In this paper, we study two-user time-varying interference channels with limited transmitter cooperation. The transmitters are connected to a central processor via wired cooperation links with individual limited capacities. The capacities of each cooperation link are just comparable to that of each link in the interference channel. We propose a reverse signal-aligned network coding (RSNC) scheme. We prove that our RSNC scheme achieves full degrees of freedom (DoF) by utilizing signal alignment and physical-layer network coding. The main idea of our RSNC scheme is that the transmitted signals are aligned at the receivers by signal alignment and the interfering signals are cancelled with each other by physical-layer network coding (PNC). This idea can be achieved by properly designing the network-coded messages conveyed from the central processor to the transmitters and the precoding matrices of the transmitters. Simulation results verify the performance of our RSNC scheme. The results also show that our scheme outperforms the orthogonal transmission scheme in the two-user case.