Zfp580 inactivation as a new therapeutic target to enhance recovery after stroke in mice

Paracrine cerebral Interleukin 6 (Il6) is relevant for stroke recovery, but systemic Il6 elevation may worsen outcome. Hence, paracrine Il6 response modulation within the neurovascular unit has emerged as an attractive therapeutic approach. Lithium modulates Il6 responses and improves stroke outcome. However, lithium may cause serious adverse effects. Here, we report that Zincfinger protein 580 (Zfp580) mediates the effects of lithium on Il6 signaling. In contrast to lithium, Zfp580 inactivation had no neurotoxic effects, and Zfp580 knock out mice showed no phenotypic changes in cognitive and motor function behavioral tests. We discovered that lithium and hypoxia disinhibited Il6 via Zfp580 suppression and post-translational modification by small ubiquitin-like modifier (SUMO). After transient middle cerebral artery occlusion, loss of Zfp580 reduced paracrine Il6 and increased Il6 trans-signaling. Aside from modulating Il6 signaling, Zfp580 loss improved endothelial resilience to ischemia, was highly neuroprotective resulting in smaller infarcts and enhanced use-dependent neuroplasticity, all of which led to improved functional outcome. In conclusion, inactivation of Zfp580 exerts positive effects on multiple key mechanisms without exhibiting relevant adverse side effects, making it potentially a more specific and effective treatment target for stroke recovery than lithium. To fully assess its potential, Zfp580 inhibitors must be developed.

Novel Zinc Finger Transcription Factor ZFP580 Facilitates All-Trans Retinoic Acid -Induced Vascular Smooth Muscle Cells Differentiation by Rarα-Mediated PI3K/Akt and ERK Signaling

BACKGROUND/AIMS

Phenotypic switching of vascular smooth muscle cells (VSMC) plays a vital role in the development of vascular diseases. All-trans retinoic acid (ATRA) is known to regulate VSMC phenotypes. However, the underlying mechanisms remain completely unknown. Here, we have investigated the probable roles and underlying mechanisms of the novel C2H2 zinc finger transcription factor ZFP580 on ATRA-induced VSMC differentiation.

METHODS

VSMCs were isolated, cultured, and identified. VSMCs were infected with an adenovirus encoding ZFP580 or Ad-siRNA to silence ZFP580. The expression levels of ZFP580, SMα-actin, SM22α, SMemb, RARα, RARβ, and RARγ were assayed by Q-PCR and western blot. A rat carotid artery injury model and morphometric analysis of intimal thickening were also used in this study.

RESULTS

ATRA caused a significant reduction of VSMC proliferation and migration in a doseand time-dependent manner. Moreover, it promoted VSMC differentiation by enhancing expression of differentiation markers and reducing expression of dedifferentiation markers. This ATRA activity was accompanied by up-regulation of ZFP580, with concomitant increases in RARα expression. In contrast, silencing of the RARα gene or inhibiting RARα with its antagonist Ro41-5253 abrogated the ATRA-induced ZFP580 expression. Furthermore, ATRA binding to RARα induced ZFP580 expression via the PI3K/Akt and ERK pathways. Adenovirusmediated overexpression of ZFP580 promoted VSMC differentiation by enhancing expression of SM22α and SMα-actin and reducing expression of SMemb. In contrast, silencing ZFP580 dramatically reduced the expression of differentiation markers and increased expression of dedifferentiation markers. The classic rat carotid artery balloon injury model demonstrated that ZFP580 inhibited proliferation and intimal hyperplasia in vivo.

CONCLUSION

The novel zinc finger transcription factor ZFP580 facilitates ATRA-induced VSMC differentiation by the RARα-mediated PI3K/Akt and ERK signaling pathways. This might represent a novel mechanism of regulation of ZFP580 by ATRA and RARα, which is critical for understanding the biological functions of retinoids during VSMC phenotypic modulation.