The IKKβ Subunit of IκB Kinase (IKK) is Essential for Nuclear Factor κB Activation and Prevention of Apoptosis

The IκB kinase (IKK) complex is composed of three subunits, IKKα, IKKβ, and IKKγ (NEMO). While IKKα and IKKβ are highly similar catalytic subunits, both capable of IκB phosphorylation in vitro, IKKγ is a regulatory subunit. Previous biochemical and genetic analyses have indicated that despite their similar structures and in vitro kinase activities, IKKα and IKKβ have distinct functions. Surprisingly, disruption of the Ikkα locus did not abolish activation of IKK by proinflammatory stimuli and resulted in only a small decrease in nuclear factor (NF)-κB activation. Now we describe the pathophysiological consequence of disruption of the Ikkβ locus. IKKβ-deficient mice die at mid-gestation from uncontrolled liver apoptosis, a phenotype that is remarkably similar to that of mice deficient in both the RelA (p65) and NF-κB1 (p50/p105) subunits of NF-κB. Accordingly, IKKβ-deficient cells are defective in activation of IKK and NF-κB in response to either tumor necrosis factor α or interleukin 1. Thus IKKβ, but not IKKα, plays the major role in IKK activation and induction of NF-κB activity. In the absence of IKKβ, IKKα is unresponsive to IKK activators

A novel pituitary transcription factor is produced by alternative splicing of the human GHF-1/PIT-1 gene

An alternative splice acceptor site in intron 1 of the human GHF-1/PIT-1 gene was sequenced. The use of this splice site is responsible for a 78-bp in-frame insertion upstream from exon 2 and leads to the hGHF-2/PIT-2 cDNA detected in normal human pituitary. © 1995.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Human neutrophils express GH-N gene transcripts and the pituitary transcription factor Pit-1b

Since GH stimulates the development and function of granulocytes, we investigated the expression of GH in granulocyte subsets. By immunocytochemistry, 25 ±7% of the human neutrophils were shown to express immunoreactive GH, whereas eosinophils were negative. Reversed transcription (RT)-PCR analysis demonstrated GH mRNA in neutrophils. Restriction analysis revealed that neutrophils express the GH-N gene but not the GH-V gene. Furthermore, we demonstrated by western blot analysis that neutrophils express an alternatively spliced variant of the pituitary transcription factor Pit-1, designated Pit-1b.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Growth hormone and prolactin are paracrine growth and differentiation factors in the haemopoietic system

The pituitary secretory proteins growth hormone (GH) and prolactin (PRL) do not, as yet, have major roles in haematology or immunology. Recent evidence indicates that these hormones are haemopoietic growth factors and exert immunomodulatory functions at physiological concentrations. Here Robert Hooghe and colleagues discuss the significance of these hormones on different aspects of the immune system.SCOPUS: re.jinfo:eu-repo/semantics/publishe

The transcription factor Pit-1/GHF-1 is expressed in hemopoietic and lymphoid tissues

The expression of the Pit-1/GHF-1 transcription factor (hereafter Pit-1), which controls the expression of growth hormone (GH) and prolactin (PRL) in the pituitary gland, has been documented in human and rat hemopoietic and lymphoid tissues and cell lines. Pit-1 mRNA was detected by in situ hybridization in about 1 % of rat bone marrow cells and in the spleen red pulp and marginal zone. Pit-1 was also expressed in human tonsils (mantle zone), in the thymus (rat and human, non-lymphoid cells), in lipopolysaccharide-stimulated rat peritoneal cells and in non-hepatocyte cells in the liver (rat and human). A detailed investigation of the rat spleen showed a very similar distribution for Pit-1, GH and PRL mRNA and Pit-1, GH and PRL proteins (detected by immunocytochemistry). Using polymerase chain reaction followed by Southern hybridization, the expression of Pit-1 could be confirmed in human and rat spleen, bone marrow and thymus. HL60 and RAJI leukemic cells were also positive. The sequence of fragments amplified from rat spleen and from human bone marrow completely matched published sequences of rat and human pituitary Pit-1, respectively. Expression of GH and PRL in lymphoid tissues has been documented. The straightforward hypothesis would therefore be that Pit-1's main function in lymphoid tissues is controlling GH and PRL expression, as in the pituitary gland. GH and PRL may be hemopoietic and lymphoid growth and differentiation factors.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Growth hormone and prolactin are paracrine growth and differentiation factors in the haemopoietic system

The pituitary secretory proteins growth hormone (GH) and prolactin (PRL) do not, as yet, have major roles in haematology or immunology. Recent evidence indicates that these hormones are haemopoietic growth factors and exert immunomodulatory functions at physiological concentrations. Here Robert Hooghe and colleagues discuss the significance of these hormones on different aspects of the immune system. © 1993.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Cafeteria diet-induced obese rats have an increased somatostatin protein content and gene expression in the periventricular nucleus

In human obesity, spontaneous and GRF stimulated growth hormone secretion have been shown to be blunted. We used cafeteria diet fed obese rats as a model to study the central mechanisms involved in growth hormone secretion changes which are observed in obesity. We analysed somatostatin messenger RNA and protein levels in the hypothalamic periventricular nucleus of the rats by non radioactive in situ hybridization and immunocytochemistry respectively. The optical density of somatostatin mRNA, measured by a computerized image system, was significantly higher in cafeteria diet fed rats (1014 ± 87 vs 444 ± 45; p < 0.05). The integrated optical density of somatostatin protein was also significantly higher in cafeteria rats compared to the control rats (222 ± 36 vs 114 ± 24; p < 0.05). In conclusion, cafeteria diet induced obese rats have a higher somatostatin biosynthesis in the periventricular nucleus. Further studies are needed to establish the possible link of this increased somatostatin gene expression with the decreased GH production.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

AP-1 and Oct-1 transcription factors down-regulate the expression of the human PIT1/GHF1 gene

The pituitary-specific transcription factor Pit-1/GHF-1 is a member of the POU domain family of regulatory proteins. It is involved in the commitment and expansion of the somatotropic cell lineage and activates the transcription of a set of anterior pituitary genes. We have cloned the human PIT1/GHF1 gene and characterized the regulatory mechanisms controlling its promoter activation and regulation. A minimal promoter region (-102 to +15) contains the cis-acting elements that confer to the human PIT1/GHF1 gene a high basal transcriptional activity, the tissue-specific expression, and the autoregulation by Pit-1/GHF-1 protein. The upstream promoter region contains a multiplicity of Pit-1/GHF-1 binding sites that do not show any synergistic interaction with the minimal promoter. The transcriptional activity is negatively regulated by Oct-1 and mediated by an octamer-binding site (OTF). In addition, we have also identified a 12-O-tetradecanoylphorbol-13-acetate- responsive element, which overlaps with a Pit-1/GHF-1 binding site. A mutually exclusive binding of the activator protein-1 (AP-1) and Pit-1/GHF-1 has been observed on this composite site, and AP-1 was shown to down- regulate PIT1/GHF1 transcription.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Pit-1/GHF-1 expression in pituitary adenomas: Further analogy between human adenomas and rat SMtTW tumours

Adenomas can develop from each cell type of the anterior pituitary. In the normal pituitary, three of these cell types, the GH-, prolactin- and TSH-secreting cells, express the transcription factor Pit-1/GHF-1 which is responsible for prolactin and GH (and probably TSH) cell commitment, differentiation, probably proliferation and gene expression. We have analysed the expression of Pit-1/GHF-1 in a panel of human pituitary adenomas. All GH-, prolactin- and TSH-expressing adenomas studied expressed the Pit-1/GHF-1 factor, as demonstrated by in-situ hybridization and immunocytochemistry. The expression was higher in adenomas than in normal human pituitary. In contrast, ACTH- adn LH-FSH-secreting and non-secreting adenomas were negative. Seven transplants of the spontaneous rat prolactinoma SMtTW were also investigated and all were found to be positive. This further stresses the analogy between these tumours and human prolactinomas. Taken together, the data confirm that Pit-1/GHF-1 expression is restricted to GH-, prolactin- and TSH-expressing cells, and the increased expression in adenomas is compatible with a role of Pit-1/GHF-1 in cell proliferation.SCOPUS: ar.jinfo:eu-repo/semantics/publishe