An American consultant living in the United Arab Emirates has begun a one-year sentence in a maximum security prison after a spoof video was ruled a threat to national security.

Shezanne Cassim, 29, from Woodbury, near St Paul, Minnesota, is behind bars in an Emirates federal prison in the desert outside Abu Dhabi, while family members, lawyers and politicians in the US work diplomatic and legal channels in their attempts to free him.

He was sentenced for allegedly threatening UAE security and endangering public order with an online satirical video mocking affluent Emirates youth who mimic gangster street behaviour while actually enjoying pampered lifestyles.

Cassim was arrested and imprisoned last April, charged with breaking strict new UAE cybercrime laws. He was sentenced on Monday to a year’s imprisonment after already serving almost nine months in custody while awaiting trial.

The video, Satwa Combat School, was posted to YouTube as a lighthearted parody, Cassim’s supporters say. The video began with a disclaimer stating it was fiction and not intended to offend anyone. “The authorities have never stated why they feel this is a breach or a danger to national security. Shezanne has not been allowed to say anything in court,” said Jennifer Gore, a spokeswoman for the Cassim family. “He is scared, he is despondent, he has lost a lot of weight,” Gore added.

She said Cassim enjoyed making comedy videos “in the spirit of Saturday Night Live” that were meant to be lighthearted, inoffensive and far from anything that a government would find threatening.

Cassim moved to Dubai after graduating from the University of Minnesota in 2006 and began working for the international consultancy giant PriceWaterhouseCoopers. He and several friends made the satirical video in October 2012 and state-owned UAE media said the group was accused of “defaming the image of United Arab Emirates society abroad”.

His supporters and human rights campaigners are trying to discover if he is the first person sentenced under the new cyberlaws. There is speculation he may have been given a harsh sentence to serve as an example to others, the Guardian was told by a source not wishing to speak openly for fear of undermining Cassim’s defence.

He is not entitled to an appeal under UAE law. His family members back in Minnesota, including his mother, a brother and sister, are distraught. “They’re not getting any sleep, they are beside themselves. Shezanne’s mother is very afraid for her son, he is her youngest,” said Gore.

Cassim has a legal representative in Dubai and Minneapolis working on his behalf and Minnesotan members of Congress have written to secretary of state John Kerry pleading for his intervention.

American consular officials attended Monday’s sentencing of Cassim at the state security court in the UAE federal capital Abu Dhabi.