Rhythmic processes in living organisms are controlled by biological clocks. The orexinergic system of the lateral hypothalamus carries circadian information to provide arousal for the brain during the active phase. r Here, we show that orexins exert an excitatory action in three parts of the lateral geniculate nucleus (LGN), in particular upon directly retinorecipient neurons in the non-image forming visual structures. r We provide evidence for the high nocturnal levels of orexins with stable circadian expression of predominant orexin receptor 2 in the LGN. r Our data additionally establish the convergence of orexinergic and pituitary adenylate cyclase (PAC)-activating peptide/PAC1 receptor systems (used by melanopsin-expressing retinal ganglion cells), which directly regulates responses to the retinal input. r These results help us better understand circadian orexinergic control over the non-image forming subcortical visual system, forming the animal's preparedness for the behaviourally active night.

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N-acetylglucosaminyltransferase III (GnT-III) is known to catalyze N-glycan “bisection” and thereby modulate the formation of highly branched complex structures within the Golgi apparatus. While active, it inhibits the action of other GlcNAc transferases such as GnT-IV and GnT-V. Moreover, GnT-III is considered as an inhibitor of the metastatic potential of cancer cells both in vitro and in vivo. However, the effects of GnT-III may be more diverse and depend on the cellular context. We describe the detailed glycomic analysis of the effect of GnT-III overexpression in WM266–4-GnT-III metastatic melanoma cells. We used MALDI-TOF and ESI-ion-trap-MS/MS together with HILIC-HPLC of 2-AA labeled N-glycans to study the N-glycome of membrane-attached and secreted proteins. We found that the overexpression of GnT-III in melanoma leads to the modification of a broad range of N-glycan types by the introduction of the “bisecting” GlcNAc residue with highly branched complex structures among them. The presence of these unusual complex N-glycans resulted in stronger interactions of cellular glycoproteins with the PHA-L. Based on the data presented here we conclude that elevated activity of GnT-III in cancer cells does not necessarily lead to a total abrogation of the formation of highly branched glycans. In addition, the modification of pre-existing N-glycans by the introduction of “bisecting” GlcNAc can modulate their capacity to interact with carbohydrate-binding proteins such as plant lectins. Our results suggest further studies on the biological function of “bisected” oligosaccharides in cancer cell biology and their interactions with carbohydrate-binding proteins.Electronic supplementary materialThe online version of this article (10.1007/s10719-018-9814-y) contains supplementary material, which is available to authorized users.

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Melanoma is the most aggressive of all skin cancers and is exceptionally resistant to therapies. During melanoma progression, cancer cells reprogram their proliferation and survival pathways and achieve resistance to treatment-induced apoptosis. Galectin-3 (gal-3) is a member of the lectin family and is involved in such biological processes as cell adhesion, growth and differentiation, the cell cycle, and apoptosis. Gal-3 also plays an important role in tumor development and metastasis. The relationship between gal-3 expression and these processes is specific to the tumor type and the stage of cancer progression. The biological functions of gal-3 depend on its localization in the cell. In the present study, human metastatic melanoma A-375 cells, characterized by weak endogenous expression of gal-3, were transfected with gal-3 cDNA and cisplatin-induced apoptosis was measured. Data from AnnexinV and mitochondrial membrane potential analysis revealed that gal-3 did not protect the A-375 melanoma cells against cisplatin. This result probably is associated with its nuclear localization in the cells.