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NF-κB is an evolutionarily conserved eukaryotic transcription factor that plays a role in many important developmental and immune-related processes by activating target gene expression. The goal of these experiments was to define the sequences required for a sea anemone NF-κB's intrinsic transactivation activity by using mutant proteins with serial deletions of the N- and C-terminal sequences. Deletion mutants were constructed that were missing the C-terminal 15, 32 or 47 amino acids (aa) or the N-terminal 17, 27 or 47 aa of the 440 aa NF-κB protein from the starlet sea anemone, Nematostella vectensis (Nv), a simple model organism in the phylum Cnidaria. These Nv-NF-κB mutants were expressed as GAL4 fusion proteins in yeast, and their transactivation activities were assessed by LacZ reporter gene assays. The deletion of 47 aa from either the N terminus or the C terminus of NF-κB completely inactivates the transactivation function of Nv-NF-κB. In addition, we identified proline-258 in the center ...

Growth and regeneration of one tissue within an organ compels accommodative changes in the surrounding tissues. However, the molecular nature and operating logic governing these concurrent changes remain poorly defined. The dermal adipose layer expands concomitantly with hair follicle downgrowth, providing a paradigm for studying coordinated changes of surrounding lineages with a regenerating tissue. Here, we discover that hair follicle transit-amplifying cells (HF-TACs) play an essential role in orchestrating dermal adipogenesis through secreting Sonic Hedgehog (SHH). Depletion of Shh from HF-TACs abrogates both dermal adipogenesis and hair follicle growth. Using cell type-specific deletion of Smo, a gene required in SHH-receiving cells, we found that SHH does not act on hair follicles, adipocytes, endothelial cells, and hematopoietic cells for adipogenesis. Instead, SHH acts directly on adipocyte precursors, promoting their proliferation and their expression of a key adipogenic gene, peroxisome proliferator-activated receptor γ (Pparg), to induce dermal adipogenesis. Our study therefore uncovers a critical role for TACs in orchestrating the generation of both their own progeny and a neighboring lineage to achieve concomitant tissue production across lineages.

Skeletal patterning in the sea urchin embryo requires coordinated signaling between the pattern-dictating ectoderm and the skeletogenic primary mesenchyme cells (PMCs); recent studies have begun to uncover the molecular basis for this process. Using an unbiased RNA-Seq-based screen, we have previously identified the TGF-s superfamily ligand, LvBMP5-8, as a skeletal patterning gene in Lytechinus variegatus embryos. This result is surprising, since both BMP5-8 and BMP2/4 ligands have been implicated in sea urchin dorsal-ventral (DV) and left-right (LR) axis specification. Here, we demonstrate that zygotic LvBMP5-8 is required for normal skeletal patterning on the left side, as well as for normal PMC positioning during gastrulation. Zygotic LvBMP5-8 is required for expression of the left-side marker soxE, suggesting that LvBMP5-8 is required for left-side specification. Interestingly, we also find that LvBMP5-8 knockdown suppresses serotonergic neurogenesis on the left side. While LvBMP5-8 overexpression is sufficient to dorsalize embryos, we find that zygotic LvBMP5-8 is not required for normal DV specification or development. In addition, ectopic LvBMP5-8 does not dorsalize LvBMP2/4 morphant embryos, indicating that, in the absence of BMP2/4, BMP5-8 is insufficient to specify dorsal. Taken together, our data demonstrate that zygotic LvBMP5-8 signaling is essential for left-side specification, and for normal left-side skeletal and neural patterning, but not for DV specification. Thus, while both BMP2/4 and BMP5-8 regulate LR axis specification, BMP2/4 but not zygotic BMP5-8 regulates DV axis specification in sea urchin embryos.

The sea urchin larval skeleton offers a simple model for developmental pattern formation. The calcium carbonate skeleton is secreted by primary mesenchyme cells (PMCs) in response to largely unknown patterning cues expressed by the ectoderm. To discover novel ectodermal cues, we performed an unbiased RNA-seq-based screen and functionally tested candidates; we thereby identified several novel skeletal patterning cues. Among these, we show that SLC26a2/7 is a ventrally expressed sulfate transporter which promotes a ventral accumulation of sulfated proteoglycans that is required for ventral PMC positioning and skeletal patterning. We show that the effects of SLC perturbation are mimicked by manipulation of either external sulfate levels or proteoglycan sulfation. These results identify novel skeletal patterning genes and demonstrate that ventral proteoglycan sulfation serves as a positional cue for the sea urchin skeletal patterning.

Besides playing a role in blood-pressure regulation and salt and fluid homeostasis, the octapeptide angiotensin II mediates cell growth and differentiation. Its effects are dependent on angiotensin receptors, of which both AT1 and AT2 receptors are extensively described. In cardiac hypertrophy and heart failure, angiotensin receptors are differentially regulated. It is established that AT1 receptors induce cell growth, while AT2 receptors have been associated with growth inhibition, differentiation, and apoptosis. The availability of receptors controlling cell function within a broad spectrum for a single hormone and the regulation of these receptors during cardiac hypertrophy and failure emphasize a complex role for angiotensin II in cardiac pathogenesis. Due to their functional properties, AT1 and AT2 receptors might counteract each other in cell growth processes. Therefore, the current clinical use of specific AT1 receptor antagonists raises questions as to the role of the AT2 receptor in disease processes such as cardiac hypertrophy and failure. Under AT1 receptor antagonist treatment, AT2 receptors are overexposed to angiotensin II. This article describes a possible role of angiotensin II through its angiotensin receptors AT1 and AT2 in cardiac hypertrophy and heart failure.

Physiological and pharmacological implications of AT1versus AT2receptors. Angiotensin II (Ang II) has diverse physiological actions that lead, for instance, to increases in extracellular volume and peripheral vascular resistance and blood pressure, and it has also been implicated in the regulation of cell growth and differentiation. Molecular cloning and pharmacological studies have defined two major classes of Ang II receptors, designated AT1 and AT2. Most effects of Ang II are mediated by AT1 receptors. Much less is known about the physiological role of AT2 receptors. Recent evidence suggests involvement of AT2 receptors in development, cell differentiation, apoptosis, and regeneration in various tissues. AT1 and AT2 receptors have been shown to exert counteracting effects on cellular growth and differentiation, vascular tone, and the release of arginine vasopressin. In each condition, the AT2 receptor appears to down-modulate actions mediated by the AT1 receptor, resulting in decreased cellular proliferation, decreased levels of serum arginine vasopressin levels, or decreased vasoconstrictor responses. In addition, in neuronal cell lines, the AT2 receptor exerts antiproliferative actions and promotes neurite outgrowth, an effect accompanied by significant changes in the expression pattern of growth/differentiation-related genes.

Angiotensin II mediates its effects through angiotensin receptors. The use of specific angiotensin receptor ligands and the cloning of these receptors allows their classification. So far, the AT1, AT2 and atypical angiotensin II receptors are recognised. The AT1 receptor is responsible for the classical effects of the renin-angiotensin system such as vasoconstriction, renal salt and water retention, central osmo-control and stimulation of cell growth. The function of the AT2 receptor is far from clear but this receptor appears to be important in fetal development, cell growth inhibition and differentiation processes. This review describes the angiotensin receptors and focuses on the possible functions of the AT2 receptor.

The renin-angiotensin system (RAS) is a widely studied hormonal system that comprises substrate-enzyme interactions, the end result of which is production of the active peptide angiotensin II (Ang II). Because Ang II affects blood pressure control, sodium and water homeostasis, and cardiovascular function and structure, a great deal of research effort has been directed toward blocking the RAS. Angiotensin II may also be involved in end-organ damage in hypertension, heart failure, and vascular disease. At least two subtypes of angiotensin II receptors have been identified: AT1 and AT2. The AT1 mediates all of the known actions of Ang II on blood pressure control. Additionally, research has indicated that the AT1 receptor modulates cardiac contractility and glomerular filtration, and increases renal tubular sodium reabsorption, and cardiac and vascular hypertrophy. Less is known regarding the function of the AT2 receptor. Evidence suggests that the AT2 receptor inhibits cell proliferation and reverses AT1-induced hypertrophy. Indeed, these receptors are thought to exert opposing effects. Angiotensin II AT1 receptor antagonists (AT1RA) inhibit the RAS at the receptor level by specifically blocking the AT1 receptor subtype. These drugs induce a dose-dependent blockade of Ang II effects, resulting in reduced blood pressure, urinary protein, and glomerular sclerosis. It is postulated that AT1RA may provide end-organ protection by blocking Ang II effects via the AT1 receptor, yet leaving the AT2 receptor unopposed. Consequently, these agents may reduce the morbidity and mortality that result from myocardial infarction (MI) and other conditions resulting from structural alterations in the heart, kidney, and vasculature.

Angiotensin II (Ang II) has diverse physiological actions leading, for example, to increases in extracellular volume, peripheral vascular resistance and blood pressure, and has also been implicated in the regulation of cell growth and differentiation. Molecular cloning and pharmacological studies have defined two major classes of Ang II receptors, designated as AT1 and AT2. Most effects of Ang II are mediated by AT1 receptors. Much less is known about the physiological role of AT2 receptors. Recent evidence suggests involvement of AT2 receptors in development, cell differentiation, apoptosis and regeneration in various tissues. AT1 and AT2 receptors have been shown to exert counteracting effects on cellular growth and differentiation, vascular tone and the release of arginine vasopressin (AVP). In each condition the AT2 receptor appears to down-modulate actions mediated by the AT1 receptor, resulting in decreased cellular proliferation, decreased levels of serum AVP levels or decreased vasoconstrictor responses. In addition, in neuronal cell lines, the AT2 receptor reportedly exerts antiproliferative effects and promotes neurite outgrowth, an effect accompanied by significant changes in the gene expression pattern of growth- and differentiation-related genes.