Genes & Cells

The COVID-19 pandemic and the increasingly tense political situation worldwide have led to an increase in the incidence of mood disorders. The occurrence of affective disorders is usually associated with neurotransmitters such as serotonin and dopamine; however, modern trends aim at studying the involvement of neurotrophic factors in the mechanisms of mood disorders.

This review aimed to summarize and systematize knowledge about key neurotrophic factors and the molecular mechanisms of their relationships.

The key metabolic mechanisms of proteins such as brain-derived neurotrophic factor, vascular endothelial growth factor, insulin-like growth factor-1, basic fibroblast growth factor-2, nerve growth factor, and glial cell-line derived neurotrophic factor are considered. Molecular pathways were analyzed, and a complex diagram of a multiple cascade with interconnected reactions was compiled, including each factor. Key molecular targets chosen included nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB) and cAMP response element-binding protein. The review also presented candidates for the role of limiting factors for these molecular targets. For the NF-kB cascade, neurotrophin receptor p75(NTR) was proposed as a limiting factor, and those for the CREB cascade were intracellular phospholipase C (PLC-γ), binary molecular switches (RAS-GTP), and protein kinase B (AKT).

The skeletal muscles are the main site of insulin-dependent glucose uptake, and the development of insulin resistance in skeletal muscles is the main factor in the progression of insulin resistance in the whole organism. This disorder is associated with defects in the canonical insulin cascade regulating glucose uptake; however, the specific molecular mechanisms are still debatable. Global mass spectrometry-based phosphoproteomic analysis appears to be an optimal approach to studying complex signaling networks.

The review summarizes data from phosphoproteomic studies investigating changes in intracellular signaling in skeletal muscles upon insulin stimulation under normal conditions and insulin resistance. In vitro and in vivo studies have shown that insulin stimulation/food intake causes large-scale changes in the phosphoproteome (hundreds of phosphosites). These changes affect not only the canonical insulin cascades but also other signaling pathways and proteins with different functions (enzymes of carbohydrate and fat metabolism, sarcomeric and mitochondrial proteins, transcription factors, chaperones, etc.) and cause transcriptomic changes. Insulin resistance impairs the phosphoproteomic response to insulin; however, these changes only slightly affect the canonical insulin cascade regulating glucose uptake. The causes of impairments in insulin-dependent glucose uptake are hypothesized to be related primarily by a combination of multiple defects in various signaling molecules that regulate glucose uptake directly or indirectly; however, they are not associated with the canonical insulin cascade.

BACKGROUND: The trophic function is one of the important but insufficiently studied features of mesenchymal stromal cells (MSCs), their microvesicles (MVs), and plasma enriched with soluble platelet factors (PRPs), which ensure the viability of target cells.

AIM: To analyze the capability of MSCs, MVs, and PRP to affect the viability and spontaneous and activation-induced apoptosis of rat spleen lymphocytes during culturing in vitro.

MATERIALS AND METHODS: MSCs were isolated from the mononuclear cell fraction of the femoral bone marrow of Wistar rats using the plastic adhesion method. MVs were obtained from the conditioned medium of MSCs by centrifugation at 14,500 g. PRP was prepared by freezing/thawing rat peripheral blood platelet concentrate. Rat spleen lymphocytes were isolated on a density gradient of 1.077 g/cm³. The viability and degree of lymphocyte apoptosis in vitro were assessed by flow cytometry for 7-AAD incorporation and binding to annexin V.

RESULTS: The presence of MSCs at 10 and 20% concentrations caused an increase in the number of living intact and PMA-activated lymphocytes by the end of 3-day in vitro cultivation. Compared with controls, the amount of necrotic cells decreased 8.3–13.5 times, and the number of apoptotic cells decreased 2.3–4.0 times, mainly due to lymphocytes at the late stage of apoptosis. MVs of MSCs at the indicated concentrations did not significantly affect the viability of lymphocytes cultured in vitro but reduced the level of apoptosis of intact and PMA-activated lymphocytes by 3.6 (р=0.03) and 4.8–5.2 (р=0.048; р=0.03) times respectively. Studies have shown that 1.25% rat PRP has a growth-stimulatory activity against MSCs but not against lymphocytes cultured in vitro. In the culture of intact lymphocytes, PRPs did not significantly affect cell viability with a slight decrease (2.7–2.9 fold, p >0.05) in the number of necrotic cells. In the culture of PMA-activated lymphocytes, 1.25–2.50% PRP increased the number of living cells by 1.6–2.2 times (р=0.002; р=0.01) and the number of necrotic cells by two times (р=0.02).

CONCLUSION: MSCs, MVs of MSCs, and PRP, in decreasing order, enhanced the viability of rat spleen lymphocytes and suppressed late apoptosis during in vitro cultivation. Lymphocytes activated by phorbol myristate acetate are more sensitive to their vital action compared with resting cells.