KTN1 mediated unfolded protein response protects keratinocytes from ionizing radiation-induced DNA damage.

BACKGROUND: The unfolded protein response (UPR) is one of the cytoprotective mechanisms against various stresses and essential for the normal function of skin. Skin injury caused by ionizing radiation (IR) is a common side effect of radiotherapy and it is unclear how UPR affects IR-induced skin injury. OBJECTIVES: To verify the effect of UPR on IR-induced DNA damage in keratinocytes and the relation between an endoplasmic reticulum (ER) protein KTN1 and UPR. METHODS: All experiments were performed on keratinocytes models: HaCaT and HEK-A. ER lumen and the expression levels of KTN1 and UPR pathway proteins (PERK, IRE1α and ATF6) were examined by transmission electron microscopy and immunoblotting, respectively. 4-PBA, an UPR inhibitor, was used to detected its effects on DNA damage and cell proliferation. Subsequently, the effects of KTN1 deletion on UPR, DNA damage and cell proliferation after IR were detected. Tunicamycin was used to reactivate UPR and then we examined its effects on DNA damage. RESULTS: UPR was activated by IR in keratinocytes. Inhibition of UPR aggravated DNA damage and suppressed cell proliferation after IR. KTN1 expression was upregulated by IR and KTN1 depletion reduced ER expansion and the expression of UPR-related proteins. Moreover, KTN1 depletion aggravated DNA damage and suppressed cell proliferation after IR could reversed by reactivation of UPR. CONCLUSION: KTN1 deletion aggravates IR-induced keratinocyte DNA damage via inhibiting UPR. Our findings provide new insights into the mechanisms of keratinocytes in response to IR-induced damage.

Biomedical bargains: Negotiating "safe sex" on antiretroviral treatment in rural South Africa.

Wide-scale availability of antiretroviral treatment (ART) has transformed the global landscape for HIV prevention, shifting emphasis away from a strictly behavioral focus on changing sexual practices towards a biomedical approach. Successful ART management is measured by an undetectable viral load, which helps maintain overall health and prevent onward viral transmission. The latter utility of ART, however, must be understood in the context of its implementation. In South Africa, ART has become easily accessible - yet ART knowledge spreads unevenly, while counseling advice and normative expectations and experiences of gender and aging interact to inform sexual practices. As ART enters the sexual lives of middle-aged and older people living with HIV (MOPLH), a population growing rapidly, how has it informed sexual decisions and negotiations? Drawing on in-depth interviews with MOPLH on ART, corroborated with focus group discussions and national ART-related policies and guidelines, we find that for MOPLH, sexual decisions increasingly feature compliance with biomedical directives and concern for ART efficacy. Seeking consensus regarding the biological risks of sex on ART becomes an important feature of sexual negotiations, and anticipated disagreements can pre-empt sexual relationships altogether. We introduce the concept of biomedical bargains to explain what happens when disagreements arise, and the terms of sex are negotiated using competing interpretations of biomedical information. For both men and women, ostensibly gender-neutral biomedical discourses provide new discursive resources and strategies for sexual decisions and negotiations, yet biomedical bargains are still embedded in gender dynamics-women invoke the dangers of jeopardizing treatment efficacy and longevity to insist on condoms or justify abstinence, while men utilize biomedical arguments in an effort to render condomless sex safe. While the full therapeutic benefits of ART are critical for the efficacy and equity of HIV programs, they will nonetheless always affect, and be affected by, social life.

Kinectin1 depletion promotes EGFR degradation via the ubiquitin-proteosome system in cutaneous squamous cell carcinoma.

Depletion of kinectin1 (KTN1) provides a potential strategy for inhibiting tumorigenesis of cutaneous squamous cell carcinoma (cSCC) via reduction of epidermal growth factor receptor (EGFR) protein levels. Yet, the underlying mechanisms of KTN1 remain obscure. In this study, we demonstrate that KTN1 knockdown induces EGFR degradation in cSCC cells by promoting the ubiquitin-proteasome system, and that this effect is tumor cell-specific. KTN1 knockdown increases the expression of CCDC40, PSMA1, and ADRM1 to mediate tumor suppressor functions in vivo and in vitro. Mechanistically, c-Myc directly binds to the promoter region of CCDC40 to trigger the CCDC40-ADRM1-UCH37 axis and promote EGFR deubiquitination. Furthermore, KTN1 depletion accelerates EGFR degradation by strengthening the competitive interaction between PSMA1 and ADRM1 to inhibit KTN1/ADRM1 interaction at residues Met1-Ala252. These results are supported by studies in mouse xenografts and human patient samples. Collectively, our findings provide novel mechanistic insight into KTN1 regulation of EGFR degradation in cSCC.