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

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

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: brian99@yonsei.ac.kr

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.

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

Ouyang Chen , Qianru He, Qingjian Han, Kenta Furutani, Yun Gu, Madelynne Olexa, Ru-Rong Ji

DOI: 10.1172/JCI160807

Abstract

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