SummaryIntegrin-b1-null keratinocytes can adhere to fibronectin through integrin avb6, but form large peripheral focal adhesions and exhibit defective cell spreading. Here we report that, in addition to the reduced avidity of avb6 integrin binding to fibronectin, the inability of integrin b6 to efficiently bind and recruit kindlin-2 to focal adhesions directly contributes to these phenotypes. Kindlins regulate integrins through direct interactions with the integrin-b cytoplasmic tail and keratinocytes express kindlin-1 and kindlin-2. Notably, although both kindlins localize to focal adhesions in wild-type cells, only kindlin-1 localizes to the integrin-b6-rich adhesions of integrin-b1-null cells. Rescue of these cells with wild-type and chimeric integrin constructs revealed a correlation between kindlin-2 recruitment and cell spreading. Furthermore, despite the presence of kindlin-1, knockdown of kindlin-2 in wild-type keratinocytes impaired cell spreading. Our data reveal unexpected functional consequences of differences in the association of two homologous kindlin isoforms with two closely related integrins, and suggest that despite their similarities, different kindlins are likely to have unique functions.

Pancreatic ductal adenocarcinoma (PDAC) is a lethal cancer type in which the mortality rate approaches the incidence rate. More than 85% of PDAC patients experience a profound loss of muscle mass and function, known as cachexia. PDAC patients with this condition suffer from decreased tolerance to anti-cancer therapies and often succumb to premature death due to respiratory and cardiac muscle wasting. Yet, there are no approved therapies available to alleviate cachexia. We previously found that upregulation of the metal ion transporter, Zip14, and altered zinc homeostasis are critical mediators of cachexia in metastatic colon, lung, and breast cancer models. Here, we show that a similar mechanism is likely driving the development of cachexia in PDAC. In two independent experimental metastasis models generated from the murine PDAC cell lines, Pan02 and FC1242, we observed aberrant Zip14 expression and increased zinc ion levels in cachectic muscles. Moreover, in advanced PDAC patients, high levels of ZIP14 in muscles correlated with the presence of cachexia. These studies underscore the importance of altered ZIP14 function in PDAC-associated cachexia development and highlight a potential therapeutic opportunity for improving the quality of life and prolonging survival in PDAC patients.