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. 2015 Jan 7;35(1):386–395. doi: 10.1523/JNEUROSCI.3284-14.2015

Figure 4.

Figure 4.

Coexpression of cJun and CREB2 in L7 enhanced expression of the constructs and evoked persistent increase in basal synapse strength. A, B, Expression of both cJun and CREB2 are enhanced when both constructs are injected simultaneously into L7 on day 4. Epifluorescent images of construct expression (A) indicate that cJun-eGFP alone is expressed on day 5 (normalized as 100 in B), while CREB2 is expressed at a significantly lower level (by more than a factor of 4), and is virtually gone by day 7. By day 9, expression of both cJun and CREB2 are at very low levels. In contrast, when the constructs were coinjected, expression of each construct is enhanced significantly (lower portion of A) and high levels of expression are maintained over time. Scale bar, 100 μm. A summary of construct expression levels (normalized) over time is depicted in B. A two-factor ANOVA (treatment and time) indicated a significant difference between the groups (F(6,76) = 86.01; p < 0.001). Individual comparisons indicated that when each bZIP factor was injected alone, intensity of cJun expression was greater than CREB2 on days 5 (F = 13.78; p < 0.01) and 7 (F = 5.928; p < 0.01), but not on day 9 (F = 0.015; p > 0.9). Expression of the constructs at each time point was significantly higher when injected simultaneously than the expression of the construct when injected alone (for cJun the range was F = 10.413–110.587; p < 0.01, and for CREB2 the range was F = 53.951–168.746; p < 0.01). C, Summary of the changes in synapse strength in controls, injection of each construct alone (see Fig. 3), and after coinjection of both constructs. A two-factor ANOVA (includes all experimental groups described in Figs. 3 and 4) indicated a significant change in EPSPs (F(6,76) = 32.34; p < 0.001). Individual comparisons indicated that coexpression increased EPSP amplitude at each time point (days 7 and 9) compared with control (F = 7.997; p < 0.01 and F = 8.485; p < 0.01), expression of cJun alone (F = 4.53; p < 0.01 and F = 6.922; p < 0.01), or expression of CREB2 alone (F = 7.599; p < 0.01 and F = 8.444; p < 0.01). Injection of each construct alone failed to increase EPSP amplitude compared with controls (range of F from 0.0004 to 0.395; p > 0.9; see also Fig. 3).