Biology subjects

Domanskyi, A.

Publications and source records attributed to Domanskyi, A..

5 recordsLinked to original sources

bioRxiv2025

Selective abundance of the stemness-promoting cluster miR-290-295 within the adult substantia nigra dopamine neurons is neuroprotective via preservation of protein synthesis

Locomotor, reward and other critical functions of the body are regulated by the ventral midbrain, with the central role played by dopamine (DA) neurons. The function of these cells from the early development to maturity is critically dependent on the orchestrated expression of coding and non-coding genes. For example, in the stem cells the miR-290-295 cluster constitutes the majority of expressed microRNAs and is critical for stemness in rodents. During development towards various terminally differentiated lineages, such as neurons, the cells typically switch off transcription of these stem cell-specific microRNAs. Here we report that within the adult Substantia Nigra pars compacta (SNpc), the miR-290-295 cluster is exclusively expressed in DA neurons (SNDA), preventing the locomotor deficits and maintaining an adequate expression of proteins involved in DA biogenesis, such as tyrosine hydroxylase (TH), dopa decarboxylase (DDC) and DA transporter (DAT). Importantly, a global knock-out of the miR-290-295 cluster leads to decreased numbers of SNDA neurons in adult mice. Using in vitro and in vivo DA cell-specific loss-of-function models, we demonstrated that miR-292a-3p, the most abundant microRNA in this cluster, directly targets PTEN, a phosphatase antagonizing the neuroprotective phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)-AKT-mechanistic target of rapamycin kinase (mTOR) pathways regulating translation initiation. Accordingly, when labelled with the click chemistry-compatible methionine analogue L-azidohomoalanine, miR-290-295 cluster-deficient SNDA neurons revealed a drastic impairment of protein synthesis, which is critical for DA biogenesis. Our surprising findings demonstrate for the first time a selective expression of stem cell-specific and stemness-promoting microRNAs in a distinct population of mature neurons to maintain their physiological functions in the adulthood, suggesting that similar epigenetic disinhibition mechanisms may be also critical for other terminally differentiated cells across species.

neuroscience↗

bioRxiv2022

PKB/AKT attenuates Lewy Body-like pathology in primary neurons via Cathepsins B and D

Motor symptoms of Parkinsons disease (PD) are caused by the loss of dopamine neurons in the substantia nigra pars compacta. Current PD therapies offer only symptomatic relief, and the research on novel ways to stop or slow down the degeneration of dopamine neurons in PD attracts considerable efforts. A characteristic feature of PD is the abnormal accumulation and spread of misfolded -synuclein (-syn) protein leading to the formation of Lewy neurites and bodies in different neuronal populations, including dopamine neurons. The process of Lewy body formation compromises neuronal functions and contributes to the progression of the disease and neurodegeneration in PD patients. Treatments preventing -syn misfolding, aggregation and/or spread may therefore provide much-needed disease-modifying therapies for PD. We and others have demonstrated that -syn aggregation and Lewy body formation can be modelled in primary neuronal cultures treated with -syn pre-formed fibrils (PFFs). Using this approach, we have identified several factors preventing the accumulation of phosphorylated -syn in dopamine neurons in vitro and in vivo. In particular, we and others have demonstrated a prominent role of PKB/AKT pathway activation in promoting the survival of dopamine neurons. Here, we utilize lentiviral vectors (LVs) to express constitutively active myristoylated serine-threonine protein kinase AKT1 (mAKT1) in primary dopamine neurons. We show that lentivirally-delivered mAKT1 promoted survival of dopamine neurons after thapsigargin-induced endoplasmic reticulum (ER) stress and prevented fibril-induced accumulation of phosphorylated -syn. Furthermore, using pharmacological tools, we demonstrate that this activity of mAKT1 is dependent on the functional Cathepsins B and D. These proof-of-principle results demonstrate the critical importance of lysosomal enzymes for processing misfolded -syn and establish a basis for the use of LVs to develop neuroprotective gene therapy strategies for dopamine neurons in PD.

neuroscience↗

bioRxiv2021

Alzheimer's disease alters astrocytic functions related to neuronal support andtranscellular internalization of mitochondria

Under physiological conditions in vivo astrocytes internalize and degrade neuronal mitochondria in a process called transmitophagy. Mitophagy is widely reported to be impaired in neurodegeneration but it is unknown whether and how transmitophagy is altered in Alzheimers disease (AD). Here we report that the internalization and degradation of neuronal mitochondria are significantly increased in astrocytes isolated from aged AD mouse brains. We also demonstrate for the first time a similar phenomenon between human neurons and AD astrocytes, and in murine hippocampi in vivo. The results suggest the involvement of S100a4 in impaired mitochondrial transfer between neurons and aged AD astrocytes. Significant increases in the mitophagy regulator Ambra1 were observed in the aged AD astrocytes. These findings demonstrate altered neuron-supporting functions of aged AD astrocytes and provide a starting point for studying the molecular mechanisms of transmitophagy in AD.

neuroscience↗

bioRxiv2019

Maturation of Neuronal Activity in Caudalized Human Brain Organoids

Human brain organoids are an emerging tool to study functional neuronal networks in health and disease. A critical challenge is the engineering of brain organoids with defined regional identity and developmental stage. Here we describe a protocol for generating hindbrain-like organoids from human pluripotent stem cells. We first generated a stable pool of caudalized stem cells that expressed hindbrain identity transcription factors and differentiated into tissue containing neurons and astrocytes. After maturation, caudalized brain organoids presented synaptically connected networks consisting of glutamate-, GABA-, and serotoninergic postmitotic neurons. These mature neurons displayed electric properties and dendritic trees resembling medulla oblongata neurons. They fired spontaneous and evoked repetitive action potentials, released serotonin and displayed excitatory and inhibitory synaptic currents, functionally resembling the activity patterns observed in normal human fetal brain. Reminiscent of infected human fetal brain, infection with Zika virus hampered organoid development, while the treatment with anticonvulsant drugs - carbamazepine and valproic acid - reduced organoid growth. Neuronal maturation also occurred in the grafted organoids in vivo. In conclusion, our approach enables efficient derivation of caudalized neuronal stem cells that differentiate into mature and functional neurons in organoids with hindbrain identity following human developmental trajectory. The organoids provide excellent model to study congenital abnormalities in brain development and for drug testing.

neuroscience↗

bioRxiv2019

GDNF/RET signaling pathway activation eliminates Lewy Body pathology in midbrain dopamine neurons

Neurodegenerative diseases are associated with proteostasis disturbances and accumulation of fibrillar proteins into insoluble aggregates. Progressive age-related degeneration of dopamine neurons is a primary cause of motor dysfunctions in Parkinsons disease (PD) and substantial evidence supports critical involvement of -synuclein (-syn) in the etiology of PD. -syn is a cytosolic protein present in high concentrations in pre-synaptic neuronal terminals and a primary constituent of intracellular protein aggregates known as Lewy Neurites or Lewy Bodies. Progression of Lewy pathology is a characteristic feature in the PD brains caused by the prion-like self-templating properties of misfolded -syn. Modelling Lewy pathology progression with application of exogenously prepared -syn preformed fibrils, we discovered that glial cell line-derived neurotrophic factor (GDNF) prevented formation of -syn aggregates in dopamine neurons in culture and in vivo after viral vector expression of GDNF. These effects were abolished by CRISPR/Cas9-mediated deletion of receptor tyrosine kinase Ret, the major GDNF signaling pathway. Similar to GDNF, expression of mutated constitutively active RET (RET_MEN2B) was able to protect dopamine neurons. GDNF protection against -syn pathology progression was abolished by Src and attenuated by Akt pathway inhibitors. For the first time, we have shown the neurotrophic factor-mediated protection against the misfolded -syn propagation in dopamine neurons, uncovered underlying receptor and intracellular signaling pathways. These results for the first time demonstrate that activation of GDNF/RET signaling can be an effective therapeutic approach to prevent Lewy pathology spread at early stages of PD.\n\n\n\nO_FIG O_LINKSMALLFIG WIDTH=145 HEIGHT=200 SRC=\"FIGDIR/small/752899v1_ufig1.gif\" ALT=\"Figure 1\">\nView larger version (57K):\norg.highwire.dtl.DTLVardef@1f5109dorg.highwire.dtl.DTLVardef@15e4a2org.highwire.dtl.DTLVardef@15571c8org.highwire.dtl.DTLVardef@a10f7d_HPS_FORMAT_FIGEXP M_FIG C_FIG

neuroscience↗