KLF7 Human

What is KLF7 and where is it expressed in humans?

KLF7 (Krüppel-like factor 7), also named ubiquitous KLF (UKLF), is a conserved transcription factor in animals that shows ubiquitous expression in adult human tissues. RT-PCR analysis has detected KLF7 expression in pancreas, liver, skeletal muscle, adipose tissue, and numerous other human tissues . At the cellular level, KLF7 expression has been observed in preadipocytes, mature adipocytes, insulin-secreting cell lines (HIT-T15, RIN-5F), skeletal muscle cells (L6), and hepatocytes (HepG2) .

What is the genomic and protein structure of human KLF7?

Human KLF7 gene (GenBank accession no. NM_003709) encodes a protein of 302 amino acids with a coding sequence spanning 837 base pairs . Like other Krüppel-like factors, KLF7 contains zinc finger domains that facilitate DNA binding to regulatory regions of target genes. The gene is located on chromosome 2, and several SNPs in this region, including rs2360675 and rs991684, have been associated with self-rated health and mild mental retardation, respectively .

How is KLF7 expression regulated during cellular differentiation?

During adipocyte differentiation, KLF7 expression undergoes dynamic changes. In mouse 3T3-L1 cells, KLF7 mRNA is abundantly expressed before differentiation begins. Upon induction of differentiation, KLF7 expression markedly decreases at 6 hours but then gradually increases according to the degree of differentiation . This regulation involves hormonal control – experimental evidence shows that both dexamethasone and IBMX (3-isobutyl-1-methylxanthine) independently suppress KLF7 expression, while insulin and pioglitazone do not significantly affect KLF7 expression levels .

What experimental evidence supports the role of KLF7 in cancer progression?

KLF7 has been identified as a promoter of colon adenocarcinoma (COAD) progression through multiple experimental approaches:

• Expression analysis:

  • Western blot analysis of paired tumor-normal human COAD samples revealed upregulation of KLF7 protein in tumors

• In vitro functional experiments:

  • Overexpression of KLF7 in SW620 cells significantly increased cell proliferation (MTT assay), colony formation, and migration (wound-healing and transwell assays)

  • KLF7 overexpression promoted epithelial-mesenchymal transition (EMT) by decreasing E-cadherin and increasing Vimentin and Snail expression

  • Conversely, KLF7 knockdown in LoVo cells suppressed proliferation, colony formation, migration, and reversed EMT marker expression

• In vivo studies:

  • Stable KLF7 knockdown significantly decreased tumor volume in BALB/c nude mice xenograft models

  • H&E staining showed reduced cancer cell density and IHC revealed decreased Ki-67 staining in KLF7 knockdown tumors

  • KLF7 overexpression promoted tumor growth and increased tumor volume and weight

These findings collectively demonstrate that KLF7 promotes both the proliferation and migration of COAD cells, suggesting its potential as a therapeutic target.

Through what mechanisms does KLF7 contribute to type 2 diabetes pathogenesis?

KLF7 contributes to type 2 diabetes pathogenesis through multiple tissue-specific mechanisms:

• Pancreatic β-cells:

  • KLF7 overexpression significantly suppresses insulin expression and glucose-induced insulin secretion

  • KLF7 reduces expression of critical β-cell genes: glucose transporter 2 (GLUT2), sulfonylurea receptor 1 (SUR1), Kir6.2, and pancreatic-duodenal homeobox factor 1 (PDX1)

  • These effects impair insulin biosynthesis and secretion pathways

• Adipocytes:

  • KLF7 overexpression decreases expression of insulin-sensitizing adiponectin and appetite-regulating leptin

  • KLF7 increases expression of pro-inflammatory IL-6

  • This dysregulation of adipocytokines may contribute to systemic insulin resistance

• Skeletal muscle:

  • KLF7 overexpression decreases hexokinase 2 expression, potentially impairing glucose utilization and insulin response

• Hepatocytes:

  • KLF7 suppresses GLUT2 expression, which may impair glucose uptake in the liver

These multi-tissue effects suggest that KLF7 may be a valuable therapeutic target for type 2 diabetes prevention and treatment through its simultaneous impact on insulin production and peripheral insulin sensitivity .

What evidence links KLF7 to neurodevelopmental disorders?

Multiple lines of evidence connect KLF7 to neurodevelopmental disorders:

• Human genetic studies:

  • KLF7 was proposed as a candidate gene for autism in patients with 2q33.3-q34 deletion

  • Four unrelated individuals with de novo KLF7 missense variants shared similar clinical features: developmental delay/intellectual disability, hypotonia, feeding/swallowing issues, psychiatric features, and neuromuscular symptoms

  • SNP (rs991684) in linkage disequilibrium with KLF7 is associated with mild mental retardation

  • GWAS analysis identified SNP (rs2360675) near KLF7 associated with self-rated health

• Animal model evidence:

  • Klf7+/- mice exhibit social interaction deficits in the three-chamber test:

    • Spend less time in chambers containing stranger mice

    • Interact less with stranger mice compared to wild-type mice

  • Klf7-/- mice show more severe social deficits:

    • Spend more time in empty chambers

    • Do not interact with stranger mice

  • Both models show learning and memory impairments in Morris water maze tests and novel object recognition tests

These findings demonstrate that KLF7 regulation affects genes involved in autism spectrum disorder and provides insights into the molecular pathogenesis of neurodevelopmental conditions .

How does KLF7 regulate cardiac metabolism and contribute to cardiomyopathy?

KLF7 simultaneously regulates key metabolic pathways in cardiac tissue:

• Metabolic targets:

  • KLF7 directly targets phosphofructokinase-1, liver (PFKL), the rate-limiting enzyme of glycolysis

  • KLF7 also targets long-chain acyl-CoA dehydrogenase (ACADL), a key enzyme for fatty acid oxidation

  • This dual targeting allows KLF7 to modulate the balance between glucose and fatty acid metabolism

• Cardiac phenotypes in genetically modified mice:

  • Cardiac-specific KLF7 knockout induces adult concentric hypertrophy

  • Cardiac-specific KLF7 overexpression causes infant eccentric hypertrophy

  • These effects occur through disruption of the normal balance between glycolysis and fatty acid oxidation

• Mechanistic validation:

  • Cardiac-specific knockdown of PFKL or overexpression of ACADL partially rescues cardiac hypertrophy in adult KLF7-deficient male mice

  • This confirms that the metabolic imbalance induced by KLF7 deficiency is mechanistically linked to the hypertrophic phenotype

The KLF7/PFKL/ACADL axis represents a critical regulatory mechanism for cardiac metabolism and may provide insights for therapeutic approaches in hypertrophied and failing hearts .

What role does KLF7 play in human pluripotent stem cells?

KLF7 functions as a general inducer of human pluripotency:

• Expression analysis:

  • KLF7 is robustly expressed in conventional human pluripotent stem cells (PSCs)

  • KLF7 is highly expressed in naive PSCs

  • In contrast, KLF4 (commonly used in reprogramming) is barely expressed in conventional human PSCs

• Functional significance:

  • KLF7 allows transcription factor-mediated somatic reprogramming

  • Forced expression of KLF7 in conventional hPSCs induces upregulation of naive markers

  • KLF7 overexpression boosts efficiency of chemical resetting to naive PSCs

These findings indicate that KLF7 is a general human pluripotency factor that could potentially offer an alternative to KLF4 in reprogramming protocols for generating induced pluripotent stem cells .

How can researchers experimentally distinguish the roles of KLF7 from other KLF family members?

Distinguishing KLF7's specific functions from other KLF family members requires strategic experimental approaches:

• Expression pattern analysis:

  • Unlike KLF4, KLF7 is robustly expressed in conventional human PSCs

  • Tissue-specific expression profiling across development can identify unique spatial and temporal patterns for KLF7

• Specific targeting strategies:

  • Design siRNAs or shRNAs targeting unique regions of KLF7 mRNA

  • Use CRISPR-Cas9 with guide RNAs targeting KLF7-specific genome regions

  • Validate specificity by measuring expression of other KLF family members

• Rescue experiments:

  • Test whether KLF7 can rescue phenotypes caused by deletion of other KLF factors and vice versa

  • For example, in pluripotency studies, determine if KLF7 can replace KLF4 in reprogramming

• Target gene identification:

  • ChIP-seq to identify KLF7-specific binding sites

  • RNA-seq after specific KLF7 modulation to identify unique transcriptional targets

  • Compare with datasets for other KLF factors to identify unique and shared targets

These approaches can help delineate the specific contributions of KLF7 in contexts where multiple KLF family members are expressed.

What are effective methods to modulate KLF7 expression for functional studies?

Researchers have successfully used several approaches to modulate KLF7 expression:

• Transient modulation:

  • Transfection of KLF7 expression vectors for overexpression

  • siRNA transfection for transient knockdown

  • These approaches have been validated in colon cancer cell lines SW620 and LoVo

• Stable genetic modification:

  • Lentiviral vectors for stable overexpression or shRNA-mediated knockdown

  • These have been used to generate stable cell lines for in vivo xenograft experiments

  • CRISPR-Cas9 genome editing for knockout or knock-in studies

• Animal models:

  • Germline knockout or heterozygous models (Klf7+/- and Klf7-/-)

  • Tissue-specific conditional models using Cre-loxP system (e.g., cardiac-specific KLF7 knockout)

• Validation techniques:

  • RT-qPCR for mRNA expression confirmation

  • Western blotting for protein expression validation

  • Both should be employed to confirm successful modulation

The appropriate approach depends on the research question, cell type, and whether acute or chronic modulation is desired.

To comprehensively identify KLF7 binding sites and transcriptional targets:

• Chromatin immunoprecipitation approaches:

  • ChIP-seq using validated KLF7 antibodies or tagged KLF7 constructs

  • CUT&RUN or CUT&Tag for improved signal-to-noise ratio

  • ChIP-qPCR for validation of specific binding sites

• Transcriptome analysis:

  • RNA-seq after KLF7 overexpression or knockdown to identify regulated genes

  • Time-course experiments to distinguish direct from indirect targets

  • Single-cell RNA-seq to capture cell-type specific responses

• Integrative bioinformatics:

  • Motif analysis to identify KLF7 binding motifs

  • Integration of ChIP-seq and RNA-seq data to identify direct targets

  • Pathway enrichment analysis to identify regulated biological processes

• Functional validation:

  • Luciferase reporter assays with wild-type and mutated binding sites

  • CRISPR activation/interference at KLF7 binding sites

  • Enhancer deletion studies for key target genes

These approaches have been used successfully to identify direct targets of KLF7 in contexts such as cardiac metabolism (PFKL, ACADL) and can be adapted to other biological systems.

How might KLF7 be targeted therapeutically in different disease contexts?

Based on KLF7's roles in multiple diseases, several therapeutic strategies could be explored:

• For type 2 diabetes:

  • Targeted inhibition of KLF7 in pancreatic β-cells could enhance insulin production and secretion

  • Modulation of KLF7 in adipose tissue could improve adipokine profiles

  • Small molecule inhibitors that disrupt KLF7 binding to metabolic gene promoters could simultaneously address multiple tissue dysfunctions

• For cancer therapy:

  • RNA interference strategies targeting KLF7 could reduce tumor growth and metastasis, as demonstrated in colon adenocarcinoma models

  • Identification of downstream effectors of KLF7-mediated cancer progression could reveal additional therapeutic targets

  • Combination approaches targeting KLF7 along with conventional therapies could be explored

• For cardiac diseases:

  • Modulation of the KLF7/PFKL/ACADL axis could rebalance cardiac metabolism in hypertrophy and heart failure

  • Tissue-specific delivery approaches would be essential to avoid disrupting KLF7's functions in other tissues

• For neurodevelopmental disorders:

  • Early developmental interventions based on KLF7 pathway modulation could be explored

  • Rescue of KLF7-related phenotypes might be possible through targeting downstream pathways

Development of such therapeutics would require further research into tissue-specific delivery methods and careful evaluation of potential off-target effects.

What are the methodological challenges in studying KLF7-related gene regulatory networks?

Several methodological challenges must be addressed for comprehensive KLF7 research:

• Antibody specificity issues:

  • KLF family members share structural similarities, making specific antibody generation challenging

  • Solution: Use epitope-tagged KLF7 constructs or validate antibodies against KLF7 knockout controls

• Cell type heterogeneity:

  • KLF7 may have different functions in different cell types within a tissue

  • Solution: Single-cell approaches (scRNA-seq, CyTOF) and cell type-specific KLF7 modulation

• Temporal dynamics:

  • KLF7's function may vary during development or disease progression

  • Solution: Inducible expression/knockout systems and time-course experiments

• Redundancy with other KLF family members:

  • Functional compensation may mask phenotypes in single gene studies

  • Solution: Combined knockdown/knockout of multiple KLF factors and comparative genomics

• Context-dependent binding and activity:

  • KLF7 may interact with different cofactors in different cell types

  • Solution: Cell type-specific proteomic approaches to identify interaction partners

Addressing these challenges requires integration of multiple complementary approaches and careful experimental design.

How does KLF7 interact with non-coding RNAs and epigenetic mechanisms?

Exploring KLF7's relationships with non-coding RNAs and epigenetic regulation represents an important frontier:

• Potential research questions:

  • Does KLF7 regulate or interact with specific non-coding RNAs?

  • Can microRNAs or lncRNAs modulate KLF7 expression?

  • Does KLF7 recruit epigenetic modifiers to target genes?

  • How does chromatin state affect KLF7 binding and function?

• Experimental approaches:

  • RNA immunoprecipitation to identify KLF7-associated RNAs

  • Analysis of histone modifications at KLF7 binding sites

  • Assessment of DNA methylation changes upon KLF7 modulation

  • Proteomics to identify epigenetic modifiers in KLF7 complexes

• Relevance to disease:

  • Epigenetic drugs could potentially normalize dysregulated KLF7 expression

  • Non-coding RNA therapeutics might be used to modulate KLF7 levels

  • KLF7-induced epigenetic changes could contribute to disease persistence

This area remains largely unexplored but could provide important insights into KLF7's broader regulatory roles and offer new therapeutic avenues.

How do genetic variants in KLF7 affect protein function and disease risk?

Genetic variation in KLF7 has been linked to several conditions, suggesting important functional consequences:

• Types of relevant variants:

  • SNPs near KLF7 (rs2360675, rs991684) associated with health traits and mental retardation

  • De novo missense variants in KLF7 associated with neurodevelopmental phenotypes

  • Potential regulatory variants affecting KLF7 expression

• Functional impact assessment approaches:

  • Expression quantitative trait loci (eQTL) analysis to link variants to expression changes

  • In vitro assays to assess variant effects on DNA binding, protein stability, or transcriptional activity

  • CRISPR-engineered cellular models with specific variants

  • Patient-derived iPSCs to study variant effects in relevant cell types

• Clinical significance:

  • Genotype-phenotype correlation studies in patient cohorts

  • Potential for genetic stratification in clinical trials

  • Development of personalized interventions based on KLF7 genotype

Systematic characterization of KLF7 variants could enhance our understanding of structure-function relationships and improve risk prediction and management strategies for associated conditions.

What is the current state of KLF7 research and what are the key unresolved questions?

KLF7 research has established its importance in multiple biological processes and disease contexts, but several key questions remain:

• Current knowledge:

  • KLF7 promotes colon adenocarcinoma progression

  • KLF7 regulates cardiac metabolism through the PFKL/ACADL axis

  • KLF7 dysfunction contributes to neurodevelopmental disorders

  • KLF7 can induce human pluripotency

  • KLF7 contributes to type 2 diabetes pathogenesis through multiple tissue-specific mechanisms

• Key unresolved questions:

  • What is the comprehensive set of KLF7 target genes across different tissues?

  • How does KLF7 interact with other transcription factors in regulatory networks?

  • What are the upstream regulators of KLF7 expression and activity?

  • How can KLF7 be therapeutically targeted with appropriate tissue specificity?

  • What is the full spectrum of diseases affected by KLF7 dysregulation?