documentclass[%
paper=a4,%
fontsize=12bp,%
parskip=half-,%
notitlepage,%
oneside,%
reqno,%
numbers=noenddot,%
listof=totoc,%
bibliography=totoc,%
index=totoc]{scrreprt}
setkomafont{sectioning}{sffamilybfseriesboldmath}
usepackage[margin=1in,noheadfoot]{geometry}
usepackage{amsmath}
usepackage[MnSymbol,quiet]{mathspec}
setmathsfont(Digits,Latin,Greek)[Numbers={Lining,Proportional}]{Minion Pro}
setmathrm{Minion Pro}
setmainfont[       Ligatures               = {Common,TeX},
                    Numbers                 = {Lowercase, Proportional},
                    SmallCapsFeatures       = {Letters     = SmallCaps,
                    Numbers                 = Lowercase,
                    Kerning                 = Uppercase,
                    LetterSpace = 5}]{Minion Pro}
begin{document}

title{Something}
author{Someone}
maketitle

blah blah blah and $mathbb{N}$
end{document}

documentclass[
  paper=a4,
  fontsize=12bp,
  parskip=half-,
  notitlepage,
  oneside,
  reqno,
  numbers=noenddot,
  listof=totoc,
  bibliography=totoc,
  index=totoc
]{scrreprt}

usepackage[margin=1in,noheadfoot]{geometry}

usepackage{amsmath}
usepackage[MnSymbol,quiet]{mathspec}

setmathsfont(Digits,Latin,Greek)[Numbers={Lining,Proportional}]{Minion Pro}
setmathrm{Minion Pro}
setmainfont[
  Ligatures = {Common,TeX},
  Numbers = {Lowercase, Proportional},
  SmallCapsFeatures = {
    Letters = SmallCaps,
    Numbers = Lowercase,
    Kerning = Uppercase,
    LetterSpace = 5
  }
]{Minion Pro}

setkomafont{sectioning}{sffamilybfseriesboldmath}

DeclareMathAlphabet{mathbb}{U}{msb}{m}{n}

begin{document}

title{Something}
author{Someone}
maketitle

blah blah blah and $mathbb{N}$
end{document}