MMP28 Human

What is the molecular structure of human MMP28?

MMP28 is a 520-amino-acid protein with a molecular mass of 59 kD. Its structure includes a signal peptide sequence, a prodomain with a unique cysteine-switch PRCGVTD motif followed by a furin cleavage RRKKR site, a catalytic domain containing a zinc-binding region, a hinge-region, and a C-terminal hemopexin-like domain . Based on these structural characteristics, MMP28 belongs to the MMP-19 subfamily . The MMP28 gene is uniquely mapped to chromosome 17q11.2 and consists of eight exons and seven introns . The full gene sequence spans approximately 1563 base pairs, encoding the complete protein structure .

What is the normal tissue distribution pattern of MMP28?

MMP28 shows a broad expression pattern across normal adult and fetal tissues, suggesting an important functional role in tissue homeostasis . It is predominantly expressed in the testis, small intestine, skin, and lungs . The Human Protein Atlas data demonstrates MMP28 expression across multiple tissue types including the hippocampal formation, cerebral cortex, thyroid gland, lung, gastrointestinal tissues, reproductive organs, and lymphoid tissues . This widespread distribution pattern distinguishes MMP28 from many other MMPs that show more restricted expression profiles, indicating potential roles in maintaining normal tissue architecture and function.

What are the primary physiological functions of MMP28?

MMP28 primarily functions as a metalloendopeptidase that can degrade casein and likely plays crucial roles in tissue homeostasis and repair . Studies suggest MMP28 is involved in the regulation of myocardial inflammation and extracellular matrix responses . In knockout mouse models, the absence of MMP28 resulted in increased levels of inflammatory factors such as macrophage inflammatory protein-1α, MIP-1β, and MMP-9 in the left ventricle, suggesting an immunomodulatory role . Additionally, MMP28 appears to participate in ECM remodeling during normal physiological processes and in response to tissue injury, contributing to wound healing and maintenance of tissue integrity.

What experimental approaches have been used to study MMP28's role in cancer progression?

Several experimental approaches have been employed to investigate MMP28's role in cancer:

What is the relationship between circulating MMP28 and cardiac function?

Circulating MMP28 levels have been found to correlate with several markers of cardiac function and prognosis . Studies have demonstrated significant associations between plasma MMP28 concentrations and important cardiac biomarkers including NT-proBNP, high-sensitivity cardiac troponin T (hs-cTnT), high-sensitivity C-reactive protein (hs-CRP), and left ventricular ejection fraction (LVEF) . In acute myocardial infarction (AMI) patients, MMP28 levels are significantly elevated compared to controls, suggesting its potential role in the pathophysiology of AMI . Cox risk regression analysis indicates that MMP28 level serves as an independent risk factor for cardiovascular events and short-term mortality following AMI .

How does MMP28 influence cardiac remodeling after myocardial infarction?

Research using MMP28 gene knockout mouse models has revealed that MMP28 plays a protective role in cardiac remodeling after myocardial infarction . When the MMP28 gene was knocked out, mice exhibited more significant ventricular remodeling and deterioration of cardiac function following myocardial infarction compared to wild-type controls . This suggests that MMP28 may help regulate the inflammatory response and extracellular matrix remodeling during post-infarction recovery. The absence of MMP28 appears to promote excessive inflammation and matrix degradation, potentially leading to adverse cardiac remodeling and poorer outcomes. These findings indicate that MMP28 may have therapeutic implications for managing post-infarction cardiac remodeling.

How does MMP28 relate to the GRACE score in cardiovascular risk assessment?

The GRACE (Global Registry of Acute Coronary Events) score is an established risk stratification tool for patients with acute coronary syndromes. Research has demonstrated a significant correlation between plasma MMP28 levels and GRACE scores in patients with acute myocardial infarction (AMI) . Higher MMP28 levels are associated with higher GRACE scores, suggesting that MMP28 could serve as a biomarker for risk stratification in AMI patients . This correlation indicates that MMP28 may reflect the severity of coronary artery disease and the extent of myocardial damage. Additionally, MMP28 has been linked to the severity of coronary artery disease in patients with stable coronary heart disease, further supporting its role as a potential biomarker for cardiovascular risk assessment .

What are the optimal methods for detecting and quantifying MMP28 in human samples?

Several methodologies are available for detecting and quantifying MMP28 in human samples:

• Enzyme-Linked Immunosorbent Assay (ELISA): Sandwich ELISA is the gold standard for quantitative determination of human MMP28 concentrations in serum, plasma, and other biological fluids . Commercial kits are available with sensitivity ranges around 0.094ng/ml and detection ranges of approximately 0.156-10ng/ml .

• Tissue Microarray (TMA) Analysis: This technique allows for semi-quantitative assessment of MMP28 protein expression in tissue samples and has been effectively used in studies of gastric cancer and other malignancies .

• Immunohistochemistry: Used for qualitative assessment of MMP28 expression patterns in tissue sections, providing information about the cellular and subcellular localization of the protein.

• Western Blotting: Enables detection of MMP28 protein levels in tissue or cell lysates, allowing differentiation between the pro-form and active form of the enzyme.

• Quantitative Real-Time PCR (qRT-PCR): Used for measuring MMP28 mRNA expression levels in tissues or cultured cells.

What considerations are important when designing experiments to study MMP28 function?

When designing experiments to investigate MMP28 function, researchers should consider several important factors:

• Specificity of Detection Methods: Ensure antibodies or primers are specific for MMP28 and do not cross-react with other MMPs, particularly those in the same subfamily.

• Pro-form vs. Active Form: Consider that MMP28 exists as both an inactive pro-form and an active enzyme after cleavage of the prodomain. Experimental designs should account for these different forms.

• Tissue Context: Given the broad expression pattern of MMP28 across tissues, experiments should consider the specific tissue context and potential tissue-specific functions.

• Appropriate Controls: Include suitable positive and negative controls, particularly when working with tissue samples or cultured cells with manipulated MMP28 expression.

• Functional Readouts: Select appropriate functional assays based on the hypothesized role of MMP28 in the biological process under investigation (e.g., invasion assays for cancer studies, fibrosis assessments for cardiovascular studies).

• In vivo vs. In vitro Models: Consider the limitations of in vitro systems and, when possible, validate findings using appropriate animal models or human samples.

How can siRNA approaches be optimized for studying MMP28 function?

RNA interference using small interfering RNA (siRNA) has proven effective for studying MMP28 function, particularly in cancer research . To optimize siRNA approaches:

• Design multiple siRNA sequences targeting different regions of the MMP28 mRNA to ensure specificity and efficacy of knockdown.

• Include appropriate controls, such as non-targeting siRNA sequences, to account for non-specific effects of the transfection process.

• Optimize transfection conditions (reagent concentrations, cell density, incubation time) for the specific cell type being studied to maximize transfection efficiency while minimizing cytotoxicity.

• Verify knockdown efficiency at both the mRNA level (using qRT-PCR) and protein level (using Western blot or ELISA) to confirm successful suppression of MMP28 expression.

• Establish a time course to determine the duration of knockdown and plan functional assays accordingly.

• Consider rescue experiments by re-expressing MMP28 in knockdown cells to confirm that observed phenotypes are specifically due to MMP28 depletion.

• Evaluate off-target effects using transcriptome analysis to ensure that observed phenotypes are specifically attributable to MMP28 knockdown.

Which genes show significant correlation with MMP28 expression?

Comprehensive analyses of transcriptomic data have identified several genes that significantly correlate with MMP28 expression, particularly in pancreatic adenocarcinoma :

• KRT19 (Keratin 19): Shows the strongest correlation with MMP28 expression in pancreatic adenocarcinoma, suggesting potential co-regulation or functional interaction .

• IL1RN (Interleukin 1 Receptor Antagonist): Strongly correlated with MMP28 expression, indicating a potential relationship between MMP28 and inflammatory signaling pathways .

• ANXA2 (Annexin A2): Significantly associated with MMP28 expression, potentially linking MMP28 to membrane dynamics and signal transduction pathways .

These correlations suggest that MMP28 may participate in specific signaling networks related to epithelial cell function, inflammatory responses, and membrane-associated signaling events. Further investigation of these relationships could reveal novel insights into the molecular mechanisms underlying MMP28's biological functions.

What regulatory mechanisms control MMP28 expression?

Network analysis has identified several potential regulatory mechanisms controlling MMP28 expression :

• MicroRNAs: The MIR-181 family has been identified as a potential regulator of MMP28 expression, suggesting post-transcriptional control mechanisms .

• Transcription Factors: TAFs (TATA-box binding protein associated factors) appear to be involved in regulating MMP28 transcription, indicating transcriptional control mechanisms .

• Cell Cycle Regulators: CDC6 (Cell Division Cycle 6) has been implicated in MMP28 regulation, suggesting potential connections to cell cycle control pathways .

Additional regulatory mechanisms likely exist, including epigenetic modifications, chromatin remodeling, and response to inflammatory signals, though these require further investigation. Understanding these regulatory mechanisms could provide insights into how MMP28 expression is dysregulated in pathological conditions and identify potential therapeutic approaches for modulating its expression.

How does MMP28 interact with the immune microenvironment?

MMP28 expression shows significant correlations with immune cell populations in both blood and the tumor microenvironment :

• In Blood: MMP28 expression correlates with the abundance of naive CD4+ T cells, naive CD8+ T cells, and mucosal-associated invariant T cells .

• In Tumor Microenvironment: High MMP28 expression in pancreatic adenocarcinoma correlates with decreased presence of B cells, naive CD4+ T cells, naive CD8+ T cells, and endothelial cells .

• Inflammatory Regulation: In cardiovascular studies, knockout of MMP28 in mice resulted in increased levels of inflammatory factors including macrophage inflammatory protein-1α, MIP-1β, and MMP-9 in the left ventricle, suggesting that MMP28 may suppress certain inflammatory responses .

These findings indicate that MMP28 may influence immune cell recruitment, activation, or function, potentially affecting immune surveillance in cancer or inflammatory responses in cardiovascular disease. The precise mechanisms by which MMP28 interacts with immune cells remain to be fully elucidated but may involve direct modulation of chemokine gradients, cytokine processing, or extracellular matrix remodeling that affects immune cell migration.

What are the most promising therapeutic applications targeting MMP28?

Based on current research, several promising therapeutic applications targeting MMP28 warrant further investigation:

• Cancer Therapeutics: Given the association between MMP28 overexpression and poor prognosis in gastric cancer and pancreatic adenocarcinoma, developing selective MMP28 inhibitors or antibodies could provide novel therapeutic approaches for these malignancies .

• Cardiovascular Protection: Since MMP28 appears to play a protective role in cardiac remodeling after myocardial infarction, therapies aimed at maintaining or enhancing MMP28 function might help prevent adverse cardiac remodeling and improve outcomes following acute coronary events .

• Biomarker Development: The correlation between MMP28 levels and disease progression/prognosis in both cancer and cardiovascular disease suggests potential applications in developing diagnostic or prognostic biomarkers to guide clinical decision-making .

• Immunomodulatory Approaches: The interactions between MMP28 and immune cell populations indicate that targeting MMP28 might be a strategy for modulating immune responses in cancer immunotherapy or inflammatory diseases .

What methodological advances could enhance MMP28 research?

Several methodological advances could significantly enhance research on MMP28:

• Development of Highly Specific Antibodies: Creating antibodies that can distinguish between the pro-form and active form of MMP28 would enable more precise studies of MMP28 activation and function.

• Advanced Imaging Techniques: Implementing techniques such as intravital microscopy or bioluminescence imaging to track MMP28 activity in real-time in living systems.

• CRISPR/Cas9 Gene Editing: Utilizing CRISPR/Cas9 technology to create precise modifications of the MMP28 gene in cellular and animal models, enabling detailed structure-function studies.

• Single-Cell Analysis: Applying single-cell RNA sequencing and proteomics to investigate cell-specific expression patterns and functions of MMP28 within heterogeneous tissues.

• Improved Animal Models: Developing conditional knockout or knock-in mouse models that allow tissue-specific or inducible modulation of MMP28 expression.

• Structural Biology Approaches: Determining the crystal structure of MMP28, particularly in complex with substrates or inhibitors, to facilitate rational drug design.

What unresolved questions remain about MMP28 function?

Despite significant advances in MMP28 research, several important questions remain unresolved:

• Substrate Specificity: While MMP28 can degrade casein , its complete substrate profile in human tissues remains poorly characterized. Identifying the physiological substrates of MMP28 would provide crucial insights into its biological functions.

• Activation Mechanisms: The precise mechanisms controlling the conversion of pro-MMP28 to its active form in different tissues and pathological conditions are not fully understood.

• Tissue-Specific Functions: Given its broad expression pattern, MMP28 likely serves tissue-specific functions that have yet to be fully elucidated.

• Signaling Pathway Integration: How MMP28 integrates with established signaling pathways in cancer, inflammation, and tissue remodeling requires further investigation.

• Compensatory Mechanisms: The potential compensation by other MMPs in the absence of MMP28 function, particularly in knockout models, remains to be systematically explored.

• Evolutionary Conservation: The evolutionary conservation of MMP28 function across species and its implications for translational research deserve further study.

• Therapeutic Targeting: The feasibility and consequences of selectively targeting MMP28 in disease states, including potential off-target effects and compensatory mechanisms, represent important areas for future research.