Ability score minimum for spells and metamagic.

[Yogibear41]

Do meta magic adjustments affect the minimum ability score needed to cast a spell?

For example: I am a 10th level cleric with a 14 wisdom so I can only cast 4th level spells and lower, but I have 5th level slots. Can I cast an extended 4th level spell using a 5th level slot, or do I need a Wisdom of 15 to do that?

[HouseRules]

"Effective Spell Level" vs "Actual Spell Level"
Since the spells do not change their "Actual Spell Level" with the exception of the "Heighten Spell" Metamagic, the minimum caster level should not change. Though there are no RAW on this topic.

Thus,

Minimum Ability Score = "Actual Spell Level" -10.
Minimum Caster Level = "Actual Spell Level" x2 (-1 if prepared, or alternative formula for non-full casters like bard)

[tyckspoon]

I'd need to go delving for the cite, but I believe 'cast lower level metamagiced spells' is actually one of the explicit examples of things you can do with a higher-level spell slot if you don't have an adequate stat to cast that actual spell level.

[Ruethgar]

Yeah, except for Sanctum and Heighten(and it’s derivatives), no metamagic changes spell level, only spell slot. So it shouldn’t affect your ability to cast Twin Cure Light Wounds or what have you.