Insulin-like 6 immunoreactivity in the mouse brain and testis

Genetic architecture and selection of Anhui autochthonous pig population revealed by whole genome resequencing

The genetic resources among pigs in Anhui Province are diverse, but their value and potential have yet to be discovered. To illustrate the genetic diversity and population structure of the Anhui pigs population, we resequenced the genome of 150 pigs from six representative Anhui pigs populations and analyzed this data together with the sequencing data from 40 Asian wild boars and commercial pigs. Our results showed that Anhui pigs were divided into two distinct types based on ancestral descent: Wannan Spotted pig (WSP) and Wannan Black pig (WBP) origins from the same ancestor and the other four populations origins from another ancestor. We also identified several potential selective sweep regions associated with domestication characteristics among Anhui pigs, including reproduction-associated genes (CABS1, INSL6, MAP3K12, IGF1R, INSR, LIMK2, PATZ1, MAPK1), lipid- and meat-related genes (SNX19, MSTN, MC5R, PRKG1, CREBBP, ADCY9), and ear size genes (MSRB3 and SOX5). Therefore, these findings expand the catalogue and how these genetic differences among pigs and this newly generated data will be a valuable resource for future genetic studies and for improving genome-assisted breeding of pigs and other domesticated animals.

Immune-related genes play an important role in the prognosis of patients with testicular germ cell tumor

Background

Testicular cancer is a very common malignancy in young men. Although testicular cancer has a high cure rate, patients have a high long-term risk of secondary malignant tumors and cardiovascular disease. In addition, for patients resistant to traditional treatment methods, new treatment methods and methods for predicting prognosis are also urgently needed.

Methods

Gene expression profiles of 165 normal testicular tissues and 156 testicular germ cell tumor (TGCT) tissues from GTEx database and TCGA database were used to obtain differentially expressed genes (DEGs) in TGCT. Through the ImmPort database, we obtained immune-related genes (IRGs). Univariate Cox regression analysis was used to identify prognostic IRGs. A transcription factor regulatory network was constructed to clarify the possible regulatory mechanism for the differential expression of these IRGs. Multivariate Cox regression analysis was used to establish a prognostic model. Gene expression data and related survival data of 108 TCGT patients from GEO database were used for external validation. Survival analysis, receiver operating characteristic curves (ROC) curve analysis, independent prognostic analysis, principal component analysis (PCA) and clinical correlation analysis were performed to evaluate this model.

Results

Three hundred and thirty-three IRGs were differentially expressed between TGCT and normal testicular tissues. We established a prognostic model (riskScore) based on 5 risk genes (SEMA6B, SEMA3G, OBP2B, INSL6 and RETN). Whether in the training cohort, the testing cohort or the entire TCGA cohort, this model could accurately stratify patients with different survival outcomes. The prognostic value of riskScore and 5 risk genes was also confirmed in the GEO database. GSEA analysis showed that DEGs in patients with better prognosis were enriched in immune-related pathways, while DEGs in patients with poorer prognosis were enriched in cancer-related pathways and cardiovascular disease-related pathways. Finally, a new Nomogram with higher prognostic value was constructed to better predict the 1-year PFS, 3-year PFS and 5-year PFS of TCGT patients.

Conclusions

We successfully established an immune-related risk model with high prognostic value and created a new Nomogram. We found that different immune status in tumor microenvironment may be responsible for the different survival outcomes among TGCT patients.

Genomic analysis reveals selection in Chinese native black pig

Identification of genomic signatures that help reveal mechanisms underlying desirable traits in domesticated pigs is of significant biological, agricultural and medical importance. To identify the genomic footprints left by selection during domestication of the Enshi black pig, a typical native and meat-lard breed in China, we generated about 72-fold coverage of the pig genome using pools of genomic DNA representing three different populations of Enshi black pigs from three different locations. Combining this data with the available whole genomes of 13 Chinese wild boars, we identified 417 protein-coding genes embedded in the selected regions of Enshi black pigs. These genes are mainly involved in developmental and metabolic processes, response to stimulus, and other biological processes. Signatures of selection were detected in genes involved in body size and immunity (RPS10 and VASN), lipid metabolism (GSK3), male fertility (INSL6) and developmental processes (TBX19). These findings provide a window into the potential genetic mechanism underlying development of desirable phenotypes in Enshi black pigs during domestication and subsequent artificial selection. Thus, our results illustrate how domestication has shaped patterns of genetic variation in Enshi black pigs and provide valuable genetic resources that enable effective use of pigs in agricultural production.

Brief alcohol exposure alters transcription in astrocytes via the heat shock pathway

Astrocytes are critical for maintaining homeostasis in the central nervous system (CNS), and also participate in the genomic response of the brain to drugs of abuse, including alcohol. In this study, we investigated ethanol regulation of gene expression in astrocytes. A microarray screen revealed that a brief exposure of cortical astrocytes to ethanol increased the expression of a large number of genes. Among the alcohol-responsive genes (ARGs) are glial-specific immune response genes, as well as genes involved in the regulation of transcription, cell proliferation, and differentiation, and genes of the cytoskeleton and extracellular matrix. Genes involved in metabolism were also upregulated by alcohol exposure, including genes associated with oxidoreductase activity, insulin-like growth factor signaling, acetyl-CoA, and lipid metabolism. Previous microarray studies performed on ethanol-treated hepatocyte cultures and mouse liver tissue revealed the induction of almost identical classes of genes to those identified in our microarray experiments, suggesting that alcohol induces similar signaling mechanisms in the brain and liver. We found that acute ethanol exposure activated heat shock factor 1 (HSF1) in astrocytes, as demonstrated by the translocation of this transcription factor to the nucleus and the induction of a family of known HSF1-dependent genes, the heat shock proteins (Hsps). Transfection of a constitutively transcriptionally active Hsf1 construct into astrocytes induced many of the ARGs identified in our microarray study supporting the hypothesis that HSF1 transcriptional activity, as part of the heat shock cascade, may mediate the ethanol induction of these genes. These data indicate that acute ethanol exposure alters gene expression in astrocytes, in part via the activation of HSF1 and the heat shock cascade.

R171H missense mutation of INSL6 in a patient with spermatogenic failure

Insulin-like peptide 6 (INSL6) is a newly identified insulin/relaxin family peptide hormone that is predominantly expressed by the male germ cells in testes. A recent murine study demonstrated that INSL6-knockout results in spermatogenic failure. In the present study, human INSL6 gene was screened for mutations that may contribute to human spermatogenic failure. Of 249 patients and 249 healthy control subjects, a heterozygous R171H missense mutation was found in one patient. The R171H mutation probably disturbed the in vivo processing of the INSL6 prohormone because it was located at the absolutely conserved tetrabasic cleavage site between the C-peptide and the A-chain, therefore the R171H missense mutation might be responsible for human spermatogenic failure.

Insulin-like 6 is induced by muscle injury and functions as a regenerative factor

The insulin-like family of factors are involved in the regulation of a variety of physiological processes, but the function of the family member termed insulin-like 6 (Insl6) in skeletal muscle has not been reported. We show that Insl6 is a myokine that is up-regulated in skeletal muscle downstream of Akt signaling and in regenerating muscle in response to cardiotoxin (CTX)-induced injury. In the CTX injury model, myofiber regeneration was improved by the intramuscular or systemic delivery of an adenovirus expressing Insl6. Skeletal muscle-specific Insl6 transgenic mice exhibited normal muscle mass under basal conditions but elevated satellite cell activation and enhanced muscle regeneration in response to CTX injury. The Insl6-mediated regenerative response was associated with reductions in muscle cell apoptosis and reduced serum levels of creatine kinase M. Overexpression of Insl6 stimulated proliferation and reduced apoptosis in cultured myogenic cells. Conversely, knockdown of Insl6 reduced proliferation and increased apoptosis. These data indicate that Insl6 is an injury-regulated myokine that functions as a myogenic regenerative factor.

Inactivation of insulin-like factor 6 disrupts the progression of spermatogenesis at late meiotic prophase

Insulin-like factor 6 (INSL6), a member of the insulin-like superfamily, is predominantly expressed in male germ cells. Expression of the Insl6 is first detected in mouse testis at postnatal d 15 when the first wave of spermatogenesis progresses to pachytene spermatocytes. To elucidate the role of INSL6 in germ cell development, we generated Insl6-deficient mice. The majority of the Insl6-deficient males on a hybrid genetic background exhibited impaired fertility, whereas females were fertile. The number of mature sperm and sperm motility were drastically reduced in the epididymis. The reduced sperm count could be due to apoptotic death of a significant number of developing germ cells. Analysis of germ cell development during the juvenile life showed an arrest of the first wave of spermatogenesis in late meiotic prophase. RNA analysis revealed a significant decrease in expression of late meiotic- and postmeiotic-specific marker genes, whereas expression of early meiotic-specific genes remains unaffected in the Insl6(-/-) testes. These results demonstrate that INSL6 is required for the progression of spermatogenesis.

C-peptide of preproinsulin-like peptide 7: localization in the rat brain and activity in vitro

With the use of a rabbit polyclonal antiserum against a conserved region (54-118) of C-peptide of human preproinsulin-like peptide 7, referred to herein as C-INSL7, neurons expressing C-INSL7-immunoreactivity (irC-INSL7) were detected in the pontine nucleus incertus, the lateral or ventrolateral periaqueductal gray, dorsal raphe nuclei and dorsal substantia nigra. Immunoreactive fibers were present in numerous forebrain areas, with a high density in the septum, hypothalamus and thalamus. Pre-absorption of C-INSL7 antiserum with the peptide C-INSL7 (1 microg/ml), but not the insulin-like peptide 7 (INSL7; 1 microg/ml), also known as relaxin 3, abolished the immunoreactivity. Optical imaging with a voltage-sensitive dye bis-[1,3-dibutylbarbituric acid] trimethineoxonol (DiSBAC4(3)) showed that C-INSL7 (100 nM) depolarized or hyperpolarized a small population of cultured rat hypothalamic neurons studied. Ratiometric imaging studies with calcium-sensitive dye fura-2 showed that C-INSL7 (10-1000 nM) produced a dose-dependent increase in cytosolic calcium concentrations [Ca2+]i in cultured hypothalamic neurons with two distinct patterns: (1) a sustained elevation lasting for minutes; and (2) a fast, transitory rise followed by oscillations. In a Ca2+-free Hanks' solution, C-INSL7 again elicited two types of calcium transients: (1) a fast, transitory increase not followed by a plateau phase, and (2) a transitory rise followed by oscillations. INSL7 (100 nM) elicited a depolarization or hyperpolarization in a small population of hypothalamic neurons, and an increase of [Ca2+]i with two patterns that were dissimilar from that of C-INSL7. [125I]C-INSL7 bindings to rat brain membranes were inhibited by C-INSL7 in a dose-dependent manner; the Kd and Bmax. values were 17.7 +/- 8.2 nM and 45.4 +/- 20.5 fmol/mg protein. INSL7 did not inhibit [125I]C-INSL7 binding to rat brain membranes, indicating that C-INSL7 and INSL7 bind to distinct binding sites. Collectively, our result raises the possibility that C-INSL7 acts as a signaling molecule independent from INSL7 in the rat CNS.

The human insulin superfamily of polypeptide hormones

The identification in the 1950s of insulin, an essential carbohydrate regulatory hormone, as consisting of not one but two peptide chains linked by three disulfide bonds in a distinctive pattern was a milestone in peptide chemistry. When it was later found that relaxin also possessed a similar overall structure, the term 'insulin superfamily' was coined. Use of methods of conventional protein chemistry followed by recombinant DNA and more recently bioinformatics has led to the recognition that insulin is the precursor to a large protein superfamily that extends beyond the human. Insulin-like peptides are found not only in vertebrates such as mammals, birds, reptiles, amphibians but also in the invertebrates such as chordates, molluscs and insects. All superfamily members share the distinctive insulin structural motif. In the human, there exists ten members of the superfamily, each of which are expressed on the ribosome as a single-chain pre-prohormone that undergoes proteolytic processing to produce eight double-chain mature proteins and two single-chain forms. The six cysteine residues that form the three insulin disulfide cross-links - one intramolecular within the A-chain and two intermolecular between that A- and B-chains - are absolutely conserved across all members of the superfamily. They are responsible for imparting a similar overall tertiary structure. The human insulin superfamily members have each evolved to assume remarkably distinctive biological functions ranging from glucose homeostasis to neuroendocrine actions. That such diversity is contained within a modestly sized superfamily is testament to efficiency of the insulin structural motif as an evolutionary template.

Insulin-like peptide 6: characterization of secretory status and posttranslational modifications

Insulin-like peptide 6 (Insl6) is a member of the insulin/relaxin superfamily with unknown biological function(s). In the current report, we establish that meiotic and postmeiotic germ cells of the testis are the principal sites of expression of Insl6. Analysis of stably or transiently transfected cells revealed that Insl6 is a secreted protein localized to the endoplasmic reticulum and Golgi. Secretion could be detected in both CHO and GC2 germ cells and was sensitive to brefeldin A treatment. In cell lysates, the predominant Insl6 band was approximately 28 kDa in size. In contrast, the predominant Insl6 species in the supernatant was 8 kDa in size, suggesting posttranslational processing of the precursor protein. Ectopically expressed Insl6 is processed and secreted in furin-deficient LoVo cells and in CHO cells treated with a furin inhibitor, although the size profile of the secreted protein is altered suggesting that Insl6 is a substrate for furin action. Furthermore, mutation of a putative furin cleavage site in the Insl6 peptide resulted in aberrant processing of the Insl6 peptide. Additional investigations of the structure of Insl6 protein provided evidence for posttranslational modifications of Insl6, including the presence of disulfide bonds, glycosylation, and ubiquitination. On the basis of the demonstrated secretory status of Insl6, we speculate that the physical proximity of the germ cell to the Sertoli cell renders the Sertoli cell a likely candidate for Insl6 action.