The different roles of 5-HT1A/2A receptors in fluoxetine ameliorated pigmentation of C57BL/6 mouse skin in response to stress

Changing human hair fibre colour and shape from the follicle

INTRODUCTION

Natural hair curvature and colour are genetically determined human traits, that we intentionally change by applying thermal and chemical treatments to the fibre. Presently, those cosmetic methodologies act externally and their recurrent use is quite detrimental to hair fibre quality and even to our health.

OBJECTIVES

This work represents a disruptive concept to modify natural hair colour and curvature. We aim to model the fibre phenotype as it is actively produced in the follicle through the topical delivery of specific bioactive molecules to the scalp.

METHODS

Transcriptome differences between curly and straight hairs were identified by microarray. In scalp samples, the most variable transcripts were mapped by in situ hybridization. Then, by using appropriate cellular models, we screened a chemical library of 1200 generic drugs, searching for molecules that could lead to changes in either fibre colour or curvature. A pilot-scale, single-centre, investigator-initiated, prospective, blind, bilateral (split-scalp) placebo-controlled clinical study with the intervention of cosmetics was conducted to obtain a proof of concept (RNEC n.92938).

RESULTS

We found 85 genes transcribed significantly different between curly and straight hair, not previously associated with this human trait. Next, we mapped some of the most variable genes to the inner root sheath of follicles, reinforcing the role of this cell layer in fibre shape moulding. From the drug library screening, we selected 3 and 4 hits as modulators of melanin synthesis and gene transcription, respectively, to be further tested in 33 volunteers. The intentional specific hair change occurred: 8 of 14 volunteers exhibited colour changes, and 16 of 19 volunteers presented curvature modifications, by the end of the study.

CONCLUSION

The promising results obtained are the first step towards future cosmetics, complementary or alternative to current methodologies, taking hair styling to a new level: changing hair from the inside out.

Serotonin/5-HT7 receptor provides an adaptive signal to enhance pigmentation response to environmental stressors through cAMP-PKA-MAPK, Rab27a/RhoA, and PI3K/AKT signaling pathways

Serotonin (5-HT), a neurotransmitter, is essential for normal and pathological pigmentation processing, and its receptors may be therapeutical targets. The effect and behavior of the 5-HT7 receptor (5-HT7R) in melanogenesis in high vertebrates remain unknown. Herein, we examine the role and molecular mechanism of 5-HT7R in the pigmentation of human skin cells, human tissue, mice, and zebrafish models. Firstly, 5-HT7R protein expression decreased significantly in stress-induced depigmentation skin and vitiligo epidermis. Stressed mice received transdermal serotonin 5-HT7R selective agonists (LP-12, 0.01%) for 12 or 60 days. Mice might recover from persistent stress-induced depigmentation. The downregulation of tyrosinase (Tyr), microphthalmia-associated transcription factor (Mitf) expression, and 5-HT7R was consistently restored in stressed skin. High-throughput RNA sequencing showed that structural organization (dendrite growth and migration) and associated pathways were activated in the dorsal skin of LP-12-treated animals. 5-HT7R selective agonist, LP-12, had been demonstrated to enhance melanin production, dendrite growth, and chemotactic motility in B16F10 cells, normal human melanocytes (NHMCs), and zebrafish. Mechanistically, the melanogenic, dendritic, and migratory functions of 5-HT7R were dependent on the downstream signaling of cAMP-PKA-ERK1/2, JNK MAPK, RhoA/Rab27a, and PI3K/AKT pathway activation. Importantly, pharmacological inhibition and genetic siRNA of 5-HT7R by antagonist SB269970 partially/completely abolished these functional properties and the related activated pathways in both NHMCs and B16F10 cells. Consistently, htr7a/7b genetic knockdown in zebrafish could blockade melanogenic effects and abrogate 5-HT-induced melanin accumulation. Collectively, we have first identified that 5-HT7R regulates melanogenesis, which may be a targeted therapy for pigmentation disorders, especially those worsened by stress.

A Novel Furocoumarin Derivative, 5-((diethylamino)me-13 thyl)-3-phenyl-7H-furo [3,2-g] chromen-7-one Upregulates Melanin Synthesis via the Activation of cAMP/PKA and MAPKs Signal Pathway: In Vitro and In Vivo Study

Psoralen, a major furocoumarin component of the Fructus Psoralen (FP), in combination with ultraviolet radiation, cures abnormal pigmentation disorder. In a previous study, we synthesized a series of linear furocoumarins with different substituents, out of which 5-((diethylamino)methyl)-3-phenyl-7H-furo [3,2-g] chromen-7-one (encoded as 5D3PC) showed better pigmenting effect than others in B16 cells. In this study, we examined the mechanism underlying the melanogenic effect of 5D3PC both in vivo and in vitro. To examine the pigmentation effect, the B16 and human melanocyte cell lines, PIG1 and PIG3V melanocytes were incubated with 5D3PC. In animal experiments, C57BL/6 mice received 5% hydroquinone and were administrated with 5D3PC for 30 days. 5D3PC upregulated the melanin synthesis and tyrosinase in B16 cell, PIG1 and PIG3V. The expression level of tyrosinase (TYR), tyrosinase-related protein-1 (TRP-1) and tyrosinase-related protein-2 (TRP-2), microphthalmia-associated transcription factor (MITF), cyclic adenosine monophosphate (cAMP), phosphorylation of cAMP-responsive element binding protein (p-CREB), phosphorylation of p38 mitogen-activated protein kinase (MAPK), c- phosphorylation of Jun N-terminal kinase (p-JNK) was significantly higher in 5D3PC-treated B16 cells. The oral administration of 5D3PC attenuated the depigmentation of the C57BL/6 vitiligo mice model by increasing the numbers of melanin-containing hair follicles, melanogenic protein, and melanogenesis-relative genes expression in skin tissues.

Serotonin (5-HT) 2A Receptor Involvement in Melanin Synthesis and Transfer via Activating the PKA/CREB Signaling Pathway

The 5-HT2A serotonin receptor (HTR2A) has been reported to be involved in the serotonin- or serotonin receptor 2A agonist-induced melanogenesis in human melanoma cells. However, the molecular mechanisms underlying HTR2A in regulating melanogenesis remain poorly understood. In this research, cultured mouse melanoma cell line B16F10, human skin, and zebrafish embryos were used to elucidate the downstream signaling of HTR2A in regulating melanogenesis and to verify the potential application of HTR2A in the treatment of pigment-associated cutaneous diseases. We demonstrated that HTR2A antagonists (AT1015 and ketanserin) attenuated the melanogenesis induction of serotonin in both mouse melanoma cells and zebrafish embryos. The agonists of HTR2A (DOI and TCB-2) increased melanin synthesis and transfer in B16F10 cells, human skin tissue, and zebrafish embryos. Furthermore, the HTR2A agonists increased the expression of proteins related to melanosome organization and melanocyte dendrites to facilitate the melanocyte migration and melanosome transport. HTR2A antagonists and genetic knockout of zebrafish htr2aa (the homologue of mammalian HTR2A gene) were also used to clarify that HTR2A mediates serotonin and DOI in regulating melanogenesis. Finally, through small scale screening of the candidate downstream pathway, we demonstrated that HTR2A mediates the melanogenesis induction of its ligands by activating the PKA/CREB signaling pathway. In this research, we further confirmed that HTR2A is a crucial protein to mediate melanocyte function. Meanwhile, this research supports that HTR2A could be designed as a drug target for the development of chemicals to treat cutaneous diseases with melanocytes or melanogenesis abnormality.

Effects of oxidative stress induced by environmental relevant concentrations of fluoxetine on the embryonic development on Danio rerio

Fluoxetine (FLX) is a psychoactive drug that acts as an antidepressant. FLX is one of the world's best-selling prescription antidepressants. FLX is widely used for the treatment of various psychiatric disorders. For these reasons, this drug may eventually end up in the aquatic environment via municipal, industrial, and hospital discharges. Even though the occurrence of FLX in aquatic environments has been reported as ubiquitous, the toxic effects that this drug may induce, especially at environmentally relevant concentrations, on essential biological processes of aquatic organisms require more attention. In the light of this information, this work aimed to investigate the influence that fluoxetine oxidative stress-induced got over the embryonic development of Danio rerio. For this purpose, D. rerio embryos (4 h post fertilization) were exposed to environmentally relevant concentrations (5, 10, 15, 20, 25, 30, 35, and 40 ng L^-1) of fluoxetine, until 96 h post fecundation. Along the exposure, survival, alterations to embryonic development, and teratogenic effects were evaluated using a stereomicroscope. Furthermore, oxidative stress biomarkers (superoxide dismutase, catalase, glutathione peroxidase, lipid peroxidation, hydroperoxide, and carbonyl content) were evaluated at 72 and 96 h post fecundation. LC₅₀, EC_50m, and teratogenic index were 30 ng L^-1, 16 ng L^-1, and 1.9, respectively. The main teratogenic effects induced by fluoxetine were pericardial edema, hatching retardation, spine alterations and craniofacial malformations. Concerning oxidative stress, our integrated biomarkers (IBR) analysis demonstrated that as the concentration increased, oxidative damage biomarkers got more influence over the embryos than antioxidant enzymes. Thus, fluoxetine induces an important oxidative stress response on the embryos of D. rerio. Collectively, our results allow us to concluded that FLX is a dangerous drug in the early life stages of D. rerio due to its high teratogenic potential and that FLX-oxidative stress induced may be involved in this toxic process.

MiR-186-5p suppresses cell migration, invasion, and epithelial mesenchymal transition in bladder cancer by targeting RAB27A/B

Bladder cancer (BCa) is a common malignancy in the urinary system. Ras-related protein Rab-27A (RAB27A) and Ras-related protein Rab-27B (RAB27B) have been verified to be closely related to the development of many tumors. Since the role of both RAB27A and RAB27B in BCa have not been reported, we intended to explore the function and mechanism of RAB27A and RAB27B in BCa development. Reverse transcription quantitative polymerase chain reaction revealed that RAB27A/B showed high expression in BCa tissues and cells. Cell counting kit-8, wound healing and Transwell assays as well as western blot analyses revealed that silencing RAB27A/B suppressed BCa cell proliferation, migration and invasion as well as the epithelial-mesenchymal transition (EMT) process. Based on bioinformatics analysis and our experiments, microRNA-186-5p (miR-186-5p) was found to be the upstream miRNA of RAB27A/B in BCa. MiR-186-5p expression was significantly downregulated in BCa cells and tissues. MiR-186-5p directly targeted the 3'-untranslated region (3'-UTR) of RAB27A/B and downregulated both mRNA and protein levels of RAB27A/B in BCa cells. MiR-186-5p overexpression suppressed BCa cell proliferation, migration and invasion as well as the EMT process in vitro and inhibited tumor growth in vivo. Overexpressing RAB27A/B rescued the inhibitory effect of miR-186-5p on malignant phenotypes of BCa cells. Furthermore, miR-186-5p inactivated the phosphatidylinositol 3-Kinase (PI3K)/mitogen-activated protein kinase (MAPK) signaling pathway by downregulating the expression of RAB27A/B, as shown in western blot analysis. Overall, miR-186-5p suppressed BCa cell proliferation, migration, invasion and EMT process and inhibited xenograft tumor growth by targeting RAB27A/B to inactivate the PI3K/MAPK signaling.

The epigenetic role of HTR1A antagonist in facilitaing GnRH expression for pubertal initiation control

Serotonin (5-hydroxytryptamine [5-HT]), a metabolite of tryptophan, acts on the components of the hypothalamus-hypophysis-gonad axis and induces puberty delay in mammals via 5-HT receptor 1A (HTR1A). However, the roles of HTR1A in the hypothalamus in pubertal regulation of gene expression are not fully understood. In the current study, the upregulated gonadotropin-releasing hormone (GnRH) expression in GT1-7 GnRH neuronal cells induced by the HTR1A antagonist WAY-100635 maleate was observed in vitro. Furthermore, RNA sequencing (RNA-seq) showed decreased expression of chromobox 4 (CBX4), a member of the polycomb-repressive complex 1 (PRC1), and the loss of RING2 and YY1 interaction with CBX4, suggesting the degradation of the PRC1 in GT1-7 cells treated with maleate. Chromatin immunoprecipitation sequencing (ChIP-seq) showed that the genome-wide occupancy of CBX4 and histone H2A lysine-119 ubiquitination (H2AK119ub) was compromised, especially on the promoter of GnRH. Finally, we determined that inactivation of phosphatidylinositol 3-kinase (PI3K)/Akt and mitogen-activated protein kinase (MAPK)/extracellular signal-regulated kinase (ERK) contributed to CBX4 downregulation. Taken together, we concluded that HTR1A antagonists could enhance GnRH transcription via PRC1 degradation and H2AK119ub loss driven by reduced CBX4 expression through PI3K/Akt and MAPK/ERK pathway suppression in GT1-7 cells and provided a potential epigenetic mechanism of action of HTR1A on GnRH gene expression for mammalian puberty onset.

Role of Amine Neurotransmitters and Their Receptors in Skin Pigmentation: Therapeutic Implication

Skin pigmentation can occur due to increased melanin, including melanocyte proliferation, melanin biosynthesis, or melanocyte migration. There are many factors that influence the melanin production process, but the role of neurotransmitters in this process is still unclear. We found that histamine and serotonin influence the different stages of melanogenesis and melanogenesis, which increase melanogenesis. Since then, several related papers have been published, and from these papers, it has been recognised that the role of neurotransmitters in skin-pigment-related diseases needs to be summarised. By introducing the role of neurotransmitters in the regulation of various pigment disorders, including vitiligo and melasma, through this review, many researchers can be expected to try to apply neurotransmitter-related agonists and antagonists as treatments for skin pigment disorders.

Anti-depressant effect of Zhi-zi-chi decoction on CUMS mice and elucidation of its signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Zhi-zi-chi decoction (ZZCD) is used for treating depression as an effectively traditional Chinese medicine. Until now, studies on pharmacological research of ZZCD have mostly been centered in pharmacokinetic level. Little was known about its pharmacological mechanism of relieving depression.

AIM OF THE STUDY

This study was to evaluate the effect of ZZCD on relieving depression via behavioral tests, serum metabolomics and signaling target expression analysis on chronic unpredictable mild stress (CUMS) model mice.

MATERIALS AND METHODS

The CUMS exposure lasted 7 consecutive weeks. The mice were administrated with ZZCD for the last 3 weeks. Behavioral tests were applied and a serum metabolomics method based on UFLC/Q-TOF-MS with multivariate statistical and global metabolic network analysis was performed to identify relevant metabolites and pathways. Finally, the protein expressions in mouse hippocampi were determined by western blot to verify the metabolomics deduction.

RESULTS

Behavioral parameters were visibly changed after modeling, while high and medium dosage groups showed status improvement compared to the model group. Seventy six metabolites were identified as potential biomarkers from the metabolomics profiles in C₁₈ and HILIC systems. In addition, 9 significant pathways related to changed biomarkers were conducted. The pathways were closely connected by some key targets, which were significantly reduced in the model group compared with those in control group, while ZZCD treated groups showed corrections after 3-week administration. The results revealed that the anti-depression efficacy of ZZCD might be associated with PKA-CREB-BDNF-TrkB-PSD-95 pathway influenced by metabolic changes, verifying the pathway annotation speculation.

CONCLUSION

This study demonstrated that ZZCD had a positive treatment effect on CUMS depression model mice. Metabolomics results revealed the holistic and interconnected metabolic changes of ZZCD in CUMS mice. The metabolic pathway annotation suggested that the anti-depression mechanism of ZZCD might be related to signaling pathway in brain. PKA-CREB-BDNF-TrkB-PSD-95 signaling expression was a verification and complement to the metabolomics results.

5-Hydroxytryptamine (5-HT) Positively Regulates Pigmentation via Inducing Melanoblast Specification and Melanin Synthesis in Zebrafish Embryos

It has been reported that 5-hydroxytryptamine (5-HT) is related to melanogenesis in mice and melanoma cells. However, the underlying mechanisms of 5-HT in regulating pigmentation remains unknown. In this study, we aim to clarify the regulatory mechanism of 5-HT in the pigmentation of zebrafish embryos and B16F10 cells. Our results show that 5-HT induces the pigmentation of zebrafish embryos in a dosage-dependent manner at concentrations of 0.01-1 mM. Whole mount in situ hybridizations and qRT-PCR in zebrafish embryos indicate that the expression of neural crest cells marker gene sox10 is not changed in embryos treated with 5-HT compared to control group. The expression of mitfa, the marker gene of melanoblasts, is increased in the presence of 5-HT. Furthermore, 5-HT increased the expression of regeneration associated genes, namely kita, mitfa, and dct, after ablation of the melanogenic cells in zebrafish embryos. The experiments in B16F10 cells show that 5-HT promotes melanin synthesis by up-regulating the expression of key proteins MITF, TYR, TRP-1, and TRP-2. Especially, the small molecule inhibitor of PKA signaling, but not AKT and MAPK signaling, attenuates the up-regulation of MITF and TYR resulted from 5-HT induction in B16F10 cells. These results will help us to further understand the regulatory network of vertebrate pigmentation.

Characterization of serotonin and N-acetylserotonin systems in the human epidermis and skin cells

Tryptophan hydroxylase (TPH) activity was detected in cultured epidermal melanocytes and dermal fibroblasts with respective Km of 5.08 and 2.83 mM and Vmax of 80.5 and 108.0 µmol/min. Low but detectable TPH activity was also seen in cultured epidermal keratinocytes. Serotonin and/or its metabolite and precursor to melatonin, N-acetylserotonin (NAS), were identified by LC/MS in human epidermis and serum. Endogenous epidermal levels were 113.18 ± 13.34 and 43.41 ± 12.45 ng/mg protein for serotonin (n = 8/8) and NAS (n = 10/13), respectively. Their production was independent of race, gender, and age. NAS was also detected in human serum (n = 13/13) at a concentration 2.44 ± 0.45 ng/mL, while corresponding serotonin levels were 295.33 ± 17.17 ng/mL (n = 13/13). While there were no differences in serum serotonin levels, serum NAS levels were slightly higher in females. Immunocytochemistry studies showed localization of serotonin to epidermal and follicular keratinocytes, eccrine glands, mast cells, and dermal fibrocytes. Endogenous production of serotonin in cultured melanocytes, keratinocytes, and dermal fibroblasts was modulated by UVB. In conclusion, serotonin and NAS are produced endogenously in the epidermal, dermal, and adnexal compartments of human skin and in cultured skin cells. NAS is also detectable in human serum. Both serotonin and NAS inhibited melanogenesis in human melanotic melanoma at concentrations of 10^-4 -10^-3  M. They also inhibited growth of melanocytes. Melanoma cells were resistant to NAS inhibition, while serotonin inhibited cell growth only at 10^-3  M. In summary, we characterized a serotonin-NAS system in human skin that is a part of local neuroendocrine system regulating skin homeostasis.

IFN-γ inhibits 5-HT-induced melanin biosynthesis via downregulation of 5-HT receptors in vivo/in vitro

Hypopigmentation disorders, such as vitiligo, are difficult for treatment due to complicated pathogenesis, resulting from multiple factors including neural and immune elements. 5-HT and IFN-γ both play crucial roles in these skin diseases. However, the interactions between 5-HT and IFN-γ in regulation of melanogenesis is still unknown. Our study aimed at exploring whether IFN-γ affects 5-HT-induced melanogenesis and searching the mechanism. In our study, IFN-γ attenuated 5-HT-induced pigmentation and green fluorescent protein (GFP) expression in zebrafishes. In addition, we found that IFN-γ decreased serum serotonin levels as well as the cutaneous expression of tryptophan hydroxylase 1 (TPH1), 5-HT1A receptor (5-HT1AR) and 5-HT1B receptor (5-HT1BR) in C57BL/6 mice. Moreover, IFN-γ attenuated 5-HT-induced melanin biosynthesis as well as the expression of 5-HT1AR, 5-HT1BR and 5-HT2A receptor (5-HT2AR) in B16F10 cells, which blocked by interferon-γ receptor 1 and interferon-γ receptor 2 (IFNGR1/IFNGR2) antibodies. In summary, IFN-γ not only affects melanogenesis alone, but also inhibits 5-HT response on melanin biosynthesis. Mediated by IFNGR1/IFNGR2, IFN-γ downregulated 5-HT receptors expression, which directly affect 5-HT-induced melanin biosynthesis. Our work may give insights into the drug development of hypopigmentation disorders with neuro-immune derangement.