RESUMEN

We identified five distinct full-length human mineralocorticoid receptor (MR) genes containing either 984 amino acids (MR-984) or 988 amino acids (MR-988), which can be distinguished by the presence or absence of Lys, Cys, Ser, and Trp (KCSW) in their DNA-binding domain (DBD) and mutations at codons 180 and 241 in their amino-terminal domain (NTD). Two human MR-KCSW genes contain either (Val-180, Val-241) or (Ile-180, Val-241) in their NTD, and three human MR-984 genes contain either (Ile-180, Ala-241), (Val-180, Val-241), or (Ile-180, Val-241). Human MR-KCSW with (Ile-180, Ala-241) has not been cloned. In contrast, chimpanzees contain four MRs: two MR-988s with KCSW in their DBD, or two MR-984s without KCSW in their DBD. Chimpanzee MRs only contain (Ile180, Val-241) in their NTD. A chimpanzee MR with either (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD has not been cloned. Gorillas and orangutans each contain one MR-988 with KCSW in the DBD and one MR-984 without KCSW, and these MRs only contain (Ile-180, Val-241) in their NTD. A gorilla MR or orangutan MR with either (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD has not been cloned. Together, these data suggest that human MRs with (Val-180, Val-241) or (Ile-180, Ala-241) in the NTD evolved after humans and chimpanzees diverged from their common ancestor. Considering the multiple functions in human development of the MR in kidney, brain, heart, skin, and lungs, as well as MR activity in interaction with the glucocorticoid receptor, we suggest that the evolution of human MRs that are absent in chimpanzees may have been important in the evolution of humans from chimpanzees. Investigation of the physiological responses to corticosteroids mediated by the MR in humans, chimpanzees, gorillas, and orangutans may provide insights into the evolution of humans and their closest relatives.

Asunto(s)

Evolución Molecular , Gorilla gorilla , Pan troglodytes , Receptores de Mineralocorticoides , Animales , Receptores de Mineralocorticoides/genética , Receptores de Mineralocorticoides/metabolismo , Humanos , Pan troglodytes/genética , Gorilla gorilla/genética , Filogenia , Pongo/genética , Secuencia de Aminoácidos , Dominios Proteicos

RESUMEN

Due to alternative splicing in an ancestral DNA-binding domain (DBD) of the mineralocorticoid receptor (MR), humans contain two almost identical MR transcripts with either 984 amino acids (MR-984) or 988 amino acids (MR-988), in which their DBDs differ by only four amino acids, Lys,Cys,Ser,Trp (KCSW). Human MRs also contain mutations at two sites, codons 180 and 241, in the amino terminal domain (NTD). Together, there are five distinct full-length human MR genes in GenBank. Human MR-984, which was cloned in 1987, has been extensively studied. Human MR-988, cloned in 1995, contains KCSW in its DBD. Neither this human MR-988 nor the other human MR-988 genes have been studied for their response to aldosterone and other corticosteroids. Here, we report that transcriptional activation of human MR-988 by aldosterone is increased by about 50 % compared to activation of human MR-984 in HEK293 cells transfected with the TAT3 promoter, while the half-maximal response (EC50) is similar for aldosterone activation of MR-984 and MR-988. Transcriptional activation of human MR also depends on the amino acids at codons 180 and 241. Interestingly, in HEK293 cells transfected with the MMTV promoter, transcriptional activation by aldosterone of human MR-988 is similar to activation of human MR-984, indicating that the promoter has a role in the regulation of the response of human MR-988 to aldosterone. The physiological responses to aldosterone and other corticosteroids in humans with MR genes containing KCSW and with differences at codons 180 and 241 in the NTD warrant investigation.

Asunto(s)

Aldosterona , Receptores de Mineralocorticoides , Activación Transcripcional , Humanos , Receptores de Mineralocorticoides/genética , Receptores de Mineralocorticoides/metabolismo , Aldosterona/farmacología , Aldosterona/metabolismo , Activación Transcripcional/efectos de los fármacos , Células HEK293 , Serina/metabolismo , Serina/genética , Lisina/metabolismo , Lisina/química , Triptófano/metabolismo , Dominios Proteicos , Cisteína/metabolismo , ADN/metabolismo , ADN/genética

RESUMEN

Atlantic sea lamprey contains two corticoid receptors (CRs), CR1 and CR2, that have identical amino acid sequences, except for a four amino acid insert (Thr-Arg-Gln-Gly) in the CR1 DNA-binding domain (DBD). Steroids are stronger transcriptional activators of CR2 than of CR1 suggesting that the insert reduces the transcriptional response of lamprey CR1 to steroids. The DBD in elephant shark mineralocorticoid receptor (MR) and glucocorticoid receptor (GR), which are descended from a CR, lack these four amino acids, suggesting that a CR2 is their common ancestor. To determine if, similar to lamprey CR1, the presence of this insert in elephant shark MR and GR decreases transcriptional activation by corticosteroids, we inserted these four CR1-specific residues into the DBD of elephant shark MR and GR. Compared to steroid activation of wild-type elephant shark MR and GR, cortisol, corticosterone, aldosterone, 11-deoxycorticosterone and 11-deoxycortisol had lower transcriptional activation of these mutant MR and GR receptors, indicating that the absence of this four-residue segment in the DBD in wild-type elephant shark MR and GR increases transcriptional activation by corticosteroids.

Asunto(s)

Antifibrinolíticos , Petromyzon , Receptores de Esteroides , Animales , Receptores de Mineralocorticoides/genética , Receptores de Glucocorticoides/genética , Aminoácidos , Esteroides , ADN

RESUMEN

Teleost fishes exhibit complex sexual characteristics in response to androgens, such as fin enlargement and courtship display. However, the molecular mechanisms underlying their evolutionary acquisition remain largely unknown. To address this question, we analyse medaka (Oryzias latipes) mutants deficient in teleost-specific androgen receptor ohnologs (ara and arb). We discovered that neither ar ohnolog was required for spermatogenesis, whilst they appear to be functionally redundant for the courtship display in males. However, both were required for reproductive success: ara for tooth enlargement and the reproductive behaviour eliciting female receptivity, arb for male-specific fin morphogenesis and sexual motivation. We further showed that differences between the two ar ohnologs in their transcription, cellular localisation of their encoded proteins, and their downstream genetic programmes could be responsible for the phenotypic diversity between the ara and arb mutants. These findings suggest that the ar ohnologs have diverged in two ways: first, through the loss of their roles in spermatogenesis and second, through gene duplication followed by functional differentiation that has likely resolved the pleiotropic roles derived from their ancestral gene. Thus, our results provide insights into how genome duplication impacts the massive diversification of sexual characteristics in the teleost lineage.

Asunto(s)

Oryzias , Receptores Androgénicos , Animales , Masculino , Femenino , Receptores Androgénicos/genética , Receptores Androgénicos/metabolismo , Antagonistas de Receptores de Angiotensina , Inhibidores de la Enzima Convertidora de Angiotensina , Peces/genética , Peces/metabolismo , Evolución Biológica , Evolución Molecular , Oryzias/genética , Oryzias/metabolismo

RESUMEN

Lampreys are jawless fish that evolved about 550 million years ago at the base of the vertebrate line. Modern lampreys contain a corticoid receptor (CR), the common ancestor of the glucocorticoid receptor (GR) and mineralocorticoid receptor (MR), which first appear in cartilaginous fish, such as sharks. Until recently, 344 amino acids at the amino terminus of adult lamprey CR were not present in the lamprey CR sequence in GenBank. A search of the recently sequenced lamprey germline genome identified two CR sequences, CR1 and CR2, containing the 344 previously un-identified amino acids. CR1 also contains a novel four amino acid insertion in the DNA-binding domain (DBD). We studied corticosteroid and progesterone activation of CR1 and CR2 and found their strongest response was to 11-deoxycorticosterone and 11-deoxycortisol, the two circulating corticosteroids in lamprey. Based on steroid specificity, both CRs are close to elephant shark MR and distant from elephant shark GR. HEK293 cells that were transfected with full-length CR1 or CR2 and the MMTV promoter have about 3-fold higher steroid-mediated activation compared to HEK293 cells transfected with these CRs and the TAT3 promoter. Deletion of the amino-terminal domain (NTD) of lamprey CR1 and CR2 to form truncated CRs decreased transcriptional activation by about 70% in HEK293 cells that were transfected with MMTV, but increased transcription by about 6-fold in cells transfected with TAT3. This indicated that the promoter has an important effect on NTD regulation of transcriptional activation of the CR by steroids. Our results also indicate that the entire lamprey CR sequence is needed for an accurate determination of steroid-mediated transcription.

Asunto(s)

Petromyzon , Receptores de Esteroides , Animales , Humanos , Petromyzon/genética , Petromyzon/metabolismo , Células HEK293 , Evolución Molecular , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo , Corticoesteroides , Cortodoxona/metabolismo , Receptores de Glucocorticoides/genética , Receptores de Glucocorticoides/metabolismo

RESUMEN

We wanted to clone the glucocorticoid receptor (GR) from slender African lungfish (Protopterus dolloi) for comparison to the P. dolloi mineralocorticoid receptor (MR), which we had cloned and were characterizing, as well as for comparison to the GRs from humans, elephant shark and zebrafish. However, although sequencing of the genome of the Australian lungfish (Neoceratodus forsteri), as well as, that of the West African lungfish (Protopterus annectens) were reported in the first three months of 2021, we could not retrieve a GR sequence with a BLAST search of GenBank, when we submitted our research for publication in July 2021. Moreover, we were unsuccessful in cloning the GR from slender African lungfish using a cDNA from the ovary of P. dolloi and PCR primers that had successfully cloned a GR from elephant shark, Xenopus and gar GRs. On October 21, 2021 the nucleotide sequence of West African lungfish (P. annectens) GR was deposited in GenBank. We used this GR sequence to construct PCR primers that successfully cloned the GR from the slender spotted lungfish. Here, we report the sequences of nine P. dolloi GR isoforms and explain the basis for the previous failure to clone a GR from slender African lungfish using PCR primers that cloned the GR from elephant shark, Xenopus and gar. Studies are underway to determine corticosteroid activation of these slender African lungfish GRs.

Asunto(s)

Proteínas de Peces , Peces , Receptores de Glucocorticoides , Animales , Clonación Molecular , Proteínas de Peces/genética , Peces/genética , Isoformas de Proteínas , Receptores de Glucocorticoides/genética

RESUMEN

There is much concern about disruption of endocrine physiology regulated by steroid hormones in humans, other terrestrial vertebrates and fish by industrial chemicals, such as bisphenol A, and pesticides, such as DDT. These endocrine-disrupting chemicals influence steroid-mediated physiology in humans and other vertebrates by competing with steroids for receptor binding sites, disrupting diverse responses involved in reproduction, development and differentiation. Here I discuss that due to evolution of the progesterone receptor (PR) and mineralocorticoid receptor (MR) after ray-finned fish and terrestrial vertebrates diverged from a common ancestor, each receptor evolved to respond to different steroids in ray-finned fish and terrestrial vertebrates. In elephant shark, a cartilaginous fish that diverged before the separation between ray-finned fish and terrestrial vertebrates, both progesterone and 17,20ß-dihydroxy-progesterone activate the PR. During the evolution of ray-finned fish and terrestrial vertebrates, the PR in terrestrial vertebrates continued responding to progesterone and evolved to weakly respond to 17,20ß-dihydroxy-progesterone. In contrast, the physiological progestin for the PR in zebrafish and other ray-finned fish is 17,20ß-dihydroxy-progesterone, and ray-finned fish PR responds weakly to progesterone. The MR in fish and terrestrial vertebrates also diverged to have different responses to progesterone. Progesterone is a potent agonist for elephant shark MR, zebrafish MR and other fish MRs, in contrast to progesterone's opposite activity as an antagonist for aldosterone, the physiological mineralocorticoid for human MR. These different physiological ligands for fish and terrestrial vertebrate PR and MR need to be considered in applying data for their disruption by chemicals in fish and terrestrial vertebrates to each other.

Asunto(s)

Receptores de Mineralocorticoides , Tiburones , Aldosterona/metabolismo , Animales , Progesterona/metabolismo , Receptores de Mineralocorticoides/metabolismo , Pez Cebra

RESUMEN

We investigated progestin and corticosteroid activation of the progesterone receptor (PR) from elephant shark, a cartilaginous fish belonging to the oldest group of jawed vertebrates. Comparison with the human PR provides insights into the evolution of steroid activation of the human PR. At 1 nM steroid, the elephant shark PR is activated by progesterone, 17-hydroxy-progesterone, 20ß-hydroxy-progesterone, 11-deoxycorticosterone (21-hydroxyprogesterone), and 11-deoxycortisol. The human PR, in comparison, is activated at 1 nM steroid, only by progesterone and 11-deoxycorticosterone, indicating increased progestin and corticosteroid specificity during the evolution of the human PR. RU486, an important clinical antagonist of the human PR, did not inhibit progesterone activation of the elephant shark PR. Cys-528 in the elephant shark PR corresponds to Gly-722 in the human PR, which is essential for RU486 inhibition of the human PR. Confirming the importance of Cys-528 in the elephant shark PR, RU486 inhibited progesterone activation of the Cys528Gly mutant PR. To investigate the physiological relevance of Gly-722 in the human PR and Cys-528 in the elephant shark PR, we studied steroid activation of the Gly722Cys human PR and Cys528Gly elephant shark PR. Compared to the wild-type human PR, there was an increase in the activation of human Gly722Cys PR by11-deoxycortisol and a decrease in activation by corticosterone, which may have been important in selection for the mutation corresponding to the human glycine-722 PR that first evolved in the platypus PR, a basal mammal.

RESUMEN

Aldosterone, the main physiological mineralocorticoid in humans and other terrestrial vertebrates, first appears in lungfish, which are lobe-finned fish that are forerunners of terrestrial vertebrates. Aldosterone activation of the MR regulates internal homeostasis of water, sodium and potassium, which was critical in the conquest of land by vertebrates. We studied transcriptional activation of the slender African lungfish MR by aldosterone, other corticosteroids and progesterone and find that aldosterone, 11-deoxycorticosterone, 11-deoxycortisol and progesterone have half-maximal responses (EC50 s) below 1 nM and are potential physiological mineralocorticoids. In contrast, EC50 s for corticosterone and cortisol were 23 nM and 66 nM, respectively. Unexpectedly, truncated lungfish MR, consisting of the DNA-binding, hinge and steroid-binding domains, had a stronger response to corticosteroids and progesterone than full-length lungfish MR, indicating that the N-terminal domain represses steroid activation of lungfish MR, unlike human MR in which the N-terminal domain contains an activation function. BLAST searches of GenBank did not retrieve a GR ortholog, leading us to test dexamethasone and triamcinolone for activation of lungfish MR. At 10 nM, both synthetic glucocorticoids are about 4-fold stronger than 10 nM aldosterone in activating full-length lungfish MR, leading us to propose that lungfish MR also functions as a GR.

Asunto(s)

Aldosterona/farmacología , Dexametasona/farmacología , Proteínas de Peces/genética , Peces/genética , Receptores de Glucocorticoides/genética , Receptores de Mineralocorticoides/genética , Animales , Corticosterona/farmacología , Cortodoxona/farmacología , Desoxicorticosterona/farmacología , Eplerenona/farmacología , Proteínas de Peces/agonistas , Proteínas de Peces/metabolismo , Peces/metabolismo , Expresión Génica , Hidrocortisona/farmacología , Cinética , Progesterona/farmacología , Dominios Proteicos , Ingeniería de Proteínas/métodos , Receptores de Glucocorticoides/agonistas , Receptores de Glucocorticoides/metabolismo , Receptores de Mineralocorticoides/agonistas , Receptores de Mineralocorticoides/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Espironolactona/farmacología , Triamcinolona/farmacología

RESUMEN

Orthologs of human glucocorticoid receptor (GR) and human mineralocorticoid receptor (MR) first appear in cartilaginous fishes. Subsequently, the MR and GR diverged to respond to different steroids: the MR to aldosterone and the GR to cortisol and corticosterone. We report that cortisol, corticosterone and aldosterone activate full-length elephant shark GR, and progesterone, which activates elephant shark MR, does not activate elephant shark GR. However, progesterone inhibits steroid binding to elephant shark GR, but not to human GR. Together, this indicates partial functional divergence of elephant shark GR from the MR. Deletion of the N-terminal domain (NTD) from elephant shark GR (truncated GR) reduced the response to corticosteroids, while truncated and full-length elephant shark MR had similar responses to corticosteroids. Swapping of NTDs of elephant shark GR and MR yielded an elephant shark MR chimera with full-length GR-like increased activation by corticosteroids and progesterone compared to full-length elephant shark MR. Elephant shark MR NTD fused to GR DBD + LBD had similar activation as full-length MR, indicating that the MR NTD lacked GR-like NTD activity. We propose that NTD activation of human GR evolved early in GR divergence from the MR.

Asunto(s)

Receptores de Glucocorticoides/química , Receptores de Glucocorticoides/metabolismo , Receptores de Mineralocorticoides/química , Receptores de Mineralocorticoides/metabolismo , Regulación Alostérica , Animales , Corticosterona/metabolismo , Corticosterona/farmacología , Relación Dosis-Respuesta a Droga , Evolución Molecular , Células HEK293 , Antagonistas de Hormonas/farmacología , Humanos , Hidrocortisona/metabolismo , Hidrocortisona/farmacología , Mifepristona/farmacología , Progesterona/administración & dosificación , Progesterona/metabolismo , Progesterona/farmacología , Dominios Proteicos , Receptores de Glucocorticoides/antagonistas & inhibidores , Receptores de Glucocorticoides/genética , Receptores de Mineralocorticoides/genética , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Tiburones , Activación Transcripcional/efectos de los fármacos , Activación Transcripcional/fisiología

RESUMEN

The progesterone receptor (PR) mediates progesterone regulation of female reproductive physiology, as well as gene transcription in non-reproductive tissues, such as brain, bone, lung and vasculature, in both women and men. An unusual property of progesterone is its high affinity for the mineralocorticoid receptor (MR), which regulates electrolyte transport in the kidney in humans and other terrestrial vertebrates. In humans, rats, alligators and frogs, progesterone antagonizes activation of the MR by aldosterone, the physiological mineralocorticoid in terrestrial vertebrates. In contrast, in elephant shark, ray-finned fishes and chickens, progesterone activates the MR. Interestingly, cartilaginous fishes and ray-finned fishes do not synthesize aldosterone, raising the question of which steroid(s) activate the MR in cartilaginous fishes and ray-finned fishes. The simpler synthesis of progesterone, compared to cortisol and other corticosteroids, makes progesterone a candidate physiological activator of the MR in elephant sharks and ray-finned fishes. Elephant shark and ray-finned fish MRs are expressed in diverse tissues, including heart, brain and lung, as well as, ovary and testis, two reproductive tissues that are targets for progesterone, which together suggests a multi-faceted physiological role for progesterone activation of the MR in elephant shark and ray-finned fish. The functional consequences of progesterone as an antagonist of some terrestrial vertebrate MRs and as an agonist of fish and chicken MRs are not fully understood. The physiological activities of progesterone through binding to vertebrate MRs merits further investigation.

Asunto(s)

Riñón/efectos de los fármacos , Ovario/metabolismo , Progesterona/metabolismo , Receptores de Mineralocorticoides/metabolismo , Aldosterona/metabolismo , Caimanes y Cocodrilos/clasificación , Caimanes y Cocodrilos/fisiología , Secuencia de Aminoácidos , Animales , Anuros/clasificación , Anuros/fisiología , Encéfalo/metabolismo , Pollos/clasificación , Pollos/fisiología , Femenino , Regulación de la Expresión Génica , Humanos , Hidrocortisona/metabolismo , Riñón/metabolismo , Ligandos , Pulmón/metabolismo , Filogenia , Progesterona/farmacología , Ratas , Receptores de Mineralocorticoides/agonistas , Receptores de Mineralocorticoides/genética , Tiburones/clasificación , Tiburones/fisiología , Transducción de Señal , Especificidad de la Especie

RESUMEN

The SLC22 family of OATs, OCTs, and OCTNs is emerging as a central hub of endogenous physiology. Despite often being referred to as "drug" transporters, they facilitate the movement of metabolites and key signaling molecules. An in-depth reanalysis supports a reassignment of these proteins into eight functional subgroups, with four new subgroups arising from the previously defined OAT subclade: OATS1 (SLC22A6, SLC22A8, and SLC22A20), OATS2 (SLC22A7), OATS3 (SLC22A11, SLC22A12, and Slc22a22), and OATS4 (SLC22A9, SLC22A10, SLC22A24, and SLC22A25). We propose merging the OCTN (SLC22A4, SLC22A5, and Slc22a21) and OCT-related (SLC22A15 and SLC22A16) subclades into the OCTN/OCTN-related subgroup. Using data from GWAS, in vivo models, and in vitro assays, we developed an SLC22 transporter-metabolite network and similar subgroup networks, which suggest how multiple SLC22 transporters with mono-, oligo-, and multi-specific substrate specificity interact to regulate metabolites. Subgroup associations include: OATS1 with signaling molecules, uremic toxins, and odorants, OATS2 with cyclic nucleotides, OATS3 with uric acid, OATS4 with conjugated sex hormones, particularly etiocholanolone glucuronide, OCT with neurotransmitters, and OCTN/OCTN-related with ergothioneine and carnitine derivatives. Our data suggest that the SLC22 family can work among itself, as well as with other ADME genes, to optimize levels of numerous metabolites and signaling molecules, involved in organ crosstalk and inter-organismal communication, as proposed by the remote sensing and signaling theory.

Asunto(s)

Regulación de la Expresión Génica , Redes Reguladoras de Genes , Mutación , Transportadores de Anión Orgánico/metabolismo , Proteínas de Transporte de Catión Orgánico/metabolismo , Biología de Sistemas/métodos , Animales , Transporte Biológico , Humanos , Familia de Multigenes , Transportadores de Anión Orgánico/clasificación , Transportadores de Anión Orgánico/genética , Proteínas de Transporte de Catión Orgánico/clasificación , Proteínas de Transporte de Catión Orgánico/genética , Transducción de Señal , Especificidad por Sustrato

RESUMEN

Considering that life on earth evolved about 3.7 billion years ago, vertebrates are young, appearing in the fossil record during the Cambrian explosion about 542 to 515 million years ago. Results from sequence analyses of genomes from bacteria, yeast, plants, invertebrates and vertebrates indicate that receptors for adrenal steroids (aldosterone, cortisol), and sex steroids (estrogen, progesterone, testosterone) also are young, with an estrogen receptor and a 3-ketosteroid receptor first appearing in basal chordates (cephalochordates: amphioxus), which are close ancestors of vertebrates. Duplication and divergence of the 3-ketosteroid receptor yielded an ancestral progesterone receptor and an ancestral corticoid receptor, the common ancestor of the glucocorticoid and mineralocorticoid receptors, in jawless vertebrates (cyclostomes: lampreys, hagfish). This was followed by evolution of an androgen receptor, distinct glucocorticoid and mineralocorticoid receptors and estrogen receptor-α and -ß in cartilaginous fishes (Chondrichthyes: sharks). Further evolution of mineralocorticoid signaling occurred with the evolution of aldosterone synthase in lungfish, a forerunner of terrestrial vertebrates. Adrenal and sex steroid receptors are not found in echinoderms and hemichordates, which are ancestors in the lineage of cephalochordates and vertebrates. The evolution of steroid receptors at key nodes in the evolution of vertebrates, in which steroid receptors act as master switches to regulate differentiation, development, reproduction, immune responses, electrolyte homeostasis and stress responses, suggests an important role for steroid receptors in the evolutionary success of vertebrates, considering that the human genome contains about 22,000 genes, which is not much larger than genomes of invertebrates, such as Caenorhabditis elegans (~18,000 genes) and Drosophila (~14,000 genes).

Asunto(s)

Evolución Molecular , Receptores de Esteroides , Transducción de Señal/fisiología , Animales , Humanos , Receptores de Esteroides/genética , Receptores de Esteroides/metabolismo

RESUMEN

The mineralocorticoid receptor (MR) is a nuclear receptor and part of a large and diverse family of transcription factors that also includes receptors for glucocorticoids, progesterone, androgens, and estrogens. The corticosteroid aldosterone is the physiological activator of the MR in humans and other terrestrial vertebrates; however, its activator is not known in cartilaginous fish, the oldest group of extant jawed vertebrates. Here, we analyzed the ability of corticosteroids and progesterone to activate the full-length MR from the elephant shark (Callorhinchus milii). On the basis of their measured activities, aldosterone, cortisol, 11-deoxycorticosterone, corticosterone, 11-deoxcortisol, progesterone, and 19-norprogesterone are potential physiological mineralocorticoids. However, aldosterone, the physiological mineralocorticoid in humans and other terrestrial vertebrates, is not found in cartilaginous or ray-finned fish. Although progesterone activates MRs in ray-finned fish, progesterone does not activate MRs in humans, amphibians, or alligator, suggesting that during the transition to terrestrial vertebrates, progesterone lost the ability to activate the MR. Both elephant shark MR and human MR are expressed in the brain, heart, ovary, testis, and other nonepithelial tissues, suggesting that MR expression in diverse tissues evolved in the common ancestor of jawed vertebrates. Our data suggest that 19-norprogesterone- and progesterone-activated MR may have unappreciated functions in reproductive physiology.

Asunto(s)

Corticoesteroides/farmacología , Proteínas de Peces/biosíntesis , Progesterona/farmacología , Receptores de Mineralocorticoides/biosíntesis , Tiburones/metabolismo , Espironolactona/farmacología , Activación Transcripcional/efectos de los fármacos , Animales , Proteínas de Peces/genética , Humanos , Especificidad de Órganos/efectos de los fármacos , Receptores de Mineralocorticoides/genética , Tiburones/genética

RESUMEN

The mineralocorticoid receptor (MR) and its kin, the glucocorticoid receptor (GR) evolved from an ancestral corticoid receptor (CR) in a cyclostome (jawless fish) through gene duplication and divergence. Distinct MR and GR orthologs first appear in cartilaginous fishes, such as sharks, skates, rays and chimaeras. Although aldosterone, the main physiological mineralocorticoid in humans and other terrestrial vertebrates, is not synthesized by cyclostomes or cartilaginous fishes, cyclostome CR and cartilaginous fish MR and GR are activated by aldosterone. Aldosterone first appears in lungfish, lobe-finned fish that are forerunners of terrestrial vertebrates. Further sequence divergence of the MR and GR in terrestrial vertebrates led to emergence of aldosterone as a selective ligand for the MR. Interestingly, ray-finned fish do not synthesize aldosterone, leaving the identity of their physiological mineralocorticoid(s) unresolved. Several steroids: cortisol, 11-deoxycortisol, corticosterone, 11-deoxycorticosterone and progesterone activate fish MR and are potential mineralocorticoids in ray-finned fish. Here we review the evolution of the MR in cartilaginous fish, terrestrial vertebrates and ray-finned fish, and discuss new insights into progesterone activation of the MR in ray-finned fish.

Asunto(s)

Aldosterona/metabolismo , Evolución Molecular , Receptores de Mineralocorticoides/genética , Receptores de Mineralocorticoides/metabolismo , Vertebrados/fisiología , Aldosterona/genética , Animales , Regulación de la Expresión Génica , Vertebrados/genética

RESUMEN

Although multiple steroid ligands of the glucocorticoid, mineralocorticoid, and progestin families bind to and regulate the activity of mineralocorticoid receptors (MRs), the responses to these ligands differ across species. To understand how the different domains of MRs contribute to the ligand-induced activation or inhibition of MR activity, we studied the response to eight steroids (aldosterone, 11-deoxycorticosterone, 11-deoxycortisol, cortisol, corticosterone, progesterone, 19-norprogesterone, and spironolactone) of human, chicken, alligator, frog, and zebrafish full-length MRs and truncated MRs, which lacked the N-terminal domain (NTD) and DNA binding domain (DBD). Compared to full-length MRs, some truncated MRs were not activated by the steroids, and others required higher steroid concentrations for activation. Progesterone, 19-norprogesterone, and spironolactone did not activate full-length or truncated human, alligator, or frog MRs. However, at 10 nM, these steroids activated full-length chicken and zebrafish MRs, whereas at 100 nM, these steroids had little activity for truncated chicken MRs, but they retained activity for truncated zebrafish MRs. This suggests that regulation of the activation of the chicken MR by progestin resides in the NTD-DBD and that of the zebrafish MR resides in the hinge-LBD. Zebrafish and chicken MRs contain a serine corresponding to Ser810 in human MR, which is required for the antagonist activity of progesterone for human MR, suggesting a previously uncharacterized mechanism of regulation of progestin activation of chicken and zebrafish MRs. These findings suggest that progesterone may be a physiological activator of chicken and zebrafish MRs.

Asunto(s)

Corticoesteroides/metabolismo , Evolución Molecular , Receptores de Mineralocorticoides/metabolismo , Activación Transcripcional , Corticoesteroides/farmacología , Caimanes y Cocodrilos , Regulación Alostérica , Animales , Pollos , Humanos , Filogenia , Receptores de Mineralocorticoides/genética , Especificidad por Sustrato , Xenopus , Pez Cebra

RESUMEN

Many actions of estradiol (E2), the principal physiological estrogen in vertebrates, are mediated by estrogen receptor-α (ERα) and ERß. An important physiological feature of vertebrate ERs is their promiscuous response to several physiological steroids, including estradiol (E2), Δ5-androstenediol, 5α-androstanediol, and 27-hydroxycholesterol. A novel structural characteristic of Δ5-androstenediol, 5α-androstanediol, and 27-hydroxycholesterol is the presence of a C19 methyl group, which precludes the presence of an aromatic A ring with a C3 phenolic group that is a defining property of E2. The structural diversity of these estrogens can explain the response of the ER to synthetic chemicals such as bisphenol A and DDT, which disrupt estrogen physiology in vertebrates, and the estrogenic activity of a variety of plant-derived chemicals such as genistein, coumestrol, and resveratrol. Diversity in the A ring of physiological estrogens also expands potential structures of industrial chemicals that can act as endocrine disruptors. Compared to E2, synthesis of 27-hydroxycholesterol and Δ5-androstenediol is simpler, leading us, based on parsimony, to propose that one or both of these steroids or a related metabolite was a physiological estrogen early in the evolution of the ER, with E2 assuming this role later as the canonical estrogen. In addition to the well-studied role of the ER in reproductive physiology, the ER also is an important transcription factor in non-reproductive tissues such as the cardiovascular system, kidney, bone, and brain. Some of these ER actions in non-reproductive tissues appeared early in vertebrate evolution, long before the emergence of mammals.

Asunto(s)

Disruptores Endocrinos/metabolismo , Estradiol/metabolismo , Estrógenos/metabolismo , Fitoquímicos/metabolismo , Receptores de Estrógenos/genética , Receptores de Estrógenos/metabolismo , Androstenodiol/metabolismo , Animales , Compuestos de Bencidrilo/toxicidad , DDT/toxicidad , Humanos , Hidroxicolesteroles/metabolismo , Anfioxos , Fenoles/toxicidad

Asunto(s)

Progesterona , Receptores de Mineralocorticoides , Aldosterona , Animales , Humanos , Antagonistas de Receptores de Mineralocorticoides , Neoplasias , Pez Cebra

RESUMEN

The mineralocorticoid receptor (MR) is descended from a corticoid receptor (CR), which has descendants in lamprey and hagfish, cyclostomes (jawless fish), a taxon that evolved at the base of the vertebrate line. A distinct MR and GR first appear in cartilaginous fishes (Chondrichthyes), such as sharks, skates, rays and chimeras. Skate MR has a strong response to corticosteroids that are mineralocorticoids and glucocorticoids in humans. The half-maximal responses (EC50s) for skate MR for the mineralocorticoids aldosterone and 11-deoxycorticosterone are 0.07 nM and 0.03 nM, respectively. EC50s for the glucocorticoids cortisol and corticosterone are 1 nM and 0.09 nM, respectively. The physiological mineralocorticoid in ray-finned fish, which do not synthesize aldosterone, is not fully understood because several 3-ketosteroids, including cortisol, 11-deoxycortisol, corticosterone, 11-deoxycorticosterone and progesterone are transcriptional activators of fish MR. Further divergence of the MR and GR in terrestrial vertebrates, which synthesize aldosterone, led to emergence of aldosterone as a selective ligand for the MR. Here, we combine sequence analysis of the CR and vertebrate MRs and GRs, analysis of crystal structures of human MR and GR and data on transcriptional activation by 3-ketosteroids of wild-type and mutant MRs and GRs to investigate the evolution of selectivity for 3-ketosteroids by the MR in terrestrial vertebrates and ray-finned fish, as well as the basis for binding of some glucocorticoids by human MR and other vertebrate MRs.

Asunto(s)

Evolución Molecular , Regulación de la Expresión Génica/fisiología , Receptores de Mineralocorticoides/genética , Receptores de Mineralocorticoides/metabolismo , Secuencia de Aminoácidos , Animales , Regulación de la Expresión Génica/efectos de los fármacos , Humanos , Mineralocorticoides/metabolismo , Mineralocorticoides/farmacología