Objective-Therapeutic arteriogenesis, that is, expansive remodeling of preexisting collaterals, using single-action factor therapies has not been as successful as anticipated. Modulation of factors that act as a master switch for relevant gene programs may prove more effective. Transcriptional coactivator p300-CBP-associated factor (PCAF) has histone acetylating activity and promotes transcription of multiple inflammatory genes. Because arteriogenesis is an inflammationdriven process, we hypothesized that PCAF acts as multifactorial regulator of arteriogenesis. Approach and Results-After induction of hindlimb ischemia, blood flow recovery was impaired in both PCAF −/− mice and healthy wild-type mice treated with the pharmacological PCAF inhibitor Garcinol, demonstrating an important role for PCAF in arteriogenesis. PCAF deficiency reduced the in vitro inflammatory response in leukocytes and vascular cells involved in arteriogenesis. In vivo gene expression profiling revealed that PCAF deficiency results in differential expression of 3505 genes during arteriogenesis and, more specifically, in impaired induction of multiple proinflammatory genes. Additionally, recruitment from the bone marrow of inflammatory cells, in particular proinflammatory Ly6C
Bastiaansen et al PCAF Regulates Arteriogenesis 1903growth are multifactorial and too complex to be modulated by therapeutics that target a single gene or pathway. In contrast, modulation of a factor that acts as a master switch for multiple relevant gene programs may be a more effective strategy to augment arteriogenesis.A protein with such master switch potential is p300-CBPassociated factor (PCAF), a transcriptional coactivator with intrinsic histone acetyltransferase activity. PCAF acetylates histones H3 and H4, but there is also increasing evidence that PCAF modulates nonhistone proteins, [13][14][15][16] including hypoxiainducible factor 1α 17 and Notch. 18 Furthermore, the histone acetylating activity of PCAF is essential for nuclear factor κB (NF-κB)-mediated gene transcription 19 and facilitates inflammatory gene regulation. 20 Because arteriogenesis is an inflammatory-like process, we hypothesized that PCAF acts as master switch that stimulates multiple inflammatory processes important for collateral remodeling.Recently, it was shown in a large patient population study (>3000 individuals)21 that a variation in the promoter region of PCAF is associated with coronary heart disease-related mortality. 22 In support of this observation, we recently demonstrated a role for PCAF in vascular remodeling in a mouse model for reactive stenosis. However, whether PCAF participates in arteriogenesis has not yet been investigated.In the present study, we investigated the contribution of PCAF to postischemic neovascularization in a hindlimb ischemia (HLI) model, 23 using PCAF-deficient (PCAF −/− ) mice. When studying arteriogenesis in a knockout model, it is possible that the gene deletion may affect vascular development in the embryo, including collaterogenesis, thus affec...