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Mitf Involved in Innate Immunity by Activating Tyrosinase-Mediated Melanin Synthesis in Pteria penguin
Ist Teil von
Frontiers in immunology, 2021-05, Vol.12, p.626493-626493
Ort / Verlag
Frontiers Media S.A
Erscheinungsjahr
2021
Link zum Volltext
Quelle
EZB Electronic Journals Library
Beschreibungen/Notizen
The microphthalmia-associated transcription factor (MITF) is an important transcription factor that plays a key role in melanogenesis, cell proliferation, survival and immune defense in vertebrate. However, its function and function mechanism in bivalve are still rarely known. In this research, first, a
Mitf
gene was characterized from
Pteria penguin
(
P. penguin
). The
PpMitf
contained an open reading frame of 1,350 bp, encoding a peptide of 449 deduced amino acids with a highly conserved basic helix-loop-helix-leucine zipper (bHLH-LZ) domain. The PpMITF shared 55.7% identity with amino acid sequence of
Crassostrea gigas
(
C. gigas
). Tissue distribution analysis revealed that
PpMitf
was highly expressed in mantle and hemocytes, which were important tissues for color formation and innate immunity. Second, the functions of
PpMitf
in melanin synthesis and innate immunity were identified. The
PpMitf
silencing significantly decreased the tyrosinase activity and melanin content, indicating
PpMitf
involved in melanin synthesis of
P. penguin.
Meanwhile, the
PpMitf
silencing clearly down-regulated the expression of
PpBcl2
(B cell lymphoma/leukemia-2 gene) and antibacterial activity of hemolymph supernatant, indicating that
PpMitf
involved in innate immunity of
P. penguin.
Third, the function mechanism of
PpMitf
in immunity was analyzed. The promoter sequence analysis of tyrosinase (
Tyr
) revealed two highly conserved E-box elements, which were specifically recognized by HLH-LZ of MITF. The luciferase activities analysis showed that
Mitf
could activate the E-box in
Tyr
promoter through highly conserved bHLH-LZ domain, and demonstrated that
PpMitf
involved in melanin synthesis and innate immunity by regulating tyrosinase expression. Finally, melanin from
P. penguin
, the final production of
Mitf
-
Tyr
-melanin pathway, was confirmed to have direct antibacterial activity. The results collectively demonstrated that
PpMitf
played a key role in innate immunity through activating tyrosinase-mediated melanin synthesis in
P. penguin.