Protein O-mannosylation: one sugar, several pathways, many functions.

Recent research has unveiled numerous important functions of protein glycosylation in development, homeostasis, and diseases. A type of glycosylation taking the center stage is protein O-mannosylation, a posttranslational modification conserved in a wide range of organisms, from yeast to humans. In animals, protein O-mannosylation plays a crucial role in the nervous system, whereas protein O-mannosylation defects cause severe neurological abnormalities and congenital muscular dystrophies.

Glia-neuron coupling via a bipartite sialylation pathway promotes neural transmission and stress tolerance in .

Modification by sialylated glycans can affect protein functions, underlying mechanisms that control animal development and physiology. Sialylation relies on a dedicated pathway involving evolutionarily conserved enzymes, including CMP-sialic acid synthetase (CSAS) and sialyltransferase (SiaT) that mediate the activation of sialic acid and its transfer onto glycan termini, respectively. In , and genes function in the nervous system, affecting neural transmission and excitability.

Protein tyrosine phosphatase 69D is a substrate of protein O-mannosyltransferases 1-2 that is required for the wiring of sensory axons in Drosophila.

Mutations in protein O-mannosyltransferases (POMTs) result in severe brain defects and congenital muscular dystrophies characterized by abnormal glycosylation of α-dystroglycan (α-Dg). However, neurological phenotypes of POMT mutants are not well understood, and the functional substrates of POMTs other than α-Dg remain unknown. Using a Drosophila model, here we reveal that Dg alone cannot account for the phenotypes of POMT mutants, and identify Protein tyrosine phosphatase 69D (PTP69D) as a gene interacting with POMTs in producing the abdomen rotation phenotype.

[Diagnostics of early signs of ocular pathology in patients with HIV/tuberculosis co-infection].

The current epidemic situation in Russia is characterized by increasing rate of co-infection (HIV/tuberculosis). Damage to the organ of vision is more common among patients with this pathology, presenting significant difficulties in diagnosis of the ophthalmic manifestations. High-tech imaging method - optical coherence tomography (OCT) allows exploration of the eye tissues with high accuracy and depth, as well as evaluation of the structure of the choroid and microcirculation parameters of the anterior and posterior eye segments.