Person or Group assigned to - read / edit permissions

Good afternoon,

I have created a sharepoint list, which stores all support tickets communicated to our team by other departments. 

The list has a column with "Reported by" and "Person or group the issue is assigned to". Both include email addresses taken from Company's data pool. I would like the list users only able to read & edit:

• items reported by them (i.e. their e-mail address is the one in "Reported by" column)
• items assigned to them (i.e. their e-mail address is the one in "Person or group the issue is assigned to"

I believe the first point can be resolved by enabling the item level permissions on the list. However, I am unable to find the fix to the second criteria, as no permission level options seem to mention the "assigned to" column. 

I will appreciate some suggestions and help on this subject.

Thank you,

Seb