RETINOIC ACID AND THYROID HORMONE REGULATE GENE EXPRESSION THROUGH A COMMON GENE ELEMENT

2009 ◽  
Vol 47 (10) ◽  
pp. 332-334
Author(s):  
Gregg Duester

A paper recently published on forebrain cortical synaptic plasticity reports that retinoic acid (RA) induces synaptopodin-dependent metaplasticity in mouse dentate granule cells (Lenz et al., 2021). Retinoic acid (RA) is the active form of vitamin A that functions as a ligand for nuclear RA receptors that directly bind genomic control regions to regulate gene expression (Chambon, 1996; Ghyselinck and Duester, 2019). However, Lenz et al. report that RA functions in a nongenomic fashion to control forebrain cortical synaptic plasticity which modulates synaptic transmission to effectively respond to specific stimuli; specifically, they report that this nongenomic response occurs in the dorsal hippocampus but not ventral hippocampus. They performed RA treatment studies which provided information on how a supraphysiological level of RA effects synaptic plasticity. However, the authors did not perform an RA loss-of-function study to verify that endogenous RA is required for synaptic plasticity.


Endocrinology ◽  
2014 ◽  
Vol 156 (2) ◽  
pp. 721-734 ◽  
Author(s):  
Luan Wen ◽  
Yun-Bo Shi

Thyroid hormone (T3) affects adult metabolism and postembryonic development in vertebrates. T3 functions mainly via binding to its receptors (TRs) to regulate gene expression. There are 2 TR genes, TRα and TRβ, with TRα more ubiquitously expressed. During development, TRα expression appears earlier than T3 synthesis and secretion into the plasma. This and the ability of TRs to regulate gene expression both in the presence and absence of T3 have indicated a role for unliganded TR during vertebrate development. On the other hand, it has been difficult to study the role of unliganded TR during development in mammals because of the difficulty to manipulate the uterus-enclosed, late-stage embryos. Here we use amphibian development as a model to address this question. We have designed transcriptional activator–like effector nucleases (TALENs) to mutate the TRα gene in Xenopus tropicalis. We show that knockdown of TRα enhances tadpole growth in premetamorphic tadpoles, in part because of increased growth hormone gene expression. More importantly, the knockdown also accelerates animal development, with the knockdown animals initiating metamorphosis at a younger age and with a smaller body size. On the other hand, such tadpoles are resistant to exogenous T3 treatment and have delayed natural metamorphosis. Thus, our studies not only have directly demonstrated a critical role of endogenous TRα in mediating the metamorphic effect of T3 but also revealed novel functions of unliganded TRα during postembryonic development, that is, regulating both tadpole growth rate and the timing of metamorphosis.


1992 ◽  
Vol 66 (1) ◽  
pp. 95-105 ◽  
Author(s):  
A M Colberg-Poley ◽  
L D Santomenna ◽  
P P Harlow ◽  
P A Benfield ◽  
D J Tenney

2019 ◽  
Vol 70 (19) ◽  
pp. 5355-5374 ◽  
Author(s):  
Dandan Zang ◽  
Jingxin Wang ◽  
Xin Zhang ◽  
Zhujun Liu ◽  
Yucheng Wang

Abstract Plant heat shock transcription factors (HSFs) are involved in heat and other abiotic stress responses. However, their functions in salt tolerance are little known. In this study, we characterized the function of a HSF from Arabidopsis, AtHSFA7b, in salt tolerance. AtHSFA7b is a nuclear protein with transactivation activity. ChIP-seq combined with an RNA-seq assay indicated that AtHSFA7b preferentially binds to a novel cis-acting element, termed the E-box-like motif, to regulate gene expression; it also binds to the heat shock element motif. Under salt conditions, AtHSFA7b regulates its target genes to mediate serial physiological changes, including maintaining cellular ion homeostasis, reducing water loss rate, decreasing reactive oxygen species accumulation, and adjusting osmotic potential, which ultimately leads to improved salt tolerance. Additionally, most cellulose synthase-like (CSL) and cellulose synthase (CESA) family genes were inhibited by AtHSFA7b; some of them were randomly selected for salt tolerance characterization, and they were mainly found to negatively modulate salt tolerance. By contrast, some transcription factors (TFs) were induced by AtHSFA7b; among them, we randomly identified six TFs that positively regulate salt tolerance. Thus, AtHSFA7b serves as a transactivator that positively mediates salinity tolerance mainly through binding to the E-box-like motif to regulate gene expression.


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