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The ATP-binding cassette transporter ABCG2 is expressed in the interfollicular epidermis and mediates the side-population phenotype in skin cells. However, the role of ABCG2 in skin is unclear. Increased expression levels of ABCG2 were found at the basal layer of transitional epidermis adjacent to cutaneous wounds in human patients, indicating that ABCG2 may be involved in regulating the wound healing process. To investigate the role of ABCG2 in cutaneous wound healing, full-thickness skin wounds were created in ABCG2 knockout ( ABCG2- KO) and wild-type mice. The healing process was analysed and revealed that ABCG2 deficiency in skin results in delays in wound closure and impairments in re-epithelialization, as evidenced by reductions in both suprabasal differentiation and in p63-expressing keratinocytes migrating from transitional epidermis to epithelial tongues. The reduction in p63-expressing cells may be due to elevated levels of reactive oxygen species in ABCG2- KO epidermis, which can cause DNA damage and lead to proliferation arrest. To determine whether ABCG2 deficiency affects the potency of epidermal stem/progenitor cells ( EPCs), transplantation studies were carried out, which demonstrated that ABCG2- KO EPCs display higher levels of γH2 AX and lose the capacity to differentiate into suprabasal keratinocytes. A competitive repopulation assay confirmed that ABCG2 expression is critical for the proper expansion and differentiation of EPCs in cutaneous wounds. As EPCs are known to contribute to the healing of larger wounds, the current findings imply a functional role for ABCG2 in the expansion and differentiation of p63-expressing EPCs. Thus, ABCG2 deficiency in skin impairs re-epithelialization in cutaneous wound healing. [ABSTRACT FROM AUTHOR]

Highlights: [•] Reduction in glycogen storage in the liver of ABCG2 knockout mice. [•] Increase in fragmental mitochondria in ABCG2-deficient hepatocytes. [•] ABCG2 knockout leads to impairment in mitochondrial dynamics and function. [•] Efflux of excessive PPIX is mediated by the ABCG2 transporter in mouse hepatocytes. [•] PPIX accumulation induces DRP-1-mediated mitochondrial fission. [ABSTRACT FROM AUTHOR]

Ag-alloy wire has been recognized to be a good candidate for interconnect in light-emitting diode (LED) technology. This study employed fine Ag-alloy wires bonded on Al-Si pad to investigate their failure mechanism under current stressing of 8×10 4 A/cm 2 at ambient temperature of 150 °C and 175 °C, respectively. We report a novel polarity effect that the spontaneous whisker growth of Ag near bonded area only happens when electrons flowed from Al to Ag, while surface of bond joints remains intact with electrons flowed from Ag to Al, suggesting that the nucleation and growth of Ag whisker is strongly affected by the direction of electron flow. We proposed that the different behaviors on the whisker growth is because compressive stress caused by current crowding effect only builds up with electrons flowed from Al to Ag. [ABSTRACT FROM AUTHOR]