Vine Star Curtis Lepore -- On Trial for Allegedly Raping Vine Star Girlfriend

Vine megastar Curtis Lepore was in court Tuesday ... facing charges of raping Vine star girlfriend Jessi Smiles while she was sleeping, TMZ has learned.

Law enforcement sources tell us ... Lepore was arrested in October -- and released on $100,000 bail -- but it flew under the radar. During Tuesday's hearing he pled not guilty.

Here's the back story. We're told Jessi flew to see Curtis in L.A. last August but things didn't go well and they broke up. Jessi stayed in L.A. and a few days later got a concussion while shooting a Vine video.

Sources close to Jessi tell TMZ ... Curtis then called her and offered to help her while she was recovering. The victim claims Curtis came over, Jessi fell asleep and that's when he allegedly raped her

The day after the incident, Jessi tweeted, "Be careful of who you trust. Always be cautious for your safety. Be strong and don't let your guard down..."

It's pretty insane. Curtis and Jessi's relationship was a HUGE deal in the Vine world -- they initially got in touch via the social media platform last summer and subsequently met in person in NYC ... in front of hundreds of their Vine fans.

Curtis' lawyer tells TMZ, "Things are not always as they appear and there are two sides to every story."

BTW ... Jessi gave us permission to use her name.