Journal Club – 23.05.26

SpiCee: A Genetic Tool for Subcellular and Cell-Specific Calcium Manipulation

Oriol Ros,1,6 Sarah Baudet,1,6 Yvrick Zagar,1 Karine Loulier,1 Fiona Roche,1 Sandrine Couvet,1 Alain Aghaie,2
Melody Atkins,3 Alice Louail,1 Christine Petit,2,4 Christine Metin,3 Yves Mechulam,5 and Xavier Nicol1,7,*


Calcium is a second messenger crucial to a myriad of cellular processes ranging from regulation of metabolism and cell survival to vesicle release and motility. Current strategies to directly manipulate endogenous calcium signals lack cellular and subcellular specificity. We introduce SpiCee, a versatile and genetically encoded chelator combining low- and high-affinity sites for calcium. This scavenger enables altering endogenous calcium signaling and functions in single cells in vitro and in vivo with biochemically controlled subcellular resolution. SpiCee paves the way to investigate local calcium signaling in vivo and directly manipulate
this second messenger for therapeutic use.

Presenter: Ju hee Ryu

Hydrogel dressing integrating FAK inhibition and ROS scavenging for mechano-chemical treatment of atopic dermatitis

Nat Commun. 2023 Apr 29;14(1):2478. doi: 10.1038/s41467-023-38209-x.

Yuanbo Jia # 1 2Jiahui Hu # 2 3Keli An 1 2Qiang Zhao 2 3Yang Dang 2 3Hao Liu 1 2Zhao Wei 1 2Songmei Geng 4Feng Xu 5 6


Atopic dermatitis (AD) is a chronic skin disease caused by skin immune dyshomeostasis and accompanied by severe pruritus. Although oxidative stress and mechanical scratching can aggravate AD inflammation, treatment targeting scratching is often overlooked, and the efficiency of mechano-chemically synergistic therapy remains unclear. Here, we find that enhanced phosphorylation of focal adhesion kinase (FAK) is associated with scratch-exacerbated AD. We then develop a multifunctional hydrogel dressing that integrates oxidative stress modulation with FAK inhibition to synergistically treat AD. We show that the adhesive, self-healing and antimicrobial hydrogel is suitable for the unique scratching and bacterial environment of AD skin. We demonstrate that it can scavenge intracellular reactive oxygen species and reduce mechanically induced intercellular junction deficiency and inflammation. Furthermore, in mouse AD models with controlled scratching, we find that the hydrogel alleviates AD symptoms, rebuilds the skin barrier, and inhibits inflammation. These results suggest that the hydrogel integrating reactive oxygen species scavenging and FAK inhibition could serve as a promising skin dressing for synergistic AD treatment.

Journal Club – 23.04.28

Sphingosylphosphorylcholine is an activator of transglutaminase activity in human keratinocytes

Kazuhiko Higuchi,* Makoto Kawashima,* Yutaka Takagi,† Hidehiko Kondo,† Yukihiro Yada,† Yoshiaki Ichikawa,† and Genji Imokawa1,†


Abstract We characterize functional roles of a newly discovered chemical, sphingosylphosphorylcholine (SPC), in the epidermis by elucidating the biological effect of SPC on human keratinocytes in culture. The intracellular calcium level of human keratinocytes was increased by incubation with SPC, but not with sphingosine (SS) or sphingomyelin(SM). The addition of SPC, sphingosine 1-phosphate (SSP), or SS to human keratinocytes at 10 mM concentrations also
significantly suppressed DNA synthesis, and SPC, but not SSP, or SS increased the activities of membrane-bound and
soluble transglutaminases (TGases). Reverse transcription polymerase chain reaction (RT-PCR) of TGase transcripts revealed that SPC treatment at 10 mM concentrations increased the expression of TGase 1 mRNA. The increased activity of soluble TGase was accompanied by the concomitant activation of cathepsin D as revealed by the increased
ratio of mature active form to inactive intermediate form of the protease. Pretreatment of human keratinocytes with
pepstatin, a protease inhibitor, blocked the increase in soluble TGase activity induced by treatment with SPC. Consistently, SPC treatment at 1–10 µM concentrations stimulated the cornified envelope formation. These findings
suggest that SPC plays an important role in the altered keratinization process of epidermis in skin diseases with high
expression of sphingomyelin deacylase, such as atopic dermatitis.—Higuchi, K., M. Kawashima, Y. Takagi, H. Kondo, Y.
Yada, Y. Ichikawa, and G. Imokawa. Sphingosylphosphorylcholine is an activator of transglutaminase activity in human
keratinocytes. J. Lipid Res. 2001. 42: 1562–1570.

Supplementary key words sphingomyelin deacylase • atopic dermatitis • sphingolipid • ceramide

Journal Club-2023.04.14

Hair growth promotion by Necrostatin‐1s

Mei Zheng1, Nahyun Choi1, YaeJi Jang1, Da Eun Kwak2, YoungSoo Kim2, Won‐Serk Kim3,Sang Ho Oh4 & Jong‐Hyuk Sung2*

1STEMORE Co. Ltd, Incheon, South Korea. 2College of Pharmacy, Institute of Pharmaceutical Sciences, Yonsei University, 85 Songdogwahakro, Yeonsu-gu, Incheon 21983, South Korea. 3Department of Dermatology, Kangbuk Samsung Hospital, Sungkyunkwan University School of Medicine, Seoul 03181, South Korea. 4Department of Dermatology, Severance Hospital and Cutaneous Biology Research Institute, Yonsei University College of Medicine, Seoul 03722, South Korea.*email:

Necrostatins (Necs) have been developed as a receptor‐interacting protein kinase 1 (RIPK1) inhibitor, thus inhibiting necroptosis. In this current study, we have investigated the possible involvement of necroptosis in the hair cycle regulation and further examined its underlying molecular mechanisms. Diverse RIPK1/3 inhibitors and siRNA were tested in the human outer‐root sheath (ORS) cells and animal models. The expression and hair cycle‐dependent expression of RIPK 1, respectively, were investigated in the hair follicles (HF) of human, pig, and the mouse. Resulting from the experiment, Nec‐1s was most effective in the hair growth promotion among several inhibitors. Nec‐1s induced the ORS cell proliferation and migration, and increased the HF length in mouse and pig organ cultures.

In addition, it accelerated the telogen‐to‐anagen transition and elongated the anagen period in
the mouse model. Both apoptosis and necroptosis were detected in hair cycle. RIPK1 and RIPK3 were highly expressed in ORS cells during the hair regression period. Nec‐1s upregulated the mRNA expression of Wnt3a and Wnt5b, and the activity of β‐catenin. Collectively, Nec‐1s promotes hair growth through inhibiting necroptosis and activating the Wnt/β‐catenin pathway. Necroptosis is involved in hair cycle regression, and Nec‐1s is a promising target for hair‐loss treatment.

Journal Club-2023.04.07

Mechanisms and treatments of neuropathic itch in a mouse model of lymphoma

Ouyang Chen Qianru HeQingjian HanKenta FurutaniYun GuMadelynne OlexaRu-Rong Ji

DOI: 10.1172/JCI160807


Our understanding of neuropathic itch is limited due to a lack of relevant animal models. Patients with cutaneous T cell lymphoma (CTCL) experience severe itching. Here, we characterize a mouse model of chronic itch with remarkable lymphoma growth, immune cell accumulation, and persistent pruritus. Intradermal CTCL inoculation produced time-dependent changes in nerve innervations in lymphoma-bearing skin. In the early phase (20 days), CTCL caused hyperinnervations in the epidermis. However, chronic itch was associated with loss of epidermal nerve fibers in the late phases (40 and 60 days). CTCL was also characterized by marked nerve innervations in mouse lymphoma. Blockade of C-fibers reduced pruritus at early and late phases, whereas blockade of A-fibers only suppressed late-phase itch. Intrathecal (i.t.) gabapentin injection reduced late-phase, but not early-phase, pruritus. IL-31 was upregulated in mouse lymphoma, whereas its receptor Il31ra was persistently upregulated in Trpv1-expressing sensory neurons in mice with CTCL. Intratumoral anti-IL-31 treatment effectively suppressed CTCL-induced scratching and alloknesis (mechanical itch). Finally, i.t. administration of a TLR4 antagonist attenuated pruritus in early and late phases and in both sexes. Collectively, we have established a mouse model of neuropathic and cancer itch with relevance to human disease. Our findings also suggest distinct mechanisms underlying acute, chronic, and neuropathic itch.

Keywords: Lymphomas; Neuroscience; Skin cancer; Therapeutics.

Presenter: Diwas Rawal

Journal club 2023-03-31

Br J Pharmacol. 2023 Mar 16. doi: 10.1111/bph.16072. Online ahead of print.

Molecular mechanisms of MrgprA3-independent activation of the transient receptor potential ion channels TRPA1 and TRPV1 by chloroquine

Tabea C Fricke 1Sebastian Pantke 1Bjarne Lüttmann 1Frank G Echtermeyer 1Christine Herzog 1Mirjam J Eberhardt 1Andreas Leffler 1


Background and purpose: Itch associates several pathologies and is a common drug-induced side effect. Chloroquine (CQ) was reported to induce itch by activating the Mas-related G protein-coupled receptor MrgprA3 and subsequently TRPA1. In this study we demonstrate that CQ employs at least two MrgprA3-independent mechanisms to activate or sensitize TRPA1 and TRPV1.

Experimental approach: Patch Clamp and calcium-imaging were utilized to examine effects of CQ on TRPA1 and TRPV1 expressed in HEK-293T cells.

Key results: In calcium-imaging, CQ induces a concentration-dependent but MrgprA3-independent activation of TRPA1 and TRPV1. While CQ itself inhibits TRPA1 and TRPV1 in patch clamp recordings, co-application of CQ and UVA-light evokes membrane currents through both channels. This effect is inhibited by the reducing agent dithiothreitol (DTT) and reduced on mutants lacking cysteine residues accounting for reactive oxygen species (ROS)-sensitivity. The combination of CQ and UVA-light triggers an accumulation of intracellular ROS, removes fast inactivation of voltage-gated sodium currents and activates TRPV2. On the other hand, CQ is a weak base and induces intracellular alkalosis. Intracellular alkalosis can activate TRPA1 and TRPV1, and CQ applied at alkaline pH-values indeed activates both channels.

Conclusion and implications: Our data reveal novel pharmacological properties of CQ allowing activation of TRPA1 and TRPV1 via photosensitization as well as intracellular alkalosis. These findings add complexity to the commonly accepted dogma that CQ-induced itch is specifically mediated by MrgprA3 coupling to TRPA1.

Keywords: chloroquine; histamine; itch; oxidative stress; sensory neuron.

Journal club – 2023.03.24

Microglia–neuron interactions promote chronic itch via the NLRP3-IL-1β-GRPR axis

Allergy 2023 Mar 6. doi: 10.1111/all.15699. Online ahead of print.

Xueting Liu 1Yanmei Wang 1Yueling Zeng 1De Wang 1Yuhuan Wen 1Limin Fan 1Ying He 1Junyan Zhang 1Weimin Sun 1Yongping Liu 1Ailin Tao 1


Background: Spinal astrocytes contribute to chronic itch via sensitization of itch-specific neurons expressing gastrin-releasing peptide receptor (GRPR). However, whether microglia-neuron interactions contribute to itch remains unclear. In this study, we aimed to explore how microglia interact with GRPR+neurons and promote chronic itch.

Methods: RNA sequencing, quantitative real-time PCR, western blot, immunohistochemistry, RNAscope ISH, pharmacologic and genetic approaches were performed to examine the roles of spinal NLRP3 (The NOD-like receptor family, pyrin-containing domain 3) inflammasome activation and IL-1β-IL1R1 signaling in chronic itch. Grpr-eGFP and Grpr KO mice were used to investigate microglia-GRPR+neuron interactions.

Results: We observed NLRP3 inflammasome activation and IL-1β production in spinal microglia under chronic itch conditions. Blockade of microglial activation and the NLRP3/caspase-1/IL-1β axis attenuated chronic itch and neuronal activation. Type 1 IL-1 receptor (IL-1R1) was expressed in GRPR+neurons, which are essential for the development of chronic itch. Our studies also find that IL-1β+microglia are localized in close proximity to GRPR+ neurons. Consistently, intrathecal injection of IL1R1 antagonist or exogenous IL-1β indicate that the IL-1β-IL-1R1 signaling pathway enhanced the activation of GRPR+ neurons. Furthermore, our results demonstrate that the microglial NLRP3/caspase-1/IL-1β axis contributes to several different chronic itches triggered by small molecules and protein allergens from the environment and drugs.

Conclusion: Our findings reveal a previously unknown mechanism in which microglia enhances the activation of GRPR+ neurons through the NLRP3/caspase-1/IL-1β/IL1R1 axis. These results will provide new insights into the pathophysiology of pruritus and novel therapeutic strategies for patients with chronic itch.

Keywords: IL-1β; NLRP3 inflammasome; chronic itch; gastrin-releasing peptide receptor; microglia.


Acid-sensing ion channel 3 is required for agmatine-induced histamine-independent itch in mice

Guo-Kun Zhou1†, Wen-Jing Xu1†, Yi Lu1†, Yan Zhou2†, Chen-Zhang Feng3†, Jiang-Tao Zhang1†, Shi-Yu Sun1, Ruo-Meng Wang2, Tong Liu1,4,5* and Bin Wu1*

Introduction: Itch is a common symptom of many skin and systemic diseases. Identifying novel endogenous itch mediators and the downstream signaling pathways involved will contribute to the development of new strategies for the treatment of chronic itch. In the present study, we adopted behavioral testing, patch clamp recording and metabonomics analysis to investigate the role of agmatine in itch and the underlying mechanism.

Methods: Behavioral analysis was used to evaluate the establishing of acute and chronic itch mice model, and to test the effects of different drugs or agents on mice itch behavior. Western blotting analysis was used to test the effect of agmatine on phosphorylation of ERK (p-ERK) expression in the spinal cord. Patch clamp recording was used to determine the effect agmatine on the excitability of DRG neurons and the role of ASIC3. Finally, the metabonomics analysis was performed to detect the concentration of agmatine in the affected skin under atopic dermatitis or psoriasis conditions.

Results: We fused a mouse model and found that an intradermal injection of agmatine (an endogenous polyamine) into the nape of the neck or cheek induced histamine-independent scratching behavior in a dose-dependent manner. In addition, the ablation of nociceptive C-fibers by resiniferatoxin (RTX) abolished agmatine-induced scratching behavior. However, agmatine-induced itch was not affected by the pharmacological inhibition of either transient receptor potential vanilloid 1 (TRPV1) or transient receptor potential ankyrin 1 (TRPA1); similar results were obtained from TRPV1−/− or TRPA1−/− mice. Furthermore, agmatine-induced itch was significantly suppressed by the administration of acid-sensing ion channel 3 (ASIC3) inhibitors, APETx2 or amiloride. Agmatine also induced the upregulation of p-ERK in the spinal cord; this effect was inhibited by amiloride. Current clamp recording showed that the acute perfusion of agmatine reduced the rheobase and increased the number of evoked action potentials in acute dissociated dorsal root ganglion (DRG) neurons while amiloride reversed agmatine-induced neuronal hyperexcitability. Finally, we identified significantly higher levels of agmatine in the affected skin of a mouse model of atopic dermatitis (AD) when compared to controls, and the scratching behavior of AD mice was significantly attenuated by blocking ASIC3.

Discussion: Collectively, these results provide evidence that agmatine is a novel mediator of itch and induces itch via the activation of ASIC3. Targeting neuronal ASIC3 signaling may represent a novel strategy for the treatment of itch.

KEYWORDS: itch, agmatine, ASIC3, atopic dermatitis, pain

Journal Club – 23.03.10

Thymic stromal lymphopoietin controls hair growth

Jessica L. Shannon,1,2 David L. Corcoran,3 John C. Murray,1 Steven F. Ziegler,4,5 Amanda S. MacLeod,1,2,6

and Jennifer Y. Zhang1,7,*
1Department of Dermatology, Duke University, P.O. Box 103052, Durham, NC 27710, USA 2Department of Immunology, Duke University, Durham, NC 27710, USA
3Genomic and Computational Biology, Duke University, Durham, NC 27705, USA 4Benaroya Research Institute, Seattle, WA 98101, USA
5Department of Immunology, University of Washington, Seattle, WA 98195, USA 6Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA 7Department of Pathology, Duke University Medical Center, Durham, NC 27710, USA


Skin tissue regeneration after injury involves the production and integration of signals by stem cells residing in hair follicles (HFSCs). Much remains unknown about how specific wound-derived factors modulate stem cell contribution to hair growth. We demonstrate that thymic stromal lymphopoietin (TSLP) is produced in response to skin injury and during the anagen phase of the hair cycle. Intra- dermal injection of TSLP promoted wound-induced hair growth (WIHG), whereas neutralizing TSLP receptor (TSLPR) inhibited WIHG. Using flow cytometry and fluorescent immunostaining, we found that TSLP promoted proliferation of transit-amplifying cells. Lgr5CreER- mediated deletion of Tslpr in HFSCs inhibited both wound-induced and exogenous TSLP-induced hair growth. Our data highlight a novel function for TSLP in regulation of hair follicle activity during homeostasis and wound healing.

Journal Club – 23.03.03

TRPC3 channel gating by lipids requires localization at the ER/PM junctions defined by STIM1


TRPC3, a member of the transient receptor potential (TRP) superfamily of cation channels, is a lipid-regulated, Ca2+-
permeable channel that mediates essential components of the receptor evoked Ca2+ signal. The modes and mechanisms by which lipids regulate TRPC3 and other members of the TRPC channel family are not well understood. Here, we report that PI(4,5)P2 regulates TRPC3 in three independent modes. PLC-dependent hydrolysis generates diacylglycerol (DAG) that interacts with lipid-binding site 2 in the channel pore. PI(4,5)P2 interacts with lipid site 1 to inhibit TRPC3 opening and regulate access of DAG to the pore lipid site 2. PI(4,5)P2 is required for regulating pore ionic selectivity by receptor stimulation. Notably, the activation and regulation of TRPC3 by PI(4,5)P2 require recruitment of TRPC3 to the ER/PM junctions at a PI(4,5)P2-rich domain. Accordingly, we identified an FFAT site at the TRPC3 N terminal loop within the linker helices that envelope the C-terminus pole helix. The FFAT site interacts with the ER-resident VAPB to recruit TRPC3 to the ER/PM junctions and control its receptor-mediated activation. The TRPC3’s lipid interacting sites are fully conserved in TRPC6 and TRPC7 and in part in other TRPC channels. These findings inform on multiple modes of regulation of ion channels by lipids that may be relevant to diseases affected by aberrant TRPC channel functions.