Cloning and DNA‐binding properties of the rat pancreatic β‐cell‐specific factor Nkx6.1

Abstract

The homeodomain (HD) protein Nkx6

NKX6 transcription factor activity is required for α- andβ-cell development in the pancreas

“…Although a requirement for Nkx6.1 in β-cell differentiation has been previously shown (Sander et al, 2000), our present study provides evidence that redundant activity of the NKX6.1 paralog NKX6.2 masks a more general (Awatramani et al, 2000;Jorgensen et al, 1999;Mirmira et al, 2000), and function both as transcriptional repressors through interaction with Gro/TLE co-repressor proteins . Second, when transfected into the developing neural tube, NKX6.1 and NKX6.2 have qualitatively similar activities in inducing motoneurons (Vallstedt et al, 2001).…”

Gene expression profiles during beta cell maturation and after IL-1? exposure reveal important roles of Pdx-1 and Nkx6.1 for IL-1? sensitivity

“…To focus our analysis on the role of Nkx6.1, a Pdx-1 negative cell system with over-expression of Nkx6.1 was used [28]. Transfection with Nkx6.1 induced a beta cell phenotype, associated with a small increase in insulin content (mRNA level and immunostaining) [28]. We demonstrated that induced Nkx6.1 expression alone in the Pdx-1 negative cells was able to further increase IL-1β sensitivity (Fig.…”

“…One based on the tetracycline-inducible stably transfected INS-1rαβ cells, with inducible expression of either Pdx-1 or a dominant-negative mutant form of Pdx-1 (DN-Pdx-1) [27]. The other cell system is the Pdx-1 and Nkx6.1 negative MSL-G-AN cells, stably transfected with Nkx6.1 (Nkx6.1 neg-ative clone 2 #584 and Nkx6.1 positive clone 3 #589 and clone 9 #624) [28].…”

“…In contrast, doxycycline induction of a DN-Pdx-1 construct did not induce IL-1β sensitivity. To focus our analysis on the role of Nkx6.1, a Pdx-1 negative cell system with over-expression of Nkx6.1 was used [28]. Transfection with Nkx6.1 induced a beta cell phenotype, associated with a small increase in insulin content (mRNA level and immunostaining) [28].…”

“…This was substantiated and extended in our array analyses to demonstrate that both Pdx-1 and Nkx6.1 were downregulated after IL-1β exposure exclusively in the beta cell phenotype. To elucidate the role of Pdx-1 and Nkx6.1 in acquired IL-1β-mediated toxicity, functional analyses were performed using two different cell systems: (i) the low Pdx-1 expressing rat insulinoma INS-1αβ cells transfected either with Pdx-1 or a dominant-negative mutant form of Pdx-1 (DN-Pdx-1) [27]; and (ii) the glugacon-producing Pdx-1 negative MSL-G-AN cell line transfected with Nkx6.1 [28].…”