Potential redox-sensitive Akt activation by dopamine activates Bad and promotes cell death in melanocytes

Dopamine-conjugated extracellular vesicles induce autophagy in Parkinson's disease

The application of extracellular vesicles (EVs) as vehicles for anti-Parkinson's agents represents a significant advance, yet their clinical translation is hampered by challenges in efficient brain delivery and complex blood-brain barrier (BBB) targeting strategies. In this study, we engineered dopamine onto the surface of adipose-derived stem cell EVs (Dopa-EVs) utilizing a facile, two-step cross-linking approach. This engineering enhanced neuronal uptake of the EVs in primary neurons and neuroblastoma cells, a process shown to be competitively inhibited by dopamine pretreatment and dopamine receptor antibodies. Notably, Dopa-EVs demonstrated increased brain accumulation in mouse Parkinson's disease (PD) models. Therapeutically, Dopa-EVs administration led to the rescue of dopaminergic neuronal loss and amelioration of behavioural deficits in both 6-hydroxydopamine (6-OHDA) and α-Syn PFF-induced PD models. Furthermore, we observed that Dopa-EVs stimulated autophagy evidenced by the upregulation of Beclin-1 and LC3-II. These findings collectively indicate that surface modification of EVs with dopamine presents a potent strategy for targeting dopaminergic neurons in the brain. The remarkable therapeutic potential of Dopa-EVs, demonstrated in PD models, positions them as a highly promising candidate for PD treatment, offering a significant advance over current therapeutic modalities.

Crosstalk with keratinocytes causes GNAQ oncogene specificity in melanoma

Different melanoma subtypes exhibit specific and non-overlapping sets of oncogene and tumor suppressor mutations, despite a common cell of origin in melanocytes. For example, activation of the Gα_q/11 signaling pathway is a characteristic initiating event in primary melanomas that arise in the dermis, uveal tract, or central nervous system. It is rare in melanomas arising in the epidermis. The mechanism for this specificity is unknown. Here, we present evidence that in the mouse, crosstalk with the epidermal microenvironment actively impairs the survival of melanocytes expressing the GNAQ^Q209L oncogene. We found that GNAQ^Q209L, in combination with signaling from the interfollicular epidermis (IFE), stimulates dendrite extension, leads to actin cytoskeleton disorganization, inhibits proliferation, and promotes apoptosis in melanocytes. The effect was reversible and paracrine. In contrast, the epidermal environment increased the survival of wildtype and Braf^V600E expressing melanocytes. Hence, our studies reveal the flip side of Gα_q/11 signaling, which was hitherto unsuspected. In the future, the identification of the epidermal signals that restrain the GNAQ^Q209L oncogene could suggest novel therapies for GNAQ and GNA11 mutant melanomas.

Plasma & urinary catecholamines & urinary vanillylmandelic acid levels in patients with generalized vitiligo

Background & objectives

Vitiligo is an acquired skin disease characterized by depigmented areas of the skin. Increased release of catecholamines from autonomic nerve endings in microenvironment of melanocytes in affected skin might be involved in the aetiopathogenesis of vitiligo. Levels of catecholamines are considered as being related to onset or worsening of the disease. Therefore, in this study, the role of catecholamines was evaluated in mapping disease stability and outcome of vitiligo patients undergoing melanocyte transfer.

Methods

In this study, circulatory and urinary levels of catecholamine (CA) and vanillylmandelic acid (VMA) were determined in 45 individuals (30 vitiligo patients and 15 healthy controls) using ELISA.

Results

A significant increase for plasma and urinary catecholamines along with VMA was observed as compared to healthy controls. When the pre- and post-intervention levels were analyzed in responders and non-responders, respectively, only dopamine showed significant decline in urine, rest of the molecules in plasma as well as urine showed non-significant decline except VMA which showed insignificant increase.

Interpretation & conclusions

Levels of plasma/urinary epinephrine, and plasma dopamine, could not be established as biomarkers for disease stability or successful outcome of autologous melanocyte transfer in generalized vitiligo patients. However, dopamine (urine) might be of help in determining the stability in patients with generalized vitiligo undergoing melanocyte transfer. Further studies need to be done on a large sample of patients to confirm our findings.

Role of JNK-1 regulation in the protection of contact-inhibited fibroblasts from oxidative stress

The molecular signaling events leading to protection from oxidative stress-induced apoptosis upon contact inhibition have not been fully investigated. Previous research has indicated a role for mitogen-activated protein kinases (MAPKs) in the regulation of contact inhibition, and these proteins have also been associated with cell cycle regulation and stress-induced apoptosis. The potential role of the MAPK JNK-1 in the stress-response of actively proliferating and contact-inhibited cells was investigated. Actively proliferating normal fibroblasts (BJ) and fibrosarcoma cells (HT-1080) were stressed with H2O2, and levels of activated JNK-1 and cleaved PARP were ascertained. Similarly, these results were compared with levels of activated JNK-1 and cleaved PARP detected in H2O2-stressed confluent fibrosarcoma or contact-inhibited fibroblast cells. Contact-inhibited fibroblasts were protected from apoptosis in comparison to subconfluent fibroblasts, concurrent with decreased JNK-1 activation. Increased culture density of fibrosarcoma cells was not protective against apoptosis, and these cells did not demonstrate density-dependent alterations in the JNK-1 stress response. This decreased activation of JNK-1 in stressed, contact-inhibited cells did not appear to be dependent upon increased expression of MKP-1; however, over-expression of MKP-1 was sufficient to result in a slight decrease in H2O2-stimulated PARP cleavage. Increasing the antioxidant capacity of fibroblasts through NAC-treatment not only lessened H2O2-stimulated JNK-1 activation, but also did not influence the expression of MKP-1. Taken together, these results suggest that regulation of negative regulation of JNK-1 upon contact inhibition is protective against apoptosis, and that this regulation is independent of MKP-1.