wide association studies (GWASs) of conformation traits, namely the Rump, Feet and Legs, Mammary System, Dairy Strength, and Final Classification traits, and (2) to identify genes and related pathways involved in physiological processes associated with conformation traits in Brazilian Holstein cattle. Phenotypic and genotypic data from 2339 Holstein animals distributed across the states of Rio Grande do Sul, Paraná, São Paulo, and Minas Gerais were used. The genotypic data were obtained with a 100 K SNP marker panel. The single-step genome-wide association study (ssGWAS) method was employed in the analyses. Genes close to a significant SNP were identified in an interval of 100 kb up- and downstream using the Ensembl database available in the BioMart tool. The DAVID database was used to identify the main metabolic pathways and the STRING program was employed to create the gene regulatory network. In total, 36 significant SNPs were found on 15 chromosomes; 27 of these SNPs were linked to genes that may influence the traits studied. Fourteen genes most closely related to the studied traits were identified, as well as four genes that showed interactions in important metabolic pathways such as myogenesis, adipogenesis, and angiogenesis. Among the total genes, four were associated with myogenesis (TMOD2, TMOD3, CCND2, and CTBP2), three with angiogenesis (FGF23, FGF1, and SCG3), and four with adipogenesis and body size and development (C5H12orf4, CCND2, EMILIN1, and FGF6). These results contribute to a better understanding of the biological mechanisms underlying phenotypic variability in conformation traits in Brazilian Holstein cattle.

Transcription factor roles in the local adaptation to temperature in the Andean Spiny Toad Rhinella spinulosa

Environmental temperature strongly influences the adaptation dynamics of amphibians, whose limited regulation capabilities render them susceptible to thermal oscillations. A central element of the adaptive strategies is the transcription factors (TFs), which act as master regulators that orchestrate stress responses, enabling species to navigate the fluctuations of their environment skillfully. Our study delves into the intricate relationship between TF expression and thermal adaptation mechanisms in the Rhinella spinulosa populations. We sought to elucidate the dynamic modulations of TF expression in prometamorphic and metamorphic tadpoles that inhabit two thermally contrasting environments (Catarpe and El Tatio Geyser, Chile) and which were exposed to two thermal treatments (25 °C vs. 20 °C). Our findings unravel an intriguing dichotomy in response strategies between these populations. First, results evidence the expression of 1374 transcription factors. Regarding the temperature shift, the Catarpe tadpoles show a multifaceted approach by up-regulating crucial TFs, including fosB, atf7, and the androgen receptor. These dynamic regulatory responses likely underpin the population's ability to navigate thermal fluctuations effectively. In stark contrast, the El Tatio tadpoles exhibit a more targeted response, primarily up-regulating foxc1. This differential expression suggests a distinct focus on specific TFs to mitigate the effects of temperature variations. Our study contributes to understanding the molecular mechanisms governing thermal adaptation responses and highlights the resilience and adaptability of amphibians in the face of ever-changing environmental conditions.

Immune-related functions of the Hivep gene family in East African cichlid fishes

Immune-related genes are often characterized by adaptive protein evolution. Selection on immune genes can be particularly strong when hosts encounter novel parasites, for instance, after the colonization of a new habitat or upon the exploitation of vacant ecological niches in an adaptive radiation. We examined a set of new candidate immune genes in East African cichlid fishes. More specifically, we studied the signatures of selection in five paralogs of the human immunodeficiency virus type I enhancer-binding protein (Hivep) gene family, tested their involvement in the immune defense, and related our results to explosive speciation and adaptive radiation events in cichlids. We found signatures of long-term positive selection in four Hivep paralogs and lineage-specific positive selection in Hivep3b in two radiating cichlid lineages. Exposure of the cichlid Astatotilapia burtoni to a vaccination with Vibrio anguillarum bacteria resulted in a positive correlation between immune response parameters and expression levels of three Hivep loci. This work provides the first evidence for a role of Hivep paralogs in teleost immune defense and links the signatures of positive selection to host-pathogen interactions within an adaptive radiation.

Finding partners: how BMPs select their targets

The bone morphogenetic protein (BMP) signaling pathway is a conserved and evolutionarily ancient regulatory module affecting a large variety of cellular behaviors. The evolutionary flexibility in using BMP responses presumably arose by co-option of a canonical BMP signaling cascade to regulate the transcription of diverse batteries of target genes. This begs the question of how seemingly interchangeable BMP signaling components elicit widely different outputs in different cell types, an important issue in the context of understanding how BMP signaling integrates with gene regulatory networks to control development. Because a molecular understanding of how BMP signaling activates different batteries of target genes is an essential prerequisite to comprehending the roles of BMPs in regulating cellular responses, here we review the current knowledge of how BMP-regulated target genes are selected by the signal transduction machinery. We highlight recent studies suggesting the evolutionary conservation of BMP target gene regulation signaling by Schnurri family zinc finger proteins. Developmental Dynamics 238:1321-1331, 2009. (c) 2009 Wiley-Liss, Inc.

Lack of Schnurri-2 expression associates with reduced bone remodeling and osteopenia

Regulation of bone remodeling determines the levels of bone mass and its imbalance causes major skeletal diseases such as osteoporosis. A zinc finger protein, Schnurri-2 (SHN-2), was recently demonstrated to regulate bone morphogenetic protein-dependent adipogenesis and lymphogenesis. However, the role of SHN-2 in bone is not known. Here, we investigated the effects of Shn-2 deficiency on bone metabolism and cell function in Shn-2-null mice. Lack of SHN-2 expression reduced bone remodeling by suppressing both osteoblastic bone formation and osteoclastic bone resorption activities in vivo. Shn-2 deficiency suppressed osterix and osteocalcin expression as well as in vitro mineralization. Conversely, Shn-2 overexpression enhanced osteocalcin promoter activity and bone morphogenetic protein-dependent osteoblastic differentiation. Shn-2 deficiency suppressed Nfatc1 and c-fos expression leading to reduction of tartrate-resistant acid phosphatase-positive cell development in vivo as well as in the cultures of bone marrow cells. These studies demonstrate that SHN-2 regulates the activities of critical transcription factors required for normal bone remodeling.

Schnurri transcription factors fromDrosophilaand vertebrates can mediate Bmp signaling through a phylogenetically conserved mechanism

Bone Morphogenetic Proteins (Bmps) are secreted growth factors that play crucial roles in animal development across the phylogenetic spectrum. Bmp signaling results in the phosphorylation and nuclear translocation of Smads,downstream signal transducers that bind DNA. In Drosophila, the zinc finger protein Schnurri (Shn) plays a key role in signaling by the Bmp2/Bmp4 homolog Decapentaplegic (Dpp), by forming a Shn/Smad repression complex on defined promoter elements in the brinker (brk) gene. Brk is a transcriptional repressor that downregulates Dpp target genes. Thus, brk inhibition by Shn results in the upregulation of Dpp-responsive genes. We present evidence that vertebrate Shn homologs can also mediate Bmp responsiveness through a mechanism similar to Drosophila Shn. We find that a Bmp response element (BRE) from the Xenopus Vent2 promoter drives Dpp-dependent expression in Drosophila. However, in sharp contrast to its activating role in vertebrates, the frog BRE mediates repression in Drosophila. Remarkably, despite these opposite transcriptional polarities, sequence changes that abolish cis-element activity in Drosophila also affect BRE function in Xenopus. These similar cis requirements reflect conservation of trans-acting factors, as human Shn1 (hShn1; HIVEP1) can interact with Smad1/Smad4 and assemble an hShn1/Smad complex on the BRE. Furthermore, both Shn and hShn1 activate the BRE in Xenopus embryos, and both repress brk and rescue embryonic patterning defects in shn mutants. Our results suggest that vertebrate Shn proteins function in Bmp signal transduction, and that Shn proteins recruit coactivators and co-repressors in a context-dependent manner,rather than acting as dedicated activators or repressors.

Schnurri-2 controls BMP-dependent adipogenesis via interaction with Smad proteins

Adipocyte differentiation is an important component of obesity, but how hormonal cues mediate adipocyte differentiation remains elusive. BMP stimulates in vitro adipocyte differentiation, but the role of BMP in adipogenesis in vivo is unknown. Drosophila Schnurri (Shn) is required for the signaling of Decapentaplegic, a Drosophila BMP homolog, via interaction with the Mad/Medea transcription factors. Vertebrates have three Shn orthologs, Shn-1, -2, and -3. Here, we report that Shn-2(-/-) mice have reduced white adipose tissue and that Shn-2(-/-) mouse embryonic fibroblasts cannot efficiently differentiate into adipocytes in vitro. Shn-2 enters the nucleus upon BMP-2 stimulation and, in cooperation with Smad1/4 and C/EBPalpha, induces the expression of PPARgamma2, a key transcription factor for adipocyte differentiation. Shn-2 directly interacts with both Smad1/4 and C/EBPalpha on the PPARgamma2 promoter. These results indicate that Shn-2-mediated BMP signaling has a critical role in adipogenesis.

Maternal determinants of embryonic cell fate

How important is the contribution of mRNAs and proteins stored in the oocyte for determining the body plan of the Xenopus embryo? Here we review the current understanding of the roles of maternally supplied transcription factors, signaling molecules, and signaling regulators in establishing the ectoderm, mesoderm, and endoderm germ layers and the embryonic axes. Key essential asymmetries of VegT, Wnt11, and Ectodermin are described, as well as the complexity of maternal transcription factors that are involved in the initial expression of early zygotic genes.