19-year old Fagerson starts at number 8 following an impressive season for the Warriors that saw him named Young Scottish Player of the Year.
Scrum-half Horne was named Player of the Season and Young Player of the Season at the Glasgow Warriors end of season awards dinner, as well as finishing as the club's top try scorer in his first season as a professional and makes the step up to international level in Houston.
Horne partners newly capped Adam Hastings at half-back, the fly-half making his first start having come off the bench to make his debut against Canada last weekend.
Tim Swinson has also been named as a vice-captain, starting on the blindside flank.
Stuart Hogg will captain his country for the first time.
Fraser Brown's inclusion on the bench makes it a total of eleven Warriors in the match day 23.
1 Jamie Bhatti (Glasgow Warriors)
2 George Turner (Glasgow Warriors)
3 Zander Fagerson (Glasgow Warriors)
4 Lewis Carmichael (Edinburgh)
5 Ben Toolis (Edinburgh)
6 Tim Swinson VICE CAPTAIN (Glasgow Warriors)
7 Luke Hamilton (unattached)
8 Matt Fagerson (Glasgow Warriors)
16 Fraser Brown (Glasgow Warriors)
17 Allan Dell (Edinburgh)
18 Murray McCallum (Edinburgh)
19 Grant Gilchrist (Edinburgh)
20 David Denton (Leicester Tigers)
21 Sam Hidalgo-Clyne (Scarlets)
22 Mark Bennett (Edinburgh)
23 Dougie Fife (Edinburgh)