Low Extracellular pH Induces Damage in the Pancreatic Acinar Cell by Enhancing Calcium Signaling

Reed, Anamika; Husain, Sohail Z.; Thrower, Edwin C.; Alexandre, Martine; Shah, Akeesha A.; Gorelick, Fred S.; Nathanson, Michael H.

doi:10.1074/jbc.m110.158329

Cited by 24 publications

(21 citation statements)

References 74 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is widely known from the literature that sustained elevations in cytosolic calcium levels accompany zymogen activation (16,25). Since the ␣ 7 -nAChR is also a calcium entry channel, it is possible that NNK is contributing to pathological increases in calcium during development of pancreatitis.…”

Section: Discussionmentioning

confidence: 99%

Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses

Alexandre

Uduman

Minervini

et al. 2012

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

Clinical studies indicate that cigarette smoking increases the risk for developing acute pancreatitis. The nicotine metabolite 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) is a major cigarette smoke toxin. We hypothesized that NNK could sensitize to pancreatitis and examined its effects in isolated rat pancreatic acini and in vivo. In acini, 100 nM NNK caused three- and fivefold activation of trypsinogen and chymotrypsinogen, respectively, above control. Furthermore, NNK pretreatment in acini enhanced zymogen activation in a cerulein pancreatitis model. The long-term effects of NNK were examined in vivo after intraperitoneal injection of NNK (100 mg/kg body wt) three times weekly for 2 wk. NNK alone caused zymogen activation (6-fold for trypsinogen and 2-fold for chymotrypsinogen vs. control), vacuolization, pyknotic nuclei, and edema. This NNK pretreatment followed by treatment with cerulein (40 μg/kg) for 1 h to induce early pancreatitis responses enhanced trypsinogen and chymotrypsinogen activation, as well as other parameters of pancreatitis, compared with cerulein alone. Potential targets of NNK include nicotinic acetylcholine receptors and β-adrenergic receptors; mRNA for both receptor types was detected in acinar cell preparations. Studies with pharmacological inhibitors of these receptors indicate that NNK can mediate acinar cell responses through an nonneuronal α(7)-nicotinic acetylcholine receptor (α(7)-nAChR). These studies suggest that prolonged exposure to this tobacco toxin can cause pancreatitis and sensitize to disease. Therapies targeting NNK-mediated pathways may prove useful in treatment of smoking-related pancreatitis.

show abstract

Section: Discussionmentioning

confidence: 99%

Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses

Alexandre

Uduman

Minervini

et al. 2012

American Journal of Physiology-Gastrointestinal and Liver Physi

View full text Add to dashboard Cite

show abstract

“…We previously showed that low pH enhances Ca 2ϩ signals in the acinar cell in the presence of low-dose cerulein (39). Lysosomal and proteasomal degradation of Cx43 has been shown to be Ca 2ϩ -dependent, involving PKC (24,25,27).…”

Section: Discussionmentioning

confidence: 99%

“…Using a cerulein model of pancreatitis, we have shown that reducing extracellular pH sensitizes to zymogen activation and cellular injury in vitro and pancreatitis in vivo (3). When exposed to acidic conditions, cells treated with a physiological, low dose of cerulein display pancreatitis responses similar to responses to supramaximal doses of cerulein (3,39). However, the mechanism responsible for the injurious effects of lowering extracellular pH remains unclear.…”

mentioning

confidence: 97%

“…For Ca 2ϩ signaling experiments and measurement of fluorescence recovery after photobleaching, smaller acinar groups of 5-15 cells were isolated as described elsewhere (39). For immunoblot and IF studies, acini were treated for 30 min with physiological (0.1 nM) or supramaximal (100 nM) cerulein in the presence or absence of 100 nM concanamycin, 5 M MG-132, 10 M lactacystin, 40 M chloroquine, 500 nM cycloheximide, or 500 M 3-methyladenine (all from Sigma, St. Louis, MO).…”

Section: Preparation and Stimulation Of Pancreatic Acinimentioning

confidence: 99%

See 1 more Smart Citation

Low pH enhances connexin32 degradation in the pancreatic acinar cell

Reed

Kolodecik

Husain

et al. 2014

American Journal of Physiology-Gastrointestinal and Liver Physi

Self Cite

View full text Add to dashboard Cite

tracellular pH is observed in a number of clinical conditions and can sensitize to the development and worsen the severity of acute pancreatitis. Because intercellular communication through gap junctions is pH-sensitive and modulates pancreatitis responses, we evaluated the effects of low pH on gap junctions in the rat pancreatic acinar cell. Decreasing extracellular pH from 7.4 to 7.0 significantly inhibited gap junctional intracellular communication. Acidic pH also significantly reduced levels of connexin32, the predominant gap junction protein in acinar cells, and altered its localization. Increased degradation through the proteasomal, lysosomal, and autophagic pathways mediated the decrease in connexin32 under low-pH conditions. These findings provide the first evidence that low extracellular pH can regulate gap junctional intercellular communication by enhancing connexin degradation. cell pH; gap junctions; protein degradation; cell-cell interaction; pancreas; acinar cell GAP JUNCTIONS ARE INTERCELLULAR membrane channels composed of connexins that allow the movement of Ͻ1,000-Da molecules, including ions, secondary messengers, and small metabolites between cells. Gap junctions in pancreatic acinar cells are composed mainly of connexin32 (Cx32) (29). In Cx32-deficient mice, mild reversible cerulein-induced pancreatitis is converted to severe disease (8). Correspondingly, irsogladine, which strengthens gap junctional coupling, attenuates the severity of cerulein-induced pancreatitis in rats (15). These studies suggest that cell-to-cell communication through gap junctions plays an important role in modulating pancreatitis responses.Gap junctional intercellular communication (GJIC) is affected by two parameters: the number of hemichannels at the membrane and the gating of these hemichannels. Gating refers to the mechanism by which the intercellular passage of molecules is restricted and is dependent on the unitary conductance and open probability of each channel (32). Although connexin gating provides a rapid mechanism to modulate GJIC, regulation of connexin degradation has been proposed as another mechanism for controlling gap junction assembly and function (33). Cx32 degradation is complex, with established roles for proteasomal and lysosomal pathways (20,23,45). The autophagic pathway has been implicated in the degradation of some connexins (2, 6, 26) but has not been studied for Cx32.Acute and chronic reductions of extracellular pH are observed in a range of disease conditions and increase the risk and severity of acute pancreatitis. Using a cerulein model of pancreatitis, we have shown that reducing extracellular pH sensitizes to zymogen activation and cellular injury in vitro and pancreatitis in vivo (3). When exposed to acidic conditions, cells treated with a physiological, low dose of cerulein display pancreatitis responses similar to responses to supramaximal doses of cerulein (3, 39). However, the mechanism responsible for the injurious effects of lowering extracellular pH remains unclear. Low pH lea...

show abstract

“…Representative tracings shown in Figure 3B demonstrate the typical peak-plateau pattern commonly observed with 1 μM carbachol. Conversely, using sub-maximal doses of the cholecystokinin analogue caerulein (10 pM) yields oscillatory calcium responses ( Figure 4 ) 10 .…”

Section: Representative Resultsmentioning

confidence: 99%

Preparation of Pancreatic Acinar Cells for the Purpose of Calcium Imaging, Cell Injury Measurements, and Adenoviral Infection

Orabi

Muili

Wang

et al. 2013

JoVE

Self Cite

View full text Add to dashboard Cite

The pancreatic acinar cell is the main parenchymal cell of the exocrine pancreas and plays a primary role in the secretion of pancreatic enzymes into the pancreatic duct. It is also the site for the initiation of pancreatitis. Here we describe how acinar cells are isolated from whole pancreas tissue and intracellular calcium signals are measured. In addition, we describe the techniques of transfecting these cells with adenoviral constructs, and subsequently measuring the leakage of lactate dehydrogenase, a marker of cell injury, during conditions that induce acinar cell injury in vitro. These techniques provide a powerful tool to characterize acinar cell physiology and pathology.

show abstract

Low Extracellular pH Induces Damage in the Pancreatic Acinar Cell by Enhancing Calcium Signaling

Cited by 24 publications

References 74 publications

Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses

Tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone initiates and enhances pancreatitis responses

Low pH enhances connexin32 degradation in the pancreatic acinar cell

Preparation of Pancreatic Acinar Cells for the Purpose of Calcium Imaging, Cell Injury Measurements, and Adenoviral Infection

Contact Info

Product

Resources

About