Pituitary adenylate cyclase-activating polypeptide (PACAP) is a 38-amino acid C-terminally α-amidated peptide that was first isolated 20 years ago from an ovine hypothalamic extract on the basis of its ability to stimulate cAMP formation in anterior pituitary cells (Miyata et al., 1989. PACAP belongs to the vasoactive intestinal polypeptide (VIP)-secretin-growth hormone-releasing hormone-glucagon superfamily. The sequence of PACAP has been remarkably well conserved during evolution from protochordates to mammals, suggesting that PACAP is involved in the regulation of important biological functions. PACAP is widely distributed in the brain and peripheral organs, notably in the endocrine pancreas, gonads, respiratory and urogenital tracts. Characterization of the PACAP precursor has revealed the existence of a PACAP-related peptide, the activity of which remains unknown. Two types of PACAP binding sites have been characterized: type I binding sites exhibit a high affinity for PACAP and a much lower affinity for VIP, whereas type II binding sites have similar affinity for PACAP and VIP. Molecular cloning of PACAP receptors has shown the existence of three distinct receptor subtypes: the PACAP-specific PAC1-R, which is coupled to several transduction systems, and the PACAP/VIP-indifferent VPAC1-R and VPAC2-R, which are primarily coupled to adenylyl cyclase. PAC1-Rs are particularly abundant in the brain, the pituitary and the adrenal gland, whereas VPAC receptors are expressed mainly in lung, liver, and testis. The development of transgenic animal models and specific PACAP receptor ligands has strongly contributed to deciphering the various actions of PACAP. Consistent with the wide distribution of PACAP and its receptors, the peptide has now been shown to exert a large array of pharmacological effects and biological functions. The present report reviews the current knowledge concerning the pleiotropic actions of PACAP and discusses its possible use for future therapeutic applications.

Our vision of cancer has changed during the past decades. Indeed tumors are now perceived as complex entities where tumoral and stromal components interact closely. Among the different elements of tumor stroma the cellular component play a primordial role. Bone Marrow derived mesenchymal cells (MSCs) are attracted to tumor sites and support tumor growth. Endothelial cells (ECs) play a major role in angiogenesis. While the literature documents many aspects of the cross talk between stromal and cancer cells, the role of direct hetero-cellular contact is not clearly established. Recently, Tunneling nanotubes (TnTs) have been shown to support cell-to-cell transfers of plasma membrane components, cytosolic molecules and organelles within cell lines. Herein, we have investigated the formation of heterocellular TnTs between stromal (MSCs and ECs) and cancer cells. We demonstrate that TnTs occur between different cancer cells, stromal cells and cancer-stromal cell lines. We showed that TnTs-like structure occurred in 3D anchorage independent spheroids and also in tumor explant cultures. In our culture condition, TnTs formation occurred after large membrane adhesion. We showed that intercellular transfers of cytoplasmic content occurred similarly between cancer cells and MSCs or ECs, but we highlighted that the exchange of mitochondria occurred preferentially between endothelial cells and cancer cells. We illustrated that the cancer cells acquiring mitochondria displayed chemoresistance. Our results illustrate the perfusion-independent role of the endothelium by showing a direct endothelial to cancer cell mitochondrial exchange associated to phenotypic modulation. This supports another role of the endothelium in the constitution of the metastatic niche.

Background—: The lymphatic system regulates interstitial tissue fluid balance, and lymphatic malfunction causes edema. The heart has an extensive lymphatic network displaying a dynamic range of lymph flow in physiology. Myocardial edema occurs in many cardiovascular diseases, eg, myocardial infarction (MI) and chronic heart failure, suggesting that cardiac lymphatic transport may be insufficient in pathology. Here, we investigate in rats the impact of MI and subsequent chronic heart failure on the cardiac lymphatic network. Further, we evaluate for the first time the functional effects of selective therapeutic stimulation of cardiac lymphangiogenesis post-MI. Methods and Results—: We investigated cardiac lymphatic structure and function in rats with MI induced by either temporary occlusion (n=160) or permanent ligation (n=100) of the left coronary artery. Although MI induced robust, intramyocardial capillary lymphangiogenesis, adverse remodeling of epicardial precollector and collector lymphatics occurred, leading to reduced cardiac lymphatic transport capacity. Consequently, myocardial edema persisted for several months post-MI, extending from the infarct to noninfarcted myocardium. Intramyocardial-targeted delivery of the vascular endothelial growth factor receptor 3–selective designer protein VEGF-C _C152S , using albumin-alginate microparticles, accelerated cardiac lymphangiogenesis in a dose-dependent manner and limited precollector remodeling post-MI. As a result, myocardial fluid balance was improved, and cardiac inflammation, fibrosis, and dysfunction were attenuated. Conclusions—: We show that, despite the endogenous cardiac lymphangiogenic response post-MI, the remodeling and dysfunction of collecting ducts contribute to the development of chronic myocardial edema and inflammation-aggravating cardiac fibrosis and dysfunction. Moreover, our data reveal that therapeutic lymphangiogenesis may be a promising new approach for the treatment of cardiovascular diseases.

The presence of nonmammalian core α(1,3)-fucose and core xylose glyco-epitopes on glycans N-linked to therapeutic glycoproteins produced in plants has raised the question of their immunogenicity in human therapy. We address this question by studying the distribution of these N-glycans in pea, rice, and maize (which are the crops intended for the production of therapeutic proteins) and by reinvestigating their immunogenicity in rodents. We found that immunization with a model glycoprotein, horseradish peroxidase, elicits in C57BL/6 mice and rats the production of antibodies (Abs) specific for core α(1,3)-fucose and core xylose epitopes. Furthermore, we demonstrated that about 50% of nonallergic blood donors contains in their sera Abs specific for core xylose, whereas 25% have Abs against core α(1,3)-fucose. These Abs probably result from sensitization to environmental antigens. Although the immunological significance of these data is too speculative at the moment, the presence of such Abs might introduce some limitations to the use of plant-derived biopharmaceutical glycoproteins, such as an accelerated clearance during human therapy.

Selenoproteins contain the essential trace element selenium, the deficiency of which is associated with cancer or accelerated aging. Although selenoproteins are thought to be instrumental for the effects of selenium, the biological function of many of these proteins remains unknown. Here, we studied the role of selenoprotein T (SelT), a selenocysteine (Sec) ‐containing protein with no known function, which we have identified as a novel target gene of the neuropeptide pituitary adenylate cyclase‐activating polypeptide (PACAP) during PC12 cell differentiation. SelT was found to be ubiquitously expressed throughout embryonic development and in adulthood in rat. Immunocytochemical analysis revealed that SelT is mainly localized to the endoplasmic reticulum through a hydrophobic domain. PACAP and cAMP induced a rapid and long‐lasting increase in SelT gene expression in PC12 cells, in a Ca ²⁺ ‐dependent manner. These results suggested a possible role of SelT in PACAP signaling during PC12 cell differentiation. Indeed, overexpression of SelT in PC12 cells provoked an increase in the concentration of intracellular Ca ²⁺ ([Ca ²⁺ ] _i ) that was dependent on the Sec residue. Conversely, SelT gene knockdown inhibited the PACAP‐induced increase in [Ca ²⁺ ] _i and reduced hormone secretion. These findings demonstrate the implication of a selenoprotein in the regulation of Ca ²⁺ homeostasis and neuroendocrine secretion in response to a cAMP‐stimulating trophic factor.— Grumolato, L., Ghzili, H., Montero‐Hadjadje, M., Gasman, S., Lesage, J., Tanguy, Y., Galas, L., Ait‐Ali, D., Leprince, J., Guerineau, N. C., Elkahloun, A. G., Fournier, A., Vieau, D., Vaudry, H., Anouar, Y. Selenoprotein T is a PACAP‐regulated gene involved in intracellular Ca2+ mobilization and neuroendocrine secretion. FASEB J. 22, 1756–1768 (2008)