nginx reverse proxy certificate

Hello

this is my topology:
client(my laptop)--https-->reverse proxy(vm1)--https-->upstream(10.X.X.X vm2)
client (public ip 1.2.3.4)
reverse proxy (public ip 5.6.7.8 , nginx, trusted certificates sign by globalsign)
upstream (private ip 10.X.X.X , IIS8, certificates signed by my own CA)

I can access from laptop to upstream web application but, browser show me untrusted certificate.
Is it possible to proxy interduce like upstream and instead upstream certificate client validate proxy certificate?

With regards
Boris