Can environmental factors contribute in triggering vitiligo and associated autoimmune thyroid diseases? Possible connection to the Chernobyl nuclear accident

Mechanism of desuccinylation of G6PD mediated by SIRT7 to promote vitiligo disease progression

BACKGROUND

Sirtuin 7 (SIRT7) is pivotal in diverse diseases progression. Importantly, SIRT7 is associated with melanin production. However, whether SIRT7 regulates vitiligo is unclear. Therefore, we aimed to investigate the effects of SIRT7 on pigmentation and the modification of glucose 6-phosphate dehydrogenase (G6PD).

METHODS

After knockdown SIRT7 and G6PD, pigmentation of melanocytes was evaluated using commercial kits, immunofluorescence, and Western blot analysis. The succinylation of G6PD mediated by SIRT7 was analyzed using co-immunoprecipitation, immunofluorescence, Western blot analysis, and cycloheximide-chase experiment.

RESULTS

We found that SIRT7 was highly expressed in vitiligo skin lesions. Knockdown of SIRT7 increased tyrosinase activity, melanin content, and the levels of α-melanocyte-stimulating hormone, MITF, TYR, TRP1, and TRP2. Additionally, SIRT7 directly interacted with G6PD. Silenced SIRT7 promoted the succinylation of G6PD and enhanced its protein stability. G6PD knockdown reversed the effect of reduced SIRT7 expression on melanin production.

CONCLSUION

Silencing of SIRT7 promotes pigmentation of melanocytes by succinylating G6PD, suggesting that SIRT7-mediated G6PD desuccinylation may promote vitiligo progression.

Decreased ZMIZ1 suppresses melanogenesis in vitiligo by regulating mTOR/AKT/GSK-3β-mediated glucose uptake

The loss of epidermal melanocytes is a distinguishing feature of vitiligo (VIT), a prevalent and long-lasting skin ailment. While various hypotheses exist to explain the cause of VIT, the precise mechanisms leading to this disease remain unclear. Zinc finger MIZ-type containing 1 (ZMIZ1) has a strong link with the development and occurrence of VIT. However, the exact role of ZMIZ1 and its underlying mechanisms in VIT are not well understood. Our study aims to illustrate that targeting ZMIZ1 is an effective therapeutic and prophylactic strategy for treating VIT. We obtained the RNA expression profile of VIT samples using RNA-seq and determined the locations and expression of ZMIZ1 in these samples via immunochemistry. Glucose uptake was analyzed through immunofluorescence and glucose uptake assay. We evaluated mRNA levels using qPCR and used plasmids transfection to knock down ZMIZ1 in PIG1 and PIG3V cell lines. The activation of the mTOR/AKT/GSK-3β signalling pathway was assessed using Western blotting analysis. We found that ZMIZ1 expression was decreased in VIT samples. Decreased ZMIZ1 expression inhibits the proliferation, migration, and invasion of melanocytes in vitro. Moreover, we revealed that decreased ZMIZ1 could also inhibit the glucose uptake of melanocytes in vitro. Decreased ZMIZ1 expression inhibits the activation of the mTOR/AKT/GSK-3β pathway and the expression of melanin synthesis-related proteins in melanocytes. Finally, we demonstrated that decreased ZMIZ1 may inhibit the cell viability of melanocytes and the synthesis of melanin by mTOR/AKT/GSK-3β-mediated oxidative stress in vitro. In conclusion, our study suggests that decreased ZMIZ1 suppresses melanogenesis in vitiligo by regulating the mTOR/AKT/GSK-3β-mediated glucose uptake in vitro, making ZMIZ1 an attractive therapeutic target for the treatment of VIT.

Vitiligo-Thyroid Disease Association: When, in Whom, and Why Should It Be Suspected? A Systematic Review

In most dermatological pathologies, the phenomena observed on the skin are a reflection of internal disorders. In patients with associated acral involvement on the dorsal sides of the hands, this "vitiligo phenotype" may lead to the investigation of certain associated pathologies that sometimes have no obvious clinical impact. To assess the link between skin depigmentation and autoimmune pathologies, we conducted a systematic review involving article selection from the PubMed database. Patients with coexisting thyroid pathologies were found to have a predisposition for developing acral vitiligo and depigmentation of the wrists, and autoimmune thyroid pathologies appeared to be the only coexisting autoimmune or inflammatory diseases in vitiligo patients to show a pattern of distribution. The association of concomitant thyroid dysfunction with depigmentation of the hands was found to be so strong that the absence of depigmented macules on the hands may exclude the coexistence of an autoimmune thyroid pathology. Although the frequency of acral involvement in patients with vitiligo and autoimmune pathologies is higher, the mechanism by which thyroid dysfunction influences this distribution pattern remains incompletely elucidated and requires future studies.

ZMIZ1 promotes the proliferation and migration of melanocytes in vitiligo

Genome wide association studies have revealed that the zinc finger MIZ-type containing 1 (ZMIZ1) is involved in the pathogenesis of vitiligo; however, the underlying mechanism remains unclear. The present study aimed to investigate the effects of ZMIZ1 on the proliferation, apoptosis and migration of the human melanocyte cell lines PIG1 and PIG3V. ZMIZ1 overexpression and knockdown PIG1 and PIG3V cell models were established by lentivirus infection, and the effects of ZMIZ1 on cell proliferation and apoptosis were determined using an MTT assay and flow cytometry, respectively. Furthermore, the expression levels of proliferation- and apoptosis-associated proteins were analyzed using western blotting. Additionally, Transwell assays were performed to determine the effect of ZMIZ1 on the migration of PIG1 and PIG3V cells. Finally, the effect of ZMIZ1 on cytoskeletal remodeling in PIG1 and PIG3V cells was analyzed using immunocytochemistry. The overexpression of ZMIZ1 promoted the proliferation and inhibited the apoptosis of PIG1 and PIG3V cells, whereas the genetic knockdown of ZMIZ1 resulted in the opposite effects. Furthermore, ZMIZ1 overexpression increased the migration, whereas the knockdown of ZMIZ1 inhibited the migration and altered remodeling of the actin cytoskeleton in PIG1 and PIG3V cells. In conclusion, the results of the present study suggest that ZMIZ1 regulates the proliferation, apoptosis and migration of PIG1 and PIG3V cells, and indicate that ZMIZ1 may serve as a potential therapeutic target for vitiligo.