Long evolutionary conservation and considerable tissue specificity of several atypical solute carrier transporters

The superfamily of Solute Carriers (SLCs) has around 384 members in the human genome grouped into at least 48 families. While many of these transporters have been well characterized with established important biological functions, there are few recently identified genes that are not studied regarding tissue distribution or evolutionary origin. Here we study 14 of these recently discovered SLC genes (HIAT1, HIATL1, MFSD1, MFSD5, MFSD6, MFSD9, MFSD10, SLC7A14, SLC7A15, SLC10A6, SLC15A5, SLC16A12, SLC30A10 and SLC21A21) with the purpose to give much better picture over the sequence relationship and tissue expression of the diverse SLC gene family. We used a range of bioinformatic methods to classify each of these genes into the different SLC gene families. We found that 9 of the 14 atypical SLCs are distant members of the Major Facilitator Superfamily (MFS) clan while the others belong to the APC clan, the DMT clan, the CPA_AT clan and the IT clan. We found most of the genes to be highly evolutionary conserved, likely to be present in most bilateral species, except for SLC21A21 that we found only present in mammals. Several of these transporter genes have highly specific tissue expression profile while it is notable that most are expressed in the CNS with the exception of SLC21A21 and SLC15A5. This work provides fundamental information on 14 transporters that previously have not received much attention enabling a more comprehensive view over the SLC superfamily.     

The G protein-coupled receptor subset of the chicken genome

G protein-coupled receptors (GPCRs) are one of the largest families of proteins, and here we scan the recently sequenced chicken genome for GPCRs. We use a homology-based approach, utilizing comparisons with all human GPCRs, to detect and verify chicken GPCRs from translated genomic alignments and Genscan predictions. We present 557 manually curated sequences for GPCRs from the chicken genome, of which 455 were previously not annotated. More than 60% of the chicken Genscan gene predictions with a human ortholog needed curation, which drastically changed the average percentage identity between the human-chicken orthologous pairs (from 56.3% to 72.9%). Of the non-olfactory chicken GPCRs, 79% had a one-to-one orthologous relationship to a human GPCR. The Frizzled, Secretin, and subgroups of the Rhodopsin families have high proportions of orthologous pairs, although the percentage of amino acid identity varies. Other groups show large differences, such as the Adhesion family and GPCRs that bind exogenous ligands. The chicken has only three bitter Taste 2 receptors, and it also lacks an ortholog to human TAS1R2 (one of three GPCRs in the human genome in the Taste 1 receptor family [TAS1R]), implying that the chicken's ability and mode of detecting both bitter and sweet taste may differ from the human's. The chicken genome contains at least 229 olfactory receptors, and the majority of these (218) originate from a chicken-specific expansion. To our knowledge, this dataset of chicken GPCRs is the largest curated dataset from a single gene family from a non-mammalian vertebrate. Both the updated human GPCR dataset, as well the chicken GPCR dataset, are available for download.     

Differences in the occurrence of glutathione transferase isoenzymes in rat lung and liver

Cytosolic GSH transferases have been purified from rat lung by affinity chromatography followed by chromatofocusing. On the criteria of order of elution, substrate specificity, apparent subunit Mr, sensitivity to inhibitors, and reaction with antibodies, transferase subunits equivalent to subunits 2, 3, and 4, in the binary combinations occurring in liver, were identified. However, subunit 1 (and therefore transferases 1-1 and 1-2) was not detected. The most conspicuous difference is the presence in lung of a new form, eluting at pH 8.7, which is not detected in rat liver. This isoenzyme (transferase "pH 8.7") is characterized by its low apparent subunit Mr and high efficiency in the conjugation of glutathione with anti-benzo(a)pyrene-7,8-dihydrodiol-9,10-epoxide, considered the ultimate carcinogen of benzo(a)-pyrene.     

Melanin-concentrating hormone (MCH) reverts the behavioral effects induced by inescapable stress

The aim of this work was to investigate if MCH modifies the feeding and freezing responses in rats exposed to stressful stimuli. We used a basic version of contextual fear, where one group of rats were placed in a novel environment and two different groups were exposed to footshock paradigms, one of them escapable and the other one inescapable. At the end of each treatment, freezing and feeding were measured. Only the animals exposed to inescapable footshock paradigm showed significant increase in the food intake and freezing behavior in comparison to the control animals. The MCH administration (intra-hippocampal or intra-amygdaline) reverted these effects elicited by inescapable footshock. Results presented in this paper lead us to the assumption that the anxiolytic effect of the peptide is responsible for the reversion of the IS effects.     

Redundancy of a functional melanocortin 1 receptor in the anti-inflammatory actions of melanocortin peptides: studies in the recessive yellow (e/e) mouse suggest an important role for melanocortin 3 receptor

The issue of which melanocortin receptor (MC-R) is responsible for the anti-inflammatory effects of melanocortin peptides is still a matter of debate. Here we have addressed this aspect using a dual pharmacological and genetic approach, taking advantage of the recent characterization of more selective agonists/antagonists at MC1 and MC3-R as well as of the existence of a naturally defective MC1-R mouse strain, the recessive yellow (e/e) mouse. RT-PCR and ultrastructural analyses showed the presence of MC3-R mRNA and protein in peritoneal macrophages (M phi) collected from recessive yellow (e/e) mice and wild-type mice. This receptor was functional as Mphi incubation (30 min) with melanocortin peptides led to accumulation of cAMP, an effect abrogated by the MC3/4-R antagonist SHU9119, but not by the selective MC4-R antagonist HS024. In vitro M phi activation, determined as release of the CXC chemokine KC and IL-1 beta, was inhibited by the more selective MC3-R agonist gamma(2)-melanocyte stimulating hormone but not by the selective MC1-R agonist MS05. Systemic treatment of mice with a panel of melanocortin peptides inhibited IL-1 beta release and PMN accumulation elicited by urate crystals in the murine peritoneal cavity. MS05 failed to inhibit any of the inflammatory parameters either in wild-type or recessive yellow (e/e) mice. SHU9119 prevented the inhibitory actions of gamma(2)-melanocyte stimulating hormone both in vitro and in vivo while HS024 was inactive in vivo. In conclusion, agonism at MC3-R expressed on peritoneal M phi leads to inhibition of experimental nonimmune peritonitis in both wild-type and recessive yellow (e/e) mice.     

Anxiety-like behavior induced by IL-1beta is modulated by alpha-MSH through central melanocortin-4 receptors

The proinflammatory cytokine interleukin-1beta (IL-1beta) influences neuroendocrine activity and produces other effects, including fever and behavioral changes such as anxiety. The melanocortin neuropeptides, such as alpha-melanocyte-stimulating hormone (alpha-MSH), antagonize many actions of IL-1, including fever, anorexia and hypothalamic-pituitary-adrenal (HPA) axis activation through specific melanocortin receptors (MC-R) in the central nervous system. The objective of the present study was to establish the effect of MSH peptides on IL-1beta-induced anxiety-like behavior and the melanocortin receptors involved. We evaluated the effects of intracerebroventricular (i.c.v.) administration of IL-1beta (30 ng) and melanocortin receptor agonists: alpha-MSH, an MC3/MC4-R agonist (0.2 microg) or gamma-MSH, an MC3-R agonist (2 microg) or HS014, an MC4-R antagonist (2 microg), on an elevated plus-maze (EPM) test. Injection of IL-1beta induced an anxiogenic-like response, as indicated by reduced open arms entries and time spent on open arms. The administration of alpha-MSH reversed IL-1beta-induced anxiety with co-administration of HS014 inhibiting the effect of alpha-MSH. However, the associated treatment with gamma-MSH did not affect the anxiety response to IL-1beta. These data suggest that alpha-MSH, through central MC4-R can modulate the anxiety-like behavior induced by IL-1beta.     

Neuroendocrine-specific protein (NSP)-reticulons as independent markers for non-small cell lung cancer with neuroendocrine differentiation

Neuroendocrine-specific protein (NSP)-reticulons have recently been discovered and were shown to exhibit a restricted, neuroendocrine/neural-specific expression pattern. These protein aggregates are anchored to the membranes of the endoplasmic reticulum and occur in small cell lung cancer (SCLC), but not in typical non-SCLC. In the current study we have examined the occurrence of NSP-reticulons in non-SCLC cell lines known to express neuroendocrine features (non-SCLC-NE). NSP-reticulon expression was observed in all three non-SCLC-NE cell lines studied, albeit with variable intensity and in varying numbers of cells. Western blot analysis confirmed the presence of NSP-reticulon expression in these non-SCLC-NE cell lines, and showed that they were predominantly of the NSP-A type. When compared to conventional neuroendocrine markers, NSP-reticulons revealed a distinct staining profile, showing only partial overlap with the other markers. The non-SCLC-NE cell lines combined these neuroendocrine characteristics with some features of non-SCLC. We conclude that NSP-reticulon expression is restricted to lung carcinoma cells with a neuroendocrine phenotype and predict that these constituents may become clinically relevant markers for the detection of neuroendocrine differentiation in solid tumours. Accepted: 27 March 1997