Detailed structural-functional analysis of the Krüppel-like factor 16 (KLF16) transcription factor reveals novel mechanisms for silencing Sp/KLF sites involved in metabolism and endocrinology.
Krüppel-like factor (KLF) proteins have elicited significant attention due to their emerging key role in metabolic and endocrine diseases. Here, we extend this knowledge through the biochemical characterization of KLF16, unveiling novel mechanisms regulating expression of genes involved in reproductive endocrinology. We found that KLF16 selectively binds three distinct KLF-binding sites (GC, CA, and BTE boxes). KLF16 also regulated the expression of several genes essential for metabolic and endocrine processes in sex steroid-sensitive uterine cells. Mechanistically, we determined that KLF16 possesses an activation domain that couples to histone acetyltransferase-mediated pathways, as well as a repression domain that interacts with the histone deacetylase chromatin-remodeling system via all three Sin3 isoforms, suggesting a higher level of plasticity in chromatin cofactor selection. Molecular modeling combined with molecular dynamic simulations of the Sin3a-KLF16 complex revealed important insights into how this interaction occurs at an atomic resolution level, predicting that phosphorylation of Tyr-10 may modulate KLF16 function. Phosphorylation of KLF16 was confirmed by in vivo (32)P incorporation and controlled by a Y10F site-directed mutant. Inhibition of Src-type tyrosine kinase signaling as well as the nonphosphorylatable Y10F mutation disrupted KLF16-mediated gene silencing, demonstrating that its function is regulatable rather than constitutive. Subcellular localization studies revealed that signal-induced nuclear translocation and euchromatic compartmentalization constitute an additional mechanism for regulating KLF16 function. Thus, this study lends insights on key biochemical mechanisms for regulating KLF sites involved in reproductive biology. These data also contribute to the new functional information that is applicable to understanding KLF16 and other highly related KLF proteins.
Department of Obstetrics and Gynecology, Mayo Clinic, Rochester, Minnesota 55905, USA. daftary.gaurang@mayo.edu
Gaurang S
GS
Daftary
Gwen A
GA
Lomberk
Navtej S
NS
Buttar
Thomas W
TW
Allen
Adrienne
A
Grzenda
Jinsan
J
Zhang
Ye
Y
Zheng
Angela J
AJ
Mathison
Ravi P
RP
Gada
Ezequiel
E
Calvo
Juan L
JL
Iovanna
Daniel D
DD
Billadeau
Franklyn G
FG
Prendergast
Raul
R
Urrutia
D021581:Active Transport, Cell Nucleus / Q000502:physiology; D019943:Amino Acid Substitution; D002843:Chromatin / Q000235:genetics / Q000378:metabolism; D061252:Feeder Cells; D005260:Female; D020868:Gene Silencing / Q000502:physiology*; D012739:Gonadal Steroid Hormones / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D051741:Kruppel-Like Transcription Factors / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D012098:Reproduction / Q000502:physiology*; D020218:Response Elements / Q000502:physiology*; D056264:Sin3 Histone Deacetylase and Corepressor Complex / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014599:Uterus / Q000166:cytology / Q000378:metabolism*
D002843:Chromatin; D012739:Gonadal Steroid Hormones; C431279:KLF16 protein, human; D051741:Kruppel-Like Transcription Factors; D019913:Nuclear Localization Signals; D056264:Sin3 Histone Deacetylase and Corepressor Complex