Related Experiment Video

Updated: Jun 4, 2026

Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model
12:37

Pharmacologic Induction of Epidermal Melanin and Protection Against Sunburn in a Humanized Mouse Model

Published on: September 7, 2013

UV-B radiation induces macrophage migration inhibitory factor-mediated melanogenesis through activation of

Akiko Enomoto1, Yoko Yoshihisa, Takako Yamakoshi

  • 1Department of Medical Information, Hokkaido Information University, Ebetsu, Japan.

The American Journal of Pathology
|February 2, 2011
PubMed

Insights

Macrophage migration inhibitory factor (MIF) promotes skin pigmentation by stimulating keratinocytes. MIF enhances melanin production indirectly, primarily through Protease-activated receptor (PAR)-2 and stem cell factor (SCF) pathways after UV exposure.

Area of Science:

  • Dermatology
  • Cell Biology
  • Molecular Biology

Background:

  • UV radiation influences skin pigmentation via paracrine signaling between keratinocytes and melanocytes.
  • Protease-activated receptor (PAR)-2 activation in keratinocytes promotes melanosome transfer, a key step in melanogenesis.

Purpose of the Study:

  • To investigate the role of macrophage migration inhibitory factor (MIF) in UV-induced melanogenesis.
  • To elucidate the mechanisms by which MIF regulates pigmentation in human skin models.

Main Methods:

  • In vitro studies using cultured human keratinocytes and melanocytes.
  • Three-dimensional reconstituted human epidermis models.
  • In vivo studies using MIF transgenic mice and UV-B exposure.

Main Results:

  • MIF stimulated PAR-2 and stem cell factor (SCF) expression in keratinocytes but not endothelin-1 or prostaglandin E2 release.
  • MIF did not directly affect melanin or tyrosinase synthesis in melanocytes.
  • MIF increased melanin content in a 3D skin model and in MIF transgenic mice after UV-B exposure.
  • Anti-MIF antibody treatment reduced UV-B-induced melanin synthesis.

Conclusions:

  • MIF plays a significant role in UV-B-induced melanogenesis.
  • MIF-mediated pigmentation primarily occurs through PAR-2 and SCF activation in keratinocytes.
  • MIF represents a potential therapeutic target for modulating skin pigmentation.

More Related Videos

Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells06:09

Spatial and Temporal Control of Murine Melanoma Initiation from Mutant Melanocyte Stem Cells

Published on: June 7, 2019

Studying Chronic Exposure of Mice to Ultraviolet B Radiation03:20

Studying Chronic Exposure of Mice to Ultraviolet B Radiation

Published on: August 19, 2025

Related Concept Videos

Skin Cancer01:30

Skin Cancer

Skin cancer is a type of cancer that occurs when there is an abnormal growth of skin cells, usually triggered by damage to the DNA within the skin cells. It is primarily caused by exposure to ultraviolet (UV) radiation from the sun or artificial sources like tanning beds. Skin cancer is the most common type of cancer worldwide, and its incidence continues to rise.
Basal Cell Carcinoma (BCC): BCC is the most common type of skin cancer, accounting for about 80% of cases. It typically develops in...
Mutations01:35

Mutations

Mutations are changes in the sequence of DNA. These changes can occur spontaneously or they can be induced by exposure to environmental factors. Mutations can be characterized in a number of different ways: whether and how they alter the amino acid sequence of the protein, whether they occur over a small or large area of DNA, and whether they occur in somatic cells or germline cells.
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
Pigmentation01:19

Pigmentation

The color of the skin is influenced by a number of pigments, including melanin, carotene, and hemoglobin. Recall that melanin is produced by cells called melanocytes, which are found scattered throughout the stratum basale of the epidermis. The melanin is transferred to the keratinocytes via melanosomes.
Melanin occurs in two primary forms: eumelanin that provides black and brown pigment and pheomelanin that provides red color. Dark-skinned individuals produce more melanin than those with pale...
Nucleotide Excision Repair01:38

Nucleotide Excision Repair

DNA Distortion and Damage
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
Receptor Downregulation in MVBs01:15

Receptor Downregulation in MVBs

Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that  lead to cell proliferation, migration, and differentiation. Overexpression of EGFR  stimulates cells to proliferate. Excessive  EGFR activation may...